Stopover Site Fidelity of Four Migrant Warblers in the Iberian Peninsula

Abstract

This paper analyses by means of ringing data the stopover site fidelity of four warbler species (Sylvia atricapilla, Sylvia borin, Phylloscopus collybita and Acrocephalus scirpaceus) during their migrations across the Iberian Peninsula. The mean recovery rates observed during migration periods (mean 0.28, range 0-0.54) were around 50% of the ones observed during the breeding and wintering seasons (mean 0.51, range 0.41-0.58). These differences in recovery rate were statistically significant in all species but Acrocephalus scirpaceus. This warbler, with its more restricted habitat requirements, showed higher recovery rates during the spring and autumn migration periods confirming the hypothesis that species depending on scarce, patchily distributed stopover habitats during their migrations show stronger stopover site fidelity during their journeys. Our results support the view that some migrant species actively select stopover sites during their migrations.