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Résumé :
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The Parrot Crossbill Loxia pytyopsittacus is regarded as a rare breeding species in Britain. During a study in Abernethy Forest, Highland, from 1995 to 2001, it was, however, found to be the most abundant crossbill species nesting there. Of all crossbills trapped, 74% were Parrot Crossbills, while only 8% were Scottish Crossbills L. scotica. Parrot Crossbills were identified from their bill measurements and/or from sonograms of tape-recorded calls. They nested in Scots Pine Pinus sylvestris, almost exclusively in stands of ancient native pinewood. Nest trees had an average height of 14.2 m and a diameter at breast height of 57 cm, while the median stand density was 60 trees per ha. The average date of the onset of incubation was 20th March (including possible repeat layings), mean clutch size was 3.86 eggs, mean brood size when about ten days old was 3.2 chicks, and average nesting success (to fledging) was 50%. Chick growth was also measured. The potential presence of Parrot Crossbills in Highland pinewoods should be borne in mind by birdwatchers when identifying crossbills.
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