Abstract

Radio telemetry has been used in many species of snakes to estimate and describe spatial ecology, resource use, and behavioral patterns. These data are especially useful in the study of endangered species such as the Turks Island Boa (Chilabothrus chrysogaster). The Turks Island Boa is found throughout the Turks and Caicos Islands (TCI), but in exceptional densities on Big Ambergris Cay, TCI. This island is undergoing increasing amounts of development that is causing concern for several endangered terrestrial reptile species whose last refuge was this island prior to development. Very little is known about habitat use in most members of the genus Chilabothrus, and hence designing conservation strategies in the face of development can be challenging if simple natural history information, such as home range sizes (the use of space by an animal during normal annual activity), are not known. To help increase the effectiveness of ongoing conservation efforts, two cohorts of boas were implanted with radio-emitting tags and tracked intermittently over the course of two years. Space use and home ranges were calculated from GPS locations obtained during tracking sessions using Kernel Density Estimation, Multi Convex Polygons, and Brownian Bridge Movement Models. Each of these models has differing assumptions, and recent papers have called out researchers for not being explicit about why specific models were chosen, or for excluding relevant details about the models that would increase repeatability of the projects. All three models were evaluated, and compared to see whether similar estimates for spatially-relevant data, such as home ranges, can be inferred from all models. Multi Convex Polygons produced the lowest home range estimates compared to Kernel Densities and Brownian Bridge models. The majority of Brownian Bridge home range and space use estimates were slightly larger than Kernel Density estimates. Averages of all estimated models for home ranges and space use were higher in Cohort A than in Cohort B. By using all three models, a more comprehensive and accurate representation of home ranges and space use can be created, as it is apparent that each model produces different estimates of these measures.

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