Hunting Ranges and Habitat Use and Selection of Urban-Breeding Merlins

Abstract

We studied hunting ranges and habitat requirements of 27 radio-tagged Merlins (Falco columbarius) breeding in Saskatoon, Saskatchewan from May to July, 1987-1990. Mean hunting range sizes of resident (hatched in the city) and immigrant (hatched outside the city) males were 6.3 _ 1.3 km2 (2.2-13.7 km2) and 33.7 _ 12.1 km2 (12.5-64.3 km2), respectively. Mean hunting range sizes of resident and immigrant females were 6.6 _ 3.4 km2 (2.5-13.4 km2) and 8.6 + 1.6 km2 (0.6-17.5 km2), respectively. Spatial overlap in hunting ranges between neighboring Merlins ranged from 0 to 77.3%. Most immigrants frequently left the city to hunt and had less urban habitats in their ranges than did residents. Merlins that hunted exclusively within the city used habitats in relation to their availability. Resident and immigrant merlins that hunted both within and outside the city avoided hunting in agricultural habitats, which had relatively low prey abundance.