Year

2020

Season

Spring

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

NACO controlled Corporate Body

University of North Florida. Department of Biology

First Advisor

Dr. Adam E. Rosenblatt

Second Advisor

Dr. Eric G. Johnson

Third Advisor

Dr. Quincy A. Gibson

Department Chair

Dr. Cliff Ross

College Dean

Dr. George Rainbolt

Abstract

Urbanization is an ever-increasing threat to wildlife and their habitats, yet research has been limited to a small number of taxa. The American alligator (Alligator mississippiensis) is an apex predator that has surprisingly received minimal attention within urban areas. To investigate the potential effects of urban land use on spatial ecology, we conducted surveys of relative alligator abundance in nine tributaries surrounding the St. Johns River. We used these data to explore the potential effects of urban development on alligator spatial distribution and habitat selection. At the coarse scale, we found no correlation between percent developed land and relative alligator abundance. Instead, salinity is the primary driver of relative abundance. At the fine scale, we found that alligators prefer habitats characterized by more open water and highly vegetated shorelines and avoid anthropogenic structure. Only one out of 93 sighted individuals was an adult, and recent data suggests that adults are relatively rare in our study area. Thus, juveniles still occupy urban habitats because they are not being targeted and they face virtually no competition from adults. To investigate the potential effects of land development on trophic ecology, we performed gut content analysis on golf course alligators found on Jekyll Island, Georgia. We made comparisons with alligators found in more natural areas on Sapelo Island, Georgia. Percent index of relative importance values reveal that there may be functional differences in prey choice or availability, but analysis of similarity, non-metric multidimensional scaling, and simplified Morisita index analyses show no significant difference. Further land development and increasing human activity may therefore degrade available habitat and limit the distribution of breeding adult alligators in once suitable areas and possibly shift diets toward reliance on prey items usually of lesser importance. These potentially interacting spatial and trophic effects could lead to local population declines.

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