Individual behavioural variability of an ecological generalist: activity patterns and local movements of Mallards Anas platyrhynchos in winter

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 between-subject 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.