Distribution and habitatEdit
A widespread species throughout the temperate and subtropical parts of the Old World, the Eurasian Sparrowhawk is resident or breeds in an estimated global range of 23,600,000 km2 (9,100,000 miles2) and had an estimated population of 1.5 million birds in 2009. Although global population trends have not been analysed, numbers seem to be stable, so it has been classified as being of Least Concern by BirdLife International. The race granti, with 100 pairs resident on Madeira and 200 pairs on the Canary Islands, is threatened by loss of habitat, egg-collecting and illegal hunting, and is listed on Annex I of the European Commission Birds Directive. It is one of the most common birds of prey in Europe, along with the Common Kestrel and Common Buzzard. The Norwegian and Albanian populations are declining and, in many parts of Europe, Eurasian Sparrowhawks are still shot. However, this low-level persecution has not affected the populations badly. In the UK, the population increased by 108% between 1970–2005, but saw a 1% decline over 1994–2006.
This species is common in most woodland types in its range and also in more open country with scattered trees. Eurasian Sparrowhawks prefer to hunt woodland edges, but migrant birds can be seen in any habitat. The increased proportion of medium-aged stands of trees created by modern forestry techniques have benefited the species, according to a Norwegian study. Unlike its larger relative the Northern Goshawk, it can be seen in gardens and in urban areas and will even breed in city parks.
Eurasian Sparrowhawks from colder regions of northern Europe and Asia migrate south for the winter, some to north Africa (some as far as equatorial east Africa) and India; members of the southern populations are resident or disperse. Juveniles begin their migration earlier than adults and juvenile females move before juvenile males. Analysis of ringing data collected at Heligoland, Germany, found that males move further and more often than females; of migrating birds ringed at Kaliningrad, Russia, the average distance moved before recovery (when the ring is read and the bird's whereabouts reported subsequently) was 1,328 km (825 miles) for males and 927 km (576 miles) for females.
A study of Eurasian Sparrowhawks in southern Scotland found that ringed birds which had been raised on "high grade" territories were recovered in greater proportion than birds which came from "low grade" territories. This suggested that the high grade territories produced young which survived better. The recovery rate also declined with increased elevation of the ground. After the post-fledging period, female birds dispersed greater distances than did males.
Food and feedingEdit
The Eurasian Sparrowhawk is a major predator of smaller woodland birds, though only 10% of its hunting attacks are successful. It hunts by surprise attack, using hedges, tree-belts, copses, orchards and other cover near woodland areas; its choice of habitat is dictated by these requirements. It also makes use of gardens in built-up areas, taking advantage of the prey found there.
It waits, hidden, for birds to come near, then breaks cover and flies out fast and low. A chase may follow, with the hawk even flipping upside-down to grab the victim from below or following it on foot through vegetation. It can "stoop" onto prey from a great height. Ian Newton describes seven modes of hunting used by Eurasian Sparrowhawks:
- High soaring and stooping
- Contour-hugging in flight
- Low quartering
- Hunting by sound
- Hunting on foot
Male Eurasian Sparrowhawks regularly kill birds weighing up to 40 g (1.4 oz) and sometimes up to 120 g (4.2 oz); females can tackle prey up to 500 g (18 oz) or more. The weight of food consumed by adult birds daily is estimated to be 40–50 g (1.4–1.8 oz) for males and 50–70 g (1.8–2.5 oz) for females. During one year, a pair of Eurasian Sparrowhawks could take 2,200 House Sparrows, 600 Common Blackbirds or 110 Wood Pigeons. Species that feed in the open, far from cover, or are conspicuous by their behaviour or coloration, are taken more often by Eurasian Sparrowhawks. For example, Great Tits and House Sparrows are vulnerable to attack. Eurasian Sparrowhawks may account for more than 50% of deaths in certain species, but the extent varies from area to area.
Males tend to take tits, finches, sparrows and buntings; females often take thrushes and starlings. Larger quarry (such as doves and magpies) may not die immediately but succumb during feather plucking and eating. More than 120 bird species have been recorded as prey and individual Eurasian Sparrowhawks may specialise in certain prey. The birds taken are usually adults or fledglings, though chicks in the nest and carrion are sometimes eaten. Small mammals, including bats, are sometimes caught but insects are eaten only very rarely.
Small birds are killed on impact or when squeezed by the Eurasian Sparrowhawk's foot, especially the two long claws. Victims which struggle are "kneaded" by the hawk, using its talons to squeeze and stab. When dealing with large prey species which peck and flap, the hawk's long legs help. It stands on top of its prey to pluck and pull it apart. The feathers are plucked and usually the breast muscles are eaten first. The bones are left, but can be broken using the notch in the bill. Like other birds of prey, Eurasian Sparrowhawks produce pellets containing indigestible parts of their prey. These range from 25 to 35 mm (1.0–1.4 inches) long and 10–18 mm (0.4–0.7 inches) wide and are round at one end and more narrow and pointed at the other. They are usually composed of small feathers, as the larger ones are plucked and not consumed.
During hunting, this species can fly 2–3 km (1.2–1.9 miles) per day. It rises above tree level mostly to display, soar above territory and to make longer journeys. A study in a forested area of Norway found that the mean size of the home ranges was 9.2 km² (3.5 miles²) for males, and 12.3 km² (4.7 miles²) for females, which was larger than studies in Great Britain had found, "probably due to lower land productivity and associated lower densities of prey species in the [Norwegian study area]".
A study looked at the effect on the population of Blue Tits in an area where a pair of Eurasian Sparrowhawks began to breed in 1990. It found that the annual adult survival rate for the tits in that area dropped from 0.485 to 0.376 (the rate in adjacent plots did not change). The size of the breeding population was not changed, but there were fewer non-breeding Blue Tits in the population. In woodland, Eurasian Sparrowhawks account for the deaths of a third of all young Great Tits; the two alarm calls given by Great Tits when mobbing a predator, and when fleeing from a nearby hawk, are within the optimum hearing range of both prey and predator; however, the high-pitched alarm call given when a distant flying Eurasian Sparrowhawk is seen "can only be heard well by the tit." Research carried out in Sussex, England, found that the impact of Eurasian Sparrowhawk predation on Grey Partridges was highest when the partridge density was lowest, while a 10-year study in Scotland found that Eurasian Sparrowhawks did not select the Common Redshanks they predated according to the waders' size or condition, probably because of the hawks' surprise-attack hunting technique.
Another study found that the risk of predation for a bird targeted by a Eurasian Sparrowhawk or Northern Goshawk increased 25-fold if the prey was infected with the blood parasite Leucocytozoon, and birds with avian malaria were 16 times more likely to be killed.
The Eurasian Sparrowhawk breeds in well-grown, extensive areas of woodland, often coniferous or mixed, preferring forest with a structure neither too dense nor too open, to allow a choice of flight paths. The nest can be located in the fork of a tree, often near the trunk and where two or three branches begin, on a horizontal branch in the lower canopy, or near the top of a tall shrub. If available, conifers are preferred. A new nest is built every year, generally close to the nest of the previous year, and sometimes using an old Wood Pigeon nest as a base; the male does most of the work. The structure, made of loose twigs up to 60 cm (2.0 ft) long, has an average diameter of 60 cm (24 in). When the eggs are laid, a lining of fine twigs or bark chippings is added.
During the breeding season, the adult male Eurasian Sparrowhawk loses a small amount of weight while feeding his mate before she lays eggs, and also when the young are large and require more food. The weight of the adult female is highest in May, when laying eggs, and lowest in August after the breeding cycle is complete. A study suggested that the number of eggs and subsequent breeding success are dependent on the female maintaining a high weight while the male is feeding her.
Sexual maturity is reached at between 1–3 years. Most Eurasian Sparrowhawks stay on the same territory for one breeding season, though others keep the same one for up to eight years. A change of mate usually triggers the change in territory. Older birds tend to stay in the same territory; failed breeding attempts make a move more likely. The birds which kept the same territories had higher nest success, though it did not increase between years; females which moved experienced more success the year after changing territory.
The eggs are pale blue with brown spots and each measure 35–46 x 28–35 mm (1.4–1.8 x 1.1–1.4 inches), and weigh about 22.5 g (0.8 oz) of which 8% is shell in a healthy egg. Usually a clutch of four or five eggs is laid. The eggs are generally laid in the morning with an interval of 2–3 days between each egg. If a clutch is lost, up to two further eggs may be laid that are smaller than the earlier eggs.
The altricial, downy chicks hatch after 33 days of incubation. After hatching, the female cares for and feeds the chicks for the first 8–14 days of life, and also during bad weather after that. The male provides food, up to six kills per day in the first week increasing to eight per day in the third and 10 per day in the last week in the nest, by which time the female is also hunting.
By 24–28 days after hatching, the young birds start to perch on branches near the nest and take their first flight. They are fed by their parents for a further 28–30 days, staying close to the nest while growing and practicing flying. The young hawks disperse after their parents stop provisioning them. Though they receive the same amount of food, male chicks (roughly half the size of females) mature more quickly and seem to be ready to leave the nest sooner. In a study in the Forest of Ae, south-west Scotland, it was found that 21% of nestlings over two days old died, with the causes of death being starvation, wet weather, predation and desertion by the parents. The parasite Leucocytozoon toddi can be passed from parent to nestling at the nest, possibly because of the number of birds sharing a small space, thus allowing transmission.
Voice: A rapid repeating 'keck' sound
Similar Species : Goshawk