Moult, sex and food are the most important factors regulated the timing of migration of north Asian Passerines

Abstract

Bird migration is a highly complex, regulated process, of which timing is an essential element. The timing of migration is influenced by moult, age, sex and food of the birds, as well as the distance between the breeding and wintering sites. In this study, we used data from a ringing station on the shores of Lake Baikal to investigate factors influencing migration timing for species with different migration and moulting strategies, wintering sites and feeding habits. In general, we found that the migration of Passerine across Lake Baikal is influenced by similar factors to those of other migratory species in other migratory flyways. For most species, adult birds migrated through the area earlier in both spring and autumn. In spring, protandrous migration was detected for most of the species, while in autumn, differences in migration timing were less common. Migratory birds migrate later in spring and earlier in autumn, the longer the distance between nesting and wintering sites. It is important to highlight, however, that in both seasons only moulting, sex and food type had an equal influence on the timing of migration, while migration distance and age regulated migration in only one season or the other. In both spring and autumn, we observed differences in the timing of the migration of different species. Studies on the migration of north Asian Passerines are important in the future as the populations of several once common species have declined dramatically in recent times.