Wetenschappelijk artikelHabitat preference of geese is affected by livestock grazing – seasonal variation in an experimental field evaluation.

The number of staging geese in northwestern Europe has increased dramatically. Growing goose numbers put strong grazing pressure on agricultural pastures. Damage to agricultural land may be mitigated by managing nature reserves in order to optimally accommodate large numbers of grazing geese. Livestock grazing has been shown to facilitate foraging geese; we take the novel approach of determining the effects of four different livestock grazing treatments in a replicated experiment on the distribution of geese. We present experimental field evidence that livestock grazing of a salt marsh in summer affects the habitat preference of foraging geese during autumn and spring staging. In an experimental field set-up with four different livestock grazing treatments we assessed goose visitation through dropping counts, in both autumn and spring. Grazing treatments included 0.5 or 1 horse/ha and 0.5 or 1 cattle/ha during the summer season. The livestock grazing regime affected goose distribution in autumn, just after livestock had been removed from the salt marsh. In autumn, goose visitation was highest in the 1 head/ha grazing treatments, where grazing intensity by livestock was also highest. In line with this result, goose visitation was lowest in the 0.5 head/ha livestock grazing treatments, where the grazing intensity by livestock was lowest. The differences in goose visitation among the experimental treatments in autumn could not be explained by the canopy height. In spring we did not find any effect of livestock grazing treatment on goose visitation. Differences in the distribution of geese over the experiment between autumn and spring may be explained by changes in the availability of nutrient-rich vegetation. Livestock summer grazing with a high stocking density, especially with horses, can be used to attract geese to salt marshes in autumn and potentially reduces damage caused by geese to inland farmland. From a nature conservation interest point of view, however, variation in structure of the vegetation is a prerequisite for other groups of organisms. Hence, we recommend grazing of salt marshes with densities of 0.5 head/ha of livestock when goose conservation is not the only management issue.