Ardea
Official journal of the Netherlands Ornithologists' Union

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Holt D.W., Paulson A. & Romero M. (2009) Corticosterone as a measure of stress in nest-bound and nest-departed Long-eared Owl Asio otus chicks. ARDEA 97 (4): 593-596
Long-eared Owl Asio otus nestlings usually depart from their nests at approximately 22 days of age, and cannot fly until approximately 35 days of age. Corticosterone has been implicated as a mechanism influencing nest departure in many avian species. We sampled corticosterone concentrations in wild nestling and nest-departed Long-eared Owl chicks to determine if this stress hormone influenced nest departure. Baseline corticosterone titres were found to be similar in nest-bound and nest-departed young (10.69 1.37 vs. 9.29 1.58 ng/ml respectively), suggesting that stress was not the trigger for nest departure. Nest-bound chicks however did show lower stress-induced titres levels than nest-departed chicks (14.62 1.98 vs. 21 .58 2.22 ng/ml, respectively). This suggests that nest-bound chicks may have a blunted response, perhaps due to age-related developmental constraints influencing corticosterone secretion, among other explanations.


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