TT , 'I . .,- 1 'TATr --r,rr 1..[la . I. 5 of the FLO IDA STATE MUSEUM Biological Sciences Volume 33 1988 Number 1 THE STATUS AND ECOLOGY OF THE AMERICAN CROCODILE IN HAITI John B. Thorbjarnarson ''i S i I I. 5 .4 . /5.5.3 -bit- 5 ®®e~X=£%5 '. UNIVERSITY OF FLORIDA GAINESVILLE Numbers of the BULLETIN OF THE FLORIDA SrATE MUSEUM, BIOLOGICAL SCIENCES, are published at irregular intervals. Volumes contain about 300 pages and are not necessarily completed in any one calendar year. S . DAVID WEBB, Editor OLIVER L. AUS['IN, JR., Editor Ememus RHODA J. BRYANT, Managing Editor ~ Communications concerning purchase or exchange of the publications and all manuscripts should be addressed to: Managing Editor, Bulletin; Florida State Museum; University of Florida; Gainesville FL 32611; U.S.A. This public document was promulgated at an annual cost of $3150.00 or $3.150 per copy. It makes available to libraries, scholars, and all interested persons the results of researches in the natural sciences, emphasizing the circum-Caribbean region. ISSN: 0071-6154 CODEN: BF 5BAS Publication date: May 17, 1988 Price: $3.15 THE STATUS AND ECOLOGY OF THE AMERICAN CROCODILE IN HAITI John B. Thorbjarnarson* ABSTRACT The American crocodile (Crocodylus acums) is the most widely distributed of the New WorId crocodiles. Due to a combination of hunting for its hide, habitat destruction, and malicious killing, the American crocodile is currently in danger of extinction, with isolated populations existing for the most part only in relatively undisturbed areas. Conservation and management programs are sorely needed to protect this species, but are hampered by a lack of knowledge concerning the current status of many of the extant populations and biological data concerning many aspects of the crocodile's natural history. In Haiti, crocodiles were once widely distributed throughout coastal and lowland areas where suitable habitat was available. Today, the range of the crocodile in this country has been greatly reduced, and the few extant populations have been severely depleted, remaining only in those areas that have a combination of relatively low human population density and sufficient mangrove habitat. Presently, no commercial hide hunting is occurring, and the taking of crocodiles for food or the use of their by-products are restricted to two areas bordering the Dominican Republic. Habitat destruction and incidental killings, primarily by fishermen, represent the greatest threat to cfocodiles in Haiti today. The largest remaining population is found in Etang Saumatre, Haiti's largest lake (113 sq km). Etang Saumatre is a brackish lake, located in a sparsely inhabited region only 30 km from the capital of Port-au-Prince. The total crocodile population in the lake is estimated at 450. Over a 13-month period, various aspects of the demography, reproductive ecology, diet, and habitat selection of these crocodiles were investigated. The results are discussed in the light of other work which has been done on crocodilians. The final section outlines several recommendations for the conservation of crocodiles in Haiti. * Florida State Museum and Department of Wildlife and Range Sciences, University of Florida, Gainesville FL 32611. THORBJARNARSON, J. B. 1988. The Status and Ecology of the American Crocodile in Haiti. Bull. Florida State Mus., Biol. Sci. 33(1):1-86. 2 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) RESUMEN El cocodrilo americano (Crocodylus acutus) tiene la distribuci6n mds amplia entre las 4 especies de los cocodrilos del Nuevo Mundo. Debido a la caza comercial para su piel, destruci6n de su habitat, y a la simple matanza por maldad, el cocodrilo americano esta en peligro de extinci6n, y hoy en dia solo quedan poblaciones aislados en zonas remotas. Se necesitan urgentemente programas de conservaci6n y manejo para la protecci6n de esta especie, pero el desarollo de cmos programas es limitado por la falta de conocimiento sobre el estado actual de la mayoria de las poblaciones, y muchos aspectos de su historia natural. En Haiti, cocodrilos tenian una distribuci6n amplia a 10 Iargo de la costa. Hoy, estadistribuci6n se ha reducido drasticamente, y las pocas poblaciones que quedan son mypequefias, ubicadas en zonas despobladas donde hay sufficiente habitat con manglares. Hoy en dia, no existe una caceria comercial para cocodrilos en Haiti, y la gente los utilizan paracomida o remedios solamente en dos zonas al lado de la frontera con la Republica Dominicana. Los dos peligros mayores para la supervivencia de los cocodrilos son ladestruci6n de habitat, y la muerte por inmer5ion al enredarse en redes de pescadores. La mayor p9blaci6n de cocodrilos en Haiti estd en Etang Saumatre, el lago mas grandedel pais (113 km«'). Etang Saumatre es de agua salobre, y esta ubicado en una zona semi- arida a solamente 30 km de la capital; Puerto Principe. Approximadamente 450 cocodrilos viven en este Iago. Durante un periodo de 13 meses, se estudiaron aspectos de la demografia, reproduci6n, dieta, y uso de habitat de esta poblacidn de cocodrilos. Los resultados estandiscutidos en relaci6n con otras investigaciones sobre cocodrilos. La secci6n final presenta algunas recomendaciones para la conservaci6n del cocodrilo en Haiti. TABLE OF CONTENTS Introdlirtinn 3 Acknowledgemenk 4 Methods f Survey of Status and Distribution..................................................................................................5 Ecological Study: Etang Saumatre Present Status and Distribution in Haiti.................................................................................................9 Introduction 9 Rpoillk 11 Discussinn 17 Ecological Study: Etang Saumpre 74 Introduction 74 Demogrprhy 71 Reproductive Ecology 41 Diet 51 Habitat Selection.............................................................................................................................53 Conservffinn 58 Discussinn 58 Recommendations...............................................................................................................60 THORBJARNARSON: AMERICAN CROCODILE IN HAITI 3 Summary 61 Literature Cited 6? TAbln 68 Appendiref RO I. Distribution of Mangrove in Haiti.........................................................................................82 II. Aquatic and Semi-aquatic Avifauna, native fish fauna,...................................................... and the Dry Forest Vegetative Association of Etang Saumatre...........................................84 III. Survey Correction Procedure.............................................................................................86 INTRODUCTION The American crocodile (Croco*lus acutus) is the most widely distributed of the four species of New World crocodiles. Although it may be found well inland in freshwater habitats, the American crocodile lives primarily in coastal areas, preferring brackish water habitats associated with mangrove forests, coastal lagoons, and the estuarine sections of rivers. As with most species of crocodilians, unregulated hide-hunting, malicious killing, and habitat destruction have resulted in drastic population declines of the American crocodile throughout its range. Today, these crocodiles exist mostly in disjunct populations where past exploitation and habitat destruction have not been overly severe. Although the general trend of local extirpations and reductions in numbers clearly has been evident for some time (Barbour 1923, Moore 1953, Casas and Guzman 1970, Alvarez del Toro 1974), very little is known about the status of existing populations. A recent review (King et al. 1982) collated reports for C acutus on a country by country basis. Detailed information was available only for a few countries, and the review pointed out the clear need for surveys to determine the present status and distribution of the remaining populations. Data of this sort are needed for the implementation of effective conservation and management schemes designed to insure the continued survival of the species. Primarily a coastal species, the range of the American crocodile includes southernmost Florida, the Atlantic coast of Mexico south through Central America and northern South America (east to the Peninsula de Paria in Venezuela), and the Caribbean islands of Cuba, Jamaica, and Hispaniola. The American crocodile is also found in Pacific Ocean drainages from northern Mexico (Sinaloa) south to the Rio Tumbes in northernmost Peru. The northern distribution of the American crocodile along the Atlantic coast of Mexico remains a question. While crocodiles are known from the states of Tamaulipas and Veracruz, all confirmed specimens from these areas are C moreleti. Nevertheless literature accounts of C acutus exist for the Atlantic coast north of the Yucatan. Further survey work is needed to determine the range of 4 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) these two species in Mexico. Very little was known about the status of crocodiles on Hispaniola prior to the mid-1970's. lIn 1975 scientists from the Museo Nacional de Historia Natural began an ecological study of crocodiles in Lago Enriquillo, the largest lake in the Dominican Republic. This lake was found to contain what may be the largest remaining C acums population anywhere (Inchaustegui and Ottenwalder pers. comm.; pers. observ.). Coastal populations in the Dominican Republic, however, appear to have been eliminated completely with the exception of the Rio Massacre along the northwestern border with Haiti. Today, both these populations are protected by law (Decreto de Veda 861, June 1979). Prior to the present study, however, the status of crocodiles in Haiti was completely unknown (Powell 1971, King et al. 1983). The objectives of this investigation were twofold: (1) to determine the status and distribution of crocodiles in Haiti; and (2) to record aspects of the ecology of this poorly known species. The findings of the status survey are somewhat unexpected in that Haiti, a country with twice the population density and a much lower standard of living than the neighboring Dominican Republic, has several coastal crocodile populations as well as a substantial population in Bang Saumatre, Haiti's largest lake. The ecological study was done in Etang Saumatre, which is, at its closest, only 5 km from Lago Enriquillo in the Dominican Republic. The crocodile population in this lake was someWhat unusual, as it was not found in typical coastal wetland habitat. The crocodiles, however, were relatively easy to locate and capture due to the limited amount of vegetative cover. In addition, the lake represented a closed system, containing an easily defined population. In contrast, coastal populations are often widespread over large areas and are not easily delimited. The inaccessible nature of many of these habitats also precludes any easily accomplished quantitative work on population parameters. Based on the findings of the status survey and the ecological investigation, the last section outlines several recommendations for the conservation of crocodiles in Haiti. ACKNOWLEDGEMENTS Many people contributed to this project. Firstly, I am indebted to F. Wayne King, mymaster's thesis chairman, for his continual support during the course of this project, and Charles Woods, who first suggested the feasibility ofwork in Haiti and then provided many ofmy initial contacts in that country. They, along with the other two members of my graduate committee, J. Robinson and M. Collopy, read and made many constructive commentsconcerning this thesis. My stay at Etang Saumatre was made possible through the generosity of Pastor Wallace and Eleanor Turnbull and Pastor Eric and Irene Lange, who provided me with a place to stay and store my equipment at Tete Source. The Langes provided constant support and companionship, as well as many greatly appreciated home-cooked meals. Work in Haiti was sponsored through the Institut de Sauvegarde du Patrimoine National, Albert THORBJARNARSON: AMERICAN CROCODILE IN HAITI 5 Mangones, Director. Paul Paryski especially provided a great deal of support. Permission to conduct the work was obtained from Jean-Baptiste, Jean-Francois, and Edmond Magny of the DEpartement de l'Agriculture des Ressources Naturelles et du D6veloppment Rural (DARNDR). Joseph Felix, also of DARNDR, kindly supplied permits for the export of some specimens. Ekke Lempke provided a great deal of information concerning crocodiles and first introduced me to Etang Saumatre. Jaques Durocher and Jimmy Stecher also supplied much information on the current distribution of crocodiles in Haiti. Jimmy Stecher and Ted Steinhauer provided logistical support for trips to the Laborieux region and La Gonave. Dan Cordier and Brent Mitchell assisted during portions of the coastal surveys. Ragnar Arnesson and Roland Roy, of the Organization of American States in Port-au-Prince, supplied considerable assistance in attending to many of the problems which arise during work in foreign countries. My assistants in Etang Saumatre were Eldee Antoine and Tony Samveiss. Pierre Milfort of DARNDR also helped during the early stages of the project. Others who provided assistance were Peter Blanchard, Drew Kutchenreuter, Jim Keith, David Pulle, Tom Greathouse, Mara McDonald, and Mike Binford. Identification of prey items was done by Robert Woodruff (insects), G.B. Edwards (spiders), Mintor Westfall (dragontly larvae), Eleanor H. Stickney (birds), and George Burgess and Richard Franz (fishes). Plant identifications were performed by David W. Hall, S. Davis, and D. Griffin. Expertise for the step-wise discriminant analysis was provided by C. Abercrombie. Work in the Dominican Republic was sponsored by the Museo Nacional de Historia Natural, in particular Lic. Jose Alberto Ottenwalder, Lic. Sixto Inchaustegui, and David Robinson. I would aIso like to thank Leslie D. Garrick for allowing me to cite some of his unpublished data from Jamaica. Funding for work, both in Haiti and the Dominican Republic, was provided by the Wildlife Conservation International (WCI) (formerly Animal Research and Conservation Center [ARC]) of the New York Zoological Society. Research in Haiti was also funded through a fellowship from the Organization of American States. Additional funding was provided by two grants-in-aid of research from Sigma Xi, The Scientific Research Society. Reynolds Aluminum kindly supplied the use of a pick-up truck over a 6-month period of time in Haiti. METHODS Survey of Status and Distribution Surveys of coastal areas and inland lakes (other than Etang Saumatre) were conducted primarily during May-June 1983. Potential crocodile habitats were initially identified on the basis of information provided by reliable informants familiar with wildlife in Haiti. Next, 1:50,000 topographic maps were used to pinpoint areas of possible crocodile habitat prior to visiting those areas. The bulk of the information on the presence or absence of crocodiles was obtained from conversations with knowledgeable local residents (mostly fishermen). Areas were surveyed on foot or by boat during the day to determine the quantity and the quality of the available habitat. Whenever possible, night surveys were also made using a headlamp to spot crocodiles or their reflected eyeshine. However, due to the limited amount of time available to conduct the surveys and the frequent lack of a suitable boat, night surveys were not conducted at all locations. The past distribution of crocodiles in Haiti was reconstructed based on (1) historical accounts of crocodiles in specific locations, (2) place names referring to "caiman," the 6 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) local word for crocodiles, and (3) the distribution of suitable crocodile habitat in coastal areas. Regions containing extirpated and extant crocodile populations were then compared on the basis of amount of mangrove habitat (determined from 1:50,000 topographic maps) and human population density based on recent population census (IHSI 1983). Ecological Study: Etang Saumatre Demography Crocodiles were censused at night from a boat using a Q-Beam spotlight (200,000 candie power) run off a 12-volt marine cell. Two censuses of the entire lakeshore were performed, one requiring three nights (11, 17, 18 August 1983) and the other two nights (7,8 January 1984). The August survey was not conducted in consecutive nights because of boat trouble. It appears, however, that crocodile movements between survey sections were not sufficiently large to introduce significant error. Surveys were conducted atan average speed of 7 km/hr, approximately 30 m from shore. The light was swept along the shoreline and periodically out into the lake. Crocodiles were spotted by their reflected eyeshine and approached to estimate size (0.3- 0.9 m, 0.9-1.8 m, 1.8-2.7 m, > 2.7 m). Because hatchlings did not form pods and were frequently found in dense vegetation along with yearlings, it was unfeasible to separate these two size classes during counts. If the crocodile submerged before an accurate estimate of size could be made, it was placed into one of the following categories: EO > 1.8 m (eyes only, greater than 1.8 m total length), EO < 1.8 m (eyes only, less than 1.8 m), or EO (eyes only). The location of all crocodiles sighted was plotted on a map of the lake as they were spotted. Surveys produced a base estimate of population size and size- class distribution. These data were then corrected for: (1) reduced sightability in areas of dense shoreline vegetation; (2) known animals that were not seen during the survey; and (3) in the January 1984 survey, line transects were conducted in two dense Conocatpus sWamps to estimate the number of crocodiles that could not be seen from the lake. A full description of the correction procedufes is given in Appendix III. After determining the size-class distribution of the population, the EO, EO < 1.8 m, and EO > 1.8 m sighting classes were divided proportionately between the four known-length size classes. As large animals generally are more wary than small ones, this may have resulted in a slight bias against the larger size classes. Sex ratio and a length-weight relationship were determined from captured individuals. Large crocodiles (> 1.8 m) were caught at night from a boat. Smaller individuals usually were captured when THORBJARNARSON: AMERICAN CROCODILE IN HAITI 7 wading through shallow water habitats. Crocodiles were caught by hand, with pilstrom tongs, or by using breakaway locking cable snares mounted on the end of a pole (Jones 1965). Crocodiles were weighed on Homs spring scales (100 g, 2 kg, or 10 kg capacity) or Hansen spring scales (136 kg capacity). All captured crocodiles were marked in two ways; by placing self-piercing monel tags in the webbing of the hind foot, and cutting numerical sequence of dorsal caudal scutes. Due to uncertainties in the sexing procedure of juveniles (> 1 m) during 1983, sex data from these animals were not used. Because of the difficulty of sexing small animals based on morphological differences in the penis/clitoris (Joanen and McNease 1979), data on the sex of animals less than 40 cm long were not taken. Growth rates were obtained using successive lengths from recaptured animals. Hatchling growth rate also was estimated by assuming a mean hatching date and length, based on hatchlings found in recently opened nests. In this manner the age and growth of first-year animals could be estimated. Biomass was determined from the length-weight relationship of captured animals and the size-class distribution of the population. The mass of a crocodile at the midpoint of each size class was used as an estimate of the average mass of a crocodile in that size class. These values then were multiplied by the total number of crocodiles for each class and summed for all four size classes. For the > 2.7 m size class, mean size was assumed to be 2.9 m. Reproductive Ecology The location of the crocodile nesting beaches and the number of 1983 nests were determined by extensively searching lakeshore habitats during May 1983. Active nests were identified by the presence of an open hole surrounded by eggshells and egg membrane fragments. In 1984, nesting beaches were monitored beginning in early January for signs of activity. Nests were located by following the tracks left by females and probing by hand under the substrate in areas where obvious digging had occurred. Once located, nests were carefully excavated to determine clutch size and egg fertility rate (by egg banding, Ferguson and Joanen 1983) and to measure nest hole dimensions. Measurements of egg dimensions and egg mass were made on a sample (n = 5) of eggs from each clutch. A 100-200 g soil sample was taken for later analysis of water content (by drying over a butanestove) and soil particle size distribution (by passing through a series of sieves). All weights were measured on a 200 g Pesola spring scale (0.5% accuracy). A variety of other parameters were recorded at each nest site. Height of vegetation was estimated to the nearest 0.5 m, height above the 8 BULLEIIN FLORIDA STATE MUSEUM VOL. 33(1) lake to the nearest 0.3 m. Percent of shrub, grass, and leaf litter cover was estimated to the nearest 10%. In six nests copper-constantan thermocouples were implanted at the top and the bottom of the clutch. Nest temperatures were recorded over a 30- hour period using an Omega 871 digital thermometer. To determine the environmental parameters important in the selection of nest sites, 15 null sites were randomly chosen along the major nesting shore. The same environmental parameters measured at the nest sites were recorded at each of the null sites (except distance to lake which was standardized at 25 m) and a stepwise discriminant analysis performed on the data set. Dietary Analysis Stomach contents from crocodiles under 1 m total length were obtained using the stomach flushing technique described in Taylor et al. (1978). For crocodiles longer than lma modified scooping technique was used. Crocodiles were strapped to a wood plank with their taped jaws immobilized in an open position around a 7.6 cm diameter section of PVC pipe. Stomach contents were extracted using natural latex (Paramold, Imperial Adhesives and Chemicals, Inc.) scoops moulded from small funnels (opening diameter 6.5 cm, 7.0 cm long). The narrow end of the funnel-shaped scoop was pushed down the esophagus using a 2.5 cm diameter rod until the scoop was felt to reach the end of the stomach. The scoop and rod were generously lubricated with vegetable oil to reduce the chance of trauma to the esophagus during this procedure. Once in the stomach, the rod was extracted and the scoop was slowly pulled out using two strings attached to opposite sides of the funnel rim. The narrow, open end of the scoop was covered with cheesecloth to allow fluids to pass through as it was drawn through the stomach. This procedure was repeated at least three times and was used on animals up to 2.88 m total length. All stomach contents were preserved in alcohol for later identification and analysis. Stomach contents were categorized into three groups: fresh, partly digested, and fragments. Items from the first two groups were individually weighed on an Ainsworth 21N analytical balance to the nearest 0.1 g. The presence of gastroliths, vegetation, and nematodes was noted. For purposes of comparison, invertebrate prey items generally were classified to the ordinal level. Representative invertebrate prey items were identified to family or genus to allow analysis of prey ecology and, by inference, crocodile foraging modes. Vertebrate prey was identified to genus or species in all cases. THORBJARNARSON: AMERICAN CROCODILEIN HAITI 9 Habitat Selection The various lakeshore habitat types were categorized by physiognomy of the vegetation or shoreline features. The extent of the habitat types was mapped on 1:25,000 topographic maps of the lake during day surveys by boat. The locations of all crocodiles seen during the population surveys were marked on a map of the lake and later assigned to one of the habitat types. Shorelines or the lake-vegetation interface also were assigned an exposure index (protected, moderate, or exposed) based on the amount of wave action they received from the predominant easternly winds. Spatial distribution of crocodiles around the lake was examined by dividing the lake into eight segments of varying length (4.3-16.0 km long) and comparing the crocodile population in each of these segments. PRESENT STATUS AND DISTRIBUTION IN HAITI Introduction The Republic of Haiti (Fig. 1) occupies 27,700 sq km of the western third of the island of Hispaniola, the second largest of the Greater Antilles (Woodring et al. 1924). A French colony until 1804, Haiti became the world's first black republic following a bloody revolution that lasted nearly 15 years. The name Haiti is derived from an Arawak Indian word meaning "mountainous land" and provides a very apt description of this country, which has peaks up to 2680 m and more than 65% of its surface area sloped greater than 20 degrees (AID 1982). Within its diverse topography, Haiti supports a wide variety of ecological life zones and associated plant communities ranging from dry thorn scrub to mountain pine forests. In fact, the Holdridge life zone classification system was first developed during work on the mountain vegetation of the La Selle ridge of southeastern Haiti (Holdridge 1947). Today, however, very little of the natural vegetation remains because of extensive deforestation. With an estimated population of more than 5 million, Haiti has one of the world's highest population densities. This, in combination with a paucity of arable land, has resulted in a degree of environmental degradation that is perhaps without equal in the world today. The chief problem is one of rampant erosion, resulting from the nearly complete deforestaton of many hillsides 10 BULLETIN FLORIDA STATEMUSEUM VOL. 33(1) ILEDE LA TORIUE PAIX CAP, HAI"EN rA.L« GONAIVES 41*/ 6 - RIVIERE ARTIBONITE ILE DE LA - GONAv E TRou CAIMAN 0 JEREMIE PORT-AU-PI~INCE E TAN 0. SAUMATRE AQUIN CAYES VACHE N ~ 20 49 km <2, FIGURE 1. Map of Haiti including some major landmarks. Inset is a map of the West Indies with the relative location of Haiti shown as a solid black area. without the implementation of any soil conservation techniques. Today, the effects of such past practices are being sorely felt by the Haitian people who have the lowest per capita income in the western hemisphere. Recognition of the problem has been slow, but currently the Haitian government, in cooperation with several foreign aid agencies and volunteer organizations, is beginning to implement reforestation projects. Centuries of human depredation and the virtually complete loss of lowland forested regions have had drastic effects on the local fauna. The hardest hit have been the endemic non-volant mammals, as out of a pre- Colombian total of 25, today only 2 species survive, and both of these are quite rare, persisting in only a few relatively undisturbed areas of suitable habitat (C. Woods pers. comm.). Similarly with reptiles, the giant rock iguanas (Cyclum comum and C dcordi) have become Very rare and today are found only in a few dry, rocky areas inhospitable to man. THORBJARNARSON: AMERICAN CROCODILE IN HAITI 11 The crocodile has managed to survive in Haiti principally because man and American crocodiles are essentially allopatric in their distribution, as man finds the coastal wetlands the crocodiles prefer marginal for agriculture or habitation. In contrast to the near total destruction of the terrestrial forests, the coastal forests, especially mangrove, have fared considerably better. During the period between 1956 and 1977 only 7% of the existing mangrove disappeared. The corresponding figure for loss of pine forest was 40-70% (FAO 1978). While the mangroves are not cleared for agricultural use as are the terrestrial forests, mangrove is used for firewood in bakeries, home cooking, distilleries, and dry cleaners. Mangrove wood also is used as fuel for burning coral rock to produce lime for cement, making charcoal, and for construction purposes. Mangrove has been spared to a large degree in the past, but as the human population continues to grow, more and more pressure will come to bear on these forests. Already the pace of mangrove destruction appears to have been accelerated (pers. observ.). Although less apparent than the cutting of mangrove, diversion of freshwater for agriculture has probably had more lasting, although as of yet largely undetermined, effects upon some of these ecosystems. This is most notable in the l'Ester region, which contains Haiti's largest mangrove swamp. Mangrove forest still remains in many parts of Haiti, however, and these areas serve as nuclei for the present coastal distribution of crocodiles (see Appendix I). This section will present the results of a country-wide survey to determine the present status of crocodiles in Haiti. The findings will then be examined in relation to the past distribution of crocodiles, as determined from historical records, to document the retreat of the crocodiles into isolated populations and to provide some useful insights into the ability of crocodiles to survive in man-dominated ecosystems. Results Past Distribution of Crocodiles in Haiti Fourteen historical accounts and eight place names were found that made reference to crocodiles (Fig. 2). These sources, plus information on the distribution of suitable crocodile habitat, were used to reconstruct the probable former distribution of crocodiles in Haiti (Fig. 3). 12 BULLETIN FLORIDA STATE MUSEUM VOL 33(1) Present Distribution of Crocodiles in Haiti Four regions containing extant coastal crocodile populations were identified: (1) the southern coast of the Tiburon Peninsula from Cote-de-Fer west to the RiviBre l'Acul, including Ile-8-Vache, (2) Ile de La Gonave, (3) the l'Ester-Artibonite mangrove swamp, and (4) the Rivi6re Massacre-Lagon aux Boefs region bordering on the Dominican Republic. In addition, the largest remaining crocodile population is found in Etang Saumatre, an inland lake not far from the capital of Port-au-Prince. The present range of crocodiles in Haiti is summarized in Figure 4. A comparison of the present and past distributions of crocodiles reveals that crocodiles have been 0 20 40i km <-J 3,7,10,13,A Dll ~ B 4,5,8 0,j 2,4,5,6 4 H 0 If 3,4,14 4 I2 FIGURE 2. Locations of historical records of crocodiles and place names referring to "caiman" in Haiti. (Historical Accounts: 1 - Las Casas 1561, 2 - Lescallierer 1764, 3 - Moreau de St. Mery 1796, 4 - Moreau de St. Mery 1797-8, 5 - Descourtilz 1809, 6 - Hearne 1834, 7 - Ritter 1836, 8 - Gosse 1851, 9 - Fortunat 1889, 10 - Hazard 1873, 11 - Rodriguez 1915, 12 - Wetmore Perrygo 1931, 13 - Loederer 1935, 14 - Steedman 1939. Place Names: A - Isleta de los Caimanes, B - Bassin Caiman, C - Calman, D - Bassin Calman, E - Carman, F - Trou Carman, G - Rividre Carman, H - Trou Carman.) THORBJARNARSON: AMERICAN CROCODILE IN HAITI 13 0 20 40 11, 1-1 N FIGURE 3. Reconstructed historical range of crocodiles in Haiti, based on Figure 2, the present crocodile distribution, and the availability of suitable habitat. extirpated from approximately 70% of their former coastal range, and two of the three inland lake systems where they were once found (Etang Laborde, Etang Miragoane). Southern Coast of the Tiburon Peninsula; A diffuse crocodile population exists in this region from immediately west of Cotes-de-Fer, west to the vicinity of the Rivitre l'Acul (Fig. 5). Crocodiles are regularly seen in a number of the more isolated coastal wetlands, specifically: the vicinity of Laborieux-L'Osiendieu, the Aquin-RiviBre Capolo region, the Rivitre Cavaillon, and the Rivitre Bondonne. Crocodiles are sporadically seen in pockets of suitable habitat between these areas, primarily associated with mangrove swamps or the dense vegetative cover at river mouths. Nesting reportedly occurs in vegetated beach strand habitats along the lower reaches of the RiviBres Cavaillon and Bondonne. During surveys, crocodiles were only seen in the Laborieux region (5 subadults seen, 17 April 1983), but according to local residents the largest population remains in a 14 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) 92,0 4,0 9-J N 0 00 FIGURE 4. Present range of crocodiles in Haiti. N 0. Alo AQUIN 3 4 2 6 CAYES BAIE D'AQUIN 7 COTES·DE·FER 8 0 20 40 KM i LE A VACHE CARIBBEAN SEA FIGURE 5. South-central Tiburon Peninsula; marked locations indicate the postion of extant or former crocodile populations (1 - Laborieux; 2 - Osiendieu, 3 - Rividre Capolo, 4 - Rividre Millionaire, 5 - Rividre Cavaillon, 6 - Rivitre Torbeck, 7 - Rivitre Bondonne, 8 - Rividre l'AcuI, 9 - l'Etang, 10 - Etang Laborde). THORBJARNARSON: AMERICAN CROCODILE IN HAITI 15 mangrove swamp at the mouth of the Rivitre Cavaillon. A recently killed specimen (1.2 m total length) was found in the Riviare Capolo (25 June 1983, UF 54208). Crocodiles were also reported from a small freshwater lake (called L'Bang) on the northwestern end of Ile a Vache, located approximately 10 km off the southern coast of Haiti. Ile de La Gonave., La Gonave is the largest of Hispaniola's satellite islands (658 sq km), or about 2.3% of Haiti's land surface. Much of the coast is protected from wave action by a barrier reef, permitting the growth of a mangrove fringe even though freshwater runoff is almost non-existent. Crocodiles were reported from several of the coastal lagoons on the western end of the island. During a night survey of Lagon Blanch (11-12 June 1983), a shallow water lagoon along the north coast near the town of Richard, a total of five subadult crocodiles (to 1.5 m total length) were observed. l'Ester-Artibonite., Hispaniola's largest mangrove swamp (8490 ha) is found in the l'Ester region just south of the town of Gonarves. Immediately to the south of the l'Ester region is the mouth of the RiviBre Artibonite, Hispaniola's longest river (240 km). Crocodiles were well documented historically from this area by Descourtilz (1809) in his treatise on the "crocodile du St. Domingue." Today, crocodiles are well known to local fishermen, although they are not seen with any frequency. During a daytime survey by sailboat (4 June 1983) and a night survey of mangroves near Gonarves (5 June 1983), no crocodiles were seen. Crocodiles were also sporadically observed by local residents of Grande Saline, at the mouth of the Rivitre Artibonite, which lacks any protective mangrove forests. Rividre Massacre-Lagon aux Boefs., Lagon aux Boefs is a 4-sq-km, mangrove-lined, freshwater lagoon connected at its northern end to the Rivitre Massacre, which forms the northeastern boundary between Haiti and the Dominican Republic. The estuarine section of the RiviBre Massacre has a mixed riverine-fringe type mangrove swamp (after Lugo and Snedaker 1974) of approximately 1030 ha, most of Which is in the neighboring Dominican Republic. Local Haitians were very familiar with crocodiles, which they would catch and eat whenever possible. This is in stark contrast to the rest of Haiti where crocodiles are not eaten. A daytime survey of Lagon aux Boefs (16 June 1983) revealed no crocodiles. During a previous night survey of the lower Rivi6re Massacre in December 1981 one 3 m crocodile was seen approximately 2 km upstream from the river's mouth. Etang Saumatre and Trou Caiman., Haiti's largest remaining crocodile population, approximately 450 individuals of all sizes, is found in Etang Saumatre, located in the Cul-de-Sac valley 30 km northeast of Port-au-Prince (see Ecological Study: Etang Saumatre). A large lake (113 sq km), Etang Saumatre is surrounded by a relatively sparsely inhabited region of the 16 BULLETIN FLORIDA SrATE MUSEUM VOL. 33(1) country. The uninhabited eastern lakeshore, bordering the Dominican Republic, contains a significant amount of juvenile crocodile habitat and virtually all the nesting sites. Trou CaYman is a marshy freshwater lake (6.9 sq km) located 6 km west of Etang Saumatre. The two are connected by a small canal. The sporadic accounts of crocodiles in this lake suggest that it does not contain a breeding population but probably serves as a dispersal area for crocodiles from Bang Saumatre. Extirpated Populations North Coast West of Ft. Libert6., Crocodiles were known historically as far west as the mouth of the Rivitre Limb6 (Bassin Cayman). It is not known exactly when the last crocodiles in this region were extirpated, but none has been seen for many years. It is likely that at one time crocodiles ranged as far west as Port-de-Paix, as pockets of suitable habitat exist at regular intervals along the coast. West of Port-de-Paix, a rocky, high-energy coast predominates, providing little in the way of crocodile habitat. Crocodiles also were reported historically in the vicinity of Cap Haitien (Rodriguez 1915) where a moderate-sized (760 ha) mangrove forest still exists along the lower reaches of the RiviBre Haut-du-Cap. Crocodiles were also found in the Caracol region between Cap Haitien and Fort Libert6. The only published account is that of Ritter (1836), who mentions seeing crocodiles at Ft. Real, which may have been the old site of Puerto Real, a Spanish colonial settlement in the Caracol region. The presence of a small lagoon (the old river bed of the Grand Rivitre du Nord) called Bassin Cayman, and the finding of crocodile mandibles in Indian middens from the area (W. Hodges pers. comm.), however, attest to the fact that crocodiles were indeed in the area at one time. North and West Coasts of the Tiburon Peninsula., Historically crocodiles were found in the vicinity of Petit Goave (Riviere Caiman), the Rivitre Grande Anse near J6r6mie (Moreau de St. Mery 1797), and the Tiburon region at the tip of the peninsula (Las Casas 1552). They also were formerly found in several inland lakes in the area (see following section). Currently there are no verified populations anywhere in this part of Haiti. Crocodiles may still be found in small numbers in the BaradBres region, although this is doubtful. The small individuals reported from Petit Goave and JEremie (all in the 1.2-1.5 m range) probably represent vagrant individuals. Inland Lakes: Etang Laborde., Etang Laborde is the largest of four lakes located on the coastal plain 12 km north of Cayes (1978 size estimate THORBJARNARSON: AMERICAN CROCODILE IN HAITI 17 0.9 sq km). The region is heavily populated and extensive agriculture occurs around the lake. The lake itself is very shallow and reportedly dried up in 1975 after an extended drought. Moreau de St. Mery (1797) stated that crocodiles were found in this lake (then called Bang Vert) but had long since disappeared, making this the earliest known extirpation of crocodiles in Haiti. No crocodiles are currently found in Etang Laborde or any of the other lakes in the region. Inland Lakes: Etang Miragoane., Etang Miragoane presently consists of two lakes (8.3 and 1.3 sq km) near the north coast of the Tiburon peninsula, adjacent to the town of Miragoane. This region also is densely populated, and there is currently much fishing activity in the lake. The lake is fresh water with extensive grass fringes. Other vegetation includes Nuphar, Nelumbo, Typha, and Potamogeton. Moreau de St. Mery (1797) mentioned that the lake had many crocodiles 2.5-3.5 m long which nested in sandy areas surrounding the lake during the summer. Bang Miragoane has no crocodiles, and no one interviewed could remember there ever being crocodiles in the area. Discussion Analysis of the Present Distribution of Crocodiles Coastal Crocodile Movements., Croco*lus acutus is one of two primarily coastal dwelling crocodiles, the other being C porosus from northern Australia, the Indo-Malayan Archipelago, and Southeast Asia. The wide coastal distribution and probable recent evolutionary derivation of both these species (Densmore 1981) suggests that they are adept at moving along coasts and possibly even making transoceanic journeys. This is best documented in the case of C porosus (Bustard and Choudhury 1980) where specimens have been spotted at sea nearly 500 km north of New Zealand (Robb 1980), on Cocos-Keeling Island in the Indian Ocean nearly 1000 km from the closest known population in Indonesia, and on Ponape in the Western Caroline Islands some 1360 km from the nearest population (Allen 1974). Messel et al . ( 1982) developed a model of C porosus population dynamics for tidal rivers in northern Australia which proposes that a large fraction of the subadult crocodiles leave the productive nesting rivers when they reach a size (0.9-1.8 m) that brings them into conflict with larger territorial adults. Such individuals, if not killed outright, are forced to leave the river and find other, usually marginal, habitats. Some perhaps move along the coast and manage to find another river where territorial adults are less common (rivers less suitable for nesting) and take up residence there. 18 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) The majority, however, probably never survive. As adults it is possible the crocodiles will move back into more suitable rivers for reproduction. The model proposes, then, that movement and mortality are quite high for these intermediate-sized crocodiles. Logically, a similar pattern may hold for C acums, which is ecologically similar but poorer known from a biological standpoint. Both Alvarez del Toro (1974) and Medem (1981) reported C acutus moving from river to river using overland routes. Alvarez del Toro (1974) stated that such movements are in response to territorial fighting and the drying up of temporary lagoons. Mazzotti (1983) found C acutus moved considerable distances in the coastal regions of southern Florida. The presence of C acums on several mid- oceanic islands (Cuba, Jamaica, Hispaniola, and formerly the Cayman Islands) as well as a number of near-shore islands (Isla Margarita, Venezuela; Islas del Rosario, Islas de Sn. Bernardo, Isla Fuerte, Isla Tortuguilla, Colombia; and the Archipelago de los Canarreos, Cuba; as well as Ile a Vache and Ile de La Gonave off Haiti) strongly suggests the species is adept at moving long distances along the coast or across open water. Fishermen in Haiti reported that on occasion crocodiles could be seen in the ocean. Crocodile movement along the coast would explain many of the unusual reports of local residents along the southern coast of the Tiburon peninsula. In this region, crocodiles were said to be found in several areas with little or no suitable habitat, and their presence in many of these areas was reported to be of irregular occurrence. Similarly, reports of crocodiles on the northern coast of the Tiburon peninsula are most likely transient individuals, as are the ones feported from Anse-a-Galets on eastern La Gonave. A pertinent point concerning these last reports was that all the animals were 1.2-1.5 m individuals, the size class that would be dispersing the most according to the Messel model. Adult crocodiles will also move along the coast, resulting in large individuals being reported in small coastal wetlands. Most of the areas where crocodiles have been reported along the Tiburon peninsula contain more than 60 ha of habitat. Only a fraction of this area, however, is available to the crocodiles because of extensive fishing, rice cultivation, and other human activities. The habitat at the mouth of the Rivitre Capolo is much smaller, however; so small it is impossible to make a size estimate from 1:50,000 topographic maps. A similar situation is found on the southern coast of Jamaica where crocodiles may be found in almost any coastal wetland one hectare or larger in size (Plotkin and Faibairn MS, referenced in Groombridge 1982). This frequent usage of small coastal habitats suggests considerable movement by crocodiles along the coast. Human-related Mortality., Five direct causes of human-related crocodile mortality can be identified in Haiti (other»than habitat destruction): (1) incidental capture in fishing nets or traps, (2) malicious killing, (3) THORBJARNARSON: AMERICAN CROCODILE IN HAm 19 hunting for sport, (4) hunting for food, and (5) nest raiding. By far the most important of these is being trapped in fishing nets and traps. When caught, crocodiles either drown or are killed by the fishermen when pulled to the surface. Inmost cases the body is simply discarded in the water. Occasionally crocodiles may be eaten (see below) or the body may be disposed of by burial or by dumping·it at sea (see Folk Beliefs section below). In Bang Saumatre, where gill netting is not commonplace, one 1.5 m crocodile was drowned in a net during the 10-month period of time I spent there. As most bodies of shallow water in Haiti are heavily fished, this source of mortality probably is considerable. Malicious killings often occur in response to crocodiles taking livestock or, in one reported case, killing humans. A large crocodile, approximately 3 m long, was killed at Tete Source in Bang Saumatre after it had taken livestock on several occasions (goats and sheep). This crocodile was also considered a nuisance because it would take fish from gill nets, leaving gaping holes. The crocodile was caught using a baited hook and then beaten to death with a long stick. Large crocodiles also are killed occasionally when they accidentally wander into populated areas. Likewise, hunting for sport claims adult crocodiles in certain areas, although the incidence of this appears to have declined in the recent past. Throughout Haiti, the people are so poor that the number of firearms is very limited, being restricted in rural areas to certain local leaders and the military. Hunting excursions from Port-au- Prince were popular in the past, especially during the 1917-1934 United States Marine occupation (Steedman 1939, Cave 1952). Crocodile hunting was also a popular pasttime of the colonial French prior to the independence of Haiti (Descourtilz 1809). Use of crocodiles for food is limited to only two areas in Haiti, the Riviare Massacre and, to a much smaller extent, in Bang Saumatre. Both these regions border on the Dominican Republic, and the usage of crocodiles is undoubtedly due to a Dominican cultural influence (where crocodiles are eaten and their by-products used). Although the better educated people in Haiti will occasionally eat crocodiles, the vast majority of Haitians will not. Active hunting of crocodiles only occurs near the Rivitre Massacre, where they are caught with harpoons, set nets, cast nets, and baited hooks. Most of the hunting in this region centers on Lagon aux Boefs, with a smaller number caught in the river itself. The meat is eaten and the fat is used to render an oil to treat pneumonia and rheumatism. The only other account of crocodile by-products being used comes from the Cayes region. Although unconfirmed, three separate sources claimed that crocodile teeth are sometimes used for false teeth in people, the work being done in a hospital in Cayes. Nest robbing probably is not a major source of mortality, although nests may be dug up and the eggs left to die. In most areas, residents reported 20 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) nests as being very difficult to find and stated that like crocodile meat, they did not eat the eggs. The only area where eggs were reported eaten (other than the Rivitre Massacre region) was Etang Saumatre. Residents of the town of Ponds Parisien, on the southern shore of the lake, will eat them on occasion (F. Conway pers. comm.). One nest near Tete Source was excavated in 1983 and the eggs sold in the local market of Thomazeau (I. Lange pers. comm.). There is no present market for crocodile skins in Haiti, and hide hunting is non-existent. Interest was shown by an Italian firm during the 1950's when it approached Mr. E. Lempke of Port-au-Prince about obtaining crocodile hides. Nothing came of this, however, and little interest in commercial hide production has surfaced since. There is a tannery in Port-au-Prince that deals with reptile leathers (mostly lizard and snake skins from South America [J. Wilson pers. comm.]). The skin of the crocodile that was killed for taking livestock in Etang Saumatre was reportedly taken to this tannery. Until recently there also was a small export trade in live juvenile crocodiles for pets. This apparently has stopped in the last few years. Folk Beliefs., The fact that crocodile meat generally is considered inedible is undoubtedly one of the major reasons why there are still crocodiles in Haiti today. Such folk beliefs evolved with the culture of the Haitian people and are deeply tied to their religious beliefs. The indigenous Indians ate crocodiles, as is evidenced by the presence of crocodile bones in middens near the Caracol mangrove swamp (W. Hodges pers. comm.). Personal observation, however, has shown that today there is a widespread cultural taboo against eating crocodiles or their eggs. In most areas crocodiles are considered inedible and simply thrown away when killed; however, there is local variation in the method of disposal. In some areas (e.g. Gonaives), dead crocodiles are buried in a grave, often in coffin-like boxes with a grave marker. Around Etang Saumatre crocodiles are beheaded, with only the head being buried, usually away from the rest of the body. This represents an attempt to keep the spirit of the dead crocodile (which resides in the head) separate from the body so that it can create no "mischief' after death (pers. obs.). On the island of La Gonave crocodiles actually are considered poisonous. When crocodiles are killed in this region, they are disposed of by being weighed down with rocks and towed out to sea. Crocodiles are eaten only in areas where there is cross-cultural exchange with Dominicans. Around the RiviBre Massacre crocodiles are accepted as being edible. Near Bang Saumatre some Haitians also will eat crocodile, but it is considered poor repast, equivalent to the Cyclura iguanas in the area. An interesting example of cultural differences occurred at Las Lajas, a border military post in the Dominican Republic. A Dominican guard had shot a 2.7 m crocodile in Etang Saumatre, dragged it ashore and cut out the tail meat to eat and the penis (which is widely believed to be an aphrodisiac in the THORBJARNARSON: AMERICAN CROCODILE IN HAITI 21 Dominican Republic). Afterward, Haitians chopped off the head and buried it several meters from the carcass to prevent the crocodile's spirit (called its loa) from doing any harm. Crocodile Distribution in Relation to Habitat., Crocodiles are found only where there is suitable habitat. The habitat provides two important functions: an environment that meets the biological needs of the animal and, if it is to sustain a crocodile population, sufficient cover to protect the crocodiles from man. Because of the extremely dense human population in Haiti, the only significant coastal habitat type that satisfies both these criteria is mangrove swamp. In areas where human densities are considerably less, the second criterion obviously becomes less important. In historical times, crocodiles probably were commonly associated with virtually all coastal wetland habitats. The pattern of disappearance from these habitats is inversely correlated with the degree of human activity in the area. Mangrove swamps provide good habitat because they are relatively impenetrable to humans and offer a wealth of hiding places. Mangroves also are a very common form of tropical coastal wetlands, growing under a variety of physiognomic conditions and, as such, have been well documented as a preferred habitat of the American crocodile throughout its range (Alvarez del Toro 1974; Ogden 1978, Medem 1981). In Haiti, there is a correlation between the amount of mangrove habitat and crocodile presence in each of the coastal D6partements (a political subdivision) and the major satellite islands (Table 1). Coastal regions with crocodiles contain, on average, significantly more mangrove (0.390 sq km/km shoreline, as measured from 1:50,000 topographic maps) than areas without (0.05 sq km/km shoreline) (t-test, p < 0.05). The limited occurrence of crocodiles in coastal non-mangrove habitats emphasizes the need for sufficient cover in which crocodiles can hide. Although much of Haiti's coastal wetlands are dominated by mangroves, there are a number of other small estuarine environments that could support crocodiles. Most of these are on the north coast between Cap Hartien and Port-de-Paix, or on the southern peninsula (e.g. Cayes Plain rivers, Rividre Grande Anse near J6r6mie). Of the non-mangrove habitats, only two still have crocodiles, both of which offer sufficient cover for the crocodiles in them: the Rivitre Artibonite (deep, murky water) and the RiviBre Bondonne (extensive herbaceous vegetation). Even with cover, however, the presence of crocodiles in these areas probably is related strongly to the nearby occurrence of mangrove habitat. When considering the suitability of mangrove habitat for crocodiles, however, there are considerations other than total area that need to be addressed. Perhaps the most important are freshwater input and the availability of nesting habitat. As Dunson (1982) demonstrated, hatchling C acums can osmoregulate properly in water up to approximately 20 parts per 22 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) thousand (ppt), but cannot tolerate full strength sea water (35 ppt) for extended periods of time. Periodic access to areas of fresh or brackish water therefore is essential for hatchling recruitment (Mazzotti 1983). The apparent lack of crocodiles in the extensive mangrove swamp at Caracol may, in fact, be due to a lack of freshwater input into the region. One river, the RiviBre Trou du Nord, does empty into the mangrove adjacent to the town of Caracol (population 3982). The heavy human use of the area and a possible lack of suitable nesting habitat provide unsuitable conditions for crocodile reproduction and recruitment. The xeric nature of the surrounding area suggests also that periodic access to freshwater lenses formed by rainfall also is unlikely. In fact, in most of the mangrove areas in Haiti, freshwater influx is very low. The majority of mangrove habitat is located in the subtropical dry forest life zone, areas receiving less than 100 cm of rain annually. The lack of freshwater runoff also is related to the high coastline to total country area ratio. The amount of freshwater runoff is proportional to the amount of land that receives rain, but mangrove habitat is a function of the length of the coastline. Hence, Haiti, with a long irregular coast and a small surface area, provides little freshwater runoff for its coastal mangrove forests. This situation is further aggravated by the fact that much of Haiti is arid, and in several areas (such as the l'Ester region) freshwater runoff is diverted for agriculture. The fringe forest of the l'Ester historically had a much larger freshwater influx than at present, because of irrigation and channelization, and this region once supported a very large crocodile population (Descourtilz 1809). Diversion of freshwater probably had a significant effect on the habitat which, in combination with intense fishing activity and past crocodile hunting, has resulted in a drastic decline in the crocodile population. The situation on the island of La Gonave also is worth mentioning in regard to freshwater availability. No surface streams exist on the island; instead, rainfall percolates down through the limestone bedrock, emerging in springs, some below sea level. In this respect, suitable hatchling habitat may be severely limiting, being restricted to the vicinity of freshwater springs that feed into coastal lagoons. The area visited on the north coast of La Gonave did, in fact, have at least one small spring adjacent to a mangrove swamp in which juvenile recruitment was occurring. Crocodile Distribution in Relation to Human Population Density., Most human-related crocodile mortality in Haiti is accidental, therefore it can be assumed to be directly proportional to the frequency of human-crocodile encounters. This, in turn, is related to the prevalence of activities that bring people into crocodile habitat or to accidentally kill cr6codiles; these activities include fishing, cutting mangrove, or collecting mangrove oysters. Although it is virtually impossible to quantify such activities, they can be assumed to be THORBJARNARSON: AMERICAN CROCODILE IN HAITI 23 more or less directly proportional to human population density in the area. In Haiti, population densities are, in fact, higher in areas where crocodiles have been extirpated than in those regions which have extant crocodile populations (Tables 2,3). Because of the large variances involved, the differences are not significant for the coastal areas (Table 2, t-test p > 0.05). Inland lakes with crocodiles, however, are in areas of significantly lower human population density (Table 3, t-testp < 0.05). A noteworthy relationship exists between the status of crocodile populations and the ecological life zone in which they are found (Table 4). All historical crocodile populations were located in the two life zones that predominate in the lowland regions: the subtropical moist and the subtropical dry life zones (OAS 1972). The majority of the crocodile populations in the moist zone (100-200 cm rain annually) have been extirpated, only remaining today on the south coast of the Tiburon peninsula and Ile A Vache. On the other hand, only two populations in the dry forest zone have disappeared (Caracol region, L'Etang near Gonalves). In the latter cases the crocodile populations were probably vulnerable because of a lack of freshwater habitat, and small population size and ephemeral habitat respectively. As adult crocodiles are often found in freshwater and hatchlings require at least some freshwater, this relationship is not due to the availability of freshwater per se. Apparently the presence or absence of crocodiles in these areas is moderated indirectly through human population density, which is higher in the greater rainfall moist zone, leading to the unexpected result of finding crocodiles primarily in areas surrounded by semi-arid habitat. In the previous discussion, crocodile distribution in Haiti has been examined in relation to habitat availability and human population density. It is reasonable to assume, however, that crocodile distribution is affected simultaneously by both factors. Ranking coastal regions by population density and the amount of mangrove habitat, neither parameter alone is significantly correlated with the presence or absence of crocodiles (Wilcoxon Rank test,p > 0.05). A composite rank combining both parameters (Table 5), however, is significant (p < 0.05), indicating that the combination of mangrove habitat and population density is a better indicator of an area's suitability for crocodiles than either parameter alone. The extirpation of crocodile populations then appears to be synergistically related to human population density and the amount of suitable habitat. As crocodiles are rather long- lived, prolific, and secretive animals, given sufficient habitat offering retreats (mostly mangrove in Haiti), they can survive even in areas of dense human populations (as along the south coast of the Tiburon peninsula). This is due in no small part to their ability to move along coasts between pockets of suitable habitat. Human-related mortality is, however, quite high and can result in extirpation, especially where crocodiles are not afforded sufficient cover (non-mangrove habitats) or where they are vulnerable (e.g. lack of 24 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) freshwater). These generalizations, however, only apply to areas where mortality is mostly incidental, that is where there is no economic motivation for killing crocodiles. Where active hunting occurs for food, or more importantly for hides, crocodilian populations are much more likely to be extirpated. ECOLOGICAL STUDY: ETANG SAUMATRE Introduction General Features of the Region Etang Saumatre is Haiti's largest lake (113 sq km) and is located in the (Jul-de-Sac Valley approximately 30 km northeast of Port-au-Prince (Fig. 6). The Cul-de-Sac graben, which has been referred to as perhaps the most NHOW.r 'r .). etfpea DE NE\P'- f41 BAIE DE ~h PORT·AU-PRINCE / 0 '' TROU R ITANG CAI#UN '~ h~ SAUMATRE PORT-AU PRINCE WPJM- lAGO NRIQUILLO LAGUNA DEL UNCON • BARAHONA CARIBBEAN SEA ¥ 0 10 20 30 km FIGURE 6. Map of the Cul-de-Sac/Valle de Neiba region. THORBJARNARSON: AMERICAN CROCODILE IN HAITI 25 striking surface feature in Haiti (Woodring et al. 1924), is a low-lying valley extending east-southeast from Port-au-Prince Bay completely across the island to the Caribbean coast of the Dominican Republic, where it is referred to as the Valle de Neiba. Mountains border the valley to the north and the south, with Morne La Selle, Haiti's highest point (2680 m) lying directly south of Etang Saumatre. The abrupt changes in elevation provide a great diversity of ecological life zones within a relatively small area (Holdridge 1947). The Cul-de-Sac/Valle de Neiba depression contains a series of lakes, from east to west: Laguna del Rincon, Lago Enriquillo, Etang Saumatre, and Trou Caiman. Lago Enriquillo, in the Dominican Republic, is the largest (180 sq km) and most unusual of the four, as it is one of the lowest lakes in the world (35 m below sea level) and is hypersaline (50 ppt in 1981). Because of hypersaline lake water, the distribution of flora and fauna of the lake are restricted principally to the fringing freshwater habitats. Etang Saumatre (elevation 15 m) is located along the Haitian- Dominican Republic border approximately 10 km west of Lago Enriquillo; the two lakes are separated by a ridge of Pleistocene limestone and alluvial GLORE TETE SOURCE, N LAS DOMINICAN 0 LAJAS REPUBLIC HAITI ETANG SAUMATRE 0 1 2 3 4 km ' GAN THIER FONDS PARISIEN • MALPASSE FIGURE 7. Map of Etang Saumatre. 26 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) deposits. Although the vast majority of the lake lies in Haiti, two small sections (at Malpasse and south of Las Lajas) extend into the Dominican Republic (Fig. 7). Like Lago Enriquillo, Etang Saum9tre has no surface outlets, although the possibility of subsurface drainage into Lago Enriquillo cannot be ruled out. Etang Saumatre is only slightly saline, and because of this its ecology is quite different from that of Lago Enriquillo, in general supporting a much more diverse flora and fauna. Geology and Shoreline Features Within the last several million years the Cul-de-Sac valley was a shallow water marine strait that separated the Sierra de Neiba/Montagnes de Trou d'Eau to the north from the Sierra de Bahoruco/Morne La Selle ridge to the south (Woodring et al. 1924). This prior separation of Hispaniola into "north" and "south" islands still is reflected in the biogeographical relations of many taxa, as has been perhaps best documented for reptiles and amphibians (Schwartz 1980). Miocene 13 Qual'inory N 3·:'::,;: 01,gocene ~~~1 Quaion,ory *In,1 1 1 Alluviola Etang -SIS* Saumatre 01234k- Nflin'11'Mnmi~mp1I,-~ FIGURE 8. Geology of the Etang Saumatre region. THORBJARNARSON: AMERICAN CROCODILE IN HAITI 27 The abundance of Quaternary limestones composed of extant coral species is evidence of the recent marine inundation of the valley floor (Woodring et al. 1924). In many areas throughout the region coraliferous deposits are still recognizable, and in a few areas, such as Isla Cabritos in Lago Enriquillo, virtually intact exposed coral reefs can be observed. The placement of the lakes within the valley has been attributed by Woodring et al. (1924) to uneven alluvial deposition from sfreams draining the mountain watersheds to the north and the south. Areas that did not accumulate sediments are now depressions that have filled with water and remain as a series of lakes. The maximum known depth of the Etang Saumatre depression is 30 m below the lake's surface, or about 15 m below sea level. The shoreline features of the lake reflect the geology of the area (Fig. 8). The western lake margin, from Tete Source south to the vicinity of Ganthier, is composed of Quaternary alluvial deposits, creating a shallow lakeshore gradient. Continuing east along the south shore, Quaternary alluvials are mixed with similar-aged limestones creating a mosaic of shallow gradient and rocky, medium gradient shorelines. Just east of Fonds Parisien, older limestones (Miocene and Oligocene) form the northern flanks of the Morne La Selle ridge, and descend abruptly to the lake creating a rocky, steep gradient shoreline. A similar rocky coast is found along the north shore from Glore east to the vicinity of Las Lajas. However, along the north coast a number of prominent valleys, filled with recent alluvial deposits, extend down to the lake and create shallow gradient, non-rocky shoreline (coves). The eastern shore, northwest of Malpasse, is a medium gradient shoreline dominated by Quaternary limestone, containing several areas of shallow gradient mudflats at the openings of arroyos. Limnology Bang Saumatre is a brackish lake, with a salinity range of 8-10 ppt. In the shallow northwestern lake region where much of the freshwater input occurs, salinity is at the lower end of this range. The lake level iluctuates periodically, apparently as a function of rainfall. During the period 1979- 1983, following a series of hurricanes, the lake rose approximately 2 m. At the turn of the century, the lake level apparently was even higher than at present. Tippenhauer (1901) reported its elevation as 20 m above sea level (5 m above present), and Wells (1893) stated that the water was potable, being only slightly brackish. Similar fluctuations in lake level and salinity are known from adjacent Lago Enriquillo (La Fuente 1976). 28 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) A number of freshwater springs (conductivity 500-600 mohmos/cm) empty into the lake, primarily in the northwestern section of the lake, the largest being at Tete Source. Several small springs are found in the southeastern section of the lake near Malpasse, located directly along a fault, giving them a high hydrogen sulfide content. Although much of the freshwater input into the lake comes from these solution channel springs, a significant amount of water enters the lake in seepage areas and, to a lesser extent, through freshwater irrigation canals. Various chemical analyses have been done on Bang Saumatre lakewater since 1921 (Table 6). The fluctuations in salinity probably reflect changes in lake volume associated with variable rainfall. The high phosphate content of the water indicates the lake is eutrophic (M. Binford and M. Brenner pers. comm.). Bond (1935) termed Etang Saumatre eutrophic and "thalassohaline," meaning its ion concentrations are in the same relative proportion as seawater. Bond (1935) argued that this was evidence of the lake's marine origin. Climate The area surrounding the lake receives an annual average of 70-90 cm of rain. With a mean monthly temperature of 26 ' C, the region is classified in the subtropical dry zone, as defined by Holdridge (1967). Rainfall follows a predictable annual pattern (Fig. 9), peaking in May and October with a long winter (November-March) and a short summer dry season (June-July). Mean monthly temperature varies from 27.9 'C in August to a low of 23.7 ' C in February. Winds are predominantly from the east, and steady 18-36 kph winds were not unusual. Under these conditions whitecaps cover the lake, with wave amplitudes in excess of 1 m. The less common westerly winds were usually associated with rainfall. Vegetation Terrestrial Vegetation., The riparian vegetation is a virtual monoculture of buttonwood mangrove (Conocatpus erecms) growing in fringe 5-20 m wide around the lake where there is sufficient soil. Because of the recent rise in lake level, the Conoca,pus frequently extended out into shallow water to a depth of approximately 1 m. The most prolific Conocarpus stands are found along the shallow gradient alluvial shorelines on the western shore between THORBJARNARSON: AMERICAN CROCODILE IN HAITI 29 -300GANTHIER MEAN MEAN50 -100 MONTHLY MONTHLY TEMPERATURE RAINFALL ('C) 30 60 (MM) 10- 11 JAN MAR MAY JUL SEP NOV MONTH FIGURE 9. Walter diagram of rainfall and temperature variation in Thomazeau, adjacent Etang Saumatre. Shaded areas represent the dry season (after Walter 1973). Tete Source and Ganthier, and on the western shore between Las Lajas and Malpasse. Most of the Conocatpus is of low stature, rarely exceeding 4 m in height. The upland areas immediately surrounding the lake are vegetated with a xeric Acacia, Prosopis, and cactus association (Appendix II). Aquatic Vegetation., The freshwater flora is restricted to a few springs, canals, and freshwater seeps around the lake. In these areas the dominant vegetation consisted of grasses (Echinochloa cnisgalli, Paspalidium geminatum), sedges (Eleochan's cellulosa, Scitpus pungens), floating vines (Ludwigia leptocarpa, L. repens, Enhydra sessilis, Commelina geniculata), submerged plants (Najas manna, NiteUa sp., Saggitaria sp.), and cattails (7*ha domingensis). The flora of the lake itself is rather limited, being restricted to several halophytic algae and a few vascular plants. Shallow water sublittoral areas usually supported dense bottom mats of algae (Chara homemannii and Batophom oersteadi). These were the most productive areas of the lake and supported large numbers of fish (mostly Tilapia). Another alga (Cladophora 30 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) sp.) frequently was found growing attached to Conocarpus roots. Ruppia mantima forms dense mats in shallow water in several parts of the lake, usually adjacent to freshwater seeps. The grass Halodule beaudettei was often encountered along shores or in shallow water areas on mud or mari, usually under Conocarpus. In the southeastern section of the lake near Malpasse, Salicomia perennis grows along the lakeshore and out into shallow water. Vertebrate Fauna Fish., West Indian freshwater fish communities generally are lacking in diversity (Myers 1937). Etang Saumatre only supports eight native species (Appendix II), three of which (Strongylura nomta, Gobionellus sp., and Dormitator maculatus) typically are marine-coastal dwellers, reflecting the marine origin of the lake. In terms of biomass the dominant native species are Cichlasoma hatiensis (in the lake and spfings) and C>prinodon bondi Cake only). The other native fishes all are poeciliids, the two genera (Limia and Gambusia) being characteristic members of Hispaniolan freshwater fish communities. Two species of introduced fish also are found in Etang Saumatre: Tilapia mossambica and carp ((*tinus calpio). Both were first introduced into the lake during the early 1950s as part of an FAO fisheries pfoject. The Tilapia have become quite abundant and probably are the dominant fish overall in the lake in terms of biomass. The carp, on the other hand, are rarely seen and almost never caught by fishermen. As carp are long-lived fish and generally require cool water conditions for spawning, it is possible that no reproduction has occurred in the lake, and the few seen are remnants of the introduced stock. Reptiles and Amphibians., Aside from crocodiles, the only aquatic reptile found in Etang Saumatre is Trachemys decorata, a little-known freshwater turtle restricted to the Cul-de-Sac/Valle de Neiba region. Very secretive in their habits, the turtles were rarely seen, with most observations being restricted to shallow water areas in or around Conocatpus. No amphibians were f6und in the lake itself although several anurans (Bufo gunthed, B. marinus, and Osteopilus dominicensis) bred in freshwater areas adjacent to the lake. Avifauna., Aquatic and semi-aquatic birds are quite common in the lake, especially during the winter when there is an influx of migrants from North America. The aquatic and semi-aquatic avifauna of the lake is listed in Appendix II. Mammals., No native mammals are found in the Etang Saumatre area. The only local mammals (besides domestic stock) were rats (Ratms ratms, R. THORBJARNARSON: AMERICAN CROCODILE IN HAITI 31 norvegicus), mice (Mus musculus), feral cats (Felis domesticus), and mongoose (Herpestes auropunctatus). Demography Population Size, Sex Ratio, and Size-class Distribution Based on the corrected survey data the total population size in Etang Saumatre was estimated to be approximately 450, including crocodiles of all size classes (Fig. 10). Because sexing juvenile crocodiles is difficult, much of the juvenile sex data was not used, so sample sizes are small (Table 7). The predominance of males in the two smaller size classes is noticeable; however, it is not significantly different from 50% (chi square, 0.25 2.7 m). This may be a slight overestimate as sexual maturity is not attained until 2.2-2.3 m total length (see Reproductive Ecology). Nevertheless, the great majority of the animals seen in the 1.8-2.7 m size-class were 2.3-2.5 m long, and the overestimate of reproductive animals is probably quite small. Only 10% of the population was in the subadult (0.9-1.8 m) size-class. The small number of subadult crocodiles appears to be a general characteristic of most crocodilian populations. Cott (1961) commented on this mysterious "disappearance" of small- and intermediate-sized crocodiles in Africa, quoting Pitman as it being "a conspicuous feature of African inland waters." Messel et al . ( 1981) noted a similar lack of subadult C porosus in northern Australia, as did Mazzotti (1983) for C acums in Everglades National Park. This apparent lack of subadults may be a result of: (1) rapid growth of young crocodiles, (2) extremely secretive behavior or occupancy of marginal habitats, or (3) high juvenile mortality. In most populations these factors are not mutually exclusive and may all play a role. Indeed, the last two 32 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) 76.9 AUGUST 1983 N=433 100 10.4 76 5.1 79.2 N U M B E R O F C R O C O D IL E S 300 JANUARY 1984 N=413 100 11.67.0 2.2 74.3 300 COMBINED N =44 7 100 5.010.0 1 . over0.3-0.9 ' 0.9-1.8 1.8-2.7 2.7 TOTAL LENGTH (m) FIGURE 10. Size-class distribution and the total population size estimated from the August 1983, January 1984, and combined survey data. THeRBJARNARSON: AMERICAN CROCODILE IN HAm 33 are major components of the population dynamics model proposed by Messel et al. (1981) for C porosus. In Etang Saumatre, rapid growth does not appear to be a factor (see following section). Subadults, however, do have a tendency to be found in more "marginal" habitats (see Habitat Selection), and this may have resulted in a slight underrepresentation of these crocodiles in the population surveys. The possibility of movement of subadults out of Etang Saumatre also cannot be ruled out. Local residents have reported crocodiles moving between Trou CaTman and Bang Saumatre, especially during periods of heavy rain. Crocodiles also have been reported crossing the arid strip between Lago Enriquillo and Bang Saumatre U. Ottenwalder pers. comm.). In both cases, however, the animals seen were most often adults; the incidence of migration of subadults remains unknown. If we assume that the population in Bang Saumatre has a stable age distribution, we then would be left with high juvenile mortality as the only explanation for the small number of subadults. While this mortality probably plays an important role, recent past events in the lake also must be considered. Prior to 1979 the lake was approximately 2 m below its present level. In many areas one can still see Conocatpus snags standing in water of this depth. Subsequently, three hurricanes hit Haiti in 1979 and 1980, causing the lake to rise to its present level and flood out into Conocatpus habitat over 41% of the lakeshore (Conocatpus fringe and Conocatpus flats habitats; see Habitat Selection). Unless exposed to considerable wave action, these areas were ideal habitat for young crocodiles, hiding by day in the Conocarpus root mats and emerging at night to feed on the abundant fiddler crabs and other invertebrates (see Diet). Although the amount of suitable juvenile habitat before the hurricanes is unknown, it almost certainly was considerably less than it is today. Aerial photographs of the lake when it was at a similarly low level (Bond 1935) show considerable stretches of barren shoreline. Furthermore, prior to 5-6 years ago, the major nesting areas on the eastern shore were the sites of temporary human settlements. People lived on the eastern lakeshore, cutting Conocatpus, making charcoal, and fishing, bringing freshwater across the lake from Fonds Parisien by boat. Remains of old thatch "ajoupas" were found in the middle of several of the nesting beaches. Nests were robbed and the eggs eaten (F. Conway pers. comm.) by residents of Fond Parisien. Undoubtedly, juvenile crocodiles also were killed. Since that time movement across the lake by boat has been outlawed by the Haitian government because of smuggling across the Dominican border, so no one lives near the nesting beaches. Consequently, because of reduced habitat availability and increased human disturbance for a period of time prior to 1977-1980, hatchling production and survivorship of juvenile crocodiles may have been 34 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) considerably lower than today. Based on growth rates of recaptured crocodiles (see Growth Rates), the ones in the 0.9-1.8 m size class would have been born during the period 1977-1980, and recruitment into this size-class would undoubtedly have been adversely affected by these factors. Thus it seem5 that both natural mortality and past changes in the level of human- related mortality and juvenile habitat availability may be factors contributing to the low observed proportion of subadults. Density and biomass Few data exist on any aspect of crocodilian population dynamics. This is especially true for C acutus where the lack of previous studies is due, at least in part, to the difficulty of accurately censusing these animals in their typical habitat (i.e. coastal wetlands). For comparative purposes, however, some information is available for several other crocodilians species, most notably Crocodylus niloticus, C. porosus, and Alligator mississippiensis. Density of crocodiles in Etang Saumatre was calculated on a linear basis (per km shoreline), as crocodiles are primarily littoral animals and generally do not move far from shore. Therefore, in [acustrine or riverine habitats, density is best described in this fashion. Based on the corrected survey data, the mean density of crocodiles in Bang Saumatre was 6.3/km (crude density, 71.2 km shore). Eliminating habitats unsuitable for crocodiles (rocky or high wave energy shores), the ecological density was 9.6/km (46.7 km shore). Density estimates for various crocodilians are presented in Table 8. The high degree of variability among these values undoubtedly results from a variety of factors such as: physical habitat structure, vegetation, water depth, degree of wave exposure, aquatic productivity and the availability of food, population structure, and even terrestrial habitat (inasmuch as it determines the suitability of the area for nesting). Little is known quantitatively about the roles these various factors play in determining population density. Crocodile density in Bang Saumatre is variable depending on habitat type and the degree of exposure to wave action (see Habitat Selection). Wood and Humphrey (1983) found that density in Alligator mississ*iensis was correlated to lake productivity (nitrogen concentration). Anecdotal accounts relate food availability to crocodile density (Montague 1983, Watson et al. 1971) or vice versa (Cott 1961, Fittkau 1970, 1975, Whitaker 1978, Glastra 1983), suggesting that in some instances crocodilians play a beneficial role in maintaining healthy fish populations. Although the factors mentioned above determine the attainable density, or carrying capacity of a particular habitat, in reality actual densities are usually held well below this value by human predation. Several hunted and THORBJARNARSON: AMERICAN CROCODILE IN HAm 35 5.0 - 7.3.22*-2.944.0 - r =0.998 LO G M A S S (g ) 3.0 - - 2.0- 11I lili 1.4 1.8 2.2 2.6 LOG TOTAL LENGTH (cm) FIGURE 11. Log-log plot of the length-mass relationship of crocodiles captured in Etang Saumatre. A maximum of 5 randomly chosen values are plotted for each 20 cm size class interval. 36 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) non-hunted populations are included in Table 8. At the time of censusing, the non-hunted Crocodylus niloticus populations probably existed in a more or less undisturbed state, and densities in these areas are quite high (13.1- 21/km). Furthermore, within each of these areas densities were considerably higher in favorable habitats. In parts of Lake Turkana, for example, densities reached 55.8/km (Graham 1968). The highest reported value for A. mississ 0.38). The importance of soil moisture content in selecting nesting areas is obvious as eggs depend on oxygen diffusion for respiration (Ackerman 1980), and gas diffusion rates are negatively correlated with the amount of water in 46 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) the soil. The mean water content of the nest soil (6.62%, SD=3.13, n=12) was significantly lower than for null sites (20.33%, SD=5.01, n=15) and reflected the fact that the areas selected for nesting were the well-drained old beach or charcoal mound sites. The mean water content for three sand nests measured in Florida was 10.3% (calculated from Lutz and Dunbar-Cooper 1982) and ranged from 4.89% to 19.25%, these extremes being recorded from a single nest over the period of incubation. As the soil parameter data were taken shortly after oviposition, the moisture values reflect what the females were encountering as they excavated the nests. On examining the nests, however, it was noted that the soil matrix near the eggs appeared to be more moist than the surrounding soil. This was tested by excavating holes of equal depth adjacent to four nests and measuring soil water content. The nest soil was found to be significantly wetter (Table 14, paired t-test,p < 0.05). The source of this moisture could be from cloacal fluids released by the female during oviposition and/or the mucous covering of the eggs. As during periods of low rainfall dessication can cause egg mortality in C acums eggs (Mazzotti 1983), this extra moisture may be important in preventing dessication mortality. Bustard (1971), however, found that Crocodylus novaeguineae eggs hatched normally in soil with only 2% water content. Vegetation., Nests generally were located near the ecotone between the Conocarpus-dominated riparian strip and the xeric upland flora, the species assemblage being a mixture of both communities (Table 15). The percent of shrub coverage at the nest sites (30.1%) was significantly lower than the null sites (40.6%) (Table 13). The canopy of these trees and shrubs was quite sparse and only provided partial shading. Nests were usually located near to, but not directly under, trees or shrubs. The mean distance from nests to the nearest tree/shrub over 1 m high was 2.1 m (SD=1.05 m). This, however, was not significantly different from the null sites (2.7 m, SD=2.7 m). Herbaceous cover was also sparse on the nesting beaches. The dominant grass, Uniola vitgata, usually was not found growing on the sand beaches or charcoal mounds used for nesting. Location of Nesting Beaches The majority of the nesting occurred over 6.6 km of shoreline on the eastern lakeshore (Fig. 12, containing 18 of the 21 nests in 1983 [2.7 nests/km shofe]). At least 13 nests occurred over the same area in 1984. Because of the difficulty of locating nests before hatching, this 1984 figure represents a minimum number and is probably anunderestimate. THORBJARNARSON: AMERICAN CROCODILE IN HAITI 47 Colonial nesting in the sense of Cott (1961), or in Lago Enriquillo where one may find 20-30 nests on a single nesting beach, was not in evidence. Nevertheless, several nesting beaches had more than one nest (Table 16). Single nests also were located on a small island near Malpasse (nesting beach L), and on Osprey Island along the north shore 2 km west of Las Lajas (nesting beach M, Fig. 12). Location of nesting beaches on the lake was primarily determined by three factors: (1) suitability of the terrestrial habitat for nesting (as discussed above), (2) human population density, and (3) the presence of nearby aquatic habitats protected from wave action. The effects of human population density can be seen in the case of a 1983 nest reported from the northwestern section of the lake near Tete Source (I. Lange pers. comm.). The nest was discovered by local residents, excavated, and the eggs were brought to a local market for sale. The area where the nest was located provides suitable nesting habitat and in the past may have been an important nesting site. High population density and heavy grazing/browsing by domestic stock today make this area marginal for nesting. Extensive searching failed to reveal any sign of nesting in 1984. All other known nesting areas are located away from areas of high human activity. The two island nest sites are relatively isolated with only occasional use by fishermen or charcoal makers. The nesting beaches along the eastern lakeshore are likewise removed from any significant human activity. Although the characteristics of the terrestrial environment are important for choosing nesting areas in that they are selected to minimize egg viability, the nature of the adjacent aquatic environment also is important. As mentioned above, deep water approaches are favored as they allow the crocodile easier access to the nest site. Nesting beaches also were located adjacent to areas protected from wave action. With the predominant winds from the east, the eastern lakeshore provides many such areas. In several locations along the western lakeshore suitable terrestrial environments exist for nesting, but these areas invariably are exposed to a high degree of wave action (the nesting area near Tete Source mentioned above is located adjacent to a protected water area). The relationship between calm water habitat and nesting is closely tied to the habitat preference of adult crocodiles, which tend to avoid areas with any wave action and concentrate in calm water habitats (see Habitat Selection). Calm water may be especially important for courtship and mating, as many of the associated behaviors are visually oriented and take place when the animals are floating at the surface of the water, thus requiring low wave amplitude. Once courtship and mating are finished, the females may select· the closest available nesting area. I observed a similar pattern of nesting beaches located adjacent to calm water habitat in Lago Enriquillo. 48 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) At the opposite extreme is the situation in Florida Bay, where crocodiles spend most of the year in protected mangrove habitat but the females venture out into the more exposed regions of Florida Bay to nest (Ogden 1978; Mazzotti 1983). Reasons for this behavior are not well understood but may be related to a lack of suitable nesting habitat in the protected regions of the bay. Clutch Size and Fertility The average clutch size at Etang Saumatre was 22.5 (SD-2.7) (Table 17), which is at the lower end of reported values for C acl£tus (Table 18). Overall egg fertility was 90.1% and ranged from 70.6 to 100% within clutches. Mean dutch mass was 2.18 kg, or approximately 4.4% of female body mass (mean female mass=49.7 kg, based on an average length of 236 cm). Clutch size has been demonstrated to be positively correlated with female size in C niloticus (Cott 1961, Graham 1968), and it is reasonable to assume that the same holds true for other crocodiles. Because the crocodiles in Etang Saumatre and Lago Enriquillo do not reach large sizes, this could explain the small dutch sizes in these lakes. Using data from Graham (1968) relating female length to dutch size (y=0.2909x-43.34, r=0.86, n=10; where y=dutch size and x=total female length in cm), the predicted clutch size for the average length female in Etang Saumatre (236 cm) is 25.3, which is in good agreement with the observed mean clutch size (22.5). Using this same relationship together with the mean egg mass (97 g) data and the length-weight relationship from this study, the predicted dutch size and mass can be calculated for females of different lengths. These relationships predict that dutch size remains a fairly constant 3-5% of body mass over a wide range of female lengths, but trending slightly downward with increasing female size (assuming that egg mass is independent of female size). Ferguson and Joanen (1983), however, found that larger female alligators laid larger eggs than smaller females. If this is true for crocodiles, clutch mass as a percentage of body mass may remain remarkably constant throughout life. Webb (1983) also found that clutch mass was approximately 5% of body mass in Croco*lus johnsoni. It should be noted that this relationship is for the average dutch size, and actual dutch size may vary considerably from year to year. Yadav (1979) reported nesting data from a captive pair of Croco*lus palustris where the female (2.80 m total length) oviposited annually for 15 consecutive years. Data for 12 years demonstrated that dutch size varied from 22 to 41 (mean=31.2, SD=5.2) with the high and low values being laid in consecutive years. THORBJARNARSON: AMERICAN CROCODILE IN HAITI 49 Nest Temperature Temperature of incubation determines the sex of Alligator mississupiensis (Ferguson and Joanen 1982, 1983), Croco*lus niloticus (Hutton 1984), C porosus, C johnsoni (Webb and Smith 1984), and a number of turtles (review in Bull 1980). As all crocodilians lack heteromorphic sex chromosomes (Cohen and Gans 1970), it is reasonable to assume that temperature dependent sex determination is a common feature shared by all crocodilians. As such, information on the temperature regimes of nests is an important aspect of nesting ecology. Thirteen temperature recordings were made for the top and the bottom of six egg clutches over a 30-hour period on 13-14 February 1984 (Table 19). Overall mean temperature for the egg clutches was 29.3 'C (SD=0.41). Temperature at the top of the clutch varied slightly more (mean temperature amplitude=0.9' C) than the bottom (0.6 'C). Nevertheless, on average, temperature remained remarkably constant, the largest temperature variation in any one nest being 1.8' C (nest 84-4, top) while air temperature over this period varied 8.9 ' C. This is even less variation than found by Lutz and Dunbar-Cooper (1982, 1984) for C acutus nests in Florida Bay (mean diel variation=l.4'C), and also less than values reported for vegetation mound nesting species (Chabreck 1973, Webb et al. 1977, Goodwin and Marion 1978). The diel temperature variation for a typical nest (84-8) is shown in Figure 14. The high thermal inertia of the soil results in the nest reaching its highest temperature during the night. Little can be said about the differences in temperature regimes between sand and charcoal nests. Of the six nests monitored, two were in charcoal mounds (84-2 and 84-8); these nests were the hottest and coolest nests measured, respectively. Nesting Behavior Crocodiles began visiting potential nest sites up to 28 days prior to nesting. Similar early visits were noted in C acums in Florida (Ogden 1978, Mazzotti 1983; P. Moler pers. comm.). During these early visits, females walk along the nesting beach and make periodic shallow digs in the substrate. As the time for nesting approached, deeper test holes were dug, often several in a very small area, or scattered around the nesting beach. These test holes either were left open or were filled in by the female before departing. Nest digging or egg laying were never observed in Etang Saumatre; however, observations in nearby Lago Enriquillo indicated that females begin nesting 50 BULLETIN FLORIDA SrATE MUSEUM VOL. 33(1) soon after dark. One female was discovered in the final stages of egg laying at 2315 h on 12 February 1982. After oviposition the female, using her tail and body, smoothed out the area surrounding the nest, making it difficult to find the exact location of the hole. During the incubation period females will remain in the vicinity of the nesting beaches, although they never were observed on land near the nest as has been reported for C niloticus (Cott 1961, Modha 1967). No nest predation was observed in Bang Saumatre during 1983 or 1984. In Lago Enriquillo dogs, and possibly mongoose (He,pestes auropunctatus), were reported to rob crocodile nests (J. Ottenwalder pers. comm.). The incidence of nest predation in Etang Saumatre, however, is very low. Crocodiles were not observed to be territorial around nest sites as has been reported for C acums in Mexico (Alvarez del Toro 1974). In fact, several nests were found within a few meters of one another, and two nests in 1984 (84-8 and 84-12) were laid (approximately 2 weeks apart) with their clutches almost contiguous. Crocodiles appear to nest on the same beaches year after year. The actual reuse of 1983 nest Sites in 1984, however, was only 46%. This figure is similar to the values obtained for C niloticus in the Okavango delta (44.3%, Graham et al. 1976; 44.1%, Blomberg in Graham et al. 1976). Of the 1984 nests, 15% were in areas used as nests prior to 1983 (based on egg shell fragments), and 31% were apparently in new sites. 34.0_ ..11 f\\\\\32.0- . CLUTCH. TOP . CLUTCH.80?10. 1 D. TE M P E R AT U R E ( 'C ) F7 28.0 16-0- , T 24.0- .-I -- 0800 1200 1600 2000 2400 0400 0800 1200 1600 HOUR FIGURE 14. Diel nest temperatufe variation (nest 84-8) over a 30-hour period, 13-14 February 1984. THORBJARNARSON: AMERICAN CROCODILE IN HAm 51 Tracks of female on nesting beaches in Etang Saumatre revealed an apparent random search component. Females could locate old nest sites without difficulty, but often would wander considerably during their nocturnal visits, or even come ashore in areas where no suitable nesting habitat occurred. This type of searching behavior may be important because of changes in the characteristics of the previously used nesting sites. In Etang Saumatre (and in Lago Enriquillo) many old nest sites have been inundated by the rising lake waters since the hurricanes of 1979 and 1980; others are unsuitable because the egg cavities would now be below the water table. This has required females to select entirely new nest sites in the last 5-6 years. This random searching by the female no doubt familiarizes her with potential nest sites in the area and facilitates switching to new nesting areas. The reuse of nest sites by individual females has been speculated on (Alvarez del Toro 1974, Ogden 1978) but is difficult to document. The only data concerning individual nest reuse for hole nesting crocodiles concerns C niloticus in Botswana (Graham et al. 1976), where aerial photographs of females on nests reveals that in two instances different females were photographed at the same nest site in consecutive years. Obviously, different females may use the same nest site in different years, and annual use of nest sites should not be construed as the work of one female unless other supporting data exists. Based on tracks, females returned to open the nest at the end of incubation. Some females were visiting the nest sites 2 weeks prior to hatching and probably visited the nest frequently before it finally opened. In several instances, eggshell membranes were found along the shoreline, indicating that females carry their young to the lake, picking up egg fragments in the process. In two of the 1983 nests, females left eggs covered in the nest after opening it. In both nests, two eggs contained pipped young, and the third egg held a dead embryo. Asynchrony in hatching also has been noted in C acums in Lago Enriquillo (J. Ottenwalder pers. comm.) and Florida (Mazzotti 1983). Diet Juvenile Crocodiles For the purposes of analyzing the differences in diet among crocodiles of varying lengths, four size-classes were defined (Table 20). The largest sample was obtained for juvenile crocodiles (the smallest two size-classes), and for these animals invertebrates composed the vast majority of prey items. No vertebrate remains were found in any crocodile of the smallest size class (< 0.5 52 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) m). In the 0.5-0.9 m class, the occurrence of vertebrates increased dramatically. Many of these, however, were samples with a few scattered mammal hairs (Mus or Rattus) or bird feathers. Prey mass represents a more unbiased estimate of diet because it considers only recently ingested food items (fresh and partly digested categories) so there is less potential for bias due to differential digestibility of prey (Jackson et al. 1974, Garnett 1985). Based on prey biomass (Table 21), invertebrates comprised the great majority (87.2%) of the food for 0.5-0.9 m crocodiles. The dominant prey item in terms of frequency of occurrence and mass was the fiddler crab, Uca beigersii. These crabs were very abundant (23.1- 121.8/m2) in all the protected shallow water habitats which juvenile crocodiles preferred. Juvenile crocodiles also ate considerable numbers of beetles (Coleoptera) and odonate larvae (Tables 20, 21). The occurrence of these prey items indicates two separate foraging strategies. The majority of beetles found in crocodile stomachs was of terrestrial origin (Table 22). Crocodiles never were seen foraging on land, but frequently were observed sitting in shallow water making sideswipes at surface disturbances. This method of prey capture probably results in the ingestion of terrestral insects (Coleoptera, Lepidoptera, and Hymenoptera) that accidentally fall into the water. The high occurrence of odonate larvae in the diet of these crocodiles suggests that they also actively forage underwater amongst the submerged vegetation and/or bottom sediments. In this manner crocodiles also may acquire gastroliths and accidentally ingest aquatic vegetation (Table 20). Very few juveniles were found with fish in their stomachs. Of the three juveniles (93%) that had recently eaten fish, two were captured in shallow water muddy lagoons where catching fish was perhaps more easily accomplished. All the fish eaten were small poeciliids (Limia sp. and Gambusia hispaniolae). Predation on mammals by juveniles was restricted to Conoca,pus swamps or in the thick marshy vegetation surrounding canal mouths. Subadult and Adult Crocodiles Only a limited sample (n=9) of stomach contents from crocodiles over 0.9 m total length was obtained (Table 20). Of these, four were over 1.1 m total length (1.20 m, 1.38 m, 1.95 m, and 2.43 m). Scooping was attempted on seven other cr*codiles over 2.0 m total length, but extracted no stomach contents. Although this may indicate a high incidence of empty stomachs (Graham 1968), it is equally likely that the scoop simply failed to bring up large food particles. THORBJARNARSON: AMERICAN CROCODILE IN HAITI 53 As has been pointed out by other authors (see Cott 1961) there is a dietary shift with age in crocodilians, from the predominantly invertebrate food of juveniles, to primarily vertebrate prey for adults. The incidence of both birds and fishes increased in the subadult and adult crocodiles in Etang Saumatre (Table 20). Large crocodiles also were known to take domestic stock (goats or sheep) and sometimes dogs. During January-February 1984, at least three goats were known to be killed and eated by crocodiles along the nesting beaches on the eastern lakeshore (pers. obs.). One adult (2.82 m male), when captured, had the remains of a goat in his mouth. At least two dogs were killed by a large male (3.5 m) in the spring at Tete Source over a 14-month period. Nevertheless, the primary food item of adults appears to be fish. Adult crocodiles frequently were seen in water 1-2 m deep where large fish (Tilapia and Cichlasoma) were abundant. In these areas crocodiles were observed sitting on the bottom making rapid sideways sweeps of the jaws to catch fish. Crocodiles also would take fish trapped in gill nets set by fishermen near Tete Source, and were not infrequently seen at night sitting on the bottom next to these nets. Habitat Selection Spatial Crocodile Distribution The distribution of crocodiles by lakeshore segment and size-class is summarized in Figures 15 (August 1983) and 16 (January 1984). These data are corrected for differences in the lengths of shoreline segments and expressed as density per km shore in Table 23. The highest concentration of hatchling and juvenile crocodiles (0.3-0.9 m) were found in section H, which contains the majority of the nesting beaches. Mazzotti (1983) found that hatchling C acutus would disperse rapidly from nest sites in areas exposed to wave action, moving to more protected waters. Hatchlings from the more protected creek nesting sites were less likely to move and generally remained in the vicinity of the nest. Rodda (1984) noted a high degree of philopatry among 10 first year C acums in Panama. These animals had average home range sizes of 330 m of shoreline and spent 80% of their time in core areas of only 200 m. In Etang Saumatre, of the 10 crocodiles (0.3-0.9 m) that were recaptured, eight were found in the same location where they were originally caught (mean recapture interval 143 days). Of the two that moved, one apparently did so in response to the rising lake waters that exposed a previously protected lagoon to considerable wave action. This juvenile moved 54 BULLETIN FLORIDA SrATE MUSEUM VOL. 33(1) 1 km into a temporarily flooded Conocarpus zone. The other juvenile moved 1.8 km along the eastern lakeshore over a period of 339 days. Subadults (0.9-1.8 m) also were found frequently in section H; they were also concentrated in the northwestern region of the lake (section E). The concentration of subadults in this area is interesting, as it also contained several apparently non-breeding males during the 1984 nesting season. Subadults had a greater tendency to move than did juveniles. Of the two subadults that were recaptured, one had moved (over 306 days) entirely across the lake, a straight-line distance of 10 km. As this individual probably moved along the shore, the actual distance travelled is closer to 22 km. The other subadult moved 0.3-0.4 km over a period of 84 days. The 1.8-2.7 m crocodiles, composed primarily of adult females, had a high density during the August survey in section G. During January the SECTION E N=25 < SECTION F N. 7 6A-10 A-3 N8. 8 8-1 C- 5 C-3 D- 2 D-0 b SECTION G N•68 A-53 8- 4 C - 10SECTION D N=7 D- 1 A-6 8-0 D-1 SECTION H N·257 A-217 8 14 C- 23 8 3 ''1, SECTION C 01234km N=14 SECTION B A- 9 N.18 8- 1 A-15C- 2JANUARY 1984 8- 0 D- 2 C- 3 - D- 0 SECTION A N.3 < A-3 C-0 8-0 0-0 FIGURE 15. Crocodile distribution by size class and lakeshore segments, August 1983. (Crocodile size classes (in m) are: A= 0.3-0.9, B= 0.9-1.8, C= 1.8-2.7,D=> 2.7; all values given represent total length.) THORBJARNARSON: AMERICAN CROCODILE IN HAm 55 majority of these animals was found in section H. In August, the 1.8-2.7 m crocodiles in section G were concentrated in 2 areas: (1) in shallow water "feeding grounds" that contained abundant TUapia, and (2) under an active heronry. Crocodilians have been reported to congregate under bird or bat colonies (Hopkins 1968, Guggisberg 1972, Messel et al. 1981), presumably to eat young or adults that fall into the water. January marks the beginning of the nesting season and therefore the concentration of 1.8-2.7 m crocodiles in section H (adjacent the nest sites) is not unexpected. Furthermore, the heronry in section G is not active during this time of year. The shift in the maximal abundance of these animals then appears to reflect the concentration of crocodiles in productive feeding grounds during the non- breeding season, and movement to the vicinity of nesting beaches sometime prior to January. Adult males (> 2.7 m) were distributed throughout the lake (excepting section A), but were found in the highest densities in section E during both the August and the January surveys. Section E contains a productive, SECTION E N,26 < SECTION F N= 11 .* A- 8 A-6 N 8-13 B-1 C- 1 C-1 D- 4 D-3 1# 77 * SECTION G N=57 A-38 8- 6 C - 11 SECTION D N=9 D- 2 A-8 8-1 D-0 SECTION H N=249 A-218 8- 16 C- 11 D- 4 lilli SECTION C 0123 4km N=18 SECTION 8 A- 13 N•18 8- 1 A-14C- 1 AUGUST 1983 B- 2D- 3 C- 1 D- 1 ~ SECTION A N.4 < A-4 C-0 8-0 D-0 FIGURE 16. Crocodile distribution by size class and lakeshore segments, January 1984. (Size classes as in Fig. 15). 56 BULLETIN FLORIDA SI'ATE MUSEUM VOL. 33(1) shallow-water (1-2 m) "feeding ground" and an abundance of Conocatpus for hiding in during the day, or during periods of rough weather. This area appears to be where the majority of crocodiles on the western lakeshore congregate. Distribution By Habitat Type The lakeshore was divided into 11 habitat types, which are listed along with their relative abundance in Table 24. Following is a brief description of each: Sand-grass-mud. Shallow gradient dropoff, sandy beaches, often ephemeral or constantly changing in conformation, Or mudflats. Usually exposed to wave action, often accumulating Batophora wrack. Salicornia flats. Restricted to the extreme southeastern end of the lake. Shallow gradient mud shores covered with Salicomia perennis. Conocarpus flats. Shallow water areas supporting dense or sparse growths of low stature Conocatpus erecms. Seepage marsh. Shoreline marsh areas, identified by the presence of freshwater vegetation, in areas where underground seepage of freshwater occurs. Canal marsh. Freshwater marsh around the mouth of irrigation runoff canals feeding into the lake. Conocarpus fringe. Moderate gradient shoreline fringed with Conocalpus that may grow out into shallow water, often on partially submerged sandbars, creating small protected lagoons. Acacia scrub. Moderate gradient sandy or somewhat rocky shores where the xeric upland floral association extends down to the lakeshore. Rocky shore, medium gradient. Medium dropoff rocky shores usually backed by xeric vegetation. Submerged forest. Found only on the eastern shore south of Las Lajas. High stature (to 10 m) Conoca,pus forest extending 20-50 m into the lake. Cove. Moderate gradient dropoff, gravel beaches located between rocky promentories along the north coast. THORBJARNARSON: AMERICAN CROCODILE IN HAITI 57 Rocky shore, steep gradient. Steep gradient dropoff rocky shores, usually little or no vegetation, usually a high degree of wave exposure. The density of crocodiles varied greatly in the different habitat types (Table 25). A chi-square goodness of fit test indicated the crocodiles were not randomly distributed throughout the various habitat types. Using a Z test of the form: s 0(i)-e(i) \,~(e(i))(1-e(i))/n (where s = test statistic, 0(i) = observed proportion of crocodiles in habitat i = o.. e(i) = proportion of the total lake shoreline in habitat i = e.. n = number of1' 1' crocodiles observed), the distribution of all crocodiles > 0.9 m was tested on a habitat by habitat basis against the null hypothesis of random distribution around the lake. Crocodiles < 0.9 m were not included in this analysis because they tended to remain in the vicinity of the nesting beaches and would bias the results towards the Conocatpus fringe habitat that contained the great majority bf the nests. The results of this 2-tailed test show the habitats where the crocodiles are significantly more abundant than would be expected according to the null hypothesis (preferred habitats), and the habitats where they are significantly less abundant (avoided habitats) (Table 26). Preferred habitats included Conoca,pus fringe, Conocatpus flats, Salicomia flats, submerged forest, and canal marsh. Both the medium and steep gradient rocky shores were avoided. Three factors determine why crocodiles are more abundant in the preferred habitats: (1) protection from wave action, (2) food availability, and (3) nesting habitat. Of these, the single most important factor was the degree of wave action. Crocodile density in exposed habitats (0.73/km) was much lower than along moderate exposure shorelines (8.55/km), which in turn had fewer crocodiles than protected habitats (10.93/km). A similar avoidance of wave action has been noted for C acutus (Ogden 1978, Mazzotti 1983) and other crocodilians (Cott 1961, Graham 1968, Woodward and Marion 1978, Messel et al. 1981). Because of the proximity of the eyes and nostrils to the surface of the water in a floating crocodile, any appreciable wave amplitude would interfere significantly with respiration and visibility. Wave action also makes movement more difficult and probably interferes significantly with feeding activity. The preference for Salicomia flats (100% protected) and Conoca/pus flats (83% moderate exposure, 17% protected) to some degree reflects this avoidance of wave action. However, these areas also were adjacent to productive shallow water areas that appeared to be favored feeding grounds for adults. 58 BULLEnN FLORIDA STATE MUSEUM VOL. 33(1) The submerged forest habitat was considered to be 100% moderately exposed to wave action, although areas well protected from wave action were located back within the vegetation. The major attraction of this habitat was, however, the presence of the active rookery with an estimated 300-400 pairs of egrets, herons, and ibises. Throughout the 3.2 km of this habitat type, crocodiles were seen only under or adjacent to the rookery. The rookery was not active during the January survey, consequently the submerged forest was not a preferred habitat during this time. In January, the preferred habitats switched to canal marsh and Conocamus fringe. Crocodiles apparently were attracted by the cover offered by the freshwater vegetation around the canals and always were found in high densities in or around these marshes. One of the two areas of canal marsh habitat type provided the only suitable crocodile habitat over 5 km of shoreline near Fonds Parisien, and so tended to concentrate crocodiles. Although crocodiles were found in high densities in these areas, the small amount of canal marsh did not make this an important habitat for the crocodiles. The preference for Conoca,pus fringe in January reflects the congregation of adult crocodiles around the nesting beaches during this time of year. The majority of the crocodiles seen in this habitat during January were 1.8-2.7 m individuals, composed primarily of adult females. Of these, 85% were seen adjacent to nesting beaches. Habitats avoided by the crocodiles typically were those exposed to wave action and offering no suitable cover. Crocodiles were rarely seen along steep or medium gradient rocky shores. Crocodiles also typically shunned the exposed sand-grass-mud habitats, although this did not show up as significant because of the tendency of some crocodiles, especially subadults (0.9-1.8 m) to use isolated patches along these shorelines (spring mouths and Conocarpus clumps). In fact, using the combined August and January surveys, the sand- grass-mud habitat is actually one of the "preferred" subadult habitats (Table 27). The relatively large number of 0.9-1.8 m crocodiles in this marginal habitat supports the suggestion of possible exclusion of some of the subadult population from more favored habitats. CONSERVATION Discussion Currently, there are few laws pertaining to wildlife in Haiti, and none concerning crocodiles. Although laws should be enacted affording protection to species currently endangered with extinction, the mere presence of laws THORBJARNARSON: AMERICAN CROCODILE IN HAm 59 protecting wildlife would have little effect (besides symbolic) as the arm of the government that deals with wildlife (Bureau des Ressources Forestieres et de la Production de la Faune, D6partement de L'Agriculture des Ressources Naturelles et de D6veloppment Rural) currently is so understaffed that effective protection could not be achieved. Furthermore, the nature of most of the human-related crocodile mortality (accidental drownings in nets or fish traps) is such that little can be done without making unrealistic attempts to change fishing techniques and/or fishermen's attitudes towards crocodiles. Even more troublesome for the crocodiles is the present rate of habitat destruction. Loss of coastal wetlands and high human population densities around those that remain have resulted in a sizeable reduction of the range of the crocodile in Haiti. The continued survival of those few, small crocodile populations that do remain, as well as that of other coastal wildlife species will depend on how these wetlands fare in the future. In this respect, perhaps the most positive step that can be taken would be to initiate a plan for the management of coastal resources. Because a significant proportion of the commercially utilized marine species of fish and invertebrates depend, at one point or another during their lifecycle, on mangrove ecosystems, the plan should, at the very least, include fisheries and mangrove harvest. The primary objectives of such a plan would be to insure the viability of these valuable coastal ecosystems which provide a livelihood and food for a significant portion of the Haitian human population. Within the framework of such a program could be included plans to protect wildlife and some of the critical habitat on which they depend. The most important region from this standpoint is the l'Ester area, containing Hispaniola's largest mangrove swamp. The l'Ester and its environs are the site of considerable fishing activity and unmanaged mangrove harvest. This area also contains a significant amount of wildlife including crocodiles, sea turtles, manatees, flamingos, and wading birds. A trial program of coastal resource management in the l'Ester region, if successful, could be expanded to include other coastal areas. Effective protection of the wildlife in coastal Haiti will depend on obtaining detailed information concerning critical habitats. With respect to crocodiles, this especially includes nesting beaches and nursery habitat for the hatchlings. Currently there has been interest shown by two international development organizations (U.S. Agency for International Development and the World Bank) in helping to develop programs fostering coastal resource management in Haiti. It is hoped that if such programs are developed in Haiti, plans will be made to include a wildlife component. The creation of wildlife preserves also could be done in conjunction with the newly established national parks program, currently being coordinated by the Institute National Haitien de la Culture et des Arts and the D6partement de L'Agriculture, des Ressources Naturelles et du D6veloppement Rural. Two areas which should be considered for protection in this regard are the 60 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) eastern shore of Etang Saumatre and the Rivitre Massacre-Lagon aux Boefs estuary. The eastern shore of Etang Saumatre is uninhabited, and contains virtually all of the lake's crocodile nesting areas. Additionally, this region supports a diversity of other wildlife including wading birds, ospreys, and a significant number of migratory waterfowl and shorebirds. Protection of this area easily could be accomplished as the vast majority of the land is owned by the Haitian government. Because.this land parcel borders on the Dominican Republic, a degree of international cooperation will be necessary if this plan is to prove effective. As the land is isolated from the rest of Haiti by water, and boats are prohibited from the lake (because of past smuggling), the area is inaccessible to Haitians. Aside from this, the lack of freshwater prevents any extensive human settlement. Currently, the only use of this land is by Dominican ranchers who graze their cattle and goats seasonally along the lakeshore. Another, more insidious, problem in Bang Saumatre is the shooting of adult crocodiles by Dominican (and Haitian) border guards. As both the border stations are adjacent to calm water areas regularly used by crocodiles, the shooting has been a steady drain on the crocodile population. During a 10-month period, at least 2 adult male crocodiles were shot by Dominican guards (the males are preferentially taken because the penis is used as an aphrodisiac). Based on a high and low estimate of 2-4 crocodiles taken in this manner every year, this represents a loss of 10-20% of the adult male population each year. This action is clearly illegal as the government of the Dominican Republic has officially declared the crocodile to be fully protected. Efforts should be made to put a stop to this unnecessary killing by bringing it to the attention of the superiors of the army personnel involved. The RiviBre Massacre, along the northeastern border with the Dominican Republic, contains Haiti's only riverine mangrove ecosystem. Crocodiles are found both in the river and in adjacent Lagon aux Boefs. The region surrounding these habitats is sparsely inhabited, and recently the Dominican Republic has declared the eastern bank of the river to be a national park. A joint Haitian-Dominican Republic project would be most effective in affording protection to the crocodile. Recommendations 1. Enact legislation protecting the crocodile. THORBJARNARSON: AMERICAN CROCODILE IN HAm 61 2. Establish a resource management area in the ['Ester region. Combine managed harvest of mangrove with protection of the region's wildlife, including crocodiles, sea turtles, manatees, flamingos, and wading birds. 3. Establish wildlife reserves on the eastern shore of Etang Saumatre and in the RiviBre Massacre/Lagon aux Boefs rea. 4. Stop the illegal shooting of crocodiles in Bang Saumatre by guards at Dominican Republic border stations. SUMMARY Prior to its colonization by Western man, probably all low elevation wetland habitats of any size in Haiti were inhabited by crocodiles. Today, the range of crocodiles in Haiti has been greatly reduced, with small populations remaining only in relatively isolated areas, usually associated with mangrove swamps. The largest remaining population (450 crocodiles of all sizes), however, is in Etang Saumatre, a landlocked lake in a semi-arid region only 30 km from the capital. The disappearance of crocodiles from their historical range has followed a consistent pattern relative to human population density and the amount of available mangrove habitat. Today, the few remaining populations are found in areas of low human population density that contain sufficient amounts of mangrove habitat for cover. An important modifying factor is the availabilty of freshwater, which is needed by hatchling crocodiles to maintain an adequate ion balance. Crocodiles are missing from Haiti's second largest mangrove area (Caracol Bay) apparently due to a lack of fresh or brackish water. Because of the tendency of crocodiles, especially subadults (0.9-1.8 m), to move long distances along the coast, in some areas (such as the southern coast of the Tiburon Peninsula and Ile de La Gonave) crocodiles are not infrequently seen over a wide distribution. In these regions crocodiles are often reported from areas not capable of supporting viable populations, but appear to be transient individuals. Habitat destruction and incidental killing, usually in fishermen's nets, represent the greatest threat to crocodiles in Haiti today. Use of croco(liles for food or their by-products is limited to areas bordering on the Dominican Republic. The crude density of crocodiles in Etang Saumatre (6.3/km shoreline) is relatively high compared to most other published values, although well below the values estimated for nearby Lago Enriquillo and several other nearly pristine African populations. This indicates that the population in Bang Saumatre is below its carrying capacity. In terms of biomass, the mean for the 62 BULLEAN FLORIDA SrATE MUSEUM VOL. 33(1) entire lake is 60.6 kg/km shore, or 92.3 kg/km shore when only considering areas of suitable habitat (ecological biomass). The sex ratio of animals below 1.8 m total length appears to be skewed towards males, over 1.8 m TL it is 1:1. Young crocodiles (> 0.9 m TL) grow at an average rate of 0.058 cm/day (21.2 cm/yr), considerably slower than reported values for C acutus in Florida. The reason for this slow growth rate is unknown. Compared to mainland populations, adults do not appear to grow as large in Etang Saumatre. The largest males seen were approximately 3.5 m TL, females 2.4 m TL. Nesting in Etang Saumatre is almost entirely restricted to the ~ uninhabited eastern lakeshore. Nests are exclusively of the hole type, generally dug in old beaches associated with moderate gradient shorefine promentories. Soil moisture appears to be the most important factor determining selection of nest sites. Egg-laying commences in late January, at the height of the dry season, and lasts approximately three weeks. Hatching begins in late April, coinciding with the start of the rainy season. Mean clutch size is low for this species (mean=22.5) and appears to be related primarily to the small size of the females. During 1983, 21 nests were located, suggesting that only 63.8% of the adult females nested that year. Egg fertility rate was 90.1%. and natural nest predation was almost non-existent. Crocodiles were found to be opportunistic feeders. The young subsisted primarily on the abundant fiddler crabs (Uca bemersii), but also ate a significant number of beetles and odonate larvae. Larger crocodiles consume an increasing proportion of vertebrate prey, the adults feeding primariliy on fish. The most important factor determining the distribution of crocodiles in the lake was the degree of wave exposure. 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The Blyth-Cadell rivers system study and the status of Crocodyfus porosus in tidaI waterways of northern Australia. Methods for analysis, and dynamics of a population of C porosus. Monog. 1. Pergamon Press, Oxford. 463 p. Messel, H., G. C. Vorlicek, A. G. Wells, and W. J. Green. 1982. Status and dynamics of Crocodylus porosus populations in the tidal waterways of northern Australia. IUCN Publ. (N.S.) Suppl. Paper. ISBN 2-8032-209-x pp 127-173. Messel, H., and G. C. Vorlicek. 1984. A review of the growth of Crocodylus porosus in northern Australia. IUCN Publ. (N.S.). ISBN 2-88032-095-1. pp. 171-215. Moore, J. C. 1953. The crocodile in the Everglades National Park. Copeia 1953:54-59. Moreau de St. Mery, M. L. E. 1796. Descripcion de la parte Espanola de Santo Domingo. Traduccion del Frances por el Lic. C. Armando R6driguez. Editora Montalvo. Santo Domingo (1944). 491 p. . 1797-8. Description topographic, physique, civile, politique et historique de la partie Francaise de l'IsIe de Saint-Domingue. 2 vols. Societe de l'Histoire des Colonies Francaises et Libraire Larose, Paris (1958). 788 p., 856 p. Modha, M. L. 1967. The ecology of the Nile crocodile (Crocody/us niloticus Laurenti) on Central Island, Lake Rudolf. E. Afr. Wild. J. 6:81-88. Montague, J. 1983. Influence of water level, hunting pressure and habitat type on crocodile abundance in the Fly River drainage, Papua New Guinea. Biol. Conserv. 26:309- 339. Myers, G. S. 1937. Freshwater fishes and West Indian zoogeography. Ann. Rep. Smithsonian Inst., pp. 339-364. OAS. 1972. Haiti. Mission d'assistance techni4ue integree. Secretariat General, Organisation des Eats Americains. Washington, D.C. 656 p. Ogden, J. C. 1978. Status and nesting biology of the American crocodile, Crocodylus acutus (Reptilia, Crocodylidae) in Florida. J. Herpetol. 12:183-196. Oviedo, F. G. de. 1526. Sumario de la natural historia de las Indias. Fondo de Cultura Economica,-Biblioteca Americana, Mexico (1950). 275 p. Parker, I . S. C., and R. M. Watson. 1970. Crocodile distribution and status in the major waters of western and central Uganda. E. Afr. Wildl. J. 8:85-103. Pooley, A. C. 1962. The, Nile crocodile Crocodyius niloticus. Notes on the incubation period and growth rate ofjuveniles. The Lammergeyer 2:1-55. Powell, J. 1971. The status of crocodilians in the United States, Mexico, Central America, and the West Indies. IUCN (N.S.) Suppl. Paper 32:72-82. 66 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) Puelle, D. W. 1983. Status of inland aquaculture in Haiti. Report to US. Agency for International Development, Port-au-Prince, Haiti. 44 p. Ritter, K 1836. Naturhistorische reise nach der westinischen Insel Hayti. Hallberger, Stuttgart. 206 p. Robb, J. 1980. New Zealand amphibians and reptiles. Collins, Auckland. 128 p. Rodda, G. 1984. Movements of juvenile American crocodiles in Gatun Lake, Panama. Herpetologica 40(4):444451. Rodriguez, C. A 1915. Geografia fisica, politica Y bistoria de la Isla de Santo Domingo o Haiti. J. R. Wa., Garcia, Santo Domingo. 460 p. Schmidt, IC P. 1924. Notes on Central American crocodiles. Field Mus. Nat. Hist. Zool. Ser. 12:77-96. Schwartz, A. 1978. The herpetogeography of Hispaniola, West Indies. Studies on the Fauna of Curacao and other Caribbean Islands 41:86-127. Staton, M. A., and J. R. Dixon. 1975. Studies on the dry season biology of Caiman crocod#us crocodilus from the Venezuelan Llanos. Mem. Soc. Cienc. Nat. La Selle 35:237- 265. Steedman, M. 1939. Unknown to the World, Haiti. Hurst and Blackett, London. 287 p. Taylor, J. A., G. J. W. Webb, and W. E. Magnusson. 1978. Methods of obtaining stomach contents from live crocodilians (Reptilia, Crocodylidae). J. Herpetol. 12:415-417. Taylor, J. A. 1979. The food and feeding habits of subadult Crocodylus porosus in northern Australia. Aust, Wildl. Res. 6:347-360. Tipenhauer, L. G. 1893. Beitrage zur geologic Haitis. V. Petermann's Mitt. 47:VII. Walter, H. 1973. Vegetation 6f the earth in relation to climate and the eco-physiological conditions. Springer-Verlag, New York. 237 p. Watson, A M., A. D. Graham,.R. H. V. Bell, and LS.C. Parker. 1971. A comparison of four East African crocodile (Crocodylus niloticus Laurenti) populations. E. Afr. Wildl. J. 9:25-34. Webb, G. J. W., R Buckworth, and S. C. Manolis. 1983. Crocodylus johnstoni in the McKinlay River area, N.T. III. Growth, movement and the population age structure. Aust. Wildl. Rel 10.383-401. Webb, G. J. W., and S. C. Manolis. 1983. Crocody/us Johnstoni in the McKinlay River area, N.T. V. Abnormalities and injuries. Aust. Wildl. Res. 10:407-420. Webb, G. J. W. and H. Messel. 1977. Abnormalities and injuries in the Estuarine crocodile, Crocodylus porosus. Aust. Wildl. Res. 4:311-319. Webb, G. J. W., H. Messel, and W. Magnusson. 1977. The nesting of Crocodyius porosus in Arnhem Land, northern Australia. Copeia 1977:238-249. Webb, G. J. W., H. Messel, J. Crawford, and M. J. Yerbury. 1978. Growth rates of Crocody/us porosus from Arnhem land, northern Australia. Aust. Wildl. Res. 5:385-399. Webb, G. J. W., and A M. A Smith. 1984. Sex ratio and survivorship in the Australian freshwater crocodile Crocodylusjbhnstom. Pp. 319-355 in M. W. J. Ferguson (ed.). The Structure, Development and Evolution of Reptiles. Academic Press, Orlando. Wells, J. W. 1893. A survey journey in Santo Domingo: West Indies. Roy. Geog. Soc. Suppl. Papers 3:104-176. Wetmore, A., and W. M. Perrygo. 1931. The cruise of the Esperanza to Haiti. Explorations and Fieldwork of the Smithsonian Institution in 1930. pp. 59-66. Whitaker, R 1978. The beneficial role of the mugger (Crocodylus palustris) in aquatic habitats. Unpubl. ms. 3 p. Whitfield, A. IC, and S. J. M. Blaker. 1979. Predation on striped mullet (Mugi/ cephalus) by Crocod*s niloticus at St. Lucia, South Africa. Copeia 1979:266-269. Wood, J. M., and S. 1 Humphrey. 1983. Analysis of Florida alligator transect data. Coop. Fish. Wildl. Res. Unit, Tech. Rept. no. 5. 49 p. Woodring, W. P., J. S. Brown, and W. S. Burbank. 1924. Geology of the Republic of Haiti. - Department of Public Works, Port-au-Prince. 631 p. Woodward, A R., and W. R. Marion. 1978. An evaluation of factors affecting night-light counts of alligators. Proc. 32nd Ann. Conf. S.E. Assoc. Fish Wildl. Agencies 32:291- 302. THORBJARNARSON: AMERICAN CROCODILE IN HAm 67 Yadav, R. N. 1979. A further report on breeding the mugger crocodile Crocodyfus palustris at Jaipur Zoo. Int. Zoo Yrbk. 19:66-68. 68 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) Table 1. Mangrove area and crocodile distribution in coastal departments (major islands considered separately). Department Mangrove area Shoreline Sq km mangrove (sq km) (km) per km shore I. Crocodiles present Nord Est 44.6 60 0.74 Artibonite 93.3 140 0.66 Sud 16.9 230 0.07 La Gonave 11.5 140 0.08 Ile A Vache 16.1 40 0.40 Mean 0.39 II. Crocodiles absent Nord 13.4 85 0.16 Nord Ouest 0.7 180 0.00 Ouest 7.5 155 0.05 Grande Anse 18.0 235 0.08 Sud-Est 0,0 145 0.00 Ile Tortue 1.1 85 0.01 Mean 0.05 Table 2. Human population density and crocodile distribution in coastal communes and major islands which historically contained crocodiles. Crocodiles present Crocodiles extirpated Commune Population Commune Population density density (per sq km) (per sq km) Ferrier 6 Caracol 10 Terrier Rouge 25 Terre Neuve 51 La Gonave 72 Baradbes 90 Aquin 116 Dame Marie 114 Gonmves 129 Bas Limba 154 Ile a Vache 158 Petit Goave 229 Grande Saline 171 Limonade 235 Cavaillon 237 Eamie 269 Torbeck 297 Cap Haitien 1079 Mean density = 134.6 Mean density = 247.9 THORBJARNARSON: AMERICAN CROCODILE IN HAITI 69 Table 3. Human population density and crocodile distribution for inland communes which historically contained crocodiles. Crocodiles present Crocodiles extirpated Commune Population Commune Population density density (per sq km) (per sq km) Ganthier 72 Miragoane 234 Thomazeau 112 Cayes 251 Mean density = 92 Mean density = 243 Table 4. Crocodile population status and ecological life zone, Crocodiles present Crocodiles extirpated Location Life Zone Location Life Zone Tiburon Peninsula, Laboreaux to Capolo dry Caracol moist Tiburon Peninsula, St. Louis du Sud- Tiburon Peninsula, l'Acul moist north and west coasts moist Ile A Vache moist La Gonave (eastern) moist La Gonave (western) dry Caracol dry Artibonite dry Etang Laborde moist l'Ester dry Etang Miragoane moist Riviere Massacre- Lagon aux Boefs dry Etang Saumatre- Trou Caiman dry 70 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) Table 5. Wilcoxon-rankanalysis ofcoastal crocodile distribution in relation to human population density and amount of mangrove habitat. Arrondissements and major islands which historically contained crocodiles. Artondissement Population Mangrove Combined Crocodiles or island rank rank rank present Gonaives 4 3 1 yes La Gonave 3 8 2.5 yes Trou-du-Nord 9 2 2.5 no Ft. Libertd 1 12 4 yes Nippes 7 6 5 no Dessalines 13 1 6 yes St. Marc 5 11 7 yes Aquin 10 7 8.5 yes Ile a Vache 12 5 8.5 yes Tiburon 2 16.5 10 no Grande Anse 6 13 11 no Limbt 11 10 12.5 no Cap Haitien 17 4 12.5 no Port-au-Prince 14 9 14.5 no Port-de-Paix 8 15 14.5 no Leogane 15 14 16 no Borgne 16 16.5 17 no Note: Arrondissements (the next largest political subdivision above Communes) wereused in this analysis as habitat area data were not available for Communes. THORBJARNARSON: AMERICAN CROCODILE IN HAITI 71 Table 6. Chemical analyses or lake water, Etang Saumatre. Sources* A B C D 1. Total dissolved Solids (ppm) 7432 10296 12700 11606 2. Conductivity (mohm/cm) ----- ----- 20000 18500 3. Dissolved oxygen 6.2 8.1-8.6 4. total phosphate 0.028 0.35 5. Nitrate trace -- 3.9 6. Ca 94 127 118.8 7. Mg 279 393 498.9 8. Na 2159 3180.0 9. K 3040 86.0 10. Cl 3660 5154 6098.0 11. SO4 711 1001 500.0 12. CO3 46 24 0.0 13. HCO3 161 223 348.7 14. Fe 0.48 trace ----- ----- 15. PH ----- 8.5 7.6 8.1 16. Transparency (m) 3.25 2.0-3.6 ----- * Sources: A = Woodring et al. 1921 B = Bond 1935 C = DARNDR 1979 D = K. L*kerkerker pers. comm. Note: In 1921 and 1933 values for Na and K were combined Table 7. Sex ratio by size class: Etang Saumatre. Size class (m) Males Females Males/Females 0.3-0.9 16 10 1.60 0.9-1.8 8 5 1.60 1.8-2.7 5 7 0.71 >2.7 3 0 ---- 72 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) Table 8. Crocodilian density estimates. Species Density Location (per km) Source Crocodylus niloticus Ethiopia: Awash River upper 7 a middle 3-20 a lower 2 a Lake Margherita 1.25 a Blue Nile 2-4 a Omo River hunted 7.5 a unhunted 21 a Uganda: Lower Semiliki River 0.81 b Lake Albert 0.06 b Albert Nile 0.39 b Victoria Nile 13.1 c Kenya: Lake Turkana 13.4 d Upper Lorian Swamp 8.5 c Tanzania: Grumeti River 2.2 c Crocodylus porosus Australia: Northern Territory mean 1.61-1.67 e highest 8.75-10.1 e Western Australia Kimberly System 2.02-2.23 e Queensland Cape York Peninsula 1.47-1.62 e Crocodylus porosus-novaguineae Papua New Guinea: hunted 0.8 f unhunted 1.6 f Crocodylus acutus Haiti: Etang Saumatre crude density 6.3 g ec6logical density 9.6 g Alligator mississippiensis USA: Florida lakes 7.8 h rivers 2.5 h canals 2.5 h Sources: a = Cott and Pooley 1971 e = Messel et al. 19828 b = Parker and Watson 1970 f = Montague 1983 c = Watson et al. 1971 g = This study d = Graham 1968 h = Wood and Humphrey 1983 Note: Figures for Messel et al. 1982 are 95% confidence intervals for non-hatchling crocodiles. Table 9. Size class contribution to total population biomass: Etang Saumatre. Size 'class (m) Biomass (kg) Percent of total bbmass 0.3-0.9 201.1 4.2 0.9-1.8 370.4 7.8 1.8-2.7 2,046.6 43.2 > 2.7 2,123.7 44.8 Total 4,741.8 100.0 Table 10. Summary of reported wild crocodile growth rates (cm/day). Age class Species Location Growth rate Source Hatchlings Crocodylus acutus Florida 0.158 a 0.112 b 0.118 c Crocodylus porosus Australia 0.188 d 0.100-0.120 e 1-2 Years Crocodylus acutus Florida 0. 107 a Crocodylus porosus Australia 0.076 e 3-4 years Crocodylus porosus Australia 0. 063 e Sources: a = Gaby et al. 1981 d = Magnusson 1978 b = Mazzotti 1983 e = Messel and Vorlicek in press c = Moler pers. comm Table 11. Reported values of annual breeding effort for adult female crocodilians. Species Locadon % breeding Source Alligator mississippiensis Louisiana 68. 1 Chabreck 1966 Crocodylus nitoticus Zambia 80.0 Cott 1961 Botswana 67.0 Blomberg 1982 Kenya 87.6 Graham 1968 Crocodylus acutus Florida 72.0 Mazzotti 1983 Haiti 63.8 This study Crocodylus johnsoni Australia 90.0 Webb et al . 1983 74 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) Table 12. Nest hole dimensions (cm): Etang Saumatre. Standard Dimension Mean deviation Range N Depth to top of clutch 24.1 4.7 16-33 13 Depth to bottom of dutch 37.9 4.3 30-45 13 Egg chamber width 32.4 4.3 28-42 12 Table 13. Summary of nest site and null site parameters for Etang Saumatre. Standard Parameter Nest/Null Mean deviation Range N Distance from lake (m) nest 27.5 11.8 7-47 31 null ..... -- Height above lake (m) nest 1.2 0.5 0.6-2.1 31 null 0.6 0.4 0.3-1.5 15 Soil pH nest 6.2 1.6 5.2-7.1 15 null --- --- ---- -- Soil moisture (% water) nest 6.62 3.13 3.4-14.3 12 null 20.33 5.01 6.25-28.57 15 Percent shrub/tree coverage nest 30.1 14.5 10-60 29 null 40.6 34.3 0-90 15 Percent grass cover nest 5.9 5.8 0-20 29 null 40.0 35.1 0-100 15 Percent leaf litter cover nest 18.4 8.6 10-30 29 null 8.0 9.4 0-30 15 Height of vegetation (m) nest 3.4 0.6 2.0-4.5 27 null 3.0 1.1 0.0-4.5 15 Distance to nearest tree nest 2.1 1.1 0.5-5.0 27 null 2.7 2.7 1.0-8.0 15 Table 14. Soil water content: nests vs adjacent holes. Soil moisture (percent water) Nest Nest Adjacent hole Difference 84-1 9.67 3.92 -5.75 84-2 4.55 3.50 -1.05 84-8 6.32 3.17 -3.15 84-11 4.29 1.45 -2.84 THORBJARNARSON: AMERICAN CROCODILE IN HAITI 75 Table 15. Incidence of vegetation over 1 m tall within a Sm radius of 25 nest sites. Species % Species % Acacia famesiana 88 Prosopis jutiflora 28 Conocamus €rectus 12 Lemaireocereus hystrix 8 Pithecellobium circinale 32 Consolea moniliformis 4 Guaicum oficinale 28 Neoabbottia paniculata 4 Table 16. Number of nests at nesting beaches Etang Saumatre 1983-1984. Nesting 1983 1984 Nesting 1983 1984 Beach Nests Nests Beach Nests Nests 3 2 H 1 0 2 3 I 1 0 2 2 J 1 0 0 4 1M U 0 0: 1> 3 2 K 0 1 2 1 L 1 0 1 1 M 1 0 20 Table 17. Egg dutch data: Etang Saumatre. Standard Parameter Mean deviation Range N Clutch size 22.5 2.7 17-28 14 Egg mass (g) 97.0 8.1 80-116 68 Egg dimensions (mm) width 45.4 1.00 42.4-48.8 83 length 76.5 3.28 70.7-82.4 83 Clutch fertility (%) 90.1 10.5 70.6-100.0 7 76 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) Table 18. Reported clutch sizes for Croco*lus acutus. Clutch Location size N Source Florida 39.3 8 Mazzotti 1983 39.1 8 Lutz and Dunbar-Cooper 1982 44 20 Ogden 1978 Colombia 40-60 -- Medem 1981 Panama 46 1 Breder 1946 Honduras 22 1 Schmidt 1924 Dominican Republic 23.8 80 Inchaustegui et al. 1980 Haiti 22.5 14 This study Mexico 30-60 -- Alvarez del Toro 1974 Table 19. Nest temperature data from six nests at Etang Saumatre. Average dutch temperature Temperature range Nest Top Bottom Mean Top Bottom 84-1 29.1 29.3 29.2 28.8-29.4 29.1-30.1 84-2 30.1 30.2 30.1 29.9-30.5 30.0-30.5 84-4 29.5 29.2 29.3 28.8-30.6 29.0-29.6 84-7 28.9 29.2 29.0 28.5-29.4 29.0-29.5 84-8 28.9 29.1 29.0 28.7-29.5 28.9-29.3 84-11 29.1 29.3 29.2 28.8-29.5 29.1-29.6 THORBJARNARSON: AMERICAN CR.OCODILE IN HAITI 77 Table 20. Crocodile diet by frequency in stomach samples. Crocodile size class <03 m 0.5-0.9 m 0.9-1.8 m >1.8 m Prey item (N=14) (N=43) (N=7) (N=2) Crustacea 85.7 90.7 71.4 0.0 Coleoptera 78.6 72.1 14.3 0.0 Odonata 64.3 46.5 42.9 0.0 Arachnida 28.6 30.2 42.9 0.0 Scolopendera 21.4 2.3 0.0 0.0 Hymenoptera 14.3 4.6 0.0 0.0 Lepidoptera 21.4 0.0 0.0 0.0 Amphipoda 14.3 0.0 0.0 0.0 Gerridae 7.1 0.0 0.0 0.0 Mantidae 0.0 2.3 0.0 0.0 Osteichthyes 0.0 11.6 0.0 100.0 Reptilia 0.0 2.3 0.0 0.0 Aves 0.0 2.3 28.6 50.0 Mammalia 0.0 11.6 14.3 0.0 Nematodes 35.7 39.5 57.1 50.0 Gastroliths 0.0 13.9 28.6 50.0 Vegetation 87.5 67.4 57.1 50.0 Table 21. Diet based on percent of mass of fresh and partly digested food items. Crocodile size class < 0.5 m 0.5-0.9 m 0.9-1.8 m Food item (N=8) (N=28) (N=5) Crustacea 33.5 62.3 32.6 Odonata 0.0 10.3 35.3 Coleoptera 0.0 8.9 0.0 Arachnida 4.0 4.9 14.5 Hymenoptera 25.0 0.5 0.0 Gerridae 12.5 0.0 0.0 Amphipoda 25.0 0.0 0.0 Osteichthyes 0.0 9.3 0.0 Aves 0.0 0.0 17.7 Reptilia 0.0 3.5 0.0 Table 22. Prey items identified from the stomach contents or observed ingestion by crocodiles from Etang Saumatre Terrestrial prey IIX Class.Mammalia I. Class Insecta Mus musculus (Muridae) Rattus ip. (Muridae) Coleoptera Capra hircus (Capridae) Canisfamiliaris (Canidde) Bothynus sp. (Scarabeidae) 6>docephala sp. (Scarabeidae) Aquatic prey Phy#ophaga sp. (Scarabeidae) Conems sp. (Elateridae) I. Class Insecta Etrophoms sp. (Elateridae) Lagocheina sp. (Cerambycidae) Coleoptera Chosoborhns sp. (Buprestidae) Tropistemus sp. (Hydrophilidk) Se/enophoms sp (Carabidae) Calosoma sp (Carabidae) Hemiptera Ciandeta sp (Cicindelidae) (Belostomatidae) Acaties sp. (Curcutionidae) Artipus sp. (Tenebrionidae) Odonata Orthoptera Macrod(plax sp (Libelluljdae) (Blattydae) Brachymesia sp. (Libelullidae) (Mantidae) Il. Class Crustacea II. Class Crustacea Decapoda Amphipoda Ucabe,gedii (Ocypodidae) Tethorchestia sp. (Talitroidae) III. Class Arachnida III. Class Chilopoda (Pisauridae) Scolopenera alkmans IV. Class Osteichthyes (Scolopendridae) Limia,sp. (Poeciliidae) IV. Class Arachnida Gambusia hispaniole (Poecil iidae) Tetragnatha sp. (Araneidae) V Class Reptilia VII. Class Aves Tmchemys.decorata (Emydidae) Dulus dominkus (Dulidae) Gallus gallus (Gallidae) THORBJARNARSON: AMERICAN CROCODILE IN HAITI 79 Table 23. Crocodile density (per km) in Etang Saumatre by shoreline section and size class. Size class (m) Shore section 0.3-0.9 0.9-1.8 1.8-2.7 >2.7 Total August survey T O m m o 0 0 0 > m Q 7 1 tr1 U n t Il > 0.49 0.00 0.00 0.00 0.49 2.00 0.29 0.14 O.14 2.57 1.26 0.10 0.10 0.29 1.75 1.07 0.13 0.00 0.00 1.20 1.86 3.02* 0.23 0.93* 6.04 0.56 0.09 0.09 0.28 1.02 5.28 0.83 1.53* 0.28 792 13.36* 1.00 0.69 0.25 15.24 Total 25.88 5.46 2.78 2.17 January survey 0.37 0.00 0.00 0.00 0.37 2.14 0.00 0.43 0.00 2.57 0.87 0.10 0.19 0.19 1.35 0.80 0.00 000 0.13 0.93 2.33 1.86* 1.16 0.46* 5.81 0.28 0.09 0.28 0.00 0.65 7.36 0.56 1.39 0.14 3.10 13.56* 0.87 1.43* 0.19 16.05 Total 27.71 3.38 4.88 1.11 * denotes highest density for that size class 80 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) Table 24. Shoreline habitat categories and amount of each habitat type. Shoreline occupied Percentlake Habitat type (km) shoreline Sand-grass-mud 3.5 4.92 Salicomia flats 2.9 4.07 Conocatpus flats 8.9 11.94 Seepage marsh 3.6 5.10 Canal marsh 0.4 0.56 Conocatpus fringe 17.2 24.72 Acacia scrub 9.5 13.34 Rocky 5hore, medium gradient 5.6 7.87 Submerged forest 3.2 4.49 Cove 0.6 0.84 Rocky shore, steep gradient 15.8 22.19 Total 71.2 100.00 Table 25. Crocodile density by habitat type. Survey Density Mean density Habitat date (per km) (per km) Sand-grass-mud August 3.14 January 1.14 2.14 Salicomia flats August 6.21 January 9.65 7.93 Conocarpus flats August 8.54 January 8.54 8.54 Seepage Marsh August 4.44 January 3.61 4.03 Canal marsh August 17.50 January 25.00 21.25 Conocatpus fringe August 14.77 January 14.24 14.51 Acacia scrub August 2.63 January 1.89 2.26 Rocky shore medium gradient August 0.36 January 1.07 0.72 Submerged forest August 3.44 January 2.19 2.82 Cove August 8.33 January 0.60 4.17 Rocky shore steep gradient August 0.13 January 0.19 0.16 THORBJARNARSON: AMERICAN CROCODILE IN HAm 81 Table 26. Preferred and avoided habitat types, subadult and adult crocodiles (> 0.9 meters). Preferred habitats Avoided habitats Salicomia flats Rocky shore, medium gradient August Conocarpus flats Rocky shore, steep gradient Submerged forest Canal marsh Rocky shore, steep gradient January Conoca,pus fringe Table 27. Preferred and avoided habitats or subadult crocodiles (0.9-1.8 m): combined survey data. Preferred habitats Avoided habitats Sand-grass-mud Rocky shore, steep gradient Salicomia flats Conocatpus flats 82 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) APPENDIX I Distribution of Mangrove in Haiti Haiti, with a shoreline of 1525 km, has approximately 22,300 ha of mangrove forest. While composing only 0.8% of the country's area, mangroves constitute what is probably the least disturbed natural forested ecosystem type in Haiti today. Although mangroves are scattered around the coast in association with sheltered bays, estuaries, and coastal lagoons, appraximately 40% (9000 ha) of the mangrove habitat is concentrated in the l'Ester- Artibonite region. Taken together, the four. largest mangrove forests contain 70.6% of the mangrove habitat (see below). Lugo and Snedaker (1974) have developed a classification of mangrove forest types based on physiognomic characteristics. Using this system, the majority of the mangroves in Haiti fall into the fringe mangrove category, growing in relatively protected areas and receiving little freshwater influx. A similar situation has been described by Lugo and Cintron (1975) in Puerto Rico, where fringe mangroves dominate in protected areas that are located in the subtropical dry forest live zone. Lugo and Cintron (1975) noted that in areas with greater rainfall and wave exposure basin and riverine mangroves tended to dominate. Similarly, in Haiti, the four largest fringe forests (1'Ester, Baie de Caracol, Port-au- Prince, and Aquin) are located in relatively low wave-energy areas which receive less than 100 cm of rain annually (subtropical) dry life zone of the Holdridge system). Basin forests are typically located in the subtropical moist zone (100-200 cm rain annually) and generally along high energy shorelines. THORBJARNARSON: AMERICAN CROCODILE IN HAITI 83 Appendix I continued. List of major mangrove swamps in Haiti. Percent of Area Country Forest Location (ha) total type I. North coast A. Ft. Libertd area 1. Rivitre Massacre 60 0.27 R,B 2. Coastal 70 0.31 B,F 2. Baie de Ft. Libert6 340 1.52 F,B o n to Baie de Caracol 3,990 17.84 F Cap Haitien 760 3.40 B,F Limba 1. Baie de l'Acul 480 2.15 F,B 2. Rivitre Limbt 100 0.45 B E. Port-de-Paix 70 0.31 B II. West Coast A. Anse Rouge 350 1.57 F B. l'Ester 8,490 37.97 F C. Artibonite 490 2.19 F,B D. Port-au-Prince 670 3.00 F III. Tiburon Peninsula A. Petit Goave 50 0.22 F B. Trouin 70 0.31 B C. Miragoane 350 1.57 F D. Baraddres 1,200 5.37 F,B E. St. Jean du Sud 180 0.81 F F. Cayes area 1. Marsay 140 0.63 F,B 2. Cavaillion 350 1.57 B 3. Mombin 60 0.27 B 4. Rivitre Millionaire 80 0.36 B 5. Scattered coastal 400 1.79 F,B G. Aquin 490 2.19 F IV. Satellite islands A. Ile Tortue 110 0.49 F B. Ile la Gonave 1,150 5.14 F C. Grand Caymite 250 1.12 F D. Ile 8 Vache - 1,610 7.20 B Total area 22,360 * Mangrove forest types: F = fringe; B = basin; R = riverine. 84 BULLErIN FLORIDA SrATE MUSEUM VOL 33(1) APPENDIX II Aquatic and Semiaquatic Avifauna, Native Fish Fauna, and the Dry Forest Vegetative Association of Etang Saumatre Common name Scientific name Family AVIFAUNA Pied-billed grebe Podilymbuspodiceps Podicepiedidae Great blue heron Ardea herodias Ardeidae Green heron Butorides viridescens Ardeidae Little blue heron Florida caerulea Ardeidae Great egret Casmerodius albus Ardeidae Snowy egret Egretta. thula Ardeidae Tricolored heron Hydranassa tricolor Ardeidae Yellow-crowned night heron Nyctanassa violaceae Ardeidae Black-crowned night heron Nycticorax nycticorax Ardeidae Least bittern Ixobrychus exilis Ardeidae Glossy ibis Plegadis falcinellus Threskiornithidae Flamingo Phoenicopterus ruber Phoenicopteridae West Indian tree duck Dendrocygna arborea Anatidae Northern pintail Anas acta Anatidae Bahama pintail Anas bahamensis Anatidae Blue winged teal Anas discors Anatidae American widgeon Anas americana Anatidae Lesser scaup Aythya afinis Anatidae Ruddy duck Oxyurajamaicensis Anatidae Masked duck Oxyura dominica Anatidae Osprey Pandion haliaetus Pandionidae Purple gallinule Porphyrula martinica Rallidae Common gallinule Gallinula chloropus Rallidae Caribbean coot Fulica caribeae Rallidae Northern jacana Jacana spinosa Jacanidae Semipalmated plover Charadrius semipalmatus Charadriidae Thick-billed plover Charadrius wilsonia Charadriidae Killdeer Charadrius vociferous Charadriidae Black-bellied plover Pluvialis squatarola Charadriidae Ruddy turnstone Arenaria interpres Charadriidae Black-necked stilt Himantopus mexicanus Recuivirostridae Spotted sandpiper Actitis macularia Scolopacidae Greater yellowlegs Tringa melanokuca Scolopacidae Lesser yellowlegs Tringa flavipes Scolopacidae Lfast sandpiper Calidris minutilla Sc6lopacidae Western sandpiper Calidris mauri Scolopacidae Laughing gull Larus atricilla Laridae Least tern Stema albifrons Laridae Royal tern Thalasseus maximus Laridae Caspian tern Hydroprognecaspia Laridae Belted kingfisher Ceryle akyon Alcedinidae THORBJARNARSON: AMERICAN CROCODILE IN HAITI 85 APPENDIX II Continued Scientific name Family ICHTHYOFAUNA Cichlasoma hatiensis Cichlidae Cyprinodon bondi Cyprinodontidae Gobionellus sp. Gobeiidae Dormitator maculatus Eleotridae Strongylwa notata Belonidae Limia tridens Poeciliidae Limia melanonotata Poeciliidae Gambusia hispaniolae Poeciliidae DRY FOREST VEGETATIVE ASSOCIATION Prosopis juliflora Leguminosae Acacia famesiana Leguminosae Bursera simaruba Burseraceae Guaicum oficinale Zygophyllaceae Phyllostylon brasiliensis Ulmaceae Zizyphus rignmi Rhamaceae Pithecellobium circinale Leguminosae Haematoxylum campechianum Leguminosae Calotropis procera Asclepiadaceae Comocladia dodonaea Anacardiaceae Consolea moniliformis Cactaceae Neoabbotia paniculata Cactaceae Lemaireocereus hystrix Cactaceae Harrisia divaricata Cactaceae 86 BULLETIN FLORIDA STATE MUSEUM VOL. 33(1) APPENDIX III Survey Correction Procedure 1. Base estimate produced from the number of crocodiles observed during night-time boat surveys. 2. Known animals (0.3-0.9 m, 0.9-1.8 m) not seen during the surveys were added. 3. Correction for reduced sightability: A. Mean of three test boat surveys along densely vegetated shore, where the actual number of crocodiles was determined by sHrveying the area on foot with a spotlight, revealed that Only 50% of the 0.3-0.9 m and 0.9-1.8 m crocodiles in these areas were observed from the boat at night. As larger crocodiles tended to avoid these densely vegetated, shallow water areas, it was assumed that reduced sightability from dense vegetation had no effect on the sightability of crocodiles over 1.8 m. B. The amount of densely vegetated shoreline was estimated from aerial photographs of the lake. C. Counts of 0.3-0.9 m and 0.9-1.8 m crocodiles were increased 50%, proportionately between the two size classes, along all densely vegetated shorelines. 4. Line transects were conducted through two especially dense habitats during January 1984 (Trou Ca'iman Canal swamp, East Bay Swamp). These data were used, rather than reduced sightability estimates, to determine the number of 0.3-0.9 m and 0.9-1.8 m crocodiles in these habitats. A. Line transects were conducted by walking slowly through the area at night, following a single compass direction as closely as possible. Crocodiles were spotted using a headlamp (4v, Mine spot) and their perpendicular distance to the transect line was estimated. In this manner the transect width was estimated to be 50 m. B. Calculation of total transect area was done by multiplying transect width (50 m) by the length (number of strides x 0.6 m). Transect width, divided by the total area being surveyed (determined from 1:25,000 topographic maps) provided an estimate of the fraction of the total area that was surveyed. Contributions to the BULLETIN OF THE FLORIDA STATE MUSEUM, BIOLOGICAL SCIENCES SERIES, may be in any field of biology. 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