Densities and dispersion of breeding Eurasian Hobbies Falco subbuteo in southeast England

Abstract

Capsule Breeding Hobbies are more numerous in parts of southeast England than previously recognized, and in suitable habitat their breeding dispersion shows a regular pattern. Aims To establish the density and breeding dispersion pattern of a population of Hobbies in southeast England. Methods Surveys to locate every pair of Hobbies present were conducted in six study areas of between 48.0 and 201.2 km2 in three counties in southeast England during 2005–10. Results Each study area held between 7 and 21 pairs. Densities were higher than in previous studies conducted in Britain, at between 9.0 and 15.0 pairs per 100 km2. Mean densities per unit area of non-developed habitat were also consistently higher than expected, at between 10.1 and 17.3 pairs per 100 km2. The mean nearest known neighbour distances fell within the range 1.8–2.8 km. In all six study areas, pairs were regularly spaced. The majority (68.0%) of nesting and territorial pairs occupied sites in woodland. Conclusions Breeding Hobbies are considerably more numerous in parts of southeast England than previously recognized, and numbers appear to be continuing to increase. Accurate population estimates for Hobbies require species-specific fieldwork.