Aerial-hawking bats adjust their biosonar in the search, approach, and capture phases of echolocation to guide aerial prey-interception. Some bat species have secondarily evolved a gleaning strategy that relies on passive acoustic cues to detect and capture prey on vegetation. Here we test the hypothesis that such a gleaning specialist, the fringe-lipped bat, Trachops cirrhosus, must use stereotyped aerial hunting echolocation phases, including a buzz when opportunistically capturing aerial prey. Using data from sound-recording tags on 8 individuals, we reject this hypothesis by showing that fringe-lipped bats can detect and intercept aerial prey by echolocation but do so with modest biosonar adjustments and without producing a high-resolution buzz. These findings challenge the notion that the stereotyped echolocation phases of hawking bats are required for aerial prey capture and show that echolocation is an extremely versatile sensory system that can be employed across otherwise specialized foraging niches.
Mortensen et al. (Fri,) studied this question.