Evaluation of the stressors for the Puerto Rican racer (<em>Borikenophis portoricensis</em>: Colubridae) populations

Abstract

Worldwide, ~3,400 species of snakes are recognized. These reptiles are an important component of tropical and temperate ecosystems because of their role as high level predators. Many snake species worldwide are threatened by various stressors. Particularly vulnerable are those that inhabit the Antilles due to the tropical climate of the Islands, topographical conditions, dense human populations, habitat loss, plus fear and misconceptions due to cultural traditions. The Puerto Rican racer (<em>Borikenophis portoricensis</em>) is a species that inhabits the Puerto Rican archipelago and shares many similarities with other Antillean colubrids. Thus, this species has the potential to be used as a model for evaluating stressors that affect colubrid populations in the Antilles. In the first chapter of this work I present the Spanish validation and subsequent use of an instrument designed to measure fear and knowledge relating snakes. I found a low but significant negative correlation between the knowledge and fear of these reptiles, suggesting that fear of snakes can be somewhat mitigated with knowledge. I also found that women have greater fear of snakes, but that males and females did not differ in their knowledge about these animals. In addition, people who had handled or manipulated a snake had less fear and more knowledge of these reptiles. In the second chapter, I present the results of a study in which cameras traps were used to assess the presence and potential threat of invasive species in three secondary karst forests in northern Puerto Rico that differed in anthropogenic activity, and where the Puerto Rican racer was common. Four invasive and one native predators were detected by the cameras, with rats being the most abundant. Significant differences were found between the forests in the detection of vertebrates, including invasive species. The third chapter presents the results of a study in which I used radiotelemetry to measure movement patterns, habitat and microhabitat use, and home range size of male and female racers in the dry/cold and rainy/hot seasons. I found significant seasonal differences between males and females in movement and home range size. Males exhibited larger home ranges in the dry/cold season than during the wet/hot season and their home ranges were larger than females in both seasons. Females were found hidden more frequently than males, were detected more often in leaf litter on the crests or tops of the mogotes. Males spent more time moving or basking and preferred fallen branches and tree roots than females. In conclusion, invasive predators are a threat to the Puerto Rican racer and, more harsh and prolonged dry seasons, as predicted by climate change models for the Caribbean, could negatively affect the survival of males and mating success. Finally, fear of snakes can be reduced by knowledge and handling of live snakes.