Population Status and Habitat Selection of an Inland Alligator (Alligator Mississippiensis) Population at the Fort Worth Nature Center and Refuge, Texas

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological and Environmental Sciences

Date of Award

Spring 2012

Abstract

Although well studied in coastal ecosystems, little information exists on the ecology of inland alligator (Alligator mississippiensis) populations. Without sufficient data, state and federal agencies base management decisions on coastal populations however, recent studies suggest that inland populations differ from coastal populations. Data for populations at the edge of the distribution range are equally lacking. Subsequently, data on population size, and age specific structure and habitat use, particularly those at the edge of the distribution range are necessary for development of sustainable harvest objectives and sound management strategies. The goal of this study is to determine the population status and habitat use of an urban, inland alligator population at the Fort Worth Nature Center and Refuge. My specific objectives were to: 1) develop standardized survey methodology for the long-term monitoring of alligator population trends; 2) collect baseline data on alligator abundance; and 3) estimate home range area and assess diel (i.e., day vs. night) habitat selection patterns. During the 2010 season, I captured 7 alligators (3 males, 3 females, 1 unknown sex) during 203 trap nights, 5 of which (2 male and 3 female) were fitted with VHF transmitters. During the 2011 season, I captured 7 alligators (2 males, 3 females, 2 unknown sex) during 213 trap nights; 4 (2 males, 2 females) were fitted with VHF transmitters. These individuals were used to determine alligator abundance, to estimate home range size and diel habitat selection patterns. During the two years, the estimated population size was 8.28 alligators (95% CI 7.07 - 30.61). Mean home range (95% kernel) for all the alligators combined was 56.9 ha (range 27.9 ha - 110.6 ha) and mean core area (50% kernel) was 16.1 ha (range 4.7 ha - 47.3 ha). American alligators primarily selected for stream/river channels and open canopy shorelines. Open water was not selected for at either the study area level or within the home range. Pressures due to recreation on Lake Worth and the FWNCR may be a cause. Additional monitoring of alligator populations in all habitat types may provide additional data for the sustainability of this population that is at the edge of its known range and also in an area with a high amount of human disturbance.

Advisor

James Cain

Subject Categories

Biology | Life Sciences

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