Bat defence in lekking ghost swifts (Hepialus humuli), a moth without ultrasonic hearing

Jens Rydell

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Publication Date

8-7-1998

Publication Title

Proceedings of the Royal Society B

Volume Number

256

Issue Number

1404

Abstract

The Hepialidae represents an early branch of the Lepidoptera, whose members lack the ultrasonic hearing and other obvious predator defence systems present in other extant moths. I observed lekking male ghost swifts, Hepialus humuli, being exploited by northern bats, Eptesicus nilssonii, over a hayfield in southern Sweden. Because the moth's display flight was restricted to a brief (30 min) period at dusk, they avoided most predators temporally but were exposed to early emerging aerial–hawking bats. Against these, they apparently employed ‘acoustic crypsis’, achieved by flying close ( 0.5 m) to the vegetation, thereby hiding from the bats among clutter (echoes returning from the background). Nevertheless, the predation risk for the displaying moth males was very high (20% per night), mainly because they sometimes left the safety of the vegetation. The lack of ‘advanced’ predator defence mechanisms in H. humuli requires alternative defence strategies, which, however, restrict the behavioural repertoire and still carry a high predation risk.

Keywords

Moths, Bats, Predation (Biology), Animal behavior, Camouflage (Biology)

Document Type

Article

Digital Object Identifier (DOI)

https://doi.org/10.1098/rspb.1998.0444

Language

English

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