Testing avian compass calibration: comparative experiments with diurnal and nocturnal passerine migrants in South Sweden

Biology Open

Christoffer Sjöholm¹  Mihaela Ilieva¹  Catharina Odin¹  Susanne Åkesson¹  Alexandra Farkas²  Gábor Horváth²  Ramón Hegedüs³ 

[1] Department of Biology, Centre for Animal Movement Research, Lund University, Ecology Building, SE-223 62 Lund, Sweden;Environmental Optics Laboratory, Department of Biological Physics, Physical Institute, Eötvös University, H-1117 Budapest, Pázmány sétány 1, Hungary;Max Planck Institute for Informatics, Campus E1.4, D-66123 Saarbrücken, Germany;

关键词: orientation;    migratory birds;    magnetic compass;    compass calibration;    passerines;    Acrocephalus schoenobaenus;    Prunella modularis;    Erithacus rubecula;   

DOI  :  10.1242/bio.20149837

来源: DOAJ

【 摘 要 】

Cue-conflict experiments were performed to study the compass calibration of one predominantly diurnal migrant, the dunnock (Prunella modularis), and two species of nocturnal passerine migrants, the sedge warbler (Acrocephalus schoenobaenus), and the European robin (Erithacus rubecula) during autumn migration in South Sweden. The birds' orientation was recorded in circular cages under natural clear and simulated overcast skies in the local geomagnetic field, and thereafter the birds were exposed to a cue-conflict situation where the horizontal component of the magnetic field (mN) was shifted +90° or −90° at two occasions, one session starting shortly after sunrise and the other ca. 90 min before sunset and lasting for 60 min. The patterns of the degree and angle of skylight polarization were measured by full-sky imaging polarimetry during the cue-conflict exposures and orientation tests. All species showed orientation both under clear and overcast skies that correlated with the expected migratory orientation towards southwest to south. For the European robin the orientation under clear skies was significantly different from that recorded under overcast skies, showing a tendency that the orientation under clear skies was influenced by the position of the Sun at sunset resulting in more westerly orientation. This sun attraction was not observed for the sedge warbler and the dunnock, both orientating south. All species showed similar orientation after the cue-conflict as compared to the preferred orientation recorded before the cue-conflict, with the clearest results in the European robin and thus, the results did not support recalibration of the celestial nor the magnetic compasses as a result of the cue-conflict exposure.

【 授权许可】

Unknown