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Résumé :
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In chilly winter nights wrens start „cluster roosting“ as a response to low temperatures in suitable locations. Up to 18 wrens used a wooden concrete nestbox for roosting, which was prepared with a monitoring camera. We can therefore report on what wrens are doing during 15 hours of a winter night. In the first frosty November night two birds visited the nestbox at sunset but only one wren stayed for the night. This paper reports on the behaviour of this single winter wren roosting in an old sparrow nest. When the two birds investigated the nestbox they communicated with series of quiet „ick-ick“-calls (sonogram is shown). There was no evidence of aggressive interspecific behaviour. When arriving at the roost the wrens were restless, entering and leaving the nestbox several times. They appeared to check the roosting site and to look for conspecifics. The remaining bird slept in a puffed up ball shape for optimal thermoregulation. Sleeping was disrupted several times at night for changing sleeping position, preening and at one time for defaecating. In the morning the bird left the nest box after stretching and preening, 42 minutes before sunrise. The observed behaviour is illustrated by more than 30 images and documents that monitoring cameras can give us new insights into the hidden life of little songbirds and other animals.
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