Abstract
Northern hemisphere wild geese have increasingly shifted in the non-breeding season from feeding on natural wetlands to grazing agricultural grasslands and, since the 1960s, to green cereals, enhancing agricultural conflicts. From an agricultural perspective, it is important to know if this shift is a response to availability (i.e. grassland conversion to arable) or a response to the enhanced feeding opportunities provided by cereals and hence goose food preferences. In an important Polish goose spring staging area, we showed no change in the extent of cereal production area between 2012 and 2018, but based on repeated goose counts, a significant increase in goose use from a mean of 20.7% (± 0.04 se during 2007–2015) use of cereal fields to 33.5% in 2023. Larger flocks of the numerically dominant Greater White-fronted Geese Anser albifrons (hereafter White-fronted) and Bean Goose Anser fabalis showed greater preference for feeding on cereals in 2023, increasingly through the staging period, whereas larger flocks preferred grass in the period 2007–2015 (although patterns differed in less numerous species). Previous studies have shown that geese can maintain higher food intake rates on monospecific cereal fields than on grass swards, suggesting the recent transition is due to improved foraging efficiency, since their availability relative to grassland and other habitats has not changed. We predict that more geese will make this transition in this study area and in many other European farmland landscapes as long as there are no fitness penalties to doing so, potentially increasing level of agricultural conflict as more geese in larger flocks depredate cereal fields.