Northern Goshawk (Accipiter gentilis)

Northern GoshawkNorthern Goshawk distribution map


Population Information

The Federal BBS information can be obtained at by clicking on Trend Estimates and selecting the species in question. All estimates are for time period (1966-2005).

There is currently no survey that adequately monitors Northern Goshawk population trends in Wisconsin or throughout North America.

WSO Checklist Project: stable (1983-2007)

Life History

Habitat Selection

The northern goshawk is a large forest-dwelling hawk generally associated with mature deciduous, coniferous, or mixed forests (Squires and Reynolds 1997). The goshawk has a holarctic distribution (Grossman and Hamlet 1964) and breeds throughout much of the forested areas of western, upper Midwest, and northeast United States (Reynolds et al. 1992).

Nests are typically found in mature to old-growth forests comprised primarily of large trees with high canopy closure (60-90%) (Squires and Reynolds 1997, Rosenfield et al. 1998). Nesting areas may contain 1-5 alternate nest trees, which are located in relatively small forest stands, approximately 0.4-100 ha in size (Reynolds et al. 1982, Speiser and Bosakowski 1991, Squires and Ruggiero 1996). Nest trees are usually the largest in the stand (Bent 1961, Bosakowski 1999). Deciduous trees are usually favored for nest building in mixed forests (Zirrer 1947, Bent 1961, Bosakowski 1999, Boal et al. 2001), because they provide a more stable structure to support the nest and have larger diameter limbs than conifers species of similar trunk diameter (Bosakowski 1999). This is in contrast with the western United States, where nearly all goshawk nests are found in conifers (Reynolds et al. 1982, Squires and Ruggiero 1996). In Wisconsin, Rosenfield et al. (1998) reported that 78% of nests were built in deciduous tress with a mean dbh of 41.0 cm (range = 36.4- 45.2), mean nest-tree height of 25.0 m (range = 23.6-25.6), mean canopy height of 25.0 m (range = 23.6-25.6) and a mean tree density of 423.0 trees/ha (range = 341.0-505.0). Woodford et al. (2003) report the mean nesting and basal areas for goshawks breeding in northern Wisconsin were 31 ha (range = 6-101 ha) and 25 m 2/ha (range = 17-36 m 2/ha), respectively. Additionally, 41% of nests were in trembling aspen (Populus tremuloids), 17% in other deciduous trees, and a small percentage in pine plantations. Rosenfield et al. (1998) reported goshawks nesting in a variety of diverse habitats throughout northern Wisconsin, as well as larger blocks of fragmented forests in central Wisconsin.

In North America, foraging habitat ranges from open-sage steppes to dense forests, including riparian areas (Squires and Reynolds 1997). In Minnesota, Boal et al. (2001) reported that old (>50yr) early successional upland forests (e.g., aspen and birch) with large amounts of down woody debris appeared to be the most preferred stand type for foraging. They suggest goshawks may use open spaces between the canopy and understory cover for flight paths through forests. However, they argue that stand structure may be more important than specific species composition. No published information is available on foraging habitat in Wisconsin.

No information exists on spring and fall migration habitat, but it may depend on prey abundance.

Habitat Availability

Goshawk nest reports exist for 22 counties in Wisconsin, mostly north of a line from Door to Menominee to Taylor to Douglas, with several nest reports in the central counties of Clark, Monroe, Juneau, Marquette, Waushara, and Sheboygan (WBBA unpublished data). Rosenfield et al. (1998) found nests scattered throughout the northern 2/3 of Wisconsin in 1996-97. They believe that the breeding range may be expanding into the southern half of the state, however evidence for this expansion is inconclusive. The Natural Heritage Inventory (NHI) database has 117 nesting area records for the time period 1980-2005. Distribution is mainly in the northern third of Wisconsin, with 60% of these active within the past 10 years (WDNR 2002). The historic distribution of the goshawk throughout Wisconsin, prior to timber harvest, is unknown. The first reported nests were from Oconto county during the late 1890s (Robbins 1991).

Recent habitat modeling using a Geographical Information System (GIS), predicted that 7.6% of the northern highland landscape of Wisconsin had >50% probability of being occupied by breeding goshawks (Woodford et al. 2003).

Population Concerns

The goshawk is currently listed as a migratory non-game bird of management concern by the U.S. Fish and Wildlife Service (Region 3), a regional forester sensitive species by the U.S. Forest Service (Region 9), and an NHI species of special concern in Wisconsin. Robbins (1991) considered the Goshawk an uncommon resident in the north and a rare winter resident in the central and southern portions of the Wisconsin. However, it is known as a common fall migrant every 8-10 years when ruffed grouse (Bonasa umbellus) and snowshoe hares (Lepus americanus) are in short supply in the northern boreal forest of Canada (Mueller et al. 1977, Mueller et al. 1997). It is believed that food availability strongly affects goshawk population dynamics (Squires and Reynolds 1997). Erdman et al. (1998) report a correlation between goshawk nesting success and grouse population cycles in northeastern Wisconsin. Thus, an increase in prey availability in areas that goshawk forage should benefit both breeding adults and winter migrants.

Harvesting of some 40-50 year old upland forest types (e.g., aspen and birch) may negatively influence productivity (Boal et al. 2001), and large clear-cut areas also encourage competitive species to move in and displace goshawks from established nesting areas (Erdman et al 1998, La Sorte et al. 2004). Goshawks appear to select late-successional forest stands for nesting (e.g., Reynolds et al. 1982). Protection of known nesting areas and the use of silvicultural practices that support late-successional forests should improve nesting area availability.

Several mammal species are known to predate goshawk nests. The list includes American marten (Martes americana), wolverine (Gulo gulo), raccoon (Procyon lotor), and fisher (Martes pennanti) (Erdman et al. 1998, Boal et al. 2001). The legal take of nestlings for falconry has a limited impact on the wild population. However, Erdman et al. (1998) reported a 5% loss of nestlings monitored from both legal and illegal take. Other factors that effect goshawk productivity are anthropic disturbances near nest areas, prey availability, weather conditions during nesting, and the age of breeding females (Squires and Reynolds 1997).

Recommended Management

Reduce disturbance during the nesting period by delineating protected areas around nest trees. Crocker-Bedford (1990) reported that small (1.2-2.4 ha) and large (16-200 ha) buffer areas were inadequate, with only 16% re-occupied nests and nestling production dropping 94% following logging activities. This may be due to increased competition from open-area competitors, and changes in foraging habitat and prey abundance. Habitat may be improved with silvicultural activities that reduce the density of shrubs, saplings, and small poles, while maintaining or enhancing the canopy of large trees within foraging range of nests (Crocker-Bedford 1990). Recent studies in the western US (reviewed in Andersen et al. 2004) have concluded that management strategies that account for interactions among habitat factors and their spatial and temporal effects on habitat suitability are likely to be more successful in retaining goshawks than prohibitive buffers around individual nests.

In Wisconsin, the Chequamegon-Nicolet National Forest manages for goshawk habitat with silviculture practices that emphasize higher residual basal areas and smaller size and number of canopy gaps. They conduct surveys for goshawk breeding pairs and active nests prior to timber harvest projects, and maintain, protect, and enlarge areas of mature hardwood, hemlock, and white pine forests with an emphasis on low fragmentation and high canopy cover (i.e., > 80% closure). Currently, WDNR is using draft management guidelines designed to protect known nesting areas. These guidelines include (1) create a no-cut buffer around the active and any alternate nest tree(s), (2) for unevenage harvests or selection thinnings maintain residual basal areas >110 ft 2/acre within the nest area or 1000 feet of the nest tree, (3) limit harvest and road/trail building activities from February 1 to August 1, and (4) limit the timber sale contract to 1 yr within 1000 feet of the nest tree or nest area center.

Goshawks do not always breed every year, are very secretive, may abandon their territories for several years, or they may have an ephemeral territory outside the sale area. Therefore, surveys should be conducted for two to 3 years in a row to ensure that resident goshawks are detected and receive adequate protection (Bosakowski 1999).

Priorities for Future Research

Squires and Reynolds (1997) list several priorities for future research including (1) determine how changes in forest structure and landscape patterns effect population viability, (2) impacts of habitat alterations to prey species, (3) effects of habitat fragmentation, (4) development of monitoring procedures to determine population trends, (5) winter ecology, and (6) dispersal capabilities and mortality rates. More recently, Andersen et al. (2004) identified the following research priorities for goshawk populations throughout North America: (1) long-term population studies, (2) coordinated studies of habitat use, (3) studies of demography and habitat use in the non-breeding season, and (4) long-term experimental studies to understand how forest management influences goshawks.

An accurate assessment of the status of goshawks in Wisconsin will require a large-scale coordinated inventory (i.e., statewide or larger). Hargis and Woodbridge (2005) have developed and tested a monitoring design for goshawks that can yield a defensible population trend. Implementation of this design is critical to the conservation and management of goshawks in Wisconsin.

Information Sources


Contact Information

Kreitinger, K., Y. Steele and A. Paulios, editors. 2013.
The Wisconsin All-bird Conservation Plan, Version 2.0. Wisconsin Bird Conservation Initiative.
Wisconsin Department of Natural Resources. Madison, WI.

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