A potential cost of responding to bats for moths flying over water

Although the evasive flight of eared moths to attacking bats has received much attention in the literature, no studies have been made of the potential costs for this behaviour. We examined the fate of moths that land upon the surface of a lake in a simulation of an evasive power dive away from a bat. Of 102 different-sized moths from 18 species that were dropped onto the surface of a lake in eastern Ontario, Canada, 61% were eaten, on average, by fish in 31.3 s with no effect of wing surface area on escape success. These results suggest that nocturnal predation on moths by fish may be underestimated and that this behaviour may cause moths to avoid lakes when flying.