Masters Theses

Date of Award

5-2004

Degree Type

Thesis

Degree Name

Master of Science

Major

Ecology and Evolutionary Biology

Major Professor

Arthur C. Echternacht

Committee Members

Gordon M. Burghardt, Susan E. Riechert, Jake F. Weltzin

Abstract

The Grand Cayman blue iguana, Cyclura lewisi, is critically endangered with an estimated 7-25 individuals remaining in the wild. This taxon is in need of intensive management, but little has been published on any aspect of its biology, and the remaining wild population is too small to be the basis of a research program. In order to aid in the conservation of this and other iguanid species, I investigated the spatial ecology and habitat use of a population of captive-bred, released C. lewisi in a botanic park on Grand Cayman. Movements and locations of these iguanas were verified through routine monitoring, radio tracking, and focal animal observation in the mating and post-mating seasons of 2001 and 2002.

Male iguanas had larger home ranges and moved greater distances than did females during the breeding season. Although home range size varied by two orders of magnitude among individuals, larger maximum home range size estimates were found in this population than have been previously reported for any species of Cyclura. Radio tracking revealed that several iguanas, especially males during the breeding season, used areas outside of the park where they are vulnerable to increased predation, death by vehicle, and hunting or collection by humans.

The reintroduced iguanas in this study preferred modified habitat to unmodified habitat throughout the year, both within the landscape and within their home ranges. Potential threats in modified and human-occupied habitats that were identified in this study included uncontrolled supplemental feeding, predation by nonnative predators, and vehicular collision. Iguanas frequently used artificial retreats and nests, and commonly occupied retreats in modified areas. The use of modified habitats and artificial retreats by reintroduced C. lewisi is encouraging, because this species may depend on disturbed landscapes and supplemental resources for future survival.

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