HABITAT USE AND HOME RANGES OF PODOMYS FLORIDANUS ON THE ORDWAY PRESERVE Cheri A. Jonesi ABSTRACT I examined habitat use and home range size ofPodomys/loridanus on the Ordway Preserve, where this species is most common in high pine communities with gopher tortoises (Gopherus polyphemus). These communities are subjected to prescribed burns in order to prevent invasion of woody species. Populations of Podomys appeared more stable on burned sites than on unbumed areas. Home ranges did not alter after prescribed burns and little or no fire-related mortality was indicated, Mean home ranges were 2601 m2 for 35 females and 4042 m2 for 40 males. Individuals who survived more than one year on the sandhill utilized the same set ofburrows each season. Home ranges of adult females did not overlap, suggesting intra-sexual territoriality. RESUMEN Examin6 el uso de habitat y tamafio del ambito de hogar de Podomys,#oridanus, en la Reserva Ordway, donde esta especie es mAs comon en comunidacles de pino alto con tortugas excavadoras (Gopherus po(yphemus). Estas comunidades estin sujetas a quemas prescritas con el objeto de prevenir la invasi6n de especies leaosas. Las poblaciones de Podomys parecieron ser mds estables en sitios quemados que en *eas no quemada~. Los hmbitos de hogar no fueron alterados despua de las quemas prescritas y se detect6 mu¥oca o ninguna mortalidad ~lacionada con el fiego. El tamaho medio de los dmbitos de hogar fue 2601 m para 35 hembras y 4042 m para 40 machos. Los individuos que sobrevivieron mas de un afto en las tierras altas arenosas, utilizaron el mismo grupo dc cuevas en cada estacidn. No hubo superposicidn en los dmbitos de hogar de hembras adultas, lo cual sugiere territorialidad intrasexual. INTRODUCTION The Florida mouse, Podomys flondanus, is one of the characteristic rodents of the Ordway Preserve. Here P. floridanus is known from high pine habitats (i.e. longleaf pine sandhills) and from ecotones between high pine and hammock or high pine and old pasture ' The authoris Curator of Mammalogy at the Demer Museum of Natural Histog, 200)1 Colorado Bhd., Dmi,er CO 80~5-5798, U.S.A. JONES, C.A. 1995. Habitat and Home Ranges of PodomysjZoridanus on the Ordway Preserve, Putnam County, Florida. Bull. Florida Mus. Nat. Hist. 38, Pt. II(7):195-209. 196 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL 38, PT: 11(7) (Brand 1987; Eisenberg 1988; Jones 1990) (Fig. 1). It is closely associated with burrows of the gopher tortoise, Gopheruspolyphemus (Jones and Franz 1990). High pine sandhills are pyrogenic communities that were subjected to frequent, cool fires; without fire, these communities convert to xeric hardwoods/mixed pine associations (Myers 1985). Management for longleaf pine on the Ordway now requires systematic prescribed burning on a three-year rotation to mimic the natural fire regime (described for the Preserve by Humphrey et al. 1985). However, aside from the study of the southeastern pocket gopher (Geomys pinetis) on the Ordway Preserve (Gates and Tanner 1988), little is known about the effects of fire on small mammals of high pine. Only two studies have examined effects of prescribed burns on Podomys. In a 15-month study, Arata (1959) compared trapping success on traplines before (3%) and after (9%) fires in Alachua County. Layne (1990) noted declines of Florida mice 10 years after the most recent fire in both scrub and sandhill sites. He also observed (1990:4) that Florida mice tend to occur in the most open microhabitats available. Jones and Franz (1990) suggested that the extensive use of tortoise burrows by Podomys on the Ordway provided shelter from both fires and the temperature extremes typical of the area. Observations of Podomys in and around these burrows led to an investigation of the home range size of these mice, and the question whether these mice maintained territories around tortoise burrows. Among peromyscines, there is considerable variation in reported home range sizes and degrees of territoriality (Eisenberg 1968; Stickel 1968; Wolff 1989). In this study I used Burt's (1943:351) definition of home range: "that area traversed by the individual in its normal activities of food gathering, mating, and caring for young. Occasional sallies outside the area... should not be considered as in part of the home range. The home range need not cover the same area during the life of the individual." Territoriality, on the other hand, includes defense by either overt or covert social interaction (Burt 1943). A territory is "a fixed portion of an individual's or group's range in which it has priority of access to one or more critical resources over others which have priority elsewhere or at another time" (Kaufmann 1983:9). To date, the only report of home range size for Podomys was that by Layne (1990:9), who compared average distances between successive captures of Podomys within trapping periods and noted that home ranges in sandhills (25 m) were larger than those in scrub (16 m). The natural history of P. foridanus is less well-known than that of other North American peromyscines. J. N. Layne has extensively studied ontogeny, parasites, and other aspects of the biology of this species (Jones and Layne 1993 plus citations therein; Layne and Jackson 1994). Results of his work suggest that dependence on tortoise burrows, and other aspects of Podomys biology, differ among populations. The purpose of this project was to examine responses to prescribed burns and home range sizes of Podomys in high pine habitats on the Ordway Preserve. ACKNOWLEDGMENTS I thank two anonymous reviewers forlheir critiques ofthe manuscripL JONES: PODOMYS PLORIDANUS ON THE ORDWAY PRESERVE 197 Ordway/Swlsher Preserve Preserve boundaries Wellands ~ I. -- - i Lakes 0 ./r n: :.-- ·n:,i = Melrose r--- lkm LP S LL-i ~ ~ n.' J r Figure 1. Distribution of Podomys on the Ordway/Swisher Preserve. Lncations of Anderson-Cue (AC), Blue Pond (BP), L,ongleaf Pine (LP), and Smith Lake (SL) sandhills are shown. Dots represent additional locations where Podomys has been captured. MATERIALS AND METHODS I trapped Podomys at tortoise burrows and on grids using standard mark-and- recapture techniques (Davis 1956). While trapping at burrows, I placed a pair of Sherman traps (baited with oatmeal) at the entrance, or just inside the entrance. Mice were marked by toe-clipping and weighed; I also noted sex, reproductive condition, and presence of ectoparasites. Animals were released near the entrance, and in most cases I recorded whether they entered the burrow or ran elsewhere. I collected the same data on three grids, one placed on the south side of Smith Lake and two set north and east of the Anderson-Cue ponds. Grids were more than 100 m apart to reduce movement of animals between grids. Each grid consisted of 10 columns and 10 rows 10 m apart (area = 10,000 m2) with a single Sherman at each intersection. Each burrow and grid intersection was marked, numbered, and mapped. Trapping efTort was measured as trapnights (one trapnight being one trap/night). Traps were opened near sundown and checked at sunrise. Excelsior was provided as insulation during cool weather. Because Podomys is susceptible to cold weather (Layne 1969; pers. obs.), trapping began in February or March and ceased in October or November. Two separate trapping regimes were conducted in order to determine home range size and the effects of prescribed burns. I trapped mice at tortoise burrows before and after 198 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 38, PT. II(7) prescribed burns on three independent sandhills (Blue Pond, Longleaf Pine Pasture, and Smith Lake) so I could examine the response to burns. Burrows at Blue Pond were trapped for 2442 trapnights March-November 1988; at Longleaf Pine for 867 trapnights July- November 1987; and at Smith Lake for 3092 trapnights in 1985 (Jones 1990). Eisenberg's unpublished trapping results from Smith Lake (1983) were included in this analysis. These sandhills are on three-year rotations of prescribed burns, but differ in area and seasonality of burns. Trapping results on burned sandhills were compared with those on smaller, neighboring sites that were not burned. Because trapping effort and area among the three sandhills were unequal, I calculated numbers of individuals per 100 trapnights per hectare. The G-test was used to test the null hypothesis that equal numbers of mice were captured at burned and unburned areas. I determined the home range sizes on the Ordway sandhills by comparing the results of trapping on grids and at burrows on the Anderson-Cue, Blue Pond, and Smith Lake sandhills. A third technique, the use of fluorescent powder as discussed by Lemen and Freeman (1985), was attempted unsuccessfully (Jones 1990). Two grids on Anderson-Cue were trapped three consecutive nights per month, August 1987-November 1988, for a total of 6400 trapnights. One grid on Smith Lake was trapped for 3900 trapnights, April 1987- November 1988. Podomys was trapped at burrows at Anderson-Cue 1986-1988, Blue Pond in 1988, and Smith Lake from 1984 through 1988. As described by Jones (1990), all three sandhills differed in area, vegetation, and elevation. RESULTS Numbers of Podomys were more constant on burned sandhills than on the unburned areas, although estimated densities fluctuated on all three sandhills (Fig. 2). Apparent densities ofPodomys at unburned burrows occasionally appeared high, which seemed to be an artifact of the small area of unburned sandhill; all animals captured on the three unburned sandhills were captured on edges of the unburned areas. More individuals were caught in burned areas following a fire (Table 1) Significantly more individuals were captured on burned sites than at unburned burrows (G = 10.597, p < 0.005). There was no significant difference in trapping success between the three months immediately preceding and following the burns. Home ranges of 13 animals captumd at least five times on burned areas did not significantly shift or change in size following the fire. There was little or no evidence of mortality directly attributable to fire. On Smith Lake, 87% of the 15 individuals trapped the month before the burn were captured the month after the fire; on Blue Pond and Longleaf Pine, all mice trapped before the fire were captured the month after (i.e. 100% survivorship). Trapping success on burned and unburned sites also was compared by examining trapping effort expressed as trapnights per total number of captures per hectare (Table 2); i.e. how much effort was required in an area to trap a mouse. No effort was made to make trapnights equivalent. Regardless of the total number of trapnights, more time was needed to catch a mouse on the unbumed sites. For all five years on the Smith Lake sandhill, the numbers of trapnights required to catch a mouse were much lower and more consistent year to year on the burned area than on the unburned area. JONES: PODOMYS FLORIDANUS ON THE ORDWAY PRESERVE 199 3.0 N~ o i o burned , 0 unburnod 9 • 11,•\ 2 2.0 1.0 . 7 1 P K .t n ,% rf A A r. n M A J A O M J S N~ F A J A O' F' 'A 'J 'A 'O' ~ 'A 'J A O 1984 1985 1 1986 1987 1 1988 Figure 2. Apparent densities (expressed as minimum numbers of individuals/ha) of P. ,#ondanus on the burned and unburned areas of the Smith Lake Sandhill. Table 1. Data obtained from trappingPodomys at burrows (n) subjected to prescribed burns on Blue Pond, Longleaf Pine, and Smith Lake sandhills. MNI is number ofindividuals caughL Pre-burn Post-burn Blue Pond (n = 26) Trapnights 416 676 MNI 10 8' Total captures 24 28 Longleaf Pine (n = 24) Trapnights 318 174 MNI 5 9 Total captures 7 5 Smith Lake (n = 57) Trapnights 558 805 MNI 15 8 Total captures 44 37 ' Encludes 4 individuals captured before the burn. ' includes 2 individuals captured before the bim r includes I O individuals captmed before the burn. In the study ofhome range, persistence (the number of days from first to last capture) ranged from 1 to 75 days for 10 females and 8 males captured on the Anderson-Cue grids, and from 1 to 75 days for 10 females and 14 males captured on the Smith Lake grid. The largest population occurred on the Smith Lake grid in the spring of 1987 and 1988, when there were 8 individuals. Excluding animals caught three times or less, mean persistence time on this grid was 196 days for females and 137 days for males. 200 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 38, PT. II(7) Table 2. Comparison oftrapping effort on unburned and burned sandhills, where TN is the total number of trapnights and trapping effort is expressed as trapnights/capture/ha Unburned site Year TN trapnights/capture/ha Blue Pond 1988 830 19.53 LongleafPine 1987 371 51.53 Smith Lake 1984 476 7.39 1985 784 14.74 1986 786 280.71 1987 429 15.32 1988 704 8.38 Burned site---Blue Pond 1988 1612 8.70 Inngleaf Pine 1987 492 6.51 Smith Lake 1984 1444 0.64 1985 2308 1.00 1986 2958 1.17 1987 1839 0.99 1988 2789 1.02 I determined whether ranges of females and males overlapped on grids by plotting home ranges ofPodomys caught during May 1987 (n=6 animals) on Anderson-Cue and May 1987 (n=8), September 1987 (n=7), and May 1988 (n=9) on Smith Lake, the three months during which populations appeared to be the largest. All mice were captured four or more times on grids. I calculated the home range area using the Exclusive Boundary Strip Method, in which a boundary is plotted as half the distance between adjacent traps (Stickel 1954). Home range data are summarized in Tables 3 and 4. Three animals were marked on the grids as juveniles (gray pelage) and died or dispersed off the grid at approximately 60 days of age. Two more animals (female 26 and male 54 at Smith Lake) marked as juveniles did not leave the grid. The male shifted his home range, but I could not distinguish between juvenile and adult home ranges for female 26, who subsequently appeared to have an activity area larger than that of other females. Generally, ranges of males and females overlapped, but ranges of adult females did not (except occasionally with juveniles or young adults), a pattern which suggests intra-sexual territoriality (Kaufmann 1983). A female juvenile overlapped with the ranges of an adult of each sex. Female 26, the one with the unusually large range, overlapped somewhat with another adult female in September 1987. Seventeen adults trapped on the Smith Lake grid and one Anderson-Cue grid had an average home range of 804 m: In general, males (mean = 910 mz) appeared to have larger home ranges than females (mean = 683 m2), but the difference was not significant (Mann-Whitney test atp = 0.01) I also estimated home ranges of adults trapped more than four times in a year at burrows on Anderson-Cue and Smith Lake, using the exclusive boundary method (Stickel 1954) as I did for grids. The boundary was set as equal to half the distance between burrows, and for burrows on the perimeter of the study site, I plotted a boundary of 10 m (a conservative estimate of distance moved beyond the burrow). All capture points were weighted equally, but in a few instances I omitted points that suggested unusual forays outside the usual home range of the animal. JONES: PODOMYSPLOR,DANUS ON THEORDWAY PRESERVE 201 Table 3. Home range data f6r 20 Podomys trapped on two grids. ID indicates sex and identification number, No is number of captures, Po is persistence on grid in days, A is area of the home range in mz for juveniles (Ai) and adults (AA). Grid ID NG Po AA A, ACI F89 6 21 700 ACI F91 7 75 500 ACI F96 4 21 400 ACI F94 6 21 916 ACI M95 5 21 750 ACI M96 5 21 800 SL F61 5 24 1000 SL F10 6 42 500 SL F18 6 36 600 SL F26 17 449 1350 SL F47 12 517 300 SL F54 6 74 300 SL M42 8 289 1850 SL M49 10 91 1200 SL M54 16 381 1093 200 SL M16 9 148 800 SL M53 6 76 600 SL M56 7 44 500 SL M59 8 74 1000 SL M 102 10 156 400 Seventy-one home ranges for 62 animals who fit the above criteria are shown in Figure 3. Home ranges for adult males frequently overlapped, but those of females did not; two Smith Lake females who appear to overlap in 1988 actually were separated temporally. This separation of home ranges, similar to that observed on grids, suggests intra-sexual territoriality. Home ranges varied in size from 210 m2 (for Smith Lake female 26, captured at a single burrow 6 times in 1987) to 11007 m2 (for Smith Lake male 11 in 1986). The average home range size for 35 females was 2601 mz (SD = 1315.1) and for 40 males was 4042 m~ (SD = 2269.4); home ranges ofthe two sexes differed significantly (Mann-Whitney U = 2.95, p = 0.01). For the Smith Lake data I also compared areas in 1983-1985 with those of 1986-1988 to see whether home range size changed after the prescribed burn in 1985, but I found no significant difference. Capture data for 75 adults are shown on Table 5. Females 86, 94, and 97 (1987) were from Anderson-Cue; the remaining animals were on Smith Lake. Each animal was trapped from 5 to 22 times during the year in question, and almost all mice utilized more than one burrow (mean number of burrows = 3.8). Estimates of persistence (the number of days between first and last captures) are minimal estimates of persistence on the sandhill. they are not comparable across years because trapping effort varied each year, nor do they represent longevity because captures of juveniles and subadults (or captures as adults in years other than those shown) are excluded. 202 B U LLE TIN FLO R ID A M U S E U M N AT U R A L H IS TO R Y VO L. 38, PT. II(7) 8 28 ' 27_ , 2333 \. .\ I-- 49 5 . .. . .. /. . 47 i./ A-.\4825 /\ \ \ 38 29 , . 34 _.1_ . .. ..If 14 .... 48 ...=ij C. 39 . 1 27 -85 Figure 3. Annual home ranges of 62 Podomys on the Smith Lake sandhill 1983-1988. Dots represent tortoise burrows where mice were trapped. Solid lines indicate home ranges offemales, broken lines for males. (a) 1983, 52 burrows; (b) 1984,61 burrows. Bar represents 20 m. 100 9~»-73 95 4 , 17 .---:U / 5.-5 1 •--91#...... . · : 88 Sh') 93. -- 23 ...-./ 11 ;-- . 76 JO NES: PO D O M YS PLO R ID AN U S O N TH E O R D W AY PRESERVE 203 1 I 7389 7 1".1.-) 11 /-\. 97 -.- -: ; .... . . 1 39 . / 98 . '30 . I . ....+7. .- :. f 4 ,---. '/n 941 . ---- 7 , I. r- 9 80-----=\.7-2.:3 ' .32 -1.-35)--K:.\:r, ..2-'-:-*. 100 , .~f ' 72 . .. .'39 Figure 3. Continued. (c) 1985,89 burrows; (d) 1986, 103 burrows. Bar represents 20 m 204 B U LLE TIN FL0R ID A M U SEU M N AT U R A L H IS TO R Y VO L. 38, PT. II(7) 17 -: 65 .- I Ir-/6 · 34 . I i 68 .. ,.1.\47 .37 -' .J N \ 26 .*~47~0 .,- T /. \ 15\ -- 4 , h:16 \ ·\ . 42 1 t-)§;3911 , \ ':. , 'f37 42 .-, p-: /:2~.~ ..:.. . I . :--/ .. 61 '. . 36 ,« 0 / 102' 51 . .. -- 0.80 . 52 /I r . 22 ' 98 20\ 4.6 '. . L .... ..72 --~7 ~.1/ ;57 *-. ' i j - -. .. .. 10 · . .. . Figure 3. Continued. (e) 1987,131 burrows; (f) 1988,136 burrows. Barrepresents 20 m JONES: PODOMYSAORIDANUSONTHE ORDWAY PRESERVE 205 Table 4. Capture data for 36 Podomys at Anderson-Cue. ID indicates sex and identification number YR is year of first capture; AGE is age at first capture (J=juvenile, SA=subadult, or A=adult); N is number of captures at grids (No), burrows (NB), and total (NT); P is persistence in days on grids (Po), burrows (PB), and total (PT)· Asterisks indicate trap mortality. ID YR AGE NB PB No Po NT PT F83 88 1 1 1 1 1 F84 88 J 3 3 3 3* F83 88 J 1 1 1 1 F86 88 A 7 109 7 109 F87 88 SA 2 2 5 33 7 33 F88 87 A 1 1 3 3 4 9 F89 87 A 6 21 6 21 F90 87 SA 1 1 1 1 F91 87 SA 7 75 7 75 F92 87 A 1 1 1 1 F93 87 A 1 1 1 1 F94 87 A 7 164 1 1 8 164 F95 87 A 1 1 3 3 4 21 F96 87 A 1 1 4 21 5 40 F97 87 A 9 171 3 3 12 193 F98 87 1 1 1 1 1 F99 87 A 1 1 1 1 F100 87 SA 4 124 4 124 MBO 88 SA 3 216 3 216 M84 88 A 2 39 2 3 4 39 M85 88 SA 3 101 3 101 M86 88 SA 1 1 1 1 M87 88 SA 2 2 2 2 M40 87 A 1 1 1 1 M88 87 J 1 1 1 1 M89 87 3 1 1 1 1 M90 87 J 1 1 1 1 M92 87 A 3 48 2 2 3 48 M93 87 SA 3 5 3 5* M94 87 A 2 106 6 21 8 106 M95 87 A 5 21 5 21 M96 87 J 5 21 5 21 M97 87 A 4 130 4 150 M98 87 ? 1 1 1 1 M99 87 SA 1 1 3 3 4 21 M100 87 A 1 1 1 1 From August 1983 to November 1988, 255 P. flondanus were toe-clipped on the Smith Lake sandhill. Of these, 12 females and 10 males (8.6% of the total) were present for more than 360 days. Male 11 was the longest-lived, persisting for more than 920 days. Animals who survived for more than one year (e.g. male 11 in 1985-87, Fig. 3) showed fidelity to the same general area every year. 206 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL 38, PT. II(7) Table 5. Capture data for 75 adultPodomys. ID is the sex and identification number of each mouse; YEAR is the year for which the home range was calculated; N~ is the number of captures, Ps is persistence (in days); #B is the number of burrows where each animal was caught; and asterisks denote animals present when trapping ceased in November 1988. ID YEAR NB PB #8 F5 1983 5 93 2 F8 6 71 3 F14 6 71 2 F27 5 114 2 F49 5 117 4 M29 5 79 2 M33 5 79 2 M47 5 99 2 M48 5 100 1 M53 5 79 2 F23 1984 8 125 2 F29 11 139 5 F34 5 56 2 F38 5 49 2 F43 15 222 3 M25 6 135 3 M27 5 61 3 M28 5 63 2 M39 14 171 5 M48 12 211 8 M85 6 99 3 F23 1985 14 212 3 F39 12 84 4 F30 8 183 5 F97 8 185 3 F100 22 265 5 M11 16 253 5 M32 13 183 6 M39 18 265 7 M98 13 265 6 M100 7 100 3 F89 1986 5 49 2 F93 5 36 3 F94 8 103 4 F95 6 107 2 Mil 19 253 8 M72 5 68 3 M73 7 79 3 M76 11 133- 7 M80 12 103 7 M88 16 259 4 M97 5 101 3 M98 5 171 3 F26 1987 6 78 1 F47 8 113 2 JONES: PODOMYSPLORIDANUSONTHE ORDWAY PRESERVE 207 Table 5 Continued ID YEAR Na PB #B F61 7 243 3 F68 6 170 5 F72 5 125 3 F86 7 109 4 F94 7 164 6 F97 9 171 8 Mll 8 143 5 M16 7 233 3 M17 5 193 2 M42 5 31 5 M57 9 242 3 M65 7 213 4 M80 9 201 5 M98 5 218 4 F10 1988 11 227* 4 F26 14 193 6 F36 3 94 3 F37 9 121 5 F46 10 151 5 F47 11 193 2 F49 8 148* 3 F52 11 151 5 M20 8 151 4 M22 8 151 7 M25 7 132 4 M34 6 104 4 M37 9 148* 5 M42 11 198* 7 M51 10 151 4 M10 13 198* 2 DISCUSSION Prescribed burns on the Ordway Preserve had no immediate impacts on mortality or the size and locations of home ranges of Podomys. More trapping effort was required to capture mice on the unburned sites and, over a period of several years, numbers of Podomys on unburned sites appeared less predictable and less stable than numbers on burned areas. On the unburned areas, all mice were captured at peripheral burrows (on the edge of unburned sandhill near old pasture or burned sandhill habitats), and in some years no animals were captured on these areas. Additional experiments with more replications (and burned and unburned sites of equal area) are needed, but these might be difficult to perform at Ordway, given the large home ranges and fluctuating populations of these animals. The immediate response of P. ,/lon'danus to the prescribed burns on the Ordway appears to be neutral (Jones 1992). However, it is clear that the cessation of fire allows conversion of high pine to xeric hardwood or mixed pine forests (Laessle 1958; Myers 1985) in which 208 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 38, PT: II(7) Podomys is absent. Prescribedfires maintain the open habitat and the tortoise populations on which these mice rely on the Ordway Preserve. Trapping on grids provided estimates of home range size and persistence, as well as demonstrating the exclusivity of home ranges of adult females. There also was evidence that males had larger home ranges that occasionally overlapped with each other and with females. However, results from trapping at burrows suggest that estimates from grids were too small. Evidently the "standard" mammal-trapping grid (10000 m2 with 10-m trap intervals) was insufficient to measure home ranges ofPodomys in sandhills. Doubling the trap interval to 20 m would produce a grid covering 40000 m2, which would encompass mean home ranges estimated at burrows for females (2601 m2) and males (4042 m2), might be more useful. No fewer than 100 trap stations should be used. However, increasing grid size on some sandhills will spread the grid into neighboring habitats. Estimates of home range produced by trapping at burrows were comparable with values reported for Peromyscus. Stickel (1968) reported that home ranges of Peromyscus varied from 0.1 to 10 acres. Hoffmeister (1981) reported mean home ranges for female (8290 m2 +/- 2688) and male (10465 m2 +/- 4043) P. truei in pinon-juniper habitat, also using the exclusive boundary strip method. Although the range of home areas of Podomys varies considerably, further research might show that my means are underestimates, based as they are on many individuals located on the edges of my study sites. I also have no measure of vertical habitat use; for example, it would be interesting to determine whether the mice occupy a larger home range volume in years when acoms are produced. In analyses of both burrow and grid data, I omitted animals that were recaptured less than three times. A possible consequence of this approach is that several animals might occupy the same space. However, the fact that both sets of data show abutment of home ranges of adult females seems good evidence of mutually exclusive home ranges, which suggests that females might be territorial. LITERATURE CITED Arata, A A 1959. Effects of burning on vegetation and rodent populations in a longleaf pine turkey oak association in north central Florida. Quart J. Florida Acad. Sci. 22:94-104. Brand, S. M. 1987. Small mammal communities and vegetative structure along a moisture gradient M.S. Thesis, Univ. Florida Gainesville, 99 pp. Burt, W. H. 1943. Territoriality and home range concepts as applied to mammals. J. 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