Ecology of the Endangered Sandy Cay Rock Iguana, Cyclura rileyi cristata, in the Bahamas

• Main Author: Fry, Shawn Kendall
• Format: Text
• Language: English
• Published: TheScholarsRepository@LLU: Digital Archive of Research, Scholarship & Creative Works 2001
• Subjects: Biology; Rattus rattus
• Online Access: https://scholarsrepository.llu.edu/etd/583; https://scholarsrepository.llu.edu/context/etd/article/1730/viewcontent/Fry__Shawn_Kendall___Ecology_of_the_Endangered_Sandy_Cay_Rock_Iguana_Cyclura_rileyi_cristata__in_the_Bahamas.pdf

In this thesis I present the results of a study on the population demographics and home range size of Cyclura rileyi cristata. There are eight species of West Indian rock iguanas, genus Cyclura. All are endangered, including C. rileyiwhich is endemic to the Bahamas. One of three recognized subspecies, C. r. cristatalives on a single cay in the Exumas chain and is among the most endangered lizards in the world. Various size measurements indicate that this taxon is among the smallest within the genus. Distance surveys and a Lincoln-Petersen estimate based on resightings of marked iguanas suggest that the total population is comprised of 134-204 animals. In contrast to other populations of C. rileyi sampled by similar means, the sex ratio was highly skewed toward male iguanas (95% of noose captures). Thus, as few as 10 female iguanas may remain in the population. Glue-traps set near burrows proved to be more effective than noosing for the selective capture of females. However, no females of reproductive size were captured. Three non-native mammals were found on Sandy Cay, including rats (Rattus rattus), mice (probably Mus musculus) and a single raccoon (Procyon lotor). Several estimates based on capture rates and resighting ratios suggested that the raccoon inflicted considerable mortality on adult iguanas (35-67% between 1996 and 1997). Comparisons of density among rat-infested versus rat-free populations and attacks observed on lizard models suggest that rats negatively impact C. rileyi populations. Home range estimates based on radio-tracking of iguanas showed highly variable home range sizes that, in males, may exceed those of other C. rileyi populations. Remarkably few social interactions were observed, which was probably a consequence of low population density. Based on these findings, I offer several recommendations for the conservation of this critically endangered lizard, including translocation and captive headstarting programs to begin a new population and formal protection of the island as a National ...