Patterns of differential migration in white-throated sparrows evaluated with isotopic measurements of feathers

Abstract

We used stable isotope techniques to investigate differential migration in the white-throated sparrow ( Zonotrichia albicollis (J.F. Gmelin, 1789)), a short-distance migrant in North America, to clarify hypotheses about patterns and consequences of migration tactics. Sparrows staging in Manitoba, Canada, exhibited sex-biased differential timing of spring arrival and latitude of wintering origin. Specifically, females arrived later and originated from more southern latitudes. Furthermore, there was a negative relationship between wintering latitude and arrival dates of individuals, although this relationship was only present during the second spring of the study, since atypical cold temperatures were associated with a pulse of late-arriving sparrows during the first spring. The negative correlation between wintering latitude and arrival date was also present within males, suggesting that the distribution of males on wintering areas could have carry-over effects to reproduction. This study demonstrates potential links between events occurring on wintering and breeding grounds of migratory songbirds.