Some aspects of the ecology and population dynamics of the American alligator in Texas /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
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1992.
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| Online Access: | Link to OAKTrust copy |
| Abstract: | The purpose of this research was to study the ecology and population dynamics of the American alligator (Alligator mississippiensis) in Texas. Two study sites were chosen, the inland Brazos Bend State Park and the coastal J.D. Murphree Wildlife Management Area. Juvenile alligator growth, survival, and diet were examined via a mark-recapture study and a non-invasive stomach pumping procedure. Several nests had core nest chamber temperatures monitored for 2 weeks during the first month of incubation. Egg number/viability and embryo sex ratio were determined. Diurnal basking censuses were conducted and compared with Texas nocturnal census data, and environmental/temporal parameters were examined to pinpoint optimal conditions for alligator visibility. A population model was developed to reflect important aspects of alligator population dynamics. The juvenile diet was predominantly composed of insects (92.8% composition and 98.9% frequency of occurrence). Juveniles had a minimum population number for the areas sampled at the J.D. Murphree Area up to 220 animals, and Schnabel population estimate values ranged from 204 to 647 alligators. Minimum survival rates were over 50% from May-August 1985, and over 30% by August 1986 for younger juveniles. The greatest increase in growth between months was from July-August when the most frequent growth increase was 18%. From May-August a 48% growth increase was the most common. Nine nests examined contained between 17 and 48 eggs, with 69% viability. Clutch sex ratios ranged from all males or females to mixed sex ratios, but there seemed to be no clearly defined relationship between the sex ratios in the wild nests and temperature range. Diurnal basking censuses were found to be particularly suitable for use at sites with smaller aquatic areas whose perimeters can be used as a census route. March and April were the best months in Texas to conduct a diurnal census, with air temperature serving as the best predictive indicator. The population model showed fecundity rates varied according to population status (stable, expanding, or declining), and displayed peaks in numbers of alligators for some of the adult size classes due to several age classes composing one size class. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Wildlife and Fisheries Sciences." |
| Physical Description: | xii, 156 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |