La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Juvenile survival in common loons Gavia immer: effects of natal lake size and pH
Auteurs :	Walter H. Piper, Auteur ; Jason S. Grear, Auteur ; Michael W. Meyer, Auteur
Type de document :	Article
Dans :	Journal of Avian Biology (43(3) MAY 2012)
Article en page(s) :	280-288
Langues:	Anglais
Résumé :	Survival is a vexing parameter to measure in many young birds because of dispersal and delayed impacts of natal rearing conditions on fitness. Drawing upon marking and resighting records from an 18-yr study of territorial behavior, we used CormackJollySeber analysis with Program MARK to estimate juvenile survival and its predictors in a population of common loons Gavia immer. In addition, we investigated predictors of chick mass, survival and inter-sibling size disparity in two-chick broods. Both small size and low pH of natal lakes predicted poor survival among chicks and juveniles; thus, features of the natal environment have both immediate and lasting effects on fitness. The pH x stage interaction retained in our MARK models indicates that the detrimental impact of lake chemistry on fitness diminishes with time; the retention of pH X lake size as a predictor of chick mass and condition pinpoints small lakes as those where acidity impacts chicks most severely. Our adjusted estimate of 0.53 probability of for survival to age 3 suggests that loon populations are healthier than often supposed.

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