Relation of group size and daily activity patterns to southern lapwing (Vanellus chilensis) behaviour

Behavioural patterns of birds commonly vary according to flock size and daily activity pattern. Southern lapwing behaviours and their relation with flock size were studied, as well as the relationship between the frequency of behaviours and the period of the day. Results showed that the proportion of time spent in foraging and vigilance was higher during the morning, when small groups were more common, and decreased from midday on, when group size increased. Maintenance and inactivity (sleeping) behaviours presented the opposite pattern. Correlation between flock size and period of the day, and their similar effects on bird behaviour may be evidence that groups of different sizes could have different functions throughout the day. Our results show that southern lapwings seem to form smaller flocks for feeding in the beginning of the day and larger flocks later for different activities (e.g., maintenance and sleeping). In this sense, it is possible that group size variation throughout the day is related to different demands for specific behaviours (functions) of groups, according to the daily activity patterns of the birds.