Productivity and mortality of Northern Goshawks in Minnesota

Compared to other regions of North America, little information exists regarding Northern Goshawk (Accipiter gentilis) ecology and population dynamics in the western Great Lakes Region. We examined productivity and nesting habitat characteristics of goshawks in Minnesota from 1998-2001. Apparent nesting success varied annually from as low as 38% to as high as 83%. The Mayfield estimate of daily survival for nests was 0.992 ?? 0.002 (SE). The mean fledgling number across years was 1.85 ?? 0.14 for successful nests and 1.14 ?? 0.17 for all nesting attempts. Twenty-one percent of all nesting attempts failed, primarily due to predation or suspected predation (52%) and inclement weather (35%). Overall, productivity of goshawks in Minnesota was at the lower end of the range reported in other studies across western North America, which is not atypical for peripheral populations. During the 3-yr study, we recorded mortalities of nine (four males and five females; eight radio-marked and one unmarked) adult goshawks-causes of mortality were avian (33%) and mammalian (22%) predation, human persecution (22%), and unknown causes (22%). Fifty-six percent of mortalities occurred during the breeding season, and 44% occurred during the winter. Based on radiotelemetry data, we estimated adult annual survival to be 74 ?? 7.8%, which is similar to survival estimated using mark-recapture analysis in three western North America studies. ?? 2005 The Raptor Research Foundation, Inc.