Light, predation and the lekking behaviour of the ghost swift Hepialus humuli (L.) (Lepidoptera: Hepialidae).

摘要

The timing of the crepuscular lekking flight of males of Hepialus humuli was studied in southern Sweden between 18 June and 6 July 1995, with respect to variations in: the quality of the visual mating signal; and the behaviour of potential vertebrate predators (mainly bats). Display flights started about 57 min after sunset, and occurred during 20-30 min at incident light intensities between 10.0 and 2.0 lux. Owing to the falling and more shortwave ambient light after sunset, the brightness contrast between the moth wings and the background (grass) increased steeply at the time of display onset. The silvery white male wing colour seemed to maximize conspicuousness, and may be a secondary adaptation facilitating visibility at low light intensities.The display timing was probably determined by other factors, possibly predation. By displaying only for a short period at dusk, the moths seemed to avoid most birds and gleaning bats. Nevertheless, aerial-hawking bats were often (54% of the evenings) seen at the leks, and one species (Eptesicus nilssonii) frequently fed on the displaying moths (22% of the moths observed).