Activity of the Insectivorous Bat Pteronotus parnellii Relative to Insect Resources and Vegetation Structure

Abstract

Riparian areas often are assumed to be necessary sites for foraging by insectivorous bats because of high insect availability and ease of movement and echolocation in the forest. However, effects of vegetation clutter and insect availability on bat activity have not been compared between riparian and nonriparian areas. We used autonomous recorders to evaluate the effects of vegetation structure, insect mass, and assemblage composition on the activity of the aerial insectivorous bat Pteronotus parnellii along stream channels and nonriparian areas in a tropical rainforest in central Brazilian Amazonia. We quantified vegetation clutter using horizontal photographs, captured nocturnal insects with light traps, and recorded bat activity for 110 nights (1,320 h) in 22 sampling plots. Pteronotus parnellii was more active in sites with dense understory vegetation, which were more common away from riparian zones. Bat activity was related to insect availability (mass and composition), independent of the habitat type. Ability to detect insects on vegetation and avoid obstacles should not restrict the activity of P. parnellii in cluttered sites. This suggests that mass and species composition of insects had stronger influences on habitat use than did vegetation clutter. Pteronotus parnellii probably selects cluttered places as feeding sites due to the availability of higher quality prey. © 2015 American Society of Mammalogists.