Home Range and Habitat Selection of an Inland Alligator (Alligator mississippiensis) Population at the Northwestern Edge of the Distribution Range

摘要

Although well studied in coastal ecosystems, comparatively little information exists on the ecology of inland Alligator mississippiensis (American Alligator) populations, particularly at the periphery of their range. Our specific objectives were to estimate home-range area and assess did (i.e., day vs. night) habitat-selection patterns of an urban, inland American Alligator population at the northwestern edge of the species' range. During 2010-2011, we captured 14 (6 female, 5 male, 3 unknown sex) American Alligators, 9 (5 female and 4 male) of which were fitted with VHF transmitters. Mean home range (95% kernel) was 68.9 ha (SD = 31.6) and 40.9 ha (SD = 20.7) and the mean core area (50% kernel) was 20.6 ha (SD = 18.5) and 10.1 ha (SD = 6.6) for males and females, respectively. American Alligators primarily selected river channels and open-canopy shorelines during both day and night. The amount of emergent or floating vegetation and canopy cover in a particular habitat influenced the probability of selection by American Alligators but this probability was dependent on the did l time period. During the day, the probability of selection was higher in areas with emergent or floating vegetation and more canopy cover, whereas at night the probability of selection decreased with increasing canopy cover. American Alligators did not select open water at either the study-area level or within the home range, which may have been due at least in part to the presence of recreational boaters or differences in food availability between open-water areas and other areas occupied by American Alligators on the Fort Worth Nature Center and Refuge. Overall, the results of our study are largely incongruent with patterns of home-range size and habitat selection reported for the species elsewhere, suggesting that further study of other American Alligator populations at the periphery of the distribution range is warranted.