It has been known for some time that many species of birds use theEarth's magnetic field to select a direction of movement--for example,during migration. However, although such birds clearly have a sense ofdirection, until now it has not been possible to train birds to move ina certain direction in the laboratory, even if they are motivated by afood reward. The reasons for this failure have been perplexing, butresearchers now report that they have been able to successfullyaccomplish this training task, providing new insight into the evolutionof magnetic sensing and opening new opportunities for further study ofmagnetoreception.
In the new work, researchers including Rafael Freire from theUniversity of New England (Australia), Wolfgang Wiltschko and RoswithaWiltschko from the University of Frankfurt, Germany, and Ursula Munrofrom the University of Technology in Sydney, demonstrated for the firsttime that birds could be trained to respond to a magnetic direction.The researchers trained domestic chicks to find an object that wasassociated with imprinting and was behind one of four screens placed inthe corners of a square apparatus, and, crucially, showed that thechicks' direction of movement during searching for the hiddenimprinting stimulus was influenced by shifting the magnetic field.
One important difference between this work and earlier attemptsto train birds is that the researchers used a social stimulus to trainthe birds, whereas most previous attempts have used food as the reward.The authors of the study hypothesize that in nature, birds do not usemagnetic signals to find food, and tests involving such a response maybe alien to them.
It is expected that this work will facilitate current effortsto understand how birds detect the magnetic field, because the newapproach does not rely on complex behaviors, such as migration orhoming, that are difficult to study in the laboratory and are dependenton the time of year. The work also shows that the ability to orientwith magnetic cues is not only present in an ancient avian lineagedating back to the cretaceous period, but has also been retained in anonmigrating bird after thousands of years of domestication.
The researchers include Rafael Freire and Lesley J. Rogers of theUniversity of New England in Armidale, NSW, Australia; Ursula H. Munroof the University of Technology in Sydney, Australia; and RoswithaWiltschko and Wolfgang Wiltschko of the Zoologisches Institut derJ.W.Goethe-Universität in Frankfurt Main, Germany. This work wassupported by the Deutsche Forschungsgemeinschaft (W.W.), the HumanFrontier Sciences Program (R.W.) and a University of New England VCpost-doctoral fellowship (R.F.).
Freire et al.: "Chickens orient using a magnetic compass" Publishing in Current Biology, Vol. 15, R620-R621, August 23, 2005 www.current-biology.com
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