The role of winter cereals as cold-weather refuge for Taiga Bean Geese Anser fabalis fabalis wintering in Denmark

Abstract Suitable foraging habitats are essential for migratory birds during their wintering period, as well as alternative staging areas to which they can relocate, e.g. due to changes in weather conditions. This study focusses on the habitat use of Taiga Bean Geese ( Anser fabalis fabalis ) at a wintering site in Denmark, that is particularly important for the geese during cold spells. Recent plans for energy constructions in this area have raised concerns about the potential loss of agricultural foraging habitats for geese. To better understand the role and importance of the different habitats, we analysed habitat use and energy intake on both agricultural fields and semi-natural pastures. We investigated the proportional use of winter cereal fields of GPS-tagged Taiga Bean Geese in relation to daily average temperatures and collected food and faecal samples on winter cereals and pastures during both cold and mild weather condition to investigate possible differences in energetic intake. The results showed an increased use of winter cereals when temperatures dropped. Moreover, during cold periods, the geese appeared to only be able to maintain a positive energy balance on winter cereals, which could explain the increased use in low temperatures. In mild situations, pastures seemed to also cover the energy requirements of wintering Taiga Bean Geese, with an energy assimilation efficiency similar to what was found on winter cereals. Our study underlines the importance of ensuring the availability of refuges that can meet the energetic needs of geese across different weather situations, especially when planning constructions that may affect those resources.