La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	No evidence for observer effects on Lark Sparrow nest survival
Auteurs :	Martin D. Jacobson, Auteur ; Eric T. Tsakiris, Auteur ; Ashley M. Long, Auteur ; William E. Jensen, Auteur
Type de document :	Article
Dans :	Journal of Field Ornithology (82(2) JUN 2011)
Article en page(s) :	184-192
Langues:	Anglais
Résumé :	Methods for monitoring bird nests might influence rates of nest predation, but the effects of various methods (e. g., visual markers and observer visitation rates) are often separately investigated among disparate avian taxa and geographic regions. Few investigators have explored the potential effects observers might have on nest success of grassland birds, despite concerns regarding population declines of these species in North America. We examined the possible effects of three monitoring techniques on daily nest survival of Lark Sparrows (Chondestes grammacus): (1) presence or absence of visible markers near nests, (2) observer visitation frequency, and (3) presence or absence of data loggers in nests. We monitored 113 Lark Sparrow nests during the 2009 breeding season. Of these nests, 88.5% failed due to predation, abandonment, weather, or unknown causes, yielding an overall nest success estimate of 9.8% based on daily survival estimation. Main effects of each monitoring technique appeared in top (Delta AICc

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