Long-term variability in terms of arrival and departure of whitethroat (Sylvia communis) and chaffinch (Fringilla coelebs) in the south-east of the lake Ladoga

In the annual cycle of birds several changing physiological states are marked out, and their duration is controlled by endogenous and environmental factors. The change in the annual cycle parameters influences the seasonal differences in the migratory behavior of species as a whole. The results of the analysis of arrival and departure terms of two bird species – long-distance migrant whitethroat (Sylvia communis) and short-distance migrant chaffinch (Fringilla coelebs) – are presented in this article. The research was based on the materials of the long-term monitoring of migration terms at the Ladoga ornithological station. The results of this research correlate to the studies of birds in the Western Europe. Annual variability of the first and last registration dates of the whitethroat is less pronounced than the dates of short-distance migrant – chaffinch. The both species have a trend to come earlier to the breeding area and to fly away later from this territory. At the same time the displacement of migration dates is significant and more long-lasting for chaffinch. In general, whitethroats stay in the South-East of the lake Ladoga on an average 8 days more, chaffinches – 31 days more (by the results of 40 years observation).