A first insight into the post-breeding dispersal strategies of adult Lesser Kestrels Falco naumanni in Italy

Abstract

ABSTRACT Capsule After breeding, Lesser Kestrels Falco naumanni do not migrate directly to Africa but exhibit a post-breeding dispersal that lasts several weeks. Tracking of four adult individuals provides the first data on distances and direction of travel, and suggests sex differences in post-breeding dispersal. Aims We aimed to: (a) detect the dispersal routes and stopover sites used by adult Lesser Kestrels during the post-breeding period in Italy, (b) deduce the strategies behind the observed dispersal behaviour, and (c) advance hypotheses about the determinants of such strategies. Methods Using Argos satellite telemetry, we tracked four individuals at neighbouring urban colonies at Gravina and Altamura (Apulia region), within the geographical area (Alta Murgia) which has the world’s highest known density of urban nesting Lesser Kestrels. Results Argos devices provided 4930 high-quality locations for 72 ± 13 (mean ± SD) days for four individuals tracked during July–September. July corresponded to the post-nestling period, with recorded dispersal distances less than 66 km from the breeding site. At the beginning of August, the birds entered the pre-migration period, with recorded dispersal distances up to 667 km from the colony. We detected four dispersal strategies: absolute fidelity to the breeding site, and short-range, mid-range, and long-range dispersal. The males had long-range and mid-range dispersal routes parallel to the eastern side of the Apennine ridge, and selected several stopover sites in central and northern Italy. The females showed absolute fidelity to the breeding site and short-range dispersal. We hypothesize that males and females had different body conditions at the beginning of the pre-migration period, which forced females to remain close to the breeding site while males could disperse further. Conclusions This work sheds light, for the first time, on the post-reproductive dispersal behaviour and schedule of the Lesser Kestrel in Italy.