Seasonal Predation by Merlins on Sooty Mustached Bats in Western Puerto Rico

Predation by Merlins (Falco columbarius) on the insectivorous bat Pteronotus fulginosus was studied for two consecutive winters at a cave in Aguadilla, Puerto Rico. Falcons were present from October to April, reaching maximum densities in January and February. Predation efficiency of falcons was greater at the more exposed of two flyways used by bats. The falcon using the most easily observed perch captured an average of 5.1 bats/day. In the first season falcons took 1800 bats from the more exposed flyway or 1.5 percent of the standing crop as estimated photographically. By the end of the second year the exposed flyway was no longer used by bats.