Eurasian goshawk

The Eurasian goshawk is a species of medium-large bird of prey in the family Accipitridae, a family which also includes other extant diurnal raptors, such as eagles, buzzards and harriers. It was formerly placed in the genus Accipiter. It is a widespread species that inhabits many of the temperate parts of Eurasia. Except in a small portion of southern Asia, it is the only species of "goshawk" in its range and it is thus often referred to, both officially and unofficially, as simply goshawk. It is mainly resident, but birds from colder regions migrate south for the winter. As of 2023, goshawks found in North America are no longer considered to be conspecific, but are now designated as the American goshawk.

Taxonomy

The Eurasian goshawk was formally described in 1758 by the Swedish naturalist Carl Linnaeus in the tenth edition of his Systema Naturae under the binomial name Falco gentilis. It was formerly placed in the genus Accipiter. When molecular phylogenetic studies found that Accipiter was polyphyletic, the genus was split to create monophyletic genera. The genus Astur was resurrected to accommodate the Eurasian goshawk and eight other species that had previously been placed in Accipiter. The resurrected genus had originally been introduced in 1799 by the French naturalist Bernard Germain de Lacépède. The scientific name is Latin; astur means "hawk" and gentilis is "noble" or "gentle" because in the Middle Ages only the nobility were permitted to fly goshawks for falconry.
A molecular genetic study published in 2019 unexpectedly found that the Eurasian goshawk and the American goshawk were not sister species. Instead, the Eurasian goshawk was most closely related to Meyer's goshawk of southeast Asia. The genus Astur is a genus of diurnal raptors. This group of agile, smallish, forest-dwelling hawks has been in existence for possibly tens of millions of years, probably as an adaptation to the explosive numbers of small birds that began to occupy the world's forest in the last few eras. The harriers are the only group of extant diurnal raptors that seem to bear remotely close relation to this genus, whereas buteonines, Old World kites, sea eagles and chanting-goshawks are much more distantly related and all other modern accipitrids are not directly related.
Within the genus Astur, the Eurasian goshawk seems to belong to a superspecies with other larger goshawks from different portions of the world. The American goshawk, found in North America, was previously considered conspecific with Eurasian goshawk, formed the species complex "northern goshawk". Meyer's goshawk, found in the South Pacific, has been posited as the most likely to be the closest related living cousin to the Eurasian goshawk, the somewhat puzzling gap in their respective ranges explained by other Palearctic raptors such as Bonelli's eagles and short-toed eagles that have extant isolated tropical island populations and were probably part of the same southwest Pacific radiation that led to the Meyer's goshawk. A presumably older radiation of this group may have occurred in Africa, where it led to both the Henst's goshawk of Madagascar and the black sparrowhawk of the mainland. While the Henst's goshawk quite resembles the northern goshawks, the black sparrowhawk is superficially described as a "sparrowhawk" due to its relatively much longer and finer legs than those of typical goshawks but overall its size and plumage is much more goshawk than sparrowhawk-like.
Outside of the presumed superspecies, the genus Erythrotriorchis may be part of an Australasian radiation of basal goshawks based largely on their similar morphology to northern goshawks.
The term goshawk comes from the Old English gōsheafoc, "goose-hawk".

Subspecies

The northern goshawk appears to have diversified in northern, central Eurasia and spread both westwards to occupy Europe and, later on, eastwards to spread into North America across the Bering Land Bridge. Fossil remains show that goshawks were present in California by the Pleistocene era. Two non-exclusive processes could have occurred to cause the notably color and size variation of northern goshawks throughout its range: isolation in the past enabled gene combinations to assort as distinct morphs that suited conditions in different geographical areas, followed by a remixing of these genotypes to result in clines, or subtle variation in modern selection pressures led to a diversity of hues and patterns. As a result of the high variation of individual goshawks in plumage characteristics and typical trends in clinal variation and size variations that largely follow Bergmann's rule and Gloger's rule, an excessive number of subspecies have been described for the northern goshawk in the past. In Europe alone, 12 subspecies were described between 1758 and 1990. Most modern authorities agree on listing nine to ten subspecies of northern goshawks from throughout its range.

A. g. gentilis – The nominate race is distributed through most of the species current European range, excluding northern Fennoscandia, northwestern Russia and possibly some of the Mediterranean islands they inhabit. Outside of Europe, this subspecies' range extends south to northwestern Africa and east in Eurasia to Urals, the Caucasus and Asia Minor. It is a typically large subspecies, with high levels of sexual dimorphism. The wing chord of males ranges from and of females from. Body mass is variable, range from in males and from in females. In some cases, the largest adult females from within a population are up to four times heavier than the smallest adult males, although this is exceptional. The highest average weights come from central Fennoscandia, where the sexes weigh on average and, respectively. The lowest come from Spain, where goshawks of this race weigh a median of in males and in females. The nominate race is generally a dark slaty-brown color on its back and wing coverts with a blackish-brown head. The supercilium is thin and the underside is generally creamy with heavy dark barring. On average, in addition to their smaller size, nominate goshawks to the south of the race's distribution have thinner supercilia and broader and denser barring on the underside. An aberrant "isabelline" morph is known mainly from central and eastern Europe, where the goshawk may be a general beige color, but such birds appear to be very rare.
A. g. arrigonii Kleinschmidt, 1903 – This is an island race found on the Mediterranean isles of Sardinia and Corsica. It averages smaller and weaker-footed than goshawks from the nominate race. The wing chord measures in males and in females. This race is typically a more blackish brown above with almost fully black head, while the underside is almost pure white and more heavily overlaid with black barring and conspicuous black shaft-streaks. This subspecies is not listed by all authorities but is often considered valid.
A. g. buteoides Menzbier, 1882 – This race is characteristic of the northern stretches of the western Eurasian range of goshawks, being found as a breeding species from northern Fennoscandia to western Siberia, ranging as far as the Lena River. In the eastern portion of its distribution, many birds may travel south to central Asia to winter. This is a large race, averaging larger than most populations of the nominate race but being about the same size as the big nominate goshawks with which they may overlap and interbreed with in Fennoscandia. The wing chord in males ranges from while that of females ranges from. The body mass of males has been reported from, with an average of, while that of females is reportedly, with an average of. Usually, this race is an altogether paler colour than the nominate, being blue-grey above with a dusky-grey crown and a broad supercilium. The underside is white with rather fine blackish-brown barring. Pale flecking on the feather shafts sometimes result in barred appearance on the contour feathers of the nape, back and upper wing. Many birds from this subspecies also have a tan to pale brown eye color. These two characteristics are sometimes considered typical of this race, but individuals are rather variable. In western Siberia, about 10% of birds of this race are nearly pure white with varied indications of darker streaking.
A. g. albidus Menzbier, 1882 – This race of goshawk is found in northeastern Siberia and Kamchatka. Many birds of this race travel south for the winter to Transbaikalia, northern Mongolia and Ussuriland. This race continues the trend for goshawks to grow mildly larger eastbound in Eurasia and may be the largest known race based on the midpoint of known measurements of this race, although limited sample sizes of measured goshawks shows they broadly overlap in size with A. g. buteoides and large-bodied populations of A. g. gentilis. The wing chord can range from in males and from in females. Known males have scaled from while a small sample of females weighed have had a body mass between. This is easily the palest race of northern goshawk. Many birds are pale grey above with much white about the head and very sparse barring below. However, about half of the goshawks of this race are more or less pure white, with at most only a few remnants of pale caramel flecking about the back or faint brownish markings elsewhere.
A. g. schvedowi Menzbier, 1882 – This race ranges from the Ural Mountains east to the Amurland, Ussuriland, Manchuria, west-central China and sporadically as a breeder into Sakhalin and the Kuril Islands. A. g. schvedowi averages smaller than the other races on the mainland of Eurasia, with seemingly the highest sexual dimorphism of any goshawk race, possibly as an adaptation to prey partitioning in the exceptionally sparse wooded fringes of the desert-like steppe habitat that characterizes this race's range. The wing chord has been found to measure in males and in females. Body mass of 15 males was found to be merely with a mean of, the lowest adult weights known for this species, while two adult females scaled, respectively, or more than twice as much on average. Beyond its smaller size, its wings are reportedly relatively shorter and feet relatively smaller and weaker than other Eurasian races. In color, this race is typically a slate-grey above with a blackish head and is densely marked below with thin brown barring.
A. g. fujiyamae Swann & Hartert, 1923 – Found through the species' range in Japan, from the islands of Hokkaido south to the large island of Honshu, in the latter down to as far south as forests a bit north of Hiroshima. A fairly small subspecies, it may average slightly smaller than A. g. schvedowi linearly, but it is less sexually dimorphic in size and weighs slightly more on average. The wing chord is the smallest known from any race, in males and in females. However, the weights of 22 males ranged from, averaging while 22 females ranged from, averaging. The coloration of this race is not dissimilar from A. g. schvedowi, but is still darker slate above and they tend to have heavier barring below, probably being the darkest race on average, rivaled only by the similar insular race from the opposite side of the Pacific, A. a. laingi.