Introduction

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Martell, M. and T. Dick. 1996. Nesting habitat characteristics of the Northern goshawk (Accipiter gentilis) in Minnesota. Final report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 30 pp.

Introduction:

Concerns over changes in northern goshawk (Accipiter gentilis) populations, and particularly whether these changes are due to modern forest management practices, have brought to light the need for data on even the most basic elements of goshawk biology in parts of North America (Reynolds et al. 1992). Against this background, recent proposals to change forestry management practices in Minnesota have raised concerns over the future of goshawk populations in the state. In response, biologists with private organizations as well as federal and state agencies have realized the need for more information in order to develop a comprehensive management plan for goshawks in Minnesota. The first steps in designing such a plan are to locate nest sites, quantify nesting habitat characteristics, and outline goshawk nesting distribution within the state.

Numerous recent studies particularly in the southwestern and western regions of the country, have investigated various aspects of goshawk population dynamics. In the Midwest, some information on goshawk nesting has been gathered (T. Erdman, S. Postulpulsky, pers. com.) although little has been published. In Minnesota, almost no quantitative information has been gathered on nesting or habitat characterization and few attempts have been made to investigate goshawk nesting in the state. Studies done by Eng and Gullion (1962), and Davis (1979), investigated goshawk predation on ruffed grouse (Bonasa umbeilus), and post fledgling movements, behavior and prey use on XXXXXX.

The northern goshawk is considered to be a year round resident in Minnesota. Nesting occurs primarily north of Pine and Crow Wing counties, although nests have been reported as far south as Hennepin County (Roberts 1932, Janssen 1987). Nesting populations have always been considered small; Roberts (1932) wrote that the species was "...rarely a summer resident" and had reports of only four nests. Janssen (1987) reported confirmed nesting in 10 counties since 1970, while Johnson (1982) reported a total of 61 nestings. Fall migration data has been collected at Hawk Ridge in Duluth since 1972 and show 10 year cycles of peak numbers (Hawk Ridge Annual Report 1995). The goshawk is considered a regular winter resident in Minnesota (Janssen 1987).

At the time this study was started, concern over the status of goshawk populations had resulted in the bird's classification as a Category 2 species (meaning that more information is needed) by the U.S. Fish and Wildlife Service (USFWS) (Smith 1992). The U.S. Forest Service (USFS) listed it as a sensitive species in the Southwest region (USDA Forest Service 1991). In the Midwest, the state of Wisconsin considered listing the species, although that proposal was not adopted. The goshawk is not currently listed by the state of Minnesota.

This report summarizes a study begun in 1994 and continuing through 1996. The objectives of this study were to 1) locate goshawk nests in Minnesota, 2) monitor nest productivity at these sites, and 3) quantify the habitat at these sites.

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Please note that all location information has been removed from this document to protect Minnesota's goshawk populations