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We used video-recording systems to collect diet information at 13 Northern Goshawk (Accipiter gentilis) nests in Minnesota during the 2000, 2001, and 2002 breeding seasons. We collected 4871 hr of video footage, from which 652 prey deliveries were recorded. The majority of prey deliveries identified were mammals (62%), whereas birds (38%) composed a smaller proportion of diet. Mammals accounted for 61% of biomass delivered, and avian prey items accounted for 39% of prey biomass. Sciurids and leporids accounted for 70% of the identified prey. Red squirrel (Tamiasciurus hudsonicus), eastern chipmunk (Tamias striatus), and snowshoe hare (Lepus americanus) were the dominant mammals identified in the diet, while American Crow (Corvus brachyrhynchos) and Ruffed Grouse (Bonasa umbellus) were the dominant avian prey delivered to nests. On average, breeding goshawks delivered 2.12 prey items/d, and each delivery averaged 275 g for a total of 551 g delivered/d. However, daily (P < 0.001) and hourly (P = 0.01) delivery rates varied among nests. Delivery rates (P = 0.01) and biomass delivered (P = 0.038) increased with brood size. Diversity and equitability of prey used was similar among nests and was low throughout the study area, most likely due to the dominance of red squirrel in the diet. ?? 2005 The Raptor Research Foundation, Inc.
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Northern Goshawk diet in Minnesota: An Analysis using video recording systems