BC Conservation Data Centre: Species Summary
Accipiter gentilis
Northern Goshawk
| Scientific Name: | Accipiter gentilis (Linnaeus, 1758) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| English Name: | Northern Goshawk | ||||||||||
| Classification / Taxonomy | |||||||||||
| Scientific Name - Concept Reference: | American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/. | ||||||||||
| Classification Level: | Species | ||||||||||
| Species Group: | Vertebrate Animal | ||||||||||
| Species Code: | B-NOGO | ||||||||||
|
|||||||||||
| Conservation Status / Legal Designation | |||||||||||
| Global Status: | G5 (Apr 2016) | ||||||||||
| Provincial Status: | S4B,S4N (Mar 2015) | ||||||||||
| BC List: | No Status | ||||||||||
| Provincial FRPA list: | |||||||||||
| Provincial Wildlife Act: | |||||||||||
| COSEWIC Status: | |||||||||||
| SARA Schedule: | |||||||||||
| General Status Canada: | 4 - Secure (2005) | ||||||||||
| Migratory Bird Convention Act: | |||||||||||
| Ecology & Life History | |||||||||||
| General Description: | A fairly large hawk with a long tail, rounded wing tips, and a conspicuous pale eyebrow; adult has dark crown, blue-gray back, white underparts with dense gray barring, and conspicuous fluffy white undertail coverts; immature is brown above, buffy below, with dense blurry streaking, undertail coverts are dark-streaked, and tail has wavy dark bands bordered with white and a thin white tip; total length is 53-66 cm, with females averaging lager than males (NGS 1983). | ||||||||||
| Global Reproduction Comments: |
Usually one clutch produced per year, from late April through early May (Squire and Reynolds 1997); however, some individuals may not breed during cold, wet springs (DeStefano et al. 1994). Egg-laying may begin later at higher elevations and during cold, wet springs (Henny et al. 1985, Younk and Bechard 1994). Clutch is typically two to four eggs, rarely one to five (Squires and Reynolds 1997). Average clutch size of 44 North American clutches is 2.7 eggs (Apfelbaum and Seelbach 1983 cited in Squires and Reynolds 1997). Eggs are laid every two to three days and incubation usually begins after the second egg is laid. Incubation, conducted principally by the female, takes 28-38 days; hatching is asynchronous. Few data regarding hatching success. In Oregon, hatching success in five nests was 81 percent (Reynolds and Wight 1978 cited in Squires and Reynolds 1997). Nest success (percentage of active nests that fledge greater than one young) in North America ranges from 44-94 percent and most populations produce 2-2.8 fledglings per successful nest (summarized in Squires and Reynolds 1997). Egg/nestling mortality has been attributed to exposure to cold and rain and siblicide (Boal and Bacorn 1994, Squires and Reynolds 1997). In northern Wisconsin, nest success dropped from 94 percent to 62 percent due to an increase in predation of nest contents and adult females by fishers. Increased predation by fishers was attributed to an increase in the fisher population and nest exposure due to tree defoliation by forest tent caterpillars (MALACOSOMA DISSTRIA; Erdman et al. 1998). Brooding and feeding of nestlings is performed principally by the female; the male brings food to the nest. The young begin flying at 35-42 days and become independent at about 70 days (Boal 1994, Squires and Reynolds 1997). Maintain one to eight alternate nests within a nest area (Squire and Reynolds 1997). Alternate nests range from 15-2066 meters apart (Reynolds and Wight 1978, cited in Squires and Reynolds 1997; Woodbridge and Detrich 1994). The average distance between nests of nearest neighboring pairs in Arizona was 3 kilometers (range = 1.6-6.4 kilometers; Reynolds et al. 1994). A small percentage (less than 10 percent) of subadults (1-2 years old) are sexually mature; however, most breeding birds are young adults (2-3 years old) or adults (Squires and Reynolds 1997). Nesting by subadults is more frequent in expanding populations and less frequent in stable populations (Reynolds and Wight 1978, cited in Squires and Reynolds 1997). | ||||||||||
| Global Ecology Comments: |
Nesting densities of most western U.S. populations range from 6.6-10.7 pairs per 100 square kilometers (summarized in Squires and Reynolds 1997). The single nesting density estimate for the eastern U.S. is 1.17 pairs per 100 square kilometers (Kimmel and Yahner 1994, cited in Squires and Reynolds 1997). Home ranges during nesting vary from 95-3500 hectares depending on sex and habitat characteristics (Squires and Reynolds 1997). Home ranges of males are typically larger than those of females (Hargis et al. 1994, Keane and Morrison 1994, Kennedy et al. 1994). Exclusive of nesting areas, home ranges of adjacent pairs are not defended and may overlap (Squires and Reynolds 1997). The core area (encompasses nest site) constitutes 32 percent of the home range (Kennedy et al. 1994). Individuals typically enlarge or sometimes shift location of home ranges after breeding (Hargis et al. 1994, Keane and Morrison 1994). Home ranges of non-breeders are poorly known, but may be larger than those of breeders (Squires and Reynolds 1997). In North America, winter home ranges are unknown. In Sweden, winter home-ranges of males and females were similar and averaged 5700 hectares (Widen 1989). In California, 76.5 percent of males and 71.4 percent of females returned to the same nesting area in subsequent years. Males were significantly more likely to return to previously-inhabited territories in consecutive years than females (Detrich and Woodbridge 1994). In Arizona, 80 percent of nest areas examined in two consecutive years were re-used the second year by one or both members of the pair banded the first year (Reynolds et al. 1994). Sixty to 72 percent of adults located in consecutive years retained the mate from the previous year (Detrich and Woodbridge 1994, Reynolds et al. 1994). Dispersal of young is not well documented. Detrich and Woodbridge (1994) recaptured two adult females, banded as nestlings 5-7 years prior, 16 and 24 kilometers from their natal sites. Three females, banded as nestlings and recaptured as breeding adults, moved an average of 21.5 kilometers from their natal sites, and another female, captured as a breeding adult seven years after being banded as a nestling, moved 100 kilometers from its natal site (Squires and Reynolds 1997). Little is known regarding survivorship in the U.S. In Arizona, annual survivorship of male and females more than 1 year old was estimated to be 68.8 percent and 86.6 percent, respectively (Squires and Reynolds 1997). In Yukon, Canada, an observed population decline was attributed to increased mortality of eggs, nestlings, immatures and adults, as well as to dispersal following a precipitous decline in number of snowshoe hares (Doyle and Smith 1994). The maximum lifespan of a wild bird is 11 years (Squires and Reynolds 1997). The sex ratio is 1:1 prior to fledging and among adults (Mueller and Berger 1968, Reynolds et al. 1994). |
||||||||||
| Migration Characteristics: (Global / Provincial) | |||||||||||
|
Nonmigrant: Local Migrant: Distant Migrant: Within Borders Migrant: |
Y / Y / N / na / |
||||||||||
| Global Migration Comments: | Generally a permanent resident or conducts only short-distance movements over most of range, but periodically has irruptions of movement out of northern portions of range. Fall migration appears to be influenced by prey availability (Squires and Reynolds 1997). For example, in Yukon Territory, Canada, year-round residents are abundant when snowshoe hares (Lepus americanus) are abundant, but scarce in winter when hare population is low (Doyle and Smith 1994). Approximately once per decade, large numbers migrate southward, apparently in response to a decline in prey populations, particularly snowshoe hares and ruffed grouse (Bonasa umbellus; Bent 1937, Doyle and Smith 1994, Mueller et al. 1977, Squires and Reynolds 1997). Depending on location and year, fall movements begin in late August through September, peak in late September through mid-November, and typically end in December. Spring movements, which are less pronounced, begin in late February and continue through late May. Movement routes are poorly defined, particularly in the western U.S. In the eastern U.S., migrates along the Great lakes, the Appalachian Mountains and the Atlantic coast (Squires and Reynolds 1997). Some birds make extensive movements; four individuals, banded in Minnesota, were recovered up to 2400 kilometers away in British Columbia (Evans and Rosenfield 1985, cited in Squires and Reynolds 1997; Campbell et al. 1990). Other birds, however, undergo short movements from one elevation to another (Squires and Reynolds 1997). | ||||||||||
| Habitats: (Type / Subtype / Dependence) |
Agriculture / Cultivated Field / Facultative - occasional use
Agriculture / Hedgerow / Facultative - occasional use Agriculture / Pasture/Old Field / Facultative - occasional use Alpine/Tundra / Alpine/Subalpine Meadow / Unknown Anthropogenic / Industrial / Facultative - occasional use Anthropogenic / Urban/Suburban / Facultative - occasional use Forest / Conifer Forest - Dry / Facultative - frequent use Forest / Conifer Forest - Mesic (average) / Facultative - frequent use Forest / Conifer Forest - Moist/wet / Facultative - frequent use Forest / Deciduous/Broadleaf Forest / Facultative - occasional use Grassland/Shrub / Meadow / Facultative - occasional use Riparian / Riparian Forest / Facultative - frequent use |
||||||||||
| Global Habitat Comments: |
BREEDING: Nests in a wide variety of forest types including deciduous, coniferous, and mixed forests. Has a complexity of habitat needs in the breeding season, which vary among forest types and region (Johnsgard 1990). Typically nests in mature or old-growth forests (Hayward and Escano 1989, Reynolds et al. 1982, Speiser and Bosakowski 1987, Squires and Ruggiero 1996, Squires and Reynolds 1997, McClaren 1998, Daw and Stefano 2001), and generally selects larger tracts of forest over smaller tracts (Bosakowski and Speiser 1994, Woodbridge and Detrich 1994). In the eastern U.S., nests in hardwood-hemlock (Tsuga canadensis) forests, where black birch (Betula lenta) and American beech (Fagus grandifolia) are preferred nest trees (Speiser and Bosakowski 1987). In the western U.S., characteristically nests in coniferous forests including those dominated by ponderosa pine (Pinus ponderosa; Bright-Smith and Mannan 1994, Reynolds et al. 1992), lodgepole pine (Pinus contorta; Squires and Ruggiero 1996), or in mixed forests dominated by various coniferous species including fir (Abies spp.), Douglas-fir (Pseudotsuga menziesii), cedar (Thuja spp.), hemlock, spruce (Picea spp.), and larch (Larix spp.; Hayward and Escano 1989, Reynolds et al. 1982). Western birds also nest in deciduous forests dominated by aspen (Populus tremuloides), paper birch (Betula papyrifera), or willow (Salix spp.; McGowan 1975, cited in Squires and Reynolds 1997; Swem and Adams 1992, cited in Squires and Reynolds 1997; Younk and Bechard 1994). While generally associated with remote habitat, goshawks in Europe apparently have adapted to human-occupied landscapes and nest near farms and settlements (Palmer 1988). Palmer noted that this species may be undergoing similar adaptation in northeastern U.S.; for example, it is apparently not uncommon in suburbs of Boston (L. Master, pers. comm.). Nests are generally constructed in the largest trees of dense, old or mature stands with high canopy closure (60-95 percent) and sparse groundcover, near the bottom of moderate slopes, and near water or dry openings(Bull and Hohmann 1994, Daw and DeStefano 2001, Hargis et al. 1994, Reynolds et al 1982, Siders and Kennedy 1994, Squires and Ruggiero 1996, Younk and Bechard 1994). Occasionally will nest in relatively open stands (10 percent canopy coverage; Reynolds et al. 1982). Nest height above the ground is significantly correlated with nest-tree height (Kennedy 1988, cited in Squires and Reynolds 1997). Nest height ranges from 2.5-43 meters (Gabrielson and Lincoln 1959, Siders and Kennedy 1994). May use same nest in successive years. May use other hawk nest as base. Nests in arctic tundra and taiga have also been documented in interior Alaska (Olendorff et al. 1989). Forages in both heavily forested and relatively open habitats. In Ponderosa pine forest of Arizona, habitat on sites selected for foraging had higher canopy coverage, greater tree density, and greater density of large trees (greater than 40.5 centimeter DBH), but lower prey abundance than non-foraging sites (Beier and Drennan 1997). In Nevada, foraged in open sagebrush (Artemisia spp.) adjacent to riparian aspen stands (Younk and Bechard 1992, cited in Squires and Reynolds 1997). NON-BREEDING: habitat requirements during winter are poorly understood, especially in the U.S. (Squires and Reynolds 1997). During winter in Sweden, inhabits a fragmented landscape of forests, clearcuts, wetlands and agricultural lands. Whereas non-forested habitats were used in proportion to their availability, large tracts of mature forest were used preferentially (Widen 1989). |
||||||||||
| Food Habits: |
Carnivore: Adult, Immature
|
||||||||||
| Global Food Habits Comments: | Forages during short flights alternated with brief prey searches from perches. Also hunts by flying rapidly along forest edges, across openings, and through dense vegetation. An opportunistic hunter, preys on a wide variety of vertebrates and, occasionally, insects. Prey is taken on the ground, in vegetation, or in the air. Despite their larger size, females do not capture larger or heavier prey than males (Boal and Mannan 1996). Dominant mammalian prey include five species of tree squirrels, four ground squirrels, and lagomorphs. Frequently killed birds include three galliformes, four corvids, six woodpeckers (piciformes) and the American robin (Turdus migratorius; Squires and Reynolds 1997). During the nesting season, the diet can vary with prey availability. For example, as more fledgling passerines become available, they make up a greater portion of the diet (Linden and Wikman 1983, Reynolds and Meslow 1984). Ratio of mammalian prey to avian prey in the diet during the breeding season (in percent): Arizona, 76:24 and 62:38 (Boal and Mannan 1994, Reynolds et al. 1994); Nevada, 67:32 (Younk and Bechard 1994); New York, 39:61 (Grzybowski and Eaton 1976); and Oregon, 42:59 and 45:55 (Bull and Hohmann 1994, Reynolds and Meslow 1984). Nonbreeding season food habits are unknown for North American populations. In Sweden, birds dominate the diet during the nesting season (86 percent of prey), whereas in winter, red squirrels (Sciurus vulgaris) comprise the bulk of the diet (79 percent; Widen 1987, cited in Squires and Reynolds 1997). |
||||||||||
| Global Phenology: |
Diurnal: Adult, Immature
|
||||||||||
| Provincial Phenology: (1st half of month/ 2nd half of month) |
|||||||||||
| Colonial Breeder: | N | ||||||||||
| Length(cm)/width(cm)/Weight(g): | 66/ / 1137 | ||||||||||
| Elevation (m) (min / max): |
Global:
Provincial: |
||||||||||
| Distribution | |||||||||||
| Endemic: | N | ||||||||||
| Global Range Comment: | BREEDING: North America: western and central Alaska to northeastern Manitoba, Labrador, and Newfoundland, south to central California, southern Arizona, eastern foothills of Rockies, central Alberta, southern Manitoba, central Michigan, Pennsylvania, northwestern Connecticut, and in the Appalachians south to West Virginia and Maryland; locally in highlands of Mexico to Jalisco and Guerrero. Eurasia: British Isles, Scandinavia, northern Russia, and northern Siberia south to the Mediterranean, Asia Minor, Iran, the Himalayas, eastern China, and Japan (Squires and Reynolds 1997, AOU 1998). NON-BREEDING: throughout breeding range and irregularly southward (Squires and Reynolds 1997, AOU 1998). In some years there are large flights (irruptions) south beyond the usual wintering range. These excursions are prompted by changing conditions on the northern breeding grounds (Mueller et al. 1977). Recorded occasionally as far south as Arkansas, Louisiana, Kentucky, Alabama, and North Carolina (Adkisson 1990). The three subspecies in the U.S. have the following ranges: 1) ATRICAPILLUS: Alaska, Canada, eastern U.S., and the more northerly mountains of the west. 2) LAINGI: islands off the Canadian Pacific coast. 3) APACHE: southern Arizona, New Mexico, and the mountains of northwestern Mexico (Jones 1979). | ||||||||||
| Authors / Contributors | |||||||||||
| Global Information Author: | PALIS, J., AND G. HAMMERSON; REVISIONS BY D.W. MEHLMAN AND M. KOENEN | ||||||||||
| Last Updated: | Nov 30, 1999 | ||||||||||
| Provincial Information Author: | |||||||||||
| Last Updated: | |||||||||||
| References and Related Literature | |||||||||||
1998. Northern Goshawk. B.C. Minist. Environ., Lands and Parks, Wildl. Branch. 2pp. |
|||||||||||
Campbell, R.W., et al. 1988. Species Notes for Selected Birds, Vol. 2 in A.P. Harcombe, tech. ed. 1988. B.C. Minist. Environ., Lands and Parks, Wildl. Branch. Rep. R-16. 131pp. |
|||||||||||
Campbell, R.W., N.K. Dawe, I. McTaggart-Cowan, J.M. Cooper, G.W. Kaiser, and M.C.E. McNall. 1990b. The Birds of British Columbia Vol. 2: Nonpasserines: Diurnal Birds of Prey through Woodpeckers. Royal British Columbia Museum, Victoria, BC. |
|||||||||||
Cooper, J.M., and V. Stevens. 2000. A Review of the Ecology, Management, and Conservation of the Northern Goshawk in British Columbia. B.C. Minist. Environ., Lands and Parks, Wildl. Branch. Bull. B-101. 30pp. |
|||||||||||
Demarchi, M.W. and M.D. Bently. 2005. Best Management Practices for Raptor Conservation during Urban and Rural Land Development in British Columbia. B.C. Minist. of Environ., Victoria, B.C. MoE BMP Series. |
|||||||||||
Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.
Suggested Citation:
B.C. Conservation Data Centre. 1999. Species Summary: Accipiter gentilis. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Apr 16, 2024).