Size and composition of northern goshawk (Accipiter gentilis) home ranges in north-central Arizona

Current guidelines for management of the northern goshawk (Accipiter gentilis atricapillus) in the Southwest recommend size and composition for managed areas. These recommendations were developed from research conducted in northern Arizona and northern New Mexico, however, they are being applied throughout the southwestern United States. I proposed viewing the recommendations as a model of goshawk habitat and conducted an independent comparison in the ponderosa pine (Pinus ponderosa) forests of north-central Arizona during 1992--1995.;I report home-range sizes calculated using three techniques, at three temporal scales. Mean home-range size for 22 individuals varied from 1051 +/- 785 ha in the breeding season to 3954 +/- 3342 ha over winter for reproductively successful adult goshawks. Pairs of goshawks utilized 3689 ha and 5408 ha for the corresponding time periods. Nonbreeding season home ranges consistently exceeded breeding season ranges. Males foraged over larger areas than their mates, regardless of season. Goshawks exhibited shifts in home-range locales, as measured by overlap. On average individual ranges overlapped 45% between seasons and 40% between years. Pair members shared 42% of the their home ranges while neighbors shared only 9.8%. The shifts resulted in cumulative ranges larger than any one component home range. Winter and year-round ranges exceeded current management guidelines' specifications.;The management guidelines for northern goshawks specify three compositions comprised of ten combinations of six vegetation structural stages and three canopy closure classes. I compared the three composition models to the habitat within ten female breeding season home ranges with principal component analysis and similarity indices. I developed a piecewise linear regression technique to determine the end of the breeding season for each female. Home-range compositions moderately resembled model compositions; similarity averaged 0.65. Similarity index values were higher for comparisons among home ranges than for comparisons of home ranges to models. The vegetative structure of few nest stands matched the nesting area model specifications, however, 80% of nest sites did. Nest sites more closely resembled the stands surrounding them than other nest sites. Modifications of the models are needed to ensure its applicability throughout the Southwest.