Behavioural responses by foraging petrels to swarms of Antarctic Krill Euphausia superba

Authors
Citation
Rr. Veit, Behavioural responses by foraging petrels to swarms of Antarctic Krill Euphausia superba, ARDEA-T NED, 87(1), 1999, pp. 41-50
Citations number
31
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Animal Sciences
Journal title
ARDEA
ISSN journal
0373-2266 → ACNP
Volume
87
Issue
1
Year of publication
1999
Pages
41 - 50
Database
ISI
SICI code
0373-2266(1999)87:1<41:BRBFPT>2.0.ZU;2-L
Abstract
Petrels feeding on Antarctic Krill Euphausia superba use two basic strategi es to locate prey patches. One strategy is area-restricted search, in which individuals interrupt straight-line motion on detecting prey, and then cir cle about. This increased rate of turning near prey increases the likelihoo d of detecting additional patches, since patches tend to be clumped in spac e. A second strategy is local enhancement, in which individuals monitor the behaviour of others, and converge on those individuals that display behavi our indicative of feeding. In this paper, attention is focused on the first strategy, area restricted search, and evidence of increased turning rates in the vicinity of krill patches is sought. The hypotheses tested were firs t, that six species of krill-feeding petrels engage in area restricted sear ch; and then that the tendency for seabirds to either sit on the water, pat ter with their feet, or seize prey was correlated with the distance to the nearest krill patch. Seabird abundance and behaviour was paired with krill abundance east of South Georgia (55 degrees S, 35 degrees W) in June 1993. Three species, Cape Petrel Daption capense, Northern Giant Petrel Macronect es halli and Southern Giant Petrel M. giganteus, changed their direction of Eight significantly more often when near krill swarms than when in krill-f ree areas, indicating that they used area restricted search. Cape Petrels w ere also significantly more likely to sit on the water and to patter along the surface when close to krill swarms.