Differences in the Use of Foraging Grounds by Greylag Goose Anser Anser and White-fronted Goose Anser Albifrons at a Spring Stopover Site

Abstract

Climate conditions may determine the foraging strategy of migratory birds at spring stopovers. For geese, this period is a crucial time for acquiring energy to fuel onward migration and ensure future breeding success. Our study, analysing the influence of weather factors on numbers of geese and foraging sites, was conducted in the Biebrza Basin (northeastern Poland) during the spring migration period in 2007–2013, when a total of 116 counts were carried out. A total of 741,865 White-fronted Geese and 20,871 Greylag Geese were counted. Numbers of geese differed among habitat types; Greylag Geese used arable lands more frequently than White-fronted Geese, which in turn preferred grasslands. Two climate factors affected numbers of the latter: the impact of mean 10-day temperature was positive but that of snowfall was negative. Neither of these factors affected the former. We conclude that changeable climate conditions in the temperate climatic zone may force a more flexible response in terms of habitat use during stopovers from short-distance migrants like Greylag Geese than from longer-distance migrants like White-fronted Geese.