Home range size, habitat use, activity patterns and hunting behaviour of urban-breeding Northern Goshawks Accipiter gentilis

• Main Author: Rutz, Christian
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2006
• Subjects: Accipiter gentilis; behavioural plasticity; Northern Goshawk; predation ecology; radio-tracking; urban ecology and wildlife; KESTREL FALCO-TINNUNCULUS; MERLINS; HAWKS; ENVIRONMENT; SELECTION; WINTER; DIET
• Online Access: https://research-portal.st-andrews.ac.uk/en/researchoutput/home-range-size-habitat-use-activity-patterns-and-hunting-behaviour-of-urbanbreeding-northern-goshawks-accipiter-gentilis(d30e17ae-a557-4e2a-a942-f39afa7c53b9).html

The Northern Goshawk Accipiter gentilis typically prefers woodland habitat for nesting and hunting. In recent decades, however, the species has started colonising urban environments across Europe. Here I present the first study on the ranging behaviour of urban-breeding Goshawks. Each year from 1997 to 1999, 1 tracked a different adult male during the breeding season in the city of Hamburg, Germany (858 hours of total tracking time; n = 5364 radio-fixes). All corresponding pairs raised young in the year of data collection (3, 3 and 4 juveniles). Average home range size was 863 ha. (100% Minimum Convex Polygons). Males spent 88% of daylight hours in patches of urban green space (mainly parks) and made short but regular hunting excursions into the matrix of built-up habitat. Built-up habitat was used less frequently than expected from its percentage availability. However, 42% of all recorded kills (n = 143) were made in this habitat type, indicating that it offered good foraging opportunities. Hawks spent 9.7% of daylight hours in active flight (1.8% inter-perch flights, 7.9% soaring). Daily activity patterns were bimodal, with peaks in the early morning and in the evening. I observed one hawk hunting regularly after sunset under artificial light conditions. Goshawks hunted by perched hunting (49%), soaring (33%), and fast contour-hugging flights (11%; n = 220 hunts). Average hunting success was 16% (n = 176 directly observed attacks), or one kill every 35 min of active flight. Home range size was smaller, time spent flying was shorter, and hunting success was higher for the monitored urban hawks than for non-urban individuals from earlier studies. Taken together, my data suggest that living conditions for Goshawks are more favourable in the city of Hamburg than in many non-urban environments.