NOCTURNAL FEEDING IN MOLTING GREYLAG GEESE ANSER-ANSER - AN ANTIPREDATOR RESPONSE

Citation
H. Kahlert et al., NOCTURNAL FEEDING IN MOLTING GREYLAG GEESE ANSER-ANSER - AN ANTIPREDATOR RESPONSE, Ardea, 84(1-2), 1996, pp. 15-22
Citations number
30
Categorie Soggetti
Ornithology
Journal title
ArdeaACNP
ISSN journal
03732266
Volume
84
Issue
1-2
Year of publication
1996
Pages
15 - 22
Database
ISI
SICI code
0373-2266(1996)84:1-2<15:NFIMGG>2.0.ZU;2-3
Abstract
The diurnal activity patterns of Greylag Geese were studied at a Danis h moulting site. Before moulting, Greylag Geese foraged throughout the 24 hour period, but changed to nocturnal feeding behaviour exclusivel y and roosted on offshore islets during the day, as they became flight less. As the moult progressed, geese preferred to feed in coastal habi tats and responded more strongly to predator-like stimuli, such as ove rflying herons and helicopters, even though real predators were absent . This increased susceptability to commonplace events may be a respons e to their restricted mobility and ability to escape potential predato rs during moult. Since the frequency of the predator-like stimuli was lowest at night, we suggest that moulting Greylag Geese compensate for their lowered tolerance threshold to predator-like stimuli by feeding at night when the probability of being disturbed is less. Alternative nutrition-related hypotheses of nocturnal feeding are discussed, howe ver these could not explain the observed changes in feeding behaviour, when Greylag Geese became flightless.