Abstract
The U.S. Forest Service recently recommended managing forests to increase abundance of prey for Northern Goshawks (Accipiter gentilis) in the southwestern United States. However, empirical data are needed to indicate whether goshawks select foraging habitat based on prey abundance, on the presence of forest structures that favor their hunting strategy, or both. During the 1993 and 1994 breeding seasons, we indexed prey abundance and measured forest structure at sites used by radio-tagged goshawks and at nearby paired sites that lacked evidence of goshawk use (contrast plots). Goshawks apparently did not select foraging sites based on prey abundance; indeed, abundances of some prey were lower on used than on contrast plots. Goshawks selected foraging sites that had higher canopy closure (P=.006), greater tree density (P=.001), and greater density of trees >40.6 cm dbh (P<.0005) than on the contrast plots. These results are consistent with the hypothesis that goshawk morphology and behavior are adapted for hunting in moderately dense, mature forests, and that prey availability is more important than prey density in habitat selection.

Management Implications (pg. 570)
U. S. Forest Service management strategies for goshawk habitat were designed to support abundant populations of 14 primary prey species (Reynolds et. al. 1992). Although findings from this study suggest that forest structure is more important than prey abundance, current Forest Service recommendations should improve foraging conditions for goshawks. These recommendations include: (1) 40% of the landscape should be in stands dominated by trees >45.7 cm dbh, (2) 60% of the stands should be dominated by trees >30.5 cm dbh (Reynolds et. al. 1992). Most ponderosa pine forests in the southwest are dominated by trees < 30.5 cm dbh, the recommendations of Reynolds et. al.(1992) should also improve prey abundance and foraging conditions.
Forest Service recommendations also prescribe a minimum 40% canopy closure in most ponderosa pine forests managed for goshawks (Reynolds et. al. 1992). Findings from this study were concurrent with Reynolds et.al. (1992). Mean canopy closure was 48% on used plots, goshawks had an aversion to canopy closures <40%, and sites with canopy closures >80% were preferred. The authors suggest that goshawk foraging will best be enhanced if managers implement the 40% canopy closure as a true minimum and not a target maximum. Creation of a diversity of canopy closures above this minimum and including >60% canopy closures in at least 20% of the area would be beneficial to goshawks in the Coconino National Forest in Northern Arizona.