La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Breeding biology of Dusky Flycatchers in a southern Utah mixed conifer-aspen woodland
Auteurs :	R. C. Dobbs, Auteur
Type de document :	Article
Dans :	Journal of Field Ornithology (76(2) SPR 2005)
Article en page(s) :	183-192
Langues:	Anglais
Résumé :	Dusky Flycatchers (Empidonax oberholseri) nesting in a mixed conifer-aspen woodland in southern Utah occurred at a breeding density of 0.44 territories/ba. Females began laying first clutches 1-26 June; adults fed nestlings (in renesting attempts) as late as mid August. Mean clutch size was 3.8 eggs in first clutches and 3.6 eggs overall. Incubating females spent 90% of daylight hours on the nest, where they were fed by males 1.1 times/hour. Incubation lasted 14-16 d; nestlings remained in the nest 15-17 d. Thirteen of 32 nests (40.6%) were successful in producing at least one fledgling, with successful nests producing 2.7 young/nest. Based on exposure, probability of a nest Surviving from egg laying to fledging was 0.40. Predation accounted for 84.2% of nest Failures; brood parasitism by a Brown-headed Cowbird (Molothrus ater) occurred at one nest.

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