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Orientation in pied flycatchers: the relative importance of magnetic and visual information at dusk

In English

Författare

Summary, in English

We investigated the orientation of juvenile pied flycatchers, Ficedula hypoleuca, during autumn migration in south Sweden using orientation cage experiments, to study the relative importance of visual and magnetic information at sunset. We performed cage tests under 12 experimental conditions that manipulated the geomagnetic and visual sunset cues available for orientation: natural clear skies in the local or a vertical magnetic field; simulated total overcast in the local or a vertical magnetic field; natural pattern of skylight polarization and directional information from stars screened off, with the sun’s position as normal or shifted 120° anticlockwise with mirrors; reduced polarization in the local or a vertical magnetic field; directions of polarization (e-vector) NE/SW and NW/SE, respectively, in the local or a vertical magnetic field. The pied flycatchers were significantly oriented towards slightly south of west

when they could use a combination of skylight and geomagnetic cues. The mean orientation was significantly shifted along with the deflection of the sunset position by mirrors. Reduced polarization had no significant effect on orientation either in the local, or in a vertical, magnetic field. The birds tended to orient parallel with the axis of polarization, but only when the artificial e-vector was aligned NW/SE. The mean orientation under simulated total overcast in a vertical, and in the local, magnetic field was not significantly different from random. It is difficult to rank either cue as dominant over the other and we conclude that both visual and magnetic cues seem to be important for the birds’ orientation when caught

and tested during active migration.

Publiceringsår

1999

Språk

Engelska

Sidor

819-828

Publikation/Tidskrift/Serie

Animal Behaviour

Volym

57

Issue

4

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Biological Sciences

Nyckelord

  • orientation bird migration visual information

Status

Published

Forskningsgrupp

  • Animal Navigation Lab

ISBN/ISSN/Övrigt

  • ISSN: 1095-8282