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Migratory blackcaps can use their magnetic compass at 5 degrees inclination, but are completely random at 0 degrees inclination

Schwarze, Susanne; Steenken, Friederike; Thiele, Nadine; Kobylkov, Dmitry; Lefeldt, Nele; Dreyer, David LU ; Schneider, Nils Lasse and Mouritsen, Henrik (2016) In Scientific Reports 6.
Abstract

It is known that night-migratory songbirds use a magnetic compass measuring the magnetic inclination angle, i.e. the angle between the Earth's surface and the magnetic field lines, but how do such birds orient at the magnetic equator? A previous study reported that birds are completely randomly oriented in a horizontal north-south magnetic field with 0° inclination angle. This seems counter-intuitive, because birds using an inclination compass should be able to separate the north-south axis from the east-west axis, so that bimodal orientation might be expected in a horizontal field. Furthermore, little is known about how shallow inclination angles migratory birds can still use for orientation. In this study, we tested the magnetic... (More)

It is known that night-migratory songbirds use a magnetic compass measuring the magnetic inclination angle, i.e. the angle between the Earth's surface and the magnetic field lines, but how do such birds orient at the magnetic equator? A previous study reported that birds are completely randomly oriented in a horizontal north-south magnetic field with 0° inclination angle. This seems counter-intuitive, because birds using an inclination compass should be able to separate the north-south axis from the east-west axis, so that bimodal orientation might be expected in a horizontal field. Furthermore, little is known about how shallow inclination angles migratory birds can still use for orientation. In this study, we tested the magnetic compass orientation of night-migratory Eurasian blackcaps (Sylvia atricapilla) in magnetic fields with 5° and 0° inclination. At 5° inclination, the birds oriented as well as they did in the normal 67° inclined field in Oldenburg. In contrast, they were completely randomly oriented in the horizontal field, showing no sign of bimodality. Our results indicate that the inclination limit for the magnetic compass of the blackcap is below 5° and that these birds indeed seem completely unable to use their magnetic compass for orientation in a horizontal magnetic field.

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author
organization
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type
Contribution to journal
publication status
published
subject
in
Scientific Reports
volume
6
publisher
Nature Publishing Group
external identifiers
  • scopus:84988849422
  • wos:000384417300001
ISSN
2045-2322
DOI
10.1038/srep33805
language
English
LU publication?
yes
id
41d61fc3-689a-4867-a0af-4dd0b31feef4
date added to LUP
2016-10-31 14:32:13
date last changed
2017-10-22 05:21:15
@article{41d61fc3-689a-4867-a0af-4dd0b31feef4,
  abstract     = {<p>It is known that night-migratory songbirds use a magnetic compass measuring the magnetic inclination angle, i.e. the angle between the Earth's surface and the magnetic field lines, but how do such birds orient at the magnetic equator? A previous study reported that birds are completely randomly oriented in a horizontal north-south magnetic field with 0° inclination angle. This seems counter-intuitive, because birds using an inclination compass should be able to separate the north-south axis from the east-west axis, so that bimodal orientation might be expected in a horizontal field. Furthermore, little is known about how shallow inclination angles migratory birds can still use for orientation. In this study, we tested the magnetic compass orientation of night-migratory Eurasian blackcaps (Sylvia atricapilla) in magnetic fields with 5° and 0° inclination. At 5° inclination, the birds oriented as well as they did in the normal 67° inclined field in Oldenburg. In contrast, they were completely randomly oriented in the horizontal field, showing no sign of bimodality. Our results indicate that the inclination limit for the magnetic compass of the blackcap is below 5° and that these birds indeed seem completely unable to use their magnetic compass for orientation in a horizontal magnetic field.</p>},
  articleno    = {33805},
  author       = {Schwarze, Susanne and Steenken, Friederike and Thiele, Nadine and Kobylkov, Dmitry and Lefeldt, Nele and Dreyer, David and Schneider, Nils Lasse and Mouritsen, Henrik},
  issn         = {2045-2322},
  language     = {eng},
  month        = {09},
  publisher    = {Nature Publishing Group},
  series       = {Scientific Reports},
  title        = {Migratory blackcaps can use their magnetic compass at 5 degrees inclination, but are completely random at 0 degrees inclination},
  url          = {http://dx.doi.org/10.1038/srep33805},
  volume       = {6},
  year         = {2016},
}