Breeding performance of Crested Goshawk Accipiter trivirgatus in urban and rural environments of Taiwan

Capsule: A Crested Goshawk population recently colonizing an urban area of Taiwan is characterized by earlier egg-laying dates, a higher ratio of mixed-age pairs and higher nesting success. Aims: To compare breeding time, productivity and pairing pattern of Crested Goshawk populations between urban and rural areas. Methods: A total of 117 nests, comprising 49 rural and 68 urban ones, were monitored in Taichung, central Taiwan over six years. Age of parents, egg-laying date, clutch size and number of fledglings were recorded from each nest. Results: The urban Crested Goshawk bred 34 days earlier on average than the rural population with a significantly higher nesting success. Mixed-age pairs occurred in a higher frequency in urban (30.9%) than in rural (14.3%) areas. Predation (55.6%) and inclement weather (27.8%) were the two main factors causing nesting failures in rural areas, whereas neither occurred in the urban area. Conclusion: We conclude that the urban Crested Goshawk population benefits from high food supply and low predation risk. The year-round abundance of prey might increase the breeding success of young adults and advance their breeding schedule, which coincidently shifts the brooding period away from the heavy rainy season.