Breeding Season Irruptions of Rough-legged Hawks (Buteo lagopus) on Insular Newfoundland

ABSTRACT. Rough-legged hawks (Buteo lagopus Pontoppidan), a species typically associated with more northerly regions, occurred in unusually high numbers on insular Newfoundland in the summers of 1988 and 1993, and some pairs nested in noncoastal areas on the island in 1993. We suggest that the island is an alternative breeding ground for the species during years of low prey abundance on the Labrador Peninsula. Our observations concur with hypotheses that rough-legged hawks nomadically search for nesting territories and exploit areas near the limits of their breeding range during such years. Forest clear-cuts were used for foraging by pairs nesting in interior Newfoundland during 1993, which suggests that forest harvesting may have opened new alternative habitats for rough-legged hawks. Key words: rough-legged hawk, Buteo lagopus Pontoppidan, breeding distribution, clear-cut, irruption, nomadism, Newfoundland, predator–prey cycles RÉSUMÉ. Un nombre inhabituellement élevé de buses pattues (Buteo lagopus Pontoppidan), une espèce typiquement associé