Activity Pattern of the Trawling Phyllostomid Bat, <i>Macrophyllum macrophyllum</i>, in Panamá¹

Abstract

ABSTRACT We studied activity patterns of long‐legged bats, Macrophyllum macrophyllum (Phyllostomidae), in the Barro Colorado Nature Monument, Panamá, using radio‐telemetry. Activity of four males and five females equipped with radio‐transmitters were monitored for 4–7 entire nights each between April and July 2002. Bats exhibited maximum activity around dusk and high activity during the night. Males and females foraged for equal amounts of time in continuous flight (mean: 7 min, maximum 1 h) with interspersed resting phases (mean: 15 min, maximum 3 h). Activity of M. macrophyllum was sensitive to several factors. Time of emergence and return to day roost were correlated with time of sunset and sunrise, respectively. Maximum bat activity coincided with high abundance of aerial insects. Finally, heavy rain caused bats to reduce or cease flight activity. Direct observations and field video recordings support the assumption that M. macrophyllum employs two distinct foraging modes: trawling of insects from and capture of aerial insects at low heights above water. Combination of foraging modes gives M. macrophyllum high flexibility and efficiency in prey search. Activity, foraging mode, and morphology, which are similar to trawling bats from other families, distinguish M. macrophyllum from all other phyllostomid species and grant it access to open habitat above water, a habitat no other phyllostomid bat has conquered.