Body size, demography, and body condition in Utila spiny-tailed iguanas, Ctenosaura bakeri

Abstract

Utila Spiny-tailed Iguanas, Ctenosaura bakeri, are listed as Critically Endangered by the IUCN Redlist Assessment and are listed under Appendix II of CITES. This species occupies a portion of Utila, a small continental island located off the northern coast of Honduras, in the Bay Islands chain. Habitat destruction and overharvesting for consumption and the pet trade are among the top threats facing this species. Though first described in 1901 (Stejneger) and currently the focus of a local conservation program, little is known concerning that basic biology of this species. Combining data from six years we examined body size, sexual size dimorphism, and changes in demography and body condition over the study period. Our results indicate that males are larger and heavier than females on average, and have a longer tail for a given snout-vent length, as is the case with most iguanas. Over the study period we found an increase in the ratio of males to females, suggesting that female biased hunting pressure is increasing. This is consistent with an increase in the human population size and a preference for consuming gravid females. The body condition of both males and females declined over the duration of the study, which is suggestive of a decrease in habitat quality. These results indicate that the situation for this endangered species is becoming increasingly threatening. Conservation measures should focus on alleviating these threats through increased law enforcement, outreach, and education.