Adult The upperparts of this species are dark steely-grey to blue-grey with darker slate-grey flight feathers. The flight feathers show faint dark banding in flight, at least on the primaries. The relatively long, broad, round-tipped tail is dark grey above and paler grey below, with 3-5 dark slate-grey bands and a narrow whitish tip. The underparts are whitish with dense, fine, dark grey barring on the breast, belly, sides, and flanks (often nearly obscuring the white background) and variable amounts of fine blackish streaking; the bushy undertail coverts are white. The underwing coverts are densely barred with dark grey and are similar in colour to the underparts. The crown and nape are dark slate-grey to blackish, and are separated from the blackish ear coverts by a bold white supercilium. The throat and cheeks are whitish with very fine blackish or dark grey streaking. Females are slightly browner than males, and have coarser and heavier dark barring and streaking on the underparts. The iris is red (orange in younger adults), the bill is dark grey with a yellow cere, and the legs and feet are yellow.
Juvenile This plumage is held for approximately one year and is usually lost during the second summer of life. In this plumage, the upperparts are brownish with paler brown or buffy edges to the feathers and, often irregular buffy patches on the scapulars and a buffy band across the upperwing coverts. The flight feathers are grey-brown with darker grey barring and narrow buffy or whitish tips. The tail is similar in pattern to that of the adult, but is browner and often shows very narrow whitish edges, or “highlights,” to the wavy dark bands. The underparts are whitish to buffy with variable (often heavy) dark brown streaking across the breast, belly, sides, and flanks and often some coarse, dark brown barring on the sides; the undertail coverts are usually whitish with dark brown streaking. The crown, nape, and ear coverts are buffy-brown with narrow dark brown streaking and a bold, white supercilium. The throat and cheeks are whitish or buffy-white with variable amounts of narrow dark brown streaking (heaviest on the malar). The iris is yellow, but bare part colouration (bill, legs, feet) is otherwise similar to the adult.
Measurements Total Length: 53-66 cm (f >m) Mass: 693-1,036 g (f >m)
Source: Squires and Reynolds (1997); Taylor (2006)
This large Accipiter can be confused with large female Cooper’s Hawks or even species of Buteo. From Cooper’s Hawk, the Northern Goshawk is a noticeably larger, bulkier bird with relatively longer, pointier wings and broader tail. There is no overlap in size between even the largest female Cooper’s Hawks and the smallest male Northern Goshawks, but this requires experience with both species in order to determine accurately in the field. In these regards, it approaches the genus Buteo in structure. Beyond size and structure, adult Northern Goshawks are easily distinguished from adult Cooper’s Hawks by a combination of their densely grey-barred underparts (densely rufous-barred in Cooper’s Hawk) and bold white eyebrow. Juveniles are more difficult to distinguish from Cooper’s Hawk based on plumage, but still tend to show a much bolder white eyebrow stripe (this is, at best, only weakly evident in juvenile Cooper’s Hawk).
Based on structure, juvenile Northern Goshawks could potentially be confused with juvenile Buteos, particularly juvenile Red-tailed Hawk, but the longer tail and relatively shorter wings of the Northern Goshawk are easily discerned and should be sufficient for identification even without noting the numerous plumage differences between the two species.
The most frequently heard call is the alarm call, which consists of a rapid series of 10-20 ki-ki-ki-ki or kak-kak-kak-kak notes; this call sometimes begins with a drawn-out kree-ya call and sometimes ends with a single kuk note. Males produce higher-pitched alarm calls than the females. Both sexes also produces a plaintive, wailing kree-yah contact call that serves a variety of functions. Single kek, guk, or chuuk notes are produced by the male as he returns to the nest with prey.
Courtship This species engages in an elaborate courtship display during nest bulding and territory establishment, known as the “Sky-Dance Display.” During this display, the male either dives at the female from soaring flight well above the canopy or pursues her in rapid flight below the canopy. Following this initiation, both sexes then fly with deep, slow wingbeats about 1 m apart, often with the white undertail coverts flared. This display can be either silent or accompanied by loud vocalizations.
Nest Nest building begins early, usually between February and April, and tends to occur during the same period as the courtship process. Pairs often reuse nests from previous seasons but usually repair or add to them for the season at hand; nests of other species are also occasionally re-used. Usually places the nest in a coniferous tree in western North America, although a variety of deciduous trees (birch, aspen, cottonwood, etc.) are used as well, particularly in areas of extensive deciduous forests (e.g., Peace River area). The Northern Goshawk typically chooses the largest trees of a stand in which to place its nest, usually placing it on the lower 1/3 of the tree or just below the canopy. Nest heights range from 6-18 m, although most are between 9 and 12 m. Occasionally selects dead trees for nesting. The nest is a large (up to 120 cm across and 36 cm high), bulky, untidy, bowl-shaped structure of coarse twigs and sticks that is placed in a main crotch of a tree, in forks of branches, on main branches against the trunk, or on the broken top of a tree. It is lined with strips of bark, green boughs, and small twigs.
Eggs Clutches of (1) 2-4 (5) eggs are laid between early April and early June, with the bulk of egg laying probably occurring in late April and early May. The incubation period is 28-38 days, but rarely exceeds 32 days; only the female incubates the eggs. The last eggs in B.C. have usually hatched by early or mid-July. The non-glossy, rough-textured eggs are pale bluish initially but quickly fade to dingy-white and are usually unmarked (occasionally sparsely blotched). This species is single-brooded.
Young Following hatching, the young remain in the nest for 34-42 days (slightly longer for females) before fledging. The nestlings are semi-altricial and downy, with short, thick, silky white down down when very young and woollier, grey-tinged down when older. The young are brooded and tended solely by the female, although the male brings food to the nest to feed both the female and young during the first 1-2 weeks after hatching. Dates for nestlings in B.C. range from late May to mid-August. The young to continue to rely on the parents for food for several weeks after fledging.
Source: Campbell et al. (1990b); Baicich and Harrison (1997); Squires and Reynolds (1997)
The Northern Goshawk is typical of the genus Accipiter in that it specializes in taking avian prey, although it is not completely restricted to such a diet and takes a variety of other foods (especially small mammals). Medium-sized birds such as grouse, jays, crows, woodpeckers (including Pileated Woodpeckers), pigeons, and various passerines (especially American Robins) are the dominant avian prey taken. During nesting, this species includes a high percentage of fledgling passerines in its diet. Small mammals such as hares, rabbits, squirrels, and ground-squirrels are also regularly taken and are particularly important in the diet of northern populations of Northern Goshawks. Other minor sources of food include reptiles, large insects, and carrion.
During bouts of hunting, the Northern Goshawk usually alternates between short, low flights and sit-and-wait hunting from a perch, and sometimes cruise rapidly along forest edges or across openings in order to surprise prey. The flight style is much more powerful than the other two species of Accipiter in B.C., especially when it is in pursuit of prey. This species also hunts prey on foot, often using the topography of the ground or vegetation for concealment, and will enter water in pursuit of aquatic species. More so than most other hawks, the Northern Goshawk seems particularly willing to recklessly crash into dense vegetation in pursuit of prey.
Source: Squires and Reynolds (1997)
The Northern Goshawk is largely a species of remote, often mountainous forested regions throughout its range. It is found in all forest types, from coniferous and mixed forests to pure deciduous forests (e.g., aspen woodlands, riparian strips, etc.), and tends to be associated with mature or old growth stands when they are available, at least during the breeding season. Nesting sites are commonly typified by dense canopy closure, especially where the canopy closure exceeds 70%, and it often hunts for prey near permanent sources of water such as along lakeshores, seacoasts, rivers, creeks, lagoons, and estuaries. It also regularly hunts along the edges of clearings, roads, or forest openings, and tends to nest in relative proximity to such habitats. Wintering birds occur in a wider diversity of habitats than during the breeding season, including parks, agricultural areas, airports, orchards, wetlands, and occasionally residential areas, although they are also found in forested habitats that are similar to those that are used during the breeding season. Migrating birds are often encountered along alpine ridges and mountain tops where they take advantage of the thermals and updrafts that occur there.
Source: Campbell et al. (1990b); Squires and Reynolds (1997)
Breeds across northern North America, from Alaska east to Labrador, ranging south as far as Pennsylvania, northern Michigan, and northern Wisconsin in the east. Western populations occur widely at higher elevations south through the western United Statesto eastern California, Arizona, and New Mexico, and isolated resident populations also occur in the highlands of western Mexico. Generally resident throughout its range, although some birds wander south in the winter (occasionally reaching as far as the Gulf of Mexico, but rarely south of the Midwestern U.S.). Also widespread across northern Eurasia.
Breeding Rare to uncommon breeder throughout most of British Columbia, being particularly scarce in the arid basins of the south-central interior and the low elevations of the Georgia Depression. It is most common in mountainous and boreal terrain, and is less common on Vancouver Island and the Queen Charlotte Islands than it is on the mainland of B.C.
Winter Uncommon in winter throughout B.C. east of the Coast-Cascade Mountains but rare along the coast, including Vancouver Island and the Queen Charlotte Islands.
Migration Although it is essentially resident in B.C., there is some migratory movement of this species throughout the province. Much of the movement is likely altitudinal, with individuals moving to lower elevations for the winter. Nonetheless, there is some indication that a minimal northward-bound movement in the spring occurs in late February and March (coast) or in April (interior), while a slightly larger southward-bound fall movement occurs from September through December, peaking in October (immatures) or November (adults). Populations of the Northern Goshawk are cyclical, closely following population cycles of its prey, and most migratory movements in B.C. appear to be correlated with peaks in this cycle and the corresponding crashes in the prey populations.
Source: Campbell et al. (1990b)
Population and Conservation Status
Populations in North America appear to be generally stable, but there are large year-to-year fluctuations that confound accurate assessment of trends. Northern Goshawks are susceptible to disturbance by forestry operations during the breeding season, and as such they require special consideration and monitoring during logging activities in B.C. The laingi subspecies of Vancouver Island and the Queen Charlotte Islands is considered Threatened by COSEWIC (Committee on the Status of Endangered Wildlife in Canada) and Endangered (Red-listed) by the British Columbia CDC (Conservation Data Centre), based largely on its low population density and restricted range.
Source: Squires and Reynolds (1997)
Ten subspecies of A.gentilis are recognized, of which three are found in North America. Two subspecies occur in British Columbia. The subspecies are generally weakly defined and clinal, and in many cases are not readily identifiable in the field outside of their known breeding ranges.
The two subspecies in B.C. are as follows:
Accipiter gentilis atricapillus (Wilson) This is the widespread subspecies in B.C., occupying the entire mainland of the province except possibly for some areas of the northern mainland coast. It is slightly paler and averages slightly larger than laingi.
Accipiter gentilis laingi (Taverner) Also known as the “Queen Charlotte Goshawk,” this insular subspecies breeds on Vancouver Island and the Queen Charlotte Islands as well as locally on the northern mainland coast and associated islands north through the Alaskan Panhandle. It averages darker than atricapillus, with the black of the crown extending onto the upperparts. The underparts are noticeably darker sooty-grey than atricapillus. It also averages slightly smaller than atricapillus.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2019. E-Fauna BC:
Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab
for Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
21/10/2019 2:42:46 AM]
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