Bulletin STATE OF ILLINOIS DwiGHT H. Green, Governor DEPARTMENT OF REGISTRATION AND EDUCATION Frank G. Thompson, Director NATURAL HISTORY SURVEY DIVISION Theodore H. Prison, Chief Volume 23 BULLETIN Article 2 Duck Populations and Kill ^n Evaluation of Some Waterfowl Regulations in Illinois FRANK C. BELLROSE, Jr. Printed by Authority of the State of Illinois URBAN A, ILLINOIS November 1944 STATE OF ILLINOIS DwiGHT H. Greek, Governor DEPARTMENT OF REGISTRATION AND EDUCATION Frank G. Thompson, Director BOARD OF NATURAL RESOURCES AND CONSERVATION Frank G. Thompson, Chairman William Trelease, D.Sc, LL.D., Biology Arthur Cutts Willard, D.Eng., LL.D., Ezra J. Kraus, Ph.D., D.Sc, Forestry President of the University of Illinois L. R. HowsoN, B.S.C.E., C.E., Engineering Norman L. Bovven, Ph.D., Geology Roger Adams, Ph.D., D.Sc, Chemistry NATURAL HISTORY SURVEY DIVISION Urbana, Illinois Scientific and Technical Staff Theolore H. Frison, Ph.D., Chief Florence A. Nyberg, Assistant to the Chief Section of Economic Entomology G. C. Decker, Ph.D., Entomologist C. C. CoMPTON, Ph.D., Associate Entomol- ogist M. D. Farrar, Ph.D., Research Entomolo- gist J. H. Bigger, M.S., Associate Entomologist S. C. Chandler, B.S., Southern Held Ento- mologist James W. Apple, M.S., Northern Field Entomologist B. G. Berger, M.A., Assistant Entomologist John M. Wright, B.A., Assistant Ento- mologist H. B. Petty, Jr., M.A., Associate in Ento- mology Extension C. J. Weinman, Ph.D., Special Research Assistant Willis N. Bruce, B.S., Special Research Assistant Section of Insect Survey H. H. Ross, Ph.D., Systematic Entomologist Carl O. Mohr, Ph.D., Associate Entomolo- gist, Artist (on leave) B. D. Burks, Ph.D., Assistant Entomologist (on leave) Milton W. Sanderson, Ph.D., Assistant Entomologist Kathryn M. Som merman, M.S., Artist, Entomological Assistant Phyllis A. Beaver, Laboratory Assistant Section of Forestry James E. Davis, M.F., Extension Forester Lee E. Yeager, Ph.D., Forester Section of Aquatic Biology George W. Bennett, Ph.D., Limnologist D. F. Hansen, Ph.D., Assistant Zoologist Bruno von Limbach, M.S., Special Re- search Assistant Section of Game Research and Management R. E. Yeatter, Ph.D., Game Specialist Section of Wildlife Experimental Areas Arthur S. Hawkins, M.S., Game Tech- nician (on leave) F. C. Bellrose, Jr., B.S., Assistant Game Technician Harold C. Hanson, M.S., Assistant Game Technician Section of Applied Botany and Plant Pathology L. R. Tehon, Ph.D., Botanist D. B. Creager, Ph.D., Research Pathologist J. C. Carter, Ph.D., Assistant Botanist G. H. Boewe, M.S., Field Botanist Bessie B. Henderson, M.S., Research Assist- ant Section of Publications James S. Ayars, B.S., Technical Editor Eleanor G. Wolff, B.Ed., Assistant Tech- nical Editor Technical Library Marguerite Simmons, M.A., M.S., Techni- cal Librarian Consultants in Herpetology: Howard K. Gloyd, Ph.D., Director of the Museum, Chicago Academy of Sciences; Clifford H. Pope, B.S., Curator of Amphibians and Reptiles, Chicago Natural History Museum This paper is a contribution from the Section of Wildlife Experimental Areas. (71255—3M—9-44) >2 CONTENTS Page Acknowledgments 327 Legal Protection 328 Regulations for Illinois 328 Open Season 328 Shooting Hours 332 Bag Limit 332 Favoring Depleted Species 332 Bait and Live Decoys 333 Three-Shell Limit 333 Evaluating Regulations 333 Vulnerability of Species 336 Influence of Open Season 340 Comparative Shooting Pressure 341 Influence of Population Density 351 Optimum Shooting Dates 354 Optimum Season Lengths 355 Optimum Shooting Hours 356 Effect of Bag Limit 359 Laws for Depleted Species 361 Effect of Bait and Live Decoys ; 364 Effect of Three-Shell Law 368 Illinois Duck Harvest 368 Total Effect of Regulations 369 Summary 370 Literature Cited 372 ^S^fe/,. fli*. jf' .V Duck Populations and Kill An Evaluation of Some Waterfowl Regulations in Illinois FRANK C. BELLROSE, Jr. ONLY after a wildlife regulation tinent's waterfowl population (Gabriel- has been in force for a number of son & Lincoln 1941). Cottam (1935) and years is it possible to evaluate its Pirnie (1935) have studied and dis- total effect. To check depletion of the cussed the broad aspects of the influence duck population of North America, of gunning practices and waterfowl several new waterfowl hunting regu- regulations. But little has been done lations and drastic modifications of ex- to evaluate each of the various regula- isting regulations were inaugurated in tions employed to limit the waterfowl the United States and Canada during kill. the 1930's. It is evident to all now that This paper was conceived and written the added restrictions, combined with in an attempt to evaluate the effect of increased waterfowl productivity re- various hunting regulations on the suiting largely from greater precipita- kill of ducks in Illinois, and to ascertain tion on the breeding grounds and a the optimum dates for Illinois hunting program of habitat restoration, swung seasons of various lengths, the duck population pendulum upward. Populations have made a noticeable Acknowledgments comeback since the low ebb of 30,000,000 ducks estimated for 1934, and, as duck The writer of this paper is indebted numbers have increased, some of the to Messrs. Homer Bradley and Milfred waterfowl regulations have been re- J. Smith of the U. S. Fish and Wildlife laxed. Service stationed at the Chautauqua Demands for abolishing certain regu- National Wildlife Refuge, Havana, Illi- lations and relaxing others have in- nois, for their co-operation in making creased in tempo with mounting water- censuses on that refuge. He appreciates fowl numbers. Some sportsmen desire the constructive criticisms of the manu- the return of decoys, others want to use script by Dr. Clarence Cottam and bait and still others would like to see Messrs. Cecil Williams and Robert larger bag limits and longer seasons. H. Smith of the U. S. Fish and Wild- What effect might the relaxing of each life Service. Mr. Ferd Luthy of Peoria or all of the existing regulations have not only provided helpful suggestions on the duck kill? With an army of on the study but furnished kill records almost 1,500,000 hunters pursuing wa- of the Duck Island Preserve dating terfowl in the United States, an unwise back to 1885. Dr. Ralph E. Yeatter loosening of restrictions might halt, if and Dr. David H. Thompson of the not actually cause a decline in, water- Illinois Natural History Survey fur- fowl on the comeback trail. nished unpublished data they com- The U. S. Fish and Wildlife Service piled from the Duck Island Preserve through its flyway biologists, its co- kill records. Dr. Thompson also aided operative waterfowl observers, its refuge the writer in the statistical analyses of personnel and game agents, and its mid- duck population and kill data. Miss winter inventory of the population an- Eleanor G. Wolff, Assistant Technical nually ascertains the status of the con- Editor of the Survey, aided in compiling [327] 328 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 the history of waterfowl regulations. Grateful appreciation is due to Mr. Bob Becker, writer on wildlife, for photo- graphs used for the frontispiece and five other halftones. The frontispiece pictures sunrise on a bayou along the Illinois River, as seen from a duck blind. Appreciation is due also to Mr. Arthur S. Hawkins for his encouragement, which he has continued even while on leave for military service. Legal Protection Written laws establishing closed sea- sons on waterfowl date back at least to Henry VIII of England. In the year 1533 his government decreed partial protection for waterfowl "between the last Day of May and the last Day of August" and, beginning in 1534, full protection for their eggs "from the first Day of March .... unto the last Day of June then next ensuing" (Anonymous 1770). As early as 1846 in the United States, Rhode Island passed a law prohibiting spring shooting of certain waterfowl (Palmer 1912). Although this law was later repealed, by 1900 in 9 states, or the territory now covered by them, all spring shooting had been abolished, and in 38 some form of legal protection for migratory water- fowl had been passed. By 1918 the number of states prohibiting all spring shooting had increased to 31, and only 3 states afforded no legal protection whatever for waterfowl (Lawyer 1918). Up to 1913, no important waterfowl hunting regulations had been enacted by the federal government except in re- lation to territories. Although many attempts had been made by conserva- tionists to establish uniformity in the laws among different groups of states, very little had been accomplished. Finallv, a federal law known as the Mi- gratory Bird Act, placing birds that regularly migrate beyond state limits under the protection of the federal gov- ernment, was passed and made effective in 1913. In 1916, a treaty was signed with Canada, which, besides covering certain migratory non-game birds, pro- vided for limited open seasons on mi- gratory game birds. The Migratory Bird Treaty Act, making this treaty effective in the United States, was passed in 1918. Regulations issued in conformity with this act then and since then over a period of years include a reduction in the length of season, in bag limit, daily shooting hours and number of shells in gun; prohibition of the use of bait and live decoys; the placing of some species under complete protection, and others under special protection by limit- ing the number taken. Regulations for Illinois The principal federal waterfowl regu- lations that apply to Illinois relate to open season, shooting hours, bag limit, the increased or complete protection of certain species, use of bait and live de- coys, and number of shells in gun. Open Season.—Changes in the length of the waterfowl hunting season in Illi- nois from 1900 through 1944 are shown in fig. 1. The long open season on water- fowl prevailing throughout the nation until enactment of the federal Migra- tory Bird Act is indicative of the desire of state legislators to get for the hunters of their respective states as many birds as possible before their passage into other states. "The fact that seasons and bag limits on migra- tory birds have remained so much more liberal than seasons on resident game," states Leopold (1933), "strongly sub- stantiates the assertion .... that people can be induced to conserve what stays on their own land, but only the exceptional individual will voluntarily conserve what he shares with the com- munity at large." In 1913, through federal regulations, the Illinois water- fowl hunting season was shortened from 225 days to 105 days and from that time until the drastic cut of 1931 the length of the waterfowl seasons changed little. Information on hunting seasons and other federal waterfowl regulations as they applied to Illinois from 1929 through 1944 are given in table 1. Even for seasons of the same length, there were various opening and closing dates. A 30-day open season extended through November in 2 years, from October 21 through November 19 in another year. A season of 45 days 1 November, 1^44 Bellrose: Duck Populations and Kill 329 extended from October 15 through November 28 in 1938 and from October 22 through December 5 the following ^ear. In 1934 a season having rest days or lay days was permitted; states were given the option of having 30 shooting days run consecutively or at and "times and lines of migratory flight" with respect to the hunting of migratory birds. The 1913 regulations divided the United States into two zones with respect to closed seasons, a northern "breeding zone" and a southern "win- 250 200 150 100 50 A- _L. 1900 1905 1910 1915 1920 1925 1930 1935 1940 Fig. 1.—Length of the waterfowl hunting seasons in Illinois, 1900-1943. The length was letermined in some years by state law and in others by federal regulations. intervals over a period not to exceed approximately 3^ months. Only two states selected a season of 30 consecu- tive days. A tew states chose a season 3f 5 days a week for 6 weeks and a few 2 days a week for 15 weeks; 30 states chose a season of 3 days a week for 10 weeks. Illinois chose 2 days a week, October 6-January 13. According to More Game Birds in America, a sports- men's organization that has since dis- banded, in the 48 states there were 21 difi^^erent combinations of shooting days and 17 difi'erent opening and closing dates (Anonymous 1936). The Migratory Bird Act of 1913 em- powered the Secretary of Agriculture to prescribe and fix closed seasons on waterfowl, "having due regard to the zones of temperature, breeding habits, and times and line of migratory flight." The Migratory Bird Treaty Act of 1918 5n granting similar powers included references to "zones of temperature," tering zone," but within the zones made several local exceptions to the general dates established for these zones. For the next few years, numerous variations in the dates of hunting seasons were tried. In 1918, four zones, on the basis of opening dates, were established. In 1935, the states were grouped into two zones, with the open season October 21 through November 19 for the north- ern zone and November 20 through December 19 for the southern zone. In 1936, three zones were established, with the hunting season October 10 through November 8 lor the northern zone, November 1 through November 30 for the central zone and November 26 through December 25 for the south- ern zone. These zones followed closely the zones of temperature as determined from records of the U. S. Weather Bureau. In most instances zones were established along state lines and thus kept at a minimum the confusion and 330 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 a < PQ "J eC .5 O — ' N u •Sq: 3 . <3i C/2 O z 1 ^ I • 00 i2 00 (\J I d Q I I I ro OJ I o CM Fig. 4.—Chronology of flight of all duck species, and species other than mallard, in relation to the hunting season in the Illinois River valley, 1939. flight during the opeit seasori. For ex- ample, the pintail, which for a 5-year period contributed 9.65 per cent of the total Illinois bag, comprised 1.17 per cent of the total Illinois flight during the open season. The vulnerability quotient jfor this period is 9.65 divided by 1.17, or 8.25, table 2. This quotient, when icompared with vulnerability quotients ifor other ducks, may be considered as a relative measure of the killability of the ipintail, or the relative ease or difficulty iwith which it is bagged. I The relationship of the bag for any species to the entire Jail flight of that ppecies also is necessary in determining takes into account a longer period of migration, tables 2-7. It is a measure of the shooting pressure placed upon a species by its vulnerability and its chro- nology of migration in relation to the hunting season. The comparative influence on each principal duck species of changes in the hunting season may be obtained by finding the ratio of the mortality quo- tient to the vulnerability quotient. A numerical expression of this relation- ship, obtained by dividing the mortality quotient by the vulnerability quotient, is termed the shooting pressure quotient, tables 2 and 8. In this figure, vulner- 336 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 ability differences between the species are partially or entirely nullified, and a measure is derived for the influence of the open season. The shooting pressure quotient can be changed for any species by altering the opening or closing dates of the season. The relative vulnerability, or killa- bility, of species is summarized for a 5-year period, 1938-1942, in table 2. A period of this length, rather than a shorter period, was used because we be- lieve there is little difference from year to year in the inherent wariness, or in the flight, flocking and feeding habits, changed materially from year to year in the period 1938-1942. Vulnerability of Species Because of variations in habits, spe- cies of ducks differ in their likelihood of being killed by hunters. Species differ in inherent wariness. Food habits in- fluence the killability of species; pref- erence for a certain food may entice one kind of duck into heavily gunned areas, while another kind remains in open water, out of reach of hunters. Flocking habits also influence the vulnerability (\J November, 1^44 Bellrose: Duck Populations and Kill 337 smaller is the percentage of ducks likely While many instances can be cited to be killed. A flock of 1,000 mallards favoring each species, veteran duck or bluebills passing over a blind is un- hunters generally give the edge to the likely to have many more individuals pintail. However, in Illinois, the flock- killed from it than a flock numbering ing and feeding habits of mallards and Fig. 6.—Chronology of flight of all duck species, and species other than mallard, bag per hunter per day and total daily kill (weekly averages expressed as per cent of yearly total) in the Illinois River valley, 1941. only 10 or 100, for after the first shot the individuals left are warned and have an opportunity to swing or climb out of range. Experienced duck hunters usu- ally refrain from shooting into large flocks, for they know such shooting "educates" ducks to avoid the area from which the shots have been fired. Of all kinds of Illinois ducks, mal- lards and black ducks, considered to- il gether, were found through this study , to be the least vulnerable to hunting, I table 2. In sporting circles, many heated debates have arisen over the question of whether the mallard, the black duck or the pintail is the wariest of our ducks. black ducks are such that a much lower percentage of the flight is killed. Mallards and black ducks now fre- quent the open waters of large lakes much of the day and night during the fall migration season in Illinois. Near sunset or before sunrise, they wing high overhead to feed in cornfields. Pintails obtain most of their food from small- seeded plants growing in marshes and along the edges of lakes. In seeking this food, they generally come within gun range much more frequently than do mallards. The mallard habit of con- centrating by the tens of thousands on about a dozen large lakes of the Illi- 338 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 nois River valley results in a lower pro- portional kill than if the population were more evenly distributed over more areas and in smaller flocks, as in the case of the pintail. Widgeons and gadwalls were taken in the years of this study more readily than were pintails by Illinois hunters, table 2. These "gray ducks" feed principally on coontail [Ceratophyllum demersum) in Illinois, and, in most in- stances, this plant reaches peak develop- ment in the ponds and potholes of river bulrush {Scirpus fluviatilis) marshes. Widgeons and gadwalls consequently chance to come within range of hunters frequently, and, while they may not respond to calling and decoys as readily as do mallards or pintails, the "gray ducks," once they decide to decoy, ap- proach with much less caution. Blue-winged and green-winged teals were killed in greater proportion to numbers present than was either species of "gray ducks," table 2. Teals, which feed extensively on the seeds of smart- weeds {Polygonum spp.), nutgrasses {Cyperus spp.) and other small-seeded plants, spend much time along the edges of marshes and lakes. While teals are fast and erratic flyers, and are thereby responsible for more misses than most of the other species, they are very unwary. They decoy readily, often with no more than a half circle to the blocks, and frequently return after being shot at. Kortright (1942) says that their habit of flying in a dense, closely bunched flock renders them very vulnerable to the fire of the gunner, and two or more birds will often fall from a single shot. They are easily killed when hit. Shovelers, or spoonbills, were found -JI5-- o z < I- !^io- _i u. _J O I- H u U a. u Q. —• TOTAL WATERFOWL FLIGHT •— WATERFOWL FLIGHT OTHER THAN MALLARD — '^ WATERFOWL KILL PER HUNTER PER DAY TOTAL DUCK KILL 942 cvj d < I I CVJ I D. LiJ to » o 1 November, 1944 Bellrose: Duck Populations and Kill 339 to be the most vulnerable of Illinois ducks, table 2. Their feeding habits frequently bring them within range of the hunter. Spoonbills do not furnish River valley. This is partly the result of their habit of seeking the extensive open water areas of large lakes and con- gregating in tremendous rafts, which in Table 2.—The vulnerability, mortality and shooting pressure quotients for each of the important duck species or groups in the Illinois River valley, 1938-1942. The higher the figures, the greater is the vulnerability, mortality and shooting pressure. Species 340 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 for open water hunters, table 2. Be- cause of their aversion to crossing marshes or timbered necks of land, they do not furnish many targets for shore and marsh hunters. Club hunters in Illinois seldom resort to open water gunning, but where this type of hunting occurs, as at the Sparland Public Shoot- ing Ground, large proportions of the ruddies present are taken (Bellrose 1944). Proportionally more ring-necked ducks than ruddies were bagged by club hunt- ers in the years of this study, table 2. There can be little doubt that much of the difference in vulnerability between blackjacks, as ring-necked ducks are often called in Illinois, and the lesser scaups resulted because blackjacks in- habit small bodies of water and marshy or inshore areas of large lakes instead of open water, and are more likely to pass under the muzzles of guns than are bluebills, as lesser scaups are sometimes known. The greater fondness of ring- necks for shoal water is reflected in their food habits; Cottam (1939) reports 81.47 per cent of the ring-neck's food consists of aquatic plants, about the same per cent as is found in the can- vasback's diet, whereas only 59.55 per cent of the lesser scaup's diet is made up of aquatic plant items. Evidence obtained in 1941 and 1942 indicates that redheads are much more readily bagged in proportion to the population than are ring-necked ducks. I believe that redheads are the least wary of the Nyroca, the most important group of diving ducks. They decoy more readily in Illinois to blocks than other members of the genus, but whether this is due to their flying in small flocks or to lack of wariness, or to both, is uncertain. In Illinois, redheads fre- quent marshy lakes and the inshore of large lakes more than any other diving ducks with the possible exception of the ring-necks. Cottam (1939) reports the food of the redhead to be 89.66 per cent vegetable material; this is the largest proportion of plant items in the diet of any diving duck important in Illi- nois. Because of differences in flocking and feeding habits, types of habitats in which they are hunted and methods by which they are hunted, the ducks dis- cussed above may not have the same relative vulnerability to the shotgun throughout North America. However, the ratings determined by this study show which species are in need of the most protection in Illinois, and probably they may serve as useful indicators of the species that are most likely to suffer from overshooting in the Midwest. Observations made in 1943 on Grass Lake, in northeastern Illinois, suggest that coots may be more readily killed than ducks (Bellrose 1944). Careful cal- culations indicate that, on the opening day of the hunting season, 18,225 coots and 108 ducks were killed. These figures represent about 95 per cent of the coot and 15 per cent of the duck popu- lation then present. The ducks that made up the bulk of the population on Grass Lake were blue-winged teals, con- sidered highly vulnerable in comparison with most other duck species. Influence of Open Season.—Be- cause duck species differ from each other to some extent in the chronology of their migration, figs. 8-10, if the rel- ative vulnerability of species is known the opening and closing of the hunting season may be adjusted to lift some or all of the shooting pressure from the most vulnerable species, or those most needing protection. Leopold once wrote (1933) that a number of states purposely set the open season on deer late in the year so that severe weather will keep all but the hardiest hunters at home. He also remarked that several states, including Michigan, open the season on prairie chickens at a late fall date to take ad- vantage of the fact that these birds are harder to kill late than early in the autumn. How have the open seasons from 1938 through 1942 influenced the duck spe- cies that migrate through Illinois? We have attempted to answer this question by comparing the vulnerability quo- tient with the mortality quotient for each important species to obtain what we have termed the shooting pressure quotient. This shooting pressure quo- tient gives a comparative evaluation of the effect of the open season on im- portant duck species in Illinois for the 1 November, 1944 Bellrose: Duck Populations and Kill 341 1938-1942 period, table 2, and for each nois during the years of this study and year during the period, table 8. may therefore be considered as the Comparative Shooting Pressure.— species most favored by the open seasons Table 8 discloses that the blue-winged from 1938 through 1942. A glance at teal had the lowest shooting pressure fig. 8 and figs. 11-15 reveals that most quotient of all important ducks in Illi- blue-wings passed through the valley 20-- 15-- I o 2 UJ u cr Q. iO-- 5-- BLUE-WINCED TEAL —c c WIDGEON — X X— SHOVELER —X X— GREErj-WINGED TEAL 10-16 17-23 24-3l 31 6 7-13 1-1-20 21-27 28-4 5-11 12-18 19-25 25-1 2-8 9-15 16 22 2329 30- b 7-i3 142021-27 AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER Fig. 8.—Five-year average, 1938-1942, of the seasonal migration of the blue-winged and green-winged teals, widgeon and shoveler in the Illinois River valley. OCTOBER 2-e 9-15 16-22 23-29 30-6 7-13 14-20 21-27 28-3 NOVEMBER DECEMBERSEPTLMBEP Fig. 9.—Five-year average, 1938-1942, of the seasonal migration of the pintail, coot and gadwall in the Illinois River valley. 342 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 prior to the opening of the hunting season. A greater proportion of the flight was present during the open seasons of 1938 and 1941 than during the other three seasons. Table 8 shows for 1938 and 1941 the highest shooting pressure quotients for this species. Second among the species most fa- vored in Illinois by the established open seasons, 1938-1942, was the shoveler. As shown by fig. 8 and figs. 11-15, much of the shoveler migration in this state occurred before the season opened. A larger proportion of the population of this species than of any other species, except the blue-winged teal, passed south before opening day. Data in table 8 disclose that extending the season to 60 days in 1940 and 70 days in 1942 did not increase the shooting pressure quo- tient for this species in those years. Figs. 11-15 reveal that much of the green-winged teal flight, like that of the blue-winged teal and shoveler, had passed through Illinois by opening day, 1938-1942. Table 8 shows that the green-wing was the third most favored species. High water in 1941 caused a large part of the green-winged teal flight to leave the Illinois River valley earlier than usual. In that year, green- wings were under less shooting pressure than in other years and were next to the blue-winged teal in being little af- fected by the open season, table 8. Next to the blue-winged teal, the pintail was, in the years of this study, the earliest migrant to arrive in Illinois, fig. 9. However, because greater pro- portions of its flight occurred during the hunting season, figs. 11-15, the pintail was subject to more shooting pressure than either of the teals or the shoveler, table 8. High water in 1941 resulted in a mass exodus of pintails from the Illinois River valley early in October, accounting at least in part for a low shooting pressure in that year, table 8 and fig. 14. While the 1942 flight was small, the majority of birds arrived during the hunting season. A late flight in 1938 helped to place pintails under greater shooting pressure in that season than in others. The widgeon, in the years of this study, was subject to more shooting pressure in Illinois than was the pintail, table 8. The figure for 1938 indicates that the later-than-usual widgeon flight in that year contributed to a heavier- 20 -- I o < I- o I- 2 UJ a UJ a > RUDDY DUCK — X X— RING-NECKED DUC t' -— ' 1 CAfJVASBACK ^ ' LESSER SCAUP MALLARD OCTOBER NOVEMBER DECEMBER JANUARY Fig. 10.—Five-year average, 1938-1942, of the seasonal migration of the ruddy duck, ring- necked duck, canvasback, lesser scaup and mallard in the Illinois River valley. November, IQ44 Bellrose: Duck Populations and Kill 343 Table 3.—Per cent of entire fall flight, per cent of total bag, and mortality quotient (indicating relative mortality from hunters) for each of the important duck species or groups in the Illinois River valley, 1938. Species* Per Cent of Flight During Entire Fall Per Cent of Total Bag Mortality Quotient Mallard and black duck Pintail Green-winged teal Blue-winged teal Widgeon Gadwall Shoveler Lesser scaup Canvasback Ruddv duck 94 1 61 44 10 35 30 06 0.02 3.01 0.07 0.04 57.07 12.76 54 35 7.27 .27 .43 .48 0.40 0.43 2. 2. 4. 0.60 8.86 95.40 9.57 24.23 37.83 121.50 1.49 5.71 10.75 100.00 100.00 *Certain species omitted because of lack of sufficient data. than-usual hunting pressure. Compara- tive figures show that hunting pressure on the widgeon was least in 1940 and 1942, table 8; in those years the widgeon population in the Illinois River valley was relatively high, tables 3-7. The gadwall, which appears to be similar to the widgeon in most habits, including wariness, was subject to about three times as much shooting pressure. This disparity existed be- cause more of the gadwall flights than ot the widgeon flights occurred during the hunting seasons, figs. 11-15. The seasons of 1939 and 1940, which ended before the gadwall flight had passed through the Illinois River valley, were marked by shooting pressures that were comparatively low for this species, table 8. There is no apparent reason for the comparatively low pressure in 1942. In calculating the kill of the widgeon and the gadwall, it was necessary to begin with the total kill of the two species for 1938 through 1940 as re- ported by duck clubs; hunters often placed widgeons in the gadwall column. An attempt was then made to correct this error through use ol data obtained from our own inspecting of hunters' bags to determine the ratio between the Table 4.—Per cent of entire fall flight, per cent of total bag, and mortality quotient (indicating relative mortality from hunters) for each of the important duck species or groups in the Illinois River valley, 1939. Species* 344 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 Table 5.—Per cent of entire fall flight, per cent of total bag, and mortality quotient (indicating relative mortality from hunters) for each of the important duck species or groups in the Illinois River valley, 1940. Species* Per Cent of Flight During Entire Fall Per Cent of Total Bag Mortality Quotient Mallard and black duck Pintail.. Green-winged teal Blue-winged teal Widgeon Gadwall Shoveler Lesser scaup Ring-necked duck Canvasback Ruddy duck 92.76 3.35 0.18 0.63 0.56 0.04 0.04 1.97 0.21 0.17 0.09 72.66 11.67 4.19 1.39 2.14 1.14 1.09 3.36 1.81 0.37 0.18 0.78 3.48 23.28 2.21 3.82 28.50 27.25 1.71 8.62 2.18 2.00 100.00 100.00 Certain species omitted because of lack of sufficient data. two species. Numerals applying to these species in 1938-1940 are based upon the ratio obtained. In 1941 and 1942 the kill record sheets were more clearly marked to differentiate the species. Hunting seasons following 1938 placed the mallard and black duck under more shooting pressure than in that year. An early ingress of mallards and black ducks into the valley in 1939, together with a season that was set 1 week later than in 1938, placed more pressure on these species in 1939 than in the pre- vious year, fig. 12 and table 8. The season was extended in 1940 from 45 to 60 days. It resulted in a marked in- crease in shooting pressure on mallards and black ducks because most of the extension was on the end of the season, when about 95 per cent of the water- fowl population in Illinois was made up of these species. There was a slight drop in shooting pressure on these species in 1941, because high water, which prevailed throughout the season, made them difficult to kill. Still more days were added to the end of the water- Table 6.—Per cent of entire fall flight, per cent of total bag, and mortality quotient (indicating relative mortality from hunters) for each of the important duck species or groups in the Illinois River valley, 1941. Species* Per Cent of Flight During Entire Fall Per Cent of Total Bag Mortality Quotient Mallard and black duck Pintail Green-winged teal Blue-winged teal Widgeon Gadwall Shoveler Lesser scaup Ring-necked duck Canvasback Redhead Ruddy duck 88.07 2.48 0.12 0.71 0.37 0.05 0.01 6.68 1.00 0.33 0.01 0.17 100.00 64.24 8.67 64 34 15 91 0.95 7.92 6.68 1.68 0.31 0.51 100.00 0.73 3.49 13.67 3.30 8.51 38.20 95.00 .19 .68 ,09 31.00 3.00 Certain species omitted because of lack of sufficient data. November, 1^44 Bellrose: Duck. Populations and Kill 345 Table 7.—Per cent of entire fall flight, per cent of total bag, and mortality quotient (indicating relative mortality from hunters) for each of the important duck species or groups in the Illinois River valley, 1942. Species* Per Cent of Flight During Entire Fall Per Cent of Total Bag Mortality Quotient Mallard and black duck Pintail Green-winged teal Blue-winged teal Widgeon Gadwall Shoveler Lesser scaup Ring-necked duck Canvasback Redhead Ruddy duck 84.98 1.18 0.03 1.22 0.99 0.04 0.03 10.14 0.55 0.47 0.01 0.36 75.12 6.16 1.48 2.54 1.98 1.20 0.94 5.29 2.31 1.78 0.41 0.79 0.88 5.22 49.33 2.08 2.00 30.00 31.33 0.52 4.20 3.79 41.00 2.19 100.00 100.00 Certain species omitted because of lack of sufficient data. fowl season in 1942. This extension in the season placed the mallard and black duck under greater shooting pressure in 1942 than in any other year of this study, table 8. Other species were not materially affected adversely by the lengthened seasons, according to the comparative data in table 8. Whereas this table discloses an almost uninterrupted rise in the shooting pres- sure on mallards and black ducks during the 5 years of this study, it indicates that no such trend has occurred in other species. As a group, diving ducks were under more shooting pressure in recent open seasons than were dabbling ducks, table 8. Figs. 10-15 disclose that most of the diving ducks arrived after Octo- ber 16, and that most of them departed southward by December 16; thus, most of the migration occurred during the hunting season. There is comparatively little differ- ence in the shooting pressure on most species of diving ducks; as fig. 10 shows, the species migrate at almost the same time. Shooting pressure was unusually high on the ruddy duck in 1938 and 1939 when the population was relatively low. Shooting pressure on most of the duck species varied from year to year during Table 8.—Shooting pressure quotient for important Illinois River valley ducks, 1938- 1942; derived by comparing vulnerability quotient of species (5-year average) with mortality quotient for 5 separate years. Species* 346 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 60 40 20 WATERFOWL CENSUS ILLINOIS RIVER 1938 AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER JANUARY Fig. 11.—Polygons, based upon number of birds per acre of water surface in the Illinois River valley in 1938, showing the chronology of flight of 11 species of waterfowl in relation to the hunting season. November^ 1^44 Bei.lrose: Duck Populations and Kill 347 30 20 10 WATERFOWL CENSUS ILLINOIS RIVER 1939 I AUGUST SEPTEMBER ' OCTOBER NOVEMBER DECEMBER JANUARY Fig. 12.—Polygons, based upon number of" birds per acre of water surface in the Illinois River valley in 1939, showing the chronology of flight of 11 species of waterfowl in relation to the hunting season. 348 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 y- < 5 u a. o < a. a. o cc CD -40 -30 -20 - 10 WATERFOWL CENSUS ILLINOIS RIVER 1 940 AUGUST 'SEPTEMBER ' OCTOBER ' NOVEMBER ' DECEMBER JANUARY Fig. 13.—Polygons, based upon number of birds per acre of water surface in the Illinois River valley in 1940, showing the chronology of flight of 12 species of waterfowl in relation to the hunting season. J November^ 1944 Bellrose: Duck Populations and Kill 349 -80 -60 -40 -20 WATERFOWL CENSUS ILLINOIS RIVER 1941 NO CENSUS TAUGUST 'SEPTEMBER OCTOBER ' NOVEMBER DECEMBER JANUARY Fig. 14.—Polygons, based upon number of birds per acre of water surface in the Illinois River valley in 1941, showing the chronology of flight of 12 species of waterfowl in relation to the hunting season. 350 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 < O UJ cr u < a. u Q. O AUGUST SEPTEMBER OCTOBER ' NOVEMBER ' DECEMBER JANUARY Fig. 15.—Polygons, based upon number of birds per acre of water surface in the Illinois River valley in 1942, showing the chronology of flight of 12 species of waterfowl in relation to the hunting season. November^ 1944 Bellrose: Duck Populations and Kill 351 Table 9.—Average daily kill per shooter, Duck Island Preserve, 1914-1936. Week 352 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 T 1 r 15 18 25 1 8 15 OCTOBER NOVEMBER Fig. 16.—Seasonal trend in activity of hunters at Illinois River valley waterfowl hunting clubs, 1940-1942. 3 20 DECEMBER 27 S 21 iij Q. 15 CO a: 12 \- z 3 X 6 3 h L NUMBER OF HUNTERS NUMBER OF DUCKS KILLED '-' oj cvj ^ Al O I^ SEPTEMBER OCTOBER NOVEMBER DECEMBER Fig. 17.—Weekly averages of number of hunters in action and ducks killed at Duck Islani Preserve over a 23-year period. 1914-1936. November^ 1944 Bellrose: Duck Populations and Kill 353 354 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 CANVASBACK--.,.^^^ RING-NECKED DUCK- LESSER SCAUP -^^ MALLARD- SHOVELER- WIDGEON AND. GADWALL PINTAIL GREEN-WINGED- TEAL BLUE-WINGED TEAL- / November, ig44 Bellrose; Duck Populations and Kill 355 Some hunters believe that the season might well be set earlier. As fig. 16 shows, most Illinois duck hunters prefer to do the greater part of their hunting early in the season, when waterfowl are rather evenly distributed and tempera- tures are comfortable. While an earlier season of 60 days or more would include a smaller proportion of the waterfowl flight, records of the Duck Island Pre- serve, table 9 and fig. 17, and figs. 5, 6 and 7 indicate that it would increase the kill of ducks in Illinois. The greater vulnerability of the species and indi- viduals present early in the season more than compensates for the reduced popu- lation in Illinois at that time. Setting the season earlier would en- able waterfowl hunters to bag more coots. It is generally agreed among wildlife technicians that a greater kill of coots could and probably should be made, and, since almost half of the coot population of the Illinois River valley is present by the middle of October, an earlier opening would result in a greater kill of that bird. Although an earlier season might pro- vide a more equitable distribution of the take and more comfortable hunting, it must be realized that in Illinois such a season would tend to increase the pres- sure on species that are least able to withstand it. The closing date for the waterfowl hunting season in Illinois should proba- bly be December 10 or earlier. According to records of the Peoria weather station, the average date of closing of the Illi- nois River by ice (1867-1930) is Decem- ber 10. In most states of the central zone the mean daily temperature falls below 32 degrees by December 15, fig. 2. While, as fig. 10 discloses, a large percentage of the mallard and black duck populations remain after the freeze-up in the Illinois River valley, winter conditions then usually do not favor duck hunting. The remaining mallards and black ducks concentrate on only a few lakes and, partly because of such local concentrations, only a small percentage of hunters continue hunting, fig. 16. Under such rigorous weather and feeding conditions as occur after the freeze-up, few ducks may be killed, or, occasionally, excessively many. Be- cause most duck hunting ends with the winter freeze-up, there is little reason to extend the season in Illinois beyond December 10 or 15. The same closing dates may be applicable to other states in the central zone. If, in the future, it is necessary once again to shrink the open season to 30 days, I believe that for Illinois the sea- son should be set from November 1 through 30. This would place most of the shooting pressure on mallards and black ducks, species that are, as already discussed, best able to take it. If con- ditions were critical enough to warrant a 30-day season, they would almost cer- tainly justify giving greater protection to some species than to others. The ducks in need of greatest protection would probably be the blue- and green- winged teals, shoveler, widgeon and ruddy duck, species that complete a large part of their fall migration through Illinois by November 1. If the status of waterfowl is such that a 45-day season is desirable, I believe the optimum period for Illinois is from October 22 through December 5. This would place flights of mallards, black ducks, lesser scaups, ring-necked ducks and canvasbacks under shotgun pres- sure longer than other species less able to withstand this pressure, and it would cover the period in which ducks are most abundant in Illinois. Should an abundance of waterfowl permit a 60-day shooting season, and most species are sufficiently numerous to be secure, the optimum season for Illinois would be from October 10 through December 8. Should the continent's waterfowl pop- ulation justify a 70-day season, then I believe the season, insofar as Illinois is concerned, might best be set at October 1 through December 9. Recommended dates for an 80-day season are September 26 through De- cember 14; recommended dates for a lO'J-day season are September 20 through December 28. Optimum Season Lengths Does the duck kill increase in direct ratio to the length of the hunting season ? Waterfowl investigators have done little 356 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 to evaluate the influence on the kill of seasons of various lengths. Fig. 21 shows the influence of open seasons of various lengths on the total yearly kill of three Illinois River valley clubs. While various shooting hours November, 1944 Bellrose: Duck Populations and Kill 357 940, it was not long until the mallards i^ere flying to the cornfields before day- ireak and leaving 15 to 30 minutes ater for the rest lakes. Where formerly nassed thousands of ducks could be een streaming back to the lakes in he bright light after sunrise, now en- ire cornfields appeared to rise into the ,ir as tens of thousands of ducks left /ith the first streaks of dawn. In 1942, waterfowl shooting hours vere extended from 4 p.m. until sunset, rhe result was that mallards, after the irst few days, would not alight or at- empt to alight in cornfields until sun- et or shortly thereafter. Consequent- y, their feeding activities occurred later han under the 4 p.m. closing hour. During cold, blustery weather, when the hermometer was below freezing, mal- ards forsook their morning and evening outine, feeding throughout the day in ields close to their rest lakes. In 1943, shooting hours were further ixtended, the legal starting time being )laced at one-half hour before sunrise. This change served no useful purpose to most hunters in Illinois; in fact, it was detrimental to duck hunting in many places. Disturbances caused by hunt- ers in going to their shooting stands at an hour when the ducks were commenc- ing to feed resulted in considerable avoidance of those areas by mallards. Field observations in 1943 revealed that, because of hunting disturbance during the early morning hours, mal- lards fed very little in cornfields close to the Illinois and Mississippi rivers until after the end of the open season. The bulk of the population obtained food in the mechanically picked corn- fields 20 to 40 miles from the rest lakes. In this vast territory, mallards were able to find fields where there was little hunting disturbance. Because of the distance they traveled for food, mallards frequently returned from the morning feeding to their rest lakes as late as 10 a.m.. Central War Time. The time of return probably depended upon the availability of the Photo by Bob Becker Duck club caretaker (left) and Illinois Natural History Survey game technician checking the composition of duck bags at a shooting club in the Illinois River valley. 358 Illinois Natural History Survey Bulletin Vol. 2j, Art. waste corn. In returning to the lakes, they flew high, out of shotgun range, until over the safety of the open waters. The evening flight to cornfields com- menced at about 5 p.m., C.W.T., almost daily in the 1943 hunting season, and, even though this was before the legal closing time, hunters seldom had targets because the mallards, after leaving open light nights they fed actively all night long. As a result many of the sand hill shooting places fed large quantities of corn but were never able to get much shooting." A valid objection to permitting water- fowl shooting until sunset is that many shooters—particularly those in the corn- fields—defy the law and shoot after Table 10.—Influence of shooting hours on duck kill as derived by comparing the kill during hunting season with the duck population, Illinois River valley, 1938-1942. November, 1944 Bellrose: Duck Populations and Kill 359 expression was that the half hour before sunrise shooting was very detrimental to hunting. Some hunters who expressed a prefer- ence for shooting hours of sunrise to sunset explained that waterfowl oc- curred on their property only at sunrise and sunset. The principal reason ad- vanced by hunters for ending shooting daily at 4 p.m., C.S.T., was that it kept waterfowl from being "burned out" of a region. Have longer shooting hours resulted in a greater kill of waterfowl ? Shooting hour regulations are difficult to evaluate because of the influence of such other variables as length of season, population, weather and food conditions. Length of seasons has changed with shooting hours; so in order to reduce the influence of varying lengths of seasons, as well as variations in the duck flight, the per- centage of the 5-year duck population present during the open season of each year has been compared with the per- centage of the 5-year kill, table 10, to give an index of the shooting pressure resulting from various shooting hours. The highest index numbers indicate the greatest shooting pressure and kill. Because of better hunting conditions in certain years than in others the data are inconsistent, but they show no evi- dence that larger kills were made in seasons of sunrise or sunset shooting than in seasons of shorter shooting days. The index figure for 1940, when sunrise shooting was permitted, was the same as for 1939, with 7 a.m. shooting, table 10. In 1941 and 1942, with sun- rise shooting, the shooting pressure, a measure of the comparative kill, was actually less than that with 7 a.m., C.S.T., shooting in 1938 and 1939. Effect of Bag Limit In recent years, several biologists have questioned the value of bag limit as an effective measure jn restricting the total 'game kill. Fig. 22, based on data assembled by Dr. Yeatter and Dr. Thompson, shows for most years from 1885 through 1938 the average daily bag of Duck Island Preserve members and the observed bag 50 45 40 NO LEGAL BAG LIMIT tr 35 iij 30 25 20 10 r o> LIMIT 1885 1890 1895 1900 1905 1910 1915 Fig. 22.—Average daily duck bag made by members of the Duck Island Preserve near Ban- ner, Illinois, during certain periods from 1885 through 1938 in relation to the bag Hmit ob- served by the club. I 360 limit. Illinois Natural History Survey Bulletin Vol. 2^, Art. 2 Gaps in the graph are due to missing records. In "the good old days" with no legal restrictions, the kill per shooter per day was little greater than it was in 1938. From 1885 through 1889 and from 1894 through 1901, the kill per hunter-day averaged slightly over 10 ducks. From 1933 and 1934, produced a further de- crease in the individual daily kill. In 1935, the legal bag limit of ducks was cut to 10 per day, and again the average daily bag made by individual members of this club dropped. It is apparent that a legal limit of 50 had little influence on the average daily Photo by Bob Becker Bag limits in the lower figures are effective means of preventing overshooting of waterfowl. A mallard and two pintails are shown above. 1914 through 1927, when the club followed the state legal daily bag limit of 15, club members took an average of about 10 to 12 ducks per day each. In 1928 and the succeeding years the club regulations conformed with the federal limit. When the club elected to ob- serve the federal bag limit of 25 in 1928 and 1929, rather than the state limit, the members' average individual daily bag rose to about 19. But in 1930 through 1932, with the federal limit lowered to 15, the Duck Island Pre- serve bag dropped to about 12. A further drop in the legal limit to 12, in Record book made available by Ferd Luthy. kill of Duck Island Preserve members. However, as the bag limit decreased, it had increasingly greater influence; on the average daily take per hunter. With a bag limit of 25, Duck Island Preserve hunters averaged each about 5 less than the limit; with a limit of 15, they averaged about 3 less; and, with a limit of 10, they averaged about 1 less than the regulations permitted. Since this duck club enjoys better shooting than most clubs in Illinois, the lag of the actual bag below the bag limit is much less than that of the average duck hunter. The better the habitat and the hunter, the more effective is the I November, 1^44 Bellrose: Duck Populations and Kill 361 legal bag limit in placing a ceiling on the daily kill per hunter. Few public shooting ground hunters in Illinois are limited in their kill of ducks by the bag limit. But the bag limit is an effective measure in restricting the individual kill of the better hunters at the best Illinois clubs. All evidence points to the proba- bility that in this state it is just as effective in limiting the total kill, for membership in Illinois waterfowl clubs has not materially increased, nor has the hunting intensity increased notice- ably as a result of lowered bag limits. The individual daily bag limit ranks next to limitation of length of season as an effective regulatory measure in management of migratory ducks in Illinois. Laws for Depleted Species As previously discussed, because of differences in native wariness, feeding, flocking and migrating habits, some kinds of ducks are more readily killed by hunters than others. Some have higher rates of productivity and so can re- cover more quickly from the effects of heavy shooting, drought or other dis- aster. Some are affected more than others by adverse weather conditions. Because of differences in numbers or in attractiveness to hunters, as well as in certain habits, some are subject to greater shooting pressure. Federal regulations of 1938-1940 re- stricting the daily individual bag of canvasbacks, redheads, ruddy ducks and buffleheads to three alone or in the aggregate ot these species were not very effective in reducing the shooting pres- sure on, or the total kill of, these species in Illinois. The shooting pressure quotient on the canvasback was 1.65 in 1938, 1.44 in 1939 and 0.63 in 1940, with the restric- tions; 1.47 in 1941 and 1.09 in 1942, without the restrictions, table 8. The shooting pressure quotient on the ruddy was 3.07 in 1938, 2.48 in 1939 and 0.57 in 1940, with the restrictions on the take; 0.86 in 1941 and 0.63 in 1942, when there were no such restrictions, table 8. This situation alone does not necessarily mean that in other sections of the United States the restricted limit did not lower the total kill of these species, but it indicates that in states where these species made up only a small part of the population, and where no special Table 11.—Per cent of bands returned from 11 species of ducks within the first year after being banded. Ducks were banded in the United States and Canada, principally since 1938.* Species 362 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 in all 48 states; in 1944 in all states but Kill records from duck clubs along the South Dakota and Massachusetts. Mississippi River in 1942 disclose that The regulation allowing one wood one-third more woodies were bagged duck in possession has caused a great there per hunter-day than along the deal of controversy among bird lovers, Illinois River. Harry Maltby, U. S. Table 12.—The numbers and species of ducks killed at 276 clubs in the Illinois River valley, 1942. Number Species* Killed Wood duck, Aix sponsa (Linnaeus) SIS] Redhead, Nyroca americana (Eyton) 332 Ruddy duck, butterball, Erismatura jamaicensis rubida (Wilson) 627 Shoveler, spoonbill. Spatula clypeata (Linnaeus) 751 Gadwall, gray duck, Chaulelasmus streperus (Linnaeus) . 953 Green-winged teal, Nettion carolinense (Gmelin) 1 , 171 Canvasback, can, Nyroca valisineria (Wilson) 1 ,415 Widgeon, baldpate, Mareca americana (Gmelin) 1 , 563 Ring-necked duck, blackjack, Nyroca collaris (Donovan) 1 , 824 Blue-winged teal, ^uerquedula discors (Linnaeus) 2,006 Lesser scaup, bluebill, Nyroca affinis (Eyton) 4, 161 Pintail, sprig, Dafila acuta tzitzihoa (Vieillot) 4, 875 Mallard, Anas platyrhynchos platyrhynchos Linnaeus ( cq cac Black duck, black mallard. Anas rubripes Brewster ) ' Other duck species occasionally seen in Illinois include the bufflehead, Charitonetla albeola (Linnaeus), and the American golden-eye or whistler, Glaucionetta clangula americana (Bonaparte). tThe actual number recorded killed was 476; however, since there was no designated place for wood ducks on the kill sheets, some club members recorded them in the unspecified duck column. Based upon number classified as unspecified in 1941, it is believed that about 200 wood ducks were so classified in 1942. conservationists and duck hunters. Does Game Agent, reporting (letter Decem- it permit too high a kill of this species? ber 27, 1943) on conditions along the Will the status of the species once again Mississippi River in Iowa during the become critical? In order to answer 1943 season, stated that a larger number these questions, at least in a limited of wood ducks were killed in that region way, let us examine the kill records of in 1943 than in 1942. This was due Illinois duck clubs and ratios of band to the greater scarcity of other species returns to birds banded. early in the season. Relatively few wood ducks were From the first season band returns killed in the Illinois River valley in before and after full legal protection 1942, table 12. While these ducks were was removed, table 13, it may be possi- relatively numerous, most hunters in ble to evaluate the effect of the regula- this region passed up shots at them to tion allowing one wood duck in posses- kill other species. Occasionally one sion. Only the bands reported from was shot to add to a low bag, and birds wood ducks either shot or "found dead" were shot accidentally in 1942, just as were recorded; the "found dead" wood- when given complete legal protection, ies are assumed to have been shot, for it Because the legal 1942 kill of wood ducks is evident, after comparing the propor- in the Illinois River valley was probably tion of other species reported found little greater than the estimated illegal dead and after noting the greatly re- kill (Hawkins & Bellrose 1939) in the duced number of woodies reported 1938 season, it must not be assumed that "found dead" when it was legal to take the one wood duck law had little ad- one, that the "found dead" report was verse effect on the species. sometimes only a subterfuge on the part Undoubtedly where other species of of hunters to escape being penalized, ducks were less abundant than along Nevertheless, a surprisingly large num- the Illinois River, proportionally more ber of protected wood ducks were wood ducks were taken by hunters, actually reported shot. Doubtless some I November, ig44 Bellrose: Duck. Populations and Kill 363 bands were not turned in because the hunters finding them feared apprehen- sion. Data presented in table 13 show that even when wood ducks were given com- plete legal protection a significant pro- portion of the population was killed by hunters. There was apparently a de- crease in the proportion killed in 1941, although, for the first time since corn- table 11. It is evident that over the nation, even with a one in bag or pos- session limit, wood ducks suffered a hunting mortality rate comparable to that of most other species. How the wood duck ranks in pro- ductivity with other species has at present not been determined. There can be little doubt that during the past 2 years in many sections of the United Table 13.—Number of wood ducks reported banded in North America, place of banding and per cent of bands reported recovered from banded birds shot or "found dead" within a year after being banded (first season returns). 364 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 season adjusted to provide less shooting pressure. In the northern and central zones, a late opening would see most of the wood ducks gone before shooting commences. Census and banding rec- ords in Illinois reveal that most of these ducks have departed from this state by November 1. Effect of Bait and Live Decoys In the years when baiting was per- mitted along the Illinois River, there were two diverse types of baited areas. In the bottomlands, bait was placed in small timbered ponds, or at shooting stands in the marshes and on the large lakes. Differing widely from such baited areas were the upland field pens, each of which consisted merely of a pen of decoys, bait and, usually, a small pond of water. The bottomland areas most success- fully baited were small timbered ponds and potholes. For the reason that the region near the mouth of the Sangamon River contained many such areas and was almost devoid of natural foods, it was the scene of the heaviest baiting. Leopold (1931) reports that in that region in 1928 clubs were putting out, on a 20-acre tract, as high as 7,000 bushels of corn per season and that rates per acre ran up to 430 bushels per season. According to Uhler (1933) field-pen shooting reached its maximum develop- ment in Mason County. The success there was due largely to the proximity of three large "rest" lakes—Clear, Jack and Crane—which at the time were not adapted to the growth of first-class duck food plants because of their extreme fluctuation in water levels. Mallards were readily attracted from these lakes to the nearby heavily baited field pens. From a plane, Uhler enumerated 250 field pens in Mason County and in the adjacent part of Tazewell County. Most of these were within 5 miles of the Illinois River bottomlands, but a few were nearly twice that distance from the river. Uhler's description of a dry-land club is as follows: "A typical field-pen con- sists of a small artificial pond supplied by water which is usually pumped from a nearby well by means of a portable gasoline engine. The basin of the pond is lined in a variety of ways to prevent seepage The pond is equipped with a flock of live decoys and baited heavily with corn on the cob or shelled. Sometimes, the entire pond is enclosed: with poultry mesh about four feet high. Other ponds have the decoys confined Plioto by Bob Becker Corn being scattered at an Illinois River valley shooting stand in the days of baiting, 10 d more years ago. Mallard and pintail silhouettes are shown being used as decoys. The combinatior, of baiting and live decoys resulted in a duck kill so high that restrictive measures were inauguratet in an effort to prevent rapid depletion of the population. November, 1944 Bellrose: Duck Populations and Kill 365 to one or more small pens extending into by Uhler in Mason County and an ad- the pond Usually from 3 to 5 joining part of Tazewell County, there blinds made of corn stalks, leafy oak were probably 200 others in the vicinity branches, or rushes fastened to portable of the Illinois River. Leopold (1931) frames surround these ponds. Many reports that 4,000 ducks were killed in dry pens were also noted. These con- 60 days on one 40-acre commercial dry- Photo by Bob Becker A pen of live decoys in front of a blind, once a familiar scene in the Illinois River valley. sist of a pen of live decoys placed in some remote field and surrounded with long bands of shelled corn or corn on the cob. The only water involved in this set-up is placed in a trough or other receptacle for the decoys to drink." Uhler reported that one of the most successful commercial shooting places fed at four field pens from 1,400 to 2,500 bushels of corn per season. He estimated that 6,000,000 bushels of corn were fed by Illinois clubs during the 1933 season. Sixty-seven clubs re- ported feeding an average of 1,243 bushels of corn and other grains. I What was the influence of baiting and decoy pens on the kill of ducks in Illinois? In addition to Uhler's 1933 report on the estimated duck kill and populations in the Illinois River valley, we have waterfowl kill records from the iState Department of Conservation for i2 years in which corn was put out for iducks, 1933 and 1935. Through band returns, we can roughly compare differ- ences in mallard mortality during and after the baiting period. Besides the 250 field pens enumerated land club. Uhler says that at one com- mercial dry-land club in 1933 an average of eight shooters per day were assured the limit up to the time of his visit in mid November. That would mean a kill of about 2,400 ducks during the first half of the season. These were among the dry-land places at which the highest kills were made. Reports of local hunters familiar with the situation indicate that an average of 500 ducks were killed at each field pen. If there were 450 field pens, the total annual kill made by these dry-land clubs amounted to about 225,000 ducks. Bottomland clubs were not affected as greatly as upland field-pen clubs by the outlawing of bait and live decoys. However, many clubs in the Sangamon River bottoms disbanded because of the low duck kill resulting from the no- bait, no-live-decoy law. With no bait or live decoys, the kill at several of the large Sangamon River clubs dropped from 7,000 or more to less than 500 per year. Some indication of the influence of bait and live decoys on the duck kill in 366 Table 14. Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 -Total reported kill of ducks at Illinois River valley waterfowl hunting clubs; average kill per club and per hunter-day. Year November, ig44 Bellrose: Duck Populations and Kill 367 pressure resulting from baited areas and live decoys fell upon the mallard and black duck than upon other species. Table 15 shows that, in 1933, 83.80 per cent of the bag was made up of mal- lards and black ducks. In the 1941 season, of comparable length and dates, 28,000 mallards at the Chautauqua Na- tional Wildlife Refuge, near Havana. As indicated by band returns, the shot- gun mortality, the first season, of 27,680 fall banded mallards was 2.9 per cent in 1939; 6.8 per cent in 1940; 2.6 per cent cent in 1941; 7.0 per cent in 1942; and Photo by Bob Becker Mallard and pintail blocks, or wooden decoys, being picked up in a marsh smartweed area that has yielded large kills of Illinois River valley ducks. only 63.72 per cent of the bag was com- posed of these species. Even in 1935, when feeding was done in areas not shot over and live decoys were outlawed, the mallards and black ducks comprised 88.79 per cent of the total bag; in 1938, mallards and black ducks formed only 55.70 per cent of the bag. The large pro- portion of those species in the 1936 and 1937 bags, when baiting and use of live decoys were illegal, was due to the fact that the open season extended from November 1 through 30, a period in which mallards formed over 90 per cent of the waterfowl population. Banding returns show that baiting and live decoys resulted in heavy shot- gun mortality to the mallard. A study of tables in Returns from Banded Birds, 1920 to 1923 (Lincoln 1924) indicates that 218, or 16.4 per cent, of the mal- lards banded by Lincoln during the autumn of 1922 near Browning, Illi- nois, were killed that hunting season in Illinois; a mallard kill rate much higher than in recent years in this state. From 1939 through 1943, the Illinois Natural History Survey banded about 5.7 per cent in 1943. Lincoln banded his mallards at a gun club, and we banded ours at a wildlife refuge. While this difference contributed to the greater survival of Chautauqua-banded mal- lards, the kill rate of Illinois mallards in 1922 must have been at least twice as great as it has been since 1939. Re- turns from 2,452 mallards banded in Canada* show a shotgun mortality, the first year, of only 8.9 per cent in 1940, 5.7 per cent in 1941 and 6.4 per cent in 1942. These mallards had to face shot- guns in the northern zone as well as in the central and southern zones and therefore had more time in the season of banding in which to be killed than did those banded by Lincoln near Browning. Data on duck mortality obtained from Illinois State Department of Conserva- tion kill records, from Uhler's 1933 re- port and from a comparison of first hunting season band returns indicate that the kill rate under baiting and live decoy conditions was two to three times as great as after their prohibition. *Information furnished by B. W. Cartwright of Ducks Unlimited (Canada). 368 Illinois Natural History Survey Bulletin Fol. 2j, Art. 2 In Illinois, the improved survival rate during the baiting era. Natural food has applied mainly to mallards and pin- resources in the Illinois River valley tails; however, all species have ben- have increased in recent years, because efited from the no-baiting, no-live-decoy navigation dams have been built on the regulations, for all species—including river and because hunting clubs have canvasbacks, scaups, redheads and ring- made greater attempts to control their necks—were attracted by bait and live water levels. Uhler (1933) estimated decoys. that mallards comprised 85 per cent of Credit for the greater survival rate the waterfowl population of the valley at cannot be given entirely to prohibition the time he made his report. Mallards of baiting and live decoys, for other and black ducks, although increasing in conservation measures were put in force numbers, formed a successively smaller at about the same time. part of the total duck population be- However, these prohibitions increased tween 1938 and 1942, dropping from the rate of duck survival more than did 94.61 to 84.98 per cent, tables 3-7. shortening the seasons, reducing bag Other species of ducks are forming a limits or limiting the shooting hours, greater percentage of the waterfowl Because the bans on bait and live de- population in the Illinois River valley, coys were initiated at approximately Improved environmental conditions for the same time it was not feasible to diving ducks are largely responsible for evaluate the effectiveness of each of this trend, these two separately. Despite the great reduction in kill Effect of Three-Shell Law following outlawing of the use of bait and live decoys, no catastrophe has Because of lack of specific data, it has befallen either the waterfowl club or the been impossible to evaluate the three- individual hunter. True, the disband- shell limit for shotguns. In the days ing of all dry-land duck clubs has re- of live decoys and baiting, when pot- suited, but these clubs contributed little shooting on massed ducks was common, to the welfare of the birds. They were the limitation of three shells to a gun parasitic. In some sections, notably would have been an important factor near the mouth of the Sangamon River,, in reducing the carnage at baited pens, bottomland waterfowl clubs have passed However, the three-shell law went into out of existence, but in other sections effect in 1935 after live decoys had been they have held their own or even in- banned and outright baiting prohibited, creased in number. In 1941, there were Ferd Luthy and other veteran Illinois 792 registered waterfowl hunting clubs duck hunters are of the opinion that the in Illinois, more than in the last years three-shell law lessens the chance of of the baiting and live decoy era. crippling ducks by reducing the number The free-lance hunter has materially of out-of-range shots. Since studies we benefited from the discontinuance of conducted in 1938 and 1939 disclosed baiting. Where formerly ducks were that about 3 ducks were crippled and concentrated in a few private, heavily lost for every 10 bagged, it is evident baited areas, today they are more that this loss is serious. If more shells evenly distributed. Now public hunt- in the gun would result in greater crip- ' ers may find fair shooting not only on pling losses, it would appear advisable several state-owned public shooting to retain the present three-shell limit, grounds and other waters not under private control, but in cornfields as well. Illinois Duck Harvest Ducks have not left the Illinois River valley, as many hunters feared would What per cent of the duck populations happen without bait to hold them, passing through the Illinois River valley Mallards, pintails and black ducks have in 1938-1942 was harvested by hunters found a ready source of food in the in this state? An answer to this ques-l waste corn left in fields by the mechani- tion may be found by comparing the kill cal pickers, and they remain in the with the population, table 16. At valley in numbers comparable to those present we must base the population II November, IQ44 Bellrose: Duck Populations and Kill 369 figures during sation When end of ducks be abl on peak numbers of each species the season, without any compen- for turnover of the populations, banding data are analyzed to the showing the rate of movement of through the valley, then we shall e to determine fairly accurately indicate that during the 1938-1942 period, 3.3 per cent of the ducks of all species in the Illinois River valley were taken by hunters, table 16. The band return data may be too low in some years because of a disproportionate amount of late season banding. After Table 16.—The approximate per cent of ducks bagged in the Illinois River valley, 1938 1942. Year 370 Illinois Natural History Survey Bulletin Vol. 2j, Art. 2 returns over the nation from approxi- mately 28,000 mallards banded on the Chautauqua Refuge, 1938-1943, amounted to only about 5 per cent, approximately one-fourth the propor- tion recorded by Lincoln near Browning. Pirnie (1935) reported that 20.5 per cent of 1,607 black ducks banded at the Munuscong Waterfowl Refuge in Mich- igan's upper peninsula between 1928 and 1934, before drastic waterfowl re- strictions were inaugurated, were re- ported shot the same season as banded. Of 1,251 black ducks banded from 1939 to 1942, inclusive, on the Seney National Wildlife Refuge in Michigan's upper peninsula, only 9.2 per cent were re- ported shot during the same season as banded (reported by C. S. Johnson to Richard Griffith). This is approxi- mately half the percentage reported by Pirnie for the earlier period from the same region. According to Phillips & Lincoln (1930) the annual duck mortality up to the time they wrote (as based on first- season band returns from stations scattered over the continent) was about 13 per cent. Banding data supplied by B. W. Cartwright of Ducks Un- limited (Canada) disclose that, in 1940, 6.7 per cent first-season band returns were received; in 1941 the returns amounted to 5.6 per cent; and in 1942 to 7.5 per cent. These figures repre- sent about half the percentage reported by Phillips & Lincoln. Although these figures are only small samples, their consistency is indicative that regulations in force in the past 10 years cut about in half the rate of kill made by hunters in the previous decade. On the whole, the measures enacted by the federal government to reduce the kill of ducks accomplished their pur- pose. Summary 1. In order to manage well the har- vest of the continental crop of migratory waterfowl, it is necessary to evaluate as closely as possible the influence each hunting regulation has on the kill and to determine the optimum dates for open seasons. Cbviously, a close evalu- ation covering all of North America is impossible at present, but it is feasible in a smaller area, such as Illinois. 2. All important waterfowl hunting regulations except those relating to territories were made by the individual states until the federal Migratory Bird Act was passed in 1913. 3. The Migratory Bird Act of 1913 and the Migratory Bird Treaty Act of 1918 applied the first major federal re- strictions on the taking of waterfowl. However, federal regulations were not very stringent until a shrinking water- fowl population, alarmingly evident by 1933, necessitated a great reduction in thekill.^ 4. Various restrictive measures im- posed on duck hunting, most of them in 1935, included reduction in the open season to 30 days, reduction in the bag and possession limits to 10 birds, limi- tation of shooting to the hours between 7 A.M. and 4 p.m., prohibition of the use of bait and live decoys, limitation of shells in gun to three or less, and re- duced limits or no open season on cer- tain species of waterfowl. 5. It is possible to regulate the kill of certain species of waterfowl in Illi- nois by opening and closing the hunting season to include all or certain proper- ; tions of the flight of these species within;! the open or closed periods. Species i differ in the time of arrival in Illinois,- in reaching maximum numbers and ini| departing. i 6. It may be necessary to protect i certain species more than others, fori each kind of duck varies in vulnerability i to the shotgun as well as to natural con- ditions. Inherent wariness, flight,:| flocking and feeding habits of ducks and.' shooting practices of hunters are factors; that affect the kill of each duck species.- 7. In Illinois, mallards and blacks ducks, as a group, were found to be the* least vulnerable to the shotgun, 1938-; 1942, followed by lesser scaups, can-j vasbacks, ruddy ducks, ring-necked i ducks, pintails, widgeons and gadwalls, ; green-winged and blue-winged teals, andj shovelers. | 8. Recent open seasons in Illinois' (1938-1942) have protected blue-winged teals more than any other species. These open seasons have protected other species in the following descending il November^ 1944 Bellrose: Duck Populations and Kill 371 order: shovelers, green-winged teals, pin- tails, widgeons, mallards and black ducks, ring-necked ducks, canvasbacks, lesser scaups, ruddy ducks and gadwalls. 9. In general, the duck species that migrate through Illinois during the early part of the fall migratory season are the ones most easily killed. Ducks of many species are most easily killed during the early part ot the season, probably because at that time juveniles predominate m the population. 10. The dates for the waterfowl hunting season in Illinois should depend upon what species of ducks need the greatest protection, and whether the hunter or the waterfowl population should be favored. Cpen dates sug- gested by this study are as follows: For a 30-day season, November 1-30; for a 45-day season, October 22-De- cember 5; for a 60-day season, October 10-December 8; for a 70-day season, October 1-December 9; for an 80-day season, September 26-December 14; for a 100-day season, September 20- December 28. 11. Although, in Illinois, the total duck bag does not vary proportionally with the number of days in the hunting season, altering the length of the season is one of the most expedient ways to regulate the duck kill. 12. Shooting hours, which were from 7 A.M. to 4 P.M., 1935-1939, from sunrise to 4 P.M., 1940-1941, then from sunrise to sunset, 1942, and from one-half hour before sunrise to sunset, 1943-1944, appear to have affected the flight habits of cornfield feeding ducks more than the kill of those ducks. Mallards, black ducks and pintails feeding in cornfields have changed the time of their daily flights so that they still generally feed before and after shooting hours. To date there is apparently no evidence that changes to earlier and later shooting hours increased the duck kill; probably the changes lowered the kill. 13. Evidence derived from records of the kill of ducks at one Illinois River valley club that furnished good shooting shows a close correlation between legal bag limits in the lower figures and the number of ducks killed per hunter-day. The higher the bag limit, the less it seemed to influence the duck kill; there was much less difference between actual daily bag and legal limit when the limit was 10 than when it was 25. The in- dividual daily bag limit is an effective regulatory measure in management of migratory ducks in Illinois. 14. Special protection has in some years been given through reduced bag limits to several species of waterfowl: canvasbacks, redheads, ruddy ducks and buffleheads. Some doubt exists as to the effectiveness in Illinois of this measure in reducing the kill of species it is intended to protect. 15. While wood ducks were killed in considerable numbers even when given complete legal protection, the regula- tion permitting one such duck in bag or in possession probably increased the kill as much as two-thirds. The hunting mortality rate of wood ducks in 1942 and 1943 was comparable to the kill of other species of ducks under no special bag restriction. Whether the produc- tivity of the wood duck will keep pace with the increased kill must be deter- mined by closely checking the popula- tion. 16. In 1933, when use of bait and live decoys was permitted, the kill of ducks in the Illinois River valley was, it is estimated, 8 to 1 1 times as great in proportion to the population as in 1941, when use of bait and live decoys was banned. The ban on the use of bait and live decoys eliminated about 450 commercial dry-land pens in Illi- nois. Most bottomland hunting clubs were not seriously affected by the ban on such practices. In 1941, there were 792 registered waterfowl hunting clubs in Illinois, more than in the last years of the baiting and live decoy era. 17. The three-shell limit on shells in gun appears to be a desirable restriction. 18. In the 1938 1942 period, about 3 to 5 per cent of the migratory ducks passing through the Illinois River valley were taken by Illinois hunters. 19. Restrictive waterfowl regulations enacted in recent years have aided in the survival of migratory ducks in North America. Available data indi- cate that over the North American continent the proportional kill in the past 10 years was about half that in the previous decade. LITERATURE CITED Anonymous 1770. The statutes at large from the first year of King Edward the Fourth to the end of the reign of Queen Elizabeth. Mark Basket, London. Vol. 2. 723 pp. 1936. A permanent solution to the waterfowl season problem. More Game Birds in America New York. 6 maps. Bellrose, Frank C, Jr. 1944. Waterfowl hunting in Illinois: its status and problems. 111. Nat. Hist. Surv. Biol Notes 17. 33 pp., 17 figs. Cottam, Clarence 1935. Waterfowl problems clarified by study of gunning practices. U. S. Dept. Ag. Year- book 1935:328-30. 1939. Food habits of North American diving ducks. U. S. Dept. Ag. Tech. Bui. 643. 13S pp., illus. Gabrielson, Ira N., and Frederick G. Lincoln 1941. What is behind the waterfowl regulations? Committee Print No. 1, Senate, 77t J Congress, 1st Session. 34 pp. 23 figs. Hawkins, Arthur S., and Frank C. Bellrose 1939. The duck flight and kill along the Illinois River during the fall of 1938. Am. Wildlife 28(4):178-86. Kortright, Francis H. 1942. The ducks, geese and swans of North America. American Wildlife Institute, Wash ington, D. C. 476 pp., illus. Lavv'yer, George A. 1918. Federal protection of migratory birds. U. S. Dept. Ag. Yearbook 1918:303-16. Leopold, Aldo 1931. Report on a game survey of the north central states. Sporting Arms and Ammunition Manufacturers' Institute, Madison, Wisconsin. 299 pp., illus. 1933. Game management. Charles Scribner's Sons, New York. 481 pp., illus. Lincoln, Frederick C. 1924. Returns from banded birds, 1920 to 1923. U. S. Dept. Ag. Dept. Bui. 1268. 55 pp., illus. Palmer, T. S. 1912. Chronology and index of the more important events in American game protection, 1776-1911. U. S. Dept. Ag. Biol. Surv. Bui. 41. 62 pp. Phillips, John C., and Frederick C. Lincoln 1930. American waterfowl, their present situation and the outlook for their future. Houghton Mifflin Company, Cambridge, Massachusetts. 312 pp., illus. Firnie, Miles David IV 1935. Michigan waterfowl management. Department of Conservation, Lansing, Michigan. 328 pp., illus. IUhler, Francis M. 1933. Effect of baiting and live decoys on the waterfowl of the upper Mississippi River valley U. S. Fish and Wildlife Service. (Unpublished report.) [ 372 ] Recent Publications A.—ILLINOIS NATURAL HISTORY SURVEY BULLETIN. Volume 21, Article 3.—Studies of Nearctic Aquatic Insects. By H. H. Ross and T. H. Frison. September, 1937. 52 pp., frontis. + 86 figs., bibliog. 50 cents. Volume 21, Article 4.—Descriptions of Nearctic Caddis Flies (Trichoptera), with special reference to the Illinois species. By Herbert H. Ross. March, 1938. 84 pp., frontis. + 123 figs., foreword, index. $1.00. 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