Two Mediterranean Blue Tit Populations: Are Differences in the Timing of Breeding Associated with Caterpillar Availability?

Abstract

A long term study on the population biology of tit species in Mediterranean habitats has documented a striking difference in breeding patterns between populations on the island of Corsica and the mainland (Blondel 1985, 1987, Blondel et al. 1987, 1989, Isenmann 1983, Isenmann et al. 1987). Blue Tit (Parus caeruleus) and Coal Tit (P. ater) populations on Corsica start laying three weeks later, have ca. 30% smaller clutches and suffer lower juvenile mortality than mainland tits. Blondel (1987) stated that it is not sufficient to focus on the community structure of these populations to understand the observed differences in breeding biology. Research should also concentrate on local environmental conditions: the availability of food, climatic factors and/or parasitism on nestlings by e.g. dipteran larvae (Blondel 1985, 1987).