Territorial calls in the Little Owl (Athene noctua): spatial dispersion and social interplay of mates and neighbours

With the aim of quantifying spatio-temporal and social factors affecting territorial calls in Little Owls, we collected data on the calling behaviour of radio tracked individuals from a low-density population in Northern Jutland, Denmark. There was considerable seasonal variation in calling activity. During the breeding season, males calling away from the nest were located in the direction of the neighbouring nesting site, and males with a neighbour within hearing distance called more often than those with a longer distance to the nearest neighbour. Call posts were on average closer to the nest than telemetry observations, but did not appear to be related to mate distance. With a sound pressure level of 82 dB(A) at 1-m distance, the territorial calls were estimated to be audible to a distance of 4.4 km. Call posts were on average 4.1 m above the ground, which probably maximizes the transmission distance.