Habitat Selection of Farmland Feeding Geese in West Jutland, Denmark: An Example of a Niche Shift

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Abstract
The autumn habitat selection of Pink-footed Geese Anser brachyrhynchus and Greylag Geese Anser anser in temporal sympatry and allopatry was studied on farmland in West Jutland, Denmark. When Greylags were alone in the area (Sep.) they positively selected stubbles and undersown stubbles. When the two species co-occurred (Oct.) the Greylags positively selected stubbles, but strongly avoided undersown stubbles, whereas the Pinkfeet positively selected undersown stubbles and stubbles. Alone (Nov.) the Pinkfeet showed the same selection. When co-occurring, the two species were differently distributed with an overlap of 0.20 in relative field utilization. It is suggested that, due to exploitative competition, the Greylags avoid the flocks of the more numerous Pinkfeet and shift habitat. Apart from habitat type the disturbance level and tolerance of disturbance are important factors segregating the two species.