La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Variation in incubation effort during egg laying in the Mountain Bluebirds and its association with hatching asynchrony
Auteurs :	L. Scott Johnson, Auteur ; Felicia M. Napolillo, Auteur ; Dovid Y. Kozlovsky, Auteur ; Rachel M. Hebert, Auteur ; Allison Allen, Auteur
Type de document :	Article
Dans :	Journal of Field Ornithology (84(3) SEP 2013)
Article en page(s) :	242-254
Langues:	Anglais
Résumé :	Females in many bird species reportedly begin incubation prior to clutch completion, but the nature of such incubation and the degree to which it varies among females remains undescribed for almost all species. We used continuous recording of nest-cup temperatures to document incubation effort during egg laying at 57 Mountain Bluebird (Sialia currucoides) nests in a high-elevation Wyoming population. We then asked whether such effort predicted the degree to which eggs hatch asynchronously. Although substantial egg heating could begin abruptly late in laying (previously reported as the norm for this species) or even after clutch completion, we found that most (>90%) females began incubation gradually, engaging in a few (usually 1-8), brief (50% of the variation in hatching asynchrony. Our results thus provide strong support for the widely held, but rarely tested, assumption that parent birds can have substantial control over the degree of hatching asynchrony by varying the amount of incubation done prior to clutch completion.

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