Breeding-site fidelity and dispersal in isolated populations of three migratory passerines

Abstract

Living in an isolated patchmay increase, for example, the extinction risk of a local population, but such risksmay bemitigated by natal and breeding dispersal.We therefore analyzed five years of Russian banding data on BootedWarbler,Whinchat and YellowWagtail (Hippolais caligata, Saxicola rubetra and Motacilla flava, respectively), within a 20-ha abandonedmeadow, isolated from similar habitat by vast areas of woodland.We individually banded 203 Booted Warblers, 193 Whinchats and 83 Yellow Wagtails. During the years following banding, fourmales ofBootedWarbler (2.0%), onemale ofWhinchat (0.4%) and 11 Yellow Wagtails (13.3%; 7 males and 4 females) returned to the study meadow. The apparent survival rate of the YellowWagtail was significantly higher than that of theWhinchat and BootedWarbler. For the YellowWagtail, the yearly numbers of recoveries varied considerably, and were linked with previous-year breeding success. Successful years were usually followed by returns to the same site next year. Moreover, recoveries of individuals that were born at the study site during the preceding years were extremely scarce (two out of a total of 258 banded nestlings). These findings suggest two important aspects: (1) species-specific returning rates and annual fluctuation in these are largely defined bymortality and reproductive success during the previous year, and (2) local populations of all three species are apparentlymostly formed by immigrants, implying that local nestling productionmay not contribute significantly to the local population. The negative consequences of living in isolated patches of habitat may be mitigated by natal and breeding dispersal.