Article Abstract:
A new study examines geographic variation in the calls of male and female blue petrels. The nocturnal habits of the petrel means it relies solely on vocalization for pairing purposes. The calls of 504 individuals were analyzed and show that there is a significant geographic variation that is more pronounced in the male. Several theories are discussed to explain the differences, including environmental effect, vocal learning and genetic drift.
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Article Abstract:
The copulatory behaviour of Montagu's Harrier has been studied, in relation to the onset of laying and courtship feeding, the occurrence of extra-pair copulations (EPCs), and their distribution. Copulation rates did not appear to be related to food provisioning by males, apart from at the early pre-laying period. Copulation rate increased in situations of increased EPC risk, particularly during the laying period.
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Article Abstract:
Plumage patterns of known-sex nestling and juvenile Short-eared Owls were examined to develop a sexing technique. Markings on secondary feathers varied depending on sex, and differences can be observed from around 10-15 days of age. Aging formulas were developed based on mass for nestlings up to 15 days of age and on wing length for older nestlings.
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