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Common and widespread species often show a large variability in behaviour and habitat use. Such variability at the species level may result from individuals themselves being very variable or, alternatively, variability may arise from differences between individuals. The aim of this study was to explore land use in general and betweensubject variability in the local movements and daily activity patterns of Mallards Anas platyrhynchos in central Switzerland during the winter. The Mallard is a common duck species and can be found on almost all types of water bodies. We equipped 24 ducks with VHF radio tags and searched for these ducks 1-3 times per day. We also used nine tags that automatically recorded their location every 30 min as well as acceleration in three dimensions every 2-5 min. These methods yielded information on the activity of the duck with a high temporal resolution both day and night. The 24 ducks were strongly linked to water, and 97% of all localisations were within 50 m of a water body. An affinity to settlements was only observed in the vicinity of the main lake in the area, but not for those ducks on smaller water bodies or fields. Some individuals were very stationary, using only a small area during the study period; others made daily commuting flights between two sites about 8 km apart while still others moved around similar distances but in varying directions. Rain and increasing wind speed correlated with decreasing movement activity. However, the effect of these weather parameters, and especially that of temperature, varied between individuals. Activity was strongly influenced by the sun's movement, with general activity and flight activity being highest around sunrise and sunset. This daily pattern was similar for all individuals. Hence, while the activity pattern was similar for all individuals, the resulting degree of local movements and the response to changing weather parameters were very variable among individuals. Keywords Mallard Á Anas platyrhynchos Á Winter Á Land use Á Daily activity pattern Zusammenfassung Individuelle Variabilität im Verhalten eines ökologischen Generalisten: Aktivitätsmuster und lokale Ortswechsel bei der Stockente (Anas platyrhynchos) im Winter Häufige und weit verbreitete Arten zeigen oft eine große Variabilität in Verhalten und Habitatnutzung. Diese Variabilität auf Artniveau kann sowohl durch ein vielfältiges Verhaltensrepertoir eines jeden Individuums entstehen, als auch durch große Unterschiede zwischen den Individuen. In dieser Studie untersuchten wir, wie Stockenten Anas Communicated by F. Bairlein.

Vineyards are likely to be regionally important for wildlife, but we lack biodiversity studies in this agroecosystem which is undergoing a rapid management revolution. As vine cultivation is restricted to arid and warm climatic regions, biodiversity-friendly management would promote species typical of southern biomes. Vineyards are often intensively cultivated, mostly surrounded by few natural features and offering a fairly mineral appearance with little ground vegetation cover. Ground vegetation cover and composition may further strongly vary with respect to season, influencing patterns of habitat selection by ecological communities. We investigated season-specific bird-habitat associations to highlight the importance of semi-natural habitat features and vineyard ground vegetation cover throughout the year. Given that avian habitat selection varies according to taxa, guilds and spatial scale, we modelled bird-habitat associations in all months at two spatial scales using mixed effects regression models. At the landscape scale, birds were recorded along 10 1-km long transects in Southwestern Switzerland (February 2014 –January 2015). At the field scale, we compared the characteristics of visited and unvisited vineyard fields (hereafter called parcels). Bird abundance in vineyards tripled in winter compared to summer. Vineyards surrounded by a greater amount of hedges and small woods harboured higher bird abundance, species richness and diversity, especially during the winter season. Regarding ground vegetation, birds showed a season-specific habitat selection pattern, notably a marked preference for ground-vegetated parcels in winter and for intermediate vegetation cover in spring and summer. These season-specific preferences might be related to species-specific life histories: more insectivorous, ground-foraging species occur during the breeding season whereas granivores predominate in winter. These results highlight the importance of investigating habitat selection at different spatial scales and all along the annual cycle in order to draw practical, season-specific management recommendations for promoting avian biodiversity in farmland.