Kestrels of the same colony do not overwinter together

Abstract

Coloniality is one of the most common strategies in birds. While the lesser kestrel (Falco naumanni) is a colonial raptor during the breeding period, it is not known whether individuals from the same breeding colony aggregate during the non-breeding period too. We GPS-tracked 40 adult lesser kestrels from different Spanish breeding colonies to study the degree of spatial aggregation between individuals from the same breeding colony in their West African non-breeding range. Lesser kestrels in our study used a large area from a wide longitudinal strip in the western Sahel: individuals used 143,697 {+/-} 98,048 km2 on average during the entire non-breeding period (95% KDE), and 1,359 {+/-} 1,424 km2 per week. On the other hand, the individuals traveled 6205 {+/-} 2407 km on average during the entire non-breeding period, and 41.1 {+/-} 11.8 km per day. There were no differences between the sexes in any of those variables. Individuals from the same breeding colony were not aggregated during the non-breeding period because the overlap between their areas (38.8 {+/-} 21.4 %) was not higher than that randomly expected. In conclusion, our study reveals some aspects of the non-breeding spatial ecology of the lesser kestrel, allowing a better understanding of the relationship of colonial birds out of the breeding season.