Northern Goshawk - Description

Description

The Northern Goshawk is the largest member of the genus Accipiter. It is a raptor with short, broad wings and a long tail, both adaptations to manoeuvring through trees in the forests it lives and nests in. Across most of the species's range, it is blue-grey above and barred grey or white below, but Asian subspecies in particular range from nearly white overall to nearly black above. The juvenile is brown above and barred brown below. Juveniles and adults have a barred tail, with dark brown or black barring. Adults always have a white eye stripe. In North America, juveniles have pale-yellow eyes, and adults develop dark red eyes usually after their second year, although nutrition and genetics may affect eye color as well. In Europe and Asia, juveniles also have pale-yellow eyes, however adults develop orange-colored eyes.

The Northern Goshawk, like all accipiters, exhibits sexual dimorphism, where females are significantly larger than males. Males, being the smaller sex by around 10–25%, are 46–57 cm (18–22 in) long and have a 89–105 cm (35–41 in) wingspan. The female is much larger, 58–69 cm (23–27 in) long with a 108–127 cm (43–50 in) wingspan. Males average around 780 g (1.7 lb), with a range of 500 to 1,200 g (1.1 to 2.6 lb). The female can be more than twice as heavy, averaging 1,220 g (2.7 lb) with a range of 820 to 2,200 g (1.8 to 4.9 lb). Among standard measurements, the wing chord is 28.6–39 cm (11.3–15 in), the tail is 20–28 cm (7.9–11 in), the culmen is 2–2.6 cm (0.79–1.0 in) and the tarsus is 6.8–9 cm (2.7–3.5 in). In Eurasia, the species follows Bergmann's rule, specimens from the northern races generally are larger-bodied than goshawks near the southern reaches of the species range. Going on wing chord length, A. g. apache, found in Mexico to Arizona and New Mexico is the largest subspecies at an average of 36.8 cm (14.5 in) and is larger than more Northern subspecies in that continent, thus running contrary to Bergmann's rule. A. g. fujiyamae of Japan is the smallest race, at 30.9 cm (12.2 in) in wing chord length. In Europe, goshawks from Finland or of Finnish ancestry are prized as bigger than other goshawks.

The flight is a characteristic "flap flap, glide", but is sometimes seen soaring in migration, and is capable of considerable, sustained, horizontal speed in pursuit of prey with speeds of 38 mph (61 km/h) reported. Goshawks are sometimes confused with gyrfalcons especially when observed in high speed pursuit, with their wingtips drawn backward in a falcon-like profile.

In Eurasia, the male is sometimes confused with a female Sparrowhawk, but is larger, much bulkier and has relatively longer wings. In North America, juveniles are sometimes confused with the smaller Cooper's Hawk, however the juvenile goshawk displays a heavier, vertical streaking pattern on their chest and abdomen and sometimes appears to have a shorter tail due to its much larger and broader body. Although there appears to be a size overlap between small male goshawks and large female Cooper's Hawks, morphometric measurements (wing and tail length) of both species demonstrate no such overlap, although weight overlap can occur due to variation in seasonal condition and food intake at time of weighing. In North America, the Sharp-shinned Hawk is markedly smaller.