ИСТИНА

In Moscow region, the increase in spring temperatures in late April over last 10-15 years was combined with opposite trend during first half of May. This climate change advanced arrival dates of Pied flycatchers (Rs = - 0.84, p = 0.001, n=11 for dates of first arrived males), but did not result in shift of mean laying dates. The response on climate change was influenced by male colour type. Amongst years, mean Drost’s (1936) colour type increased (birds became more “pale”) in males which attempted to acquire nest holes during pre-breeding period. However, there has been no similar trend in successful breeders. The probability of future return of adult conspicuous males to their previous breeding area positively correlated with ambient temperatures in late April and was not markedly related to their reproductive success in the current season. Amongst years, the future return rate of conspicuous males gradually increased. The return rate of pale males did not change among years and was strongly affected by their reproductive success in the current season. On the contrary to conspicuous males, breeding failure led to consecutive disappearance of the majority of pale birds from the local population. At the same time, the proportion of pale males was higher in old (>=2 ys) immigrants than that in previous local breeders. We suggest that weather-dependent changes of phenotypic structure of Pied flycatcher population could be explained by differences between conspicuous and pale phenotypes in tolerance to cold during advertising period (Ivankina et al., 2002) and breeding area fidelity.