The Cuban Treefrog, Osteopilus septentrionalis, is a species native to the western region of the Caribbean. Its native distribution includes Cuba, the Cayman Islands, and the Bahamas. A few species of birds and reptiles have been reported to prey on adults and juveniles of O. septentrionalis in its native geographic distribution and areas where this species has been introduced (e.g., Florida and St Croix, U.S.A.). In Puerto Rico, this species was introduced in the early 1950s, and it is now frequently found in coastal areas in western, northern and eastern Puerto Rico, and some municipalities further inland. In this study, we document the first accounts of predation of O. septentrionalis by the Puerto Rican Racer (snake), Borikenophis portoricensis, from northern Puerto Rico. We document preliminary results on the prey-predator interaction between several individuals of O. septentrionalis and an adult B. portoricensis under laboratory conditions.
Results/Conclusions
In the presence of the predator, an adult individual of O. septentrionalis showed an anti-predatory behavior, which consisted of raising its body in its four legs and inclined it dorsally facing towards the predator as to appear a prey larger in body size to the eyes of the predator. The snake captured the frog, which elicited several high-pitched release-calls, only to be ingested by the snake later on. In a separate event in the laboratory, more than five adult individuals of O. septentrionalis were added sequentially to the terrarium, and the snake captured and ingested each one of them. The behavioral response of the frogs included the release-call but also used all four limbs to press against the head and mouth of the snake to avoid ingestion. We kept the snake in the terrarium for observation during several weeks, and the snake never showed ill-effects attributed to the prey. Presumably, the toxins secreted by the skin of O. septentrionalis have negligible to no effect on this individual of B. portoricensis, and the snake already identified this frog as a natural prey-item. Our accounts in the laboratory support observations of predation events involving O. septentrionalis and B. portoricensis documented from the wild. Therefore, this study adds to our knowledge on trophic relationships in the Puerto Rican wildlife, and we suggest that O. septentrionalis has become a more-significant prey-item to native species like B. portoricensis than it is frequently acknowledged in Puerto Rico, and thus, this frog has become a regular member of local food-webs.