Philopatry in a changing world: response of pink-footed geese Anser brachyrhynchus to the loss of a key autumn staging area due to restoration of Fils0 Lake, Denmark

摘要

Site fidelity is a strong and widespread feature of many waterfowl species, but little is known about the response of philopatric birds to changing environmental conditions at their preferred staging sites. In this study we analyse the response of pink-footed geese Anser brachyr-hynchus to the sudden loss of a major autumn staging area along their migration corridor, Fils0 in Denmark, which followed the re-establishment of a former lake on open arable land serving as foraging site to tens of thousands of geese. Comparisons of goose usage before and after the restoration event revealed that (1) approximately 80 % of pink-footed geese abandoned this staging area and (2) formerly site-faithful geese moved to other staging areas along the Danish west coast rather than moving further south to the Netherlands. Despite these significant changes in site use, the subsequent spring body condition of birds formerly philopatric to the Fils0 area was unaffected, suggesting that geese quickly moved to other areas and responded well to the sudden decline in available food at their formerly preferred staging site. These findings indicate that, at least for pink-footed geese, the cognitive plasticity necessary to alter site use allows a swift response to rapidly changing environmental conditions. This may partly be due to the agricultural habitat use of this species, leaving them plenty of alternatives in the modern Danish landscape.