Are migrant passerines faithful to their individual paths and migration timing throughout their lives?

Abstract

Some publications report that passerine birds, compared with geese and waders, show much less annual faithfulness to migration routes and stopover sites, and that faithfulness to them decreases with increasing length of the migration path. The analysis of numerous recaptures of ringed birds in the Curonian Spit (Eastern Baltic) led to the opposite conclusions. The calculations were carried out on thousands of recaptures obtained over 30 years (1957–1986) from two of the most numerous species, chaffinch Fringilla coelebs Linnaeus, 1758 (Fringillidae) and willow warbler Phylloscopus trochilus (Linnaeus, 1758) (Phylloscopidae). It turned out that a significant part of the migratory populations (34–41% of recaptured birds) retains the same migration path and approximately the same migration timing in other years after ringing. Assumptions about the dependence of the degree of fidelity to migration routes on their length have not been confirmed, since the fidelity indicators of willow warbler, which has a much longer route than chaffinch, were even higher than those of the chaffinch. The data on the individual life longevity of the recaptured migrants (up to 9 years in the chaffinch and up to 4 years in the willow warbler) confirm the fidelity to the same migration path throughout the life of the studied birds.