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The Eurasian (or Northern) Sparrowhawk (Accipiter nisus) is a small bird of prey in the family Accipitridae which includes many other diurnal raptor such as eagles, buzzards, harrier, and other sparrowhawks. Adult male Eurasian Sparrowhawks have bluish grey upperparts and orange-barred underparts; females and juveniles are brown above with brown bars below. The male is up to 25% smaller than the female – one of the largest differences between the sexes in any bird species.

It is a predator which specialises in catching woodland birds, but it can be seen in any habitat and often hunts garden birds in towns and cities. Male Eurasian Sparrowhawks tend to take tits, finches, and sparrows; females catch thrush and starlings, but are capable of killing birds weighing 500 g or more. Eurasian Sparrowhawks breed in suitable woodland of any type.

It is now one of the most common birds of prey in Europe, but the population crashed after the Second World War. Organochlorine insecticides used to treat seeds prior to sowing built up in the bird population and the concentrations in Eurasian Sparrowhawks were enough to kill some outright and incapacitate others; affected birds laid eggs with fragile shells which broke during incubation.

Taxonomy

Within the Accipitridae family, the Sparrowhawk is a member of the large genus Accipiter, consisting of small to medium-sized woodland hawks. Most of the Old World members of the genus are named as sparrowhawks or goshawks.

The Eurasian Sparrowhawk was described by Linnaeus in his 18th century work, Systema Naturae, as Falco nisus. The current scientific name is derived from the Latin accipiter, meaning 'hawk' and nisus, the sparrowhawk. The Eurasian Sparrowhawk forms a superspecies with the Rufous-chested Sparrowhawk of eastern and southern Africa, and possibly the Madagascar Sparrowhawk.

Six subspecies are generally recognised:
  • A. n. nisus, the nominate subspecies, was described by Linnaeus in 1758. It breeds in Europe and west Asia to western Siberiamarker and Iranmarker; northern populations winter south to the Mediterraneanmarker, north-east Africa, Arabia and Pakistanmarker.
  • A. n. nisosimilis was described by Samuel Tickell in 1833. This subspecies breeds in central and eastern Siberia east to Kamchatkamarker and Japanmarker, and south to north Chinamarker; it is wholly migratory, wintering from Pakistanmarker and Indiamarker eastwards through South-East Asia and south China to Koreamarker and Japan, some even reaching Africa.
  • A. n. melaschistos was described by Allan Octavian Hume in 1869. It breeds in mountains from Afghanistanmarker through the Himalayamarker and south Tibet to west China and winters in the plains. It is longer tailed than nisosimilis, is larger, dark slate-coloured on its upperparts, and with more distinct rufous barring on the underparts.
  • A. n. wolterstorffi was described by Otto Kleinschmidt in 1900. It is resident in Sardinia and Corsicamarker, smaller, darker on the upperparts and more barred.
  • A. n. granti was described by Richard Bowdler Sharpe in 1890. It is confined to Madeiramarker and the Canary Islandsmarker, small and dark.
  • A. n. punicus was described by Erlanger in 1897. It is resident in north-west Africa north of the Sahara. It is very similar to nisus, being large and pale.


Description

This bird is a small bird of prey with short, broad wings and a long tail, both adaptations to manoeuvring through trees. Female Eurasian Sparrowhawks can be up to 25 % larger than males – the largest difference between the sexes in any bird species, though Ferguson-Lees and Christie say that "nine other mainly bird-eating Accipiters have the difference even more marked." When females are larger than males, it is known as reverse sexual dimorphism; this is unusual in higher vertebrates but typical in birds of prey.

adult male is 29–34 cm long with a 59–64 cm wingspan, and is slate-grey above (though some are more bluish). The underparts are finely barred reddish, looking plain orange from a distance; his irides are orange-yellow or orange-red. He weighs between 131–180 g. The female is much larger at 35–41 cm in length with a 67–80 cm wingspan, weighing between 186–345 g. She has dark brown, or greyish-brown, upperparts and brown-barred underparts, and bright yellow to orange eyes. The juvenile is warm brown above, with rusty fringes to the upperparts and coarsely barred or spotted brown below, with pale yellow eyes. All have long, yellow legs with black claws. The throat has dark streaks and lacks a mesial stripe.

In Great Britainmarker, Eurasian Sparrowhawks living further north are bigger than their more southerly counterparts, with wing length (the most reliable indicator of body size) increasing by an average of 0.86 mm in males, and 0.75 mm in females, for each degree further north.

Old Englishmarker folk names for this species include Blue Hawk, referring to the adult male's colouration, as well as Spar Hawk, Spur Hawk and Stone Falcon.

Identification

The flight is a characteristic "flap-flap-glide", with the glide creating an undulating pattern. This species is similar in size to the Levant Sparrowhawk but bigger than the Shikra; the male is only slightly bigger than the Merlin. Because of the overlap in sizes, the female can be confused with the similarly-sized male Northern Goshawk, but lacks the bulk of that species. Eurasian Sparrowhawks are smaller, more slender and have shorter wings, a square-ended tail and fly with faster wingbeats. A confusion species in Chinamarker is the Besra, though A. n. melaschistos is considerably larger.

Lifespan and demography

The oldest recorded ringed Eurasian Sparrowhawk in Europe was a bird trapped in Denmarkmarker which was 20 years, 3 months old. The typical lifespan is three years. Data analysis by the British Trust for Ornithology shows that the proportion of juveniles surviving their first year of life is 39 %; adult survival from one year to the next is 65.7 %. Birds in their first year of life weigh less than adults, and are especially light in the two months after reaching independence. There is probably high mortality, especially for young males, during this time.

A study of female Eurasian Sparrowhawks found "strong evidence" that their rate of survival increased for the first three years of life and declined for the last five to six years. Senescence (ageing) was the cause of the decline as the birds became older.

Distribution and habitat

A widespread species throughout the temperate and subtropical parts of the Old World, the Eurasian Sparrowhawk has an estimated global range of between 100,000–1,000,000 km2 and an estimated population of 1 million to 10 million birds; it is one of the most common birds of prey in Europe, along with the Common Kestrel and Common Buzzard. 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 Madeiramarker and 200 pairs on the Canary Islandsmarker, is threatened by loss of habitat, egg-collecting and illegal hunting, and is listed on Annex I of the European Commissionmarker Birds Directive. The Norwegianmarker and Albanianmarker populations are declining and, in many parts of Europe, Eurasian Sparrowhawks are still shot. However, such 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.

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, found a Norwegianmarker 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 Indiamarker; 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 Heligolandmarker, Germanymarker, found that males move further and more often than females; of migrating birds ringed at Kaliningradmarker, Russiamarker, the average distance moved before recovery (when the ring is read and the bird's whereabouts reported subsequently) was 1,328 km for males and 927 km for females.

A study of Eurasian Sparrowhawks in southern Scotlandmarker 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 feeding

Male on kill
Eurasian Sparrowhawk is a main predator of smaller woodland birds. It hunts by surprise attack, using hedges, tree-belts, copses, orchards and other cover near woodland areas; their choice of habitat is dictated by these requirements. 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. Sparrowhawks do not hesitate to make use of gardens in built-up areas and take advantage of the prey found there. Only 10% of Eurasian Sparrowhawk attacks result in prey being caught.

Male Sparrowhawks regularly kill birds weighing up to 40 g and sometimes up to 120 g; females can tackle prey up to 500 g or more. The weight of food consumed by adult birds daily is estimated to be 40–50 g for males and 50–70 g for females. During one year, a pair of sparrowhawks could take 2,200 House Sparrows, 600 Common Blackbirds or 110 Woodpigeons. In woodland, Eurasian Sparrowhawks account for the deaths of a third of all young Great Tits. The species taken are those whose behaviour makes them easy targets.

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 Sparrowhawks may specialise in certain prey. The birds taken are usually adults or fledglings, though chicks in the nest and carrion are sometimes eaten as well as small mammals, including bats, are sometimes caught but insects are eaten only very rarely.

When eating, Eurasian Sparrowhawks pluck the feathers and usually eat the breast muscles first. The bones are left, but can be broken using the notch in the bill. Like other birds of prey, Sparrowhawks produce pellets containing indigestible parts of their prey. These range from 25 to 35 mm long and 10–18 mm 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 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 Norwaymarker found that the mean size of the home ranges was 9.2 km² for males, and 12.3 km² for females, which was larger than studies in Great Britainmarker 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. 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 sparrowhawk is seen "can only be heard well by the tit." 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.

Breeding

The Eurasian Sparrowhawk breeds in well-grown, extensive areas of woodland, often coniferous or mixed, preferring that with structure neither too dense or 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, with the male doing most of the work, close to that of the previous year and sometimes using an old Woodpigeon nest as a base. The structure of loose twigs (up to 60 cm long) has an average diameter of 60 cm. 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.

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.

Eggs

Illustration of an egg.
The background colour of the eggs changes from light blue to white on storage in collections.
The eggs are pale blue with brown spots and each measure 35–46 x 28–35 mm, and weigh about 22.5 g 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.

Young

The altricial, downy chicks hatch after 33 days of incubation and fledge after between 27 and 31 days. 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.

At between 24–28 days after hatching, the young birds start to perch on branches near the nest, though they remain dependent on their parents for 28–30 days after fledging. 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 Aemarker, south-west Scotlandmarker, 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.

Relationship with humans

Pollutants

In flight as seen from below
The Eurasian Sparrowhawk population in Europe crashed in the second half of the 20th Century. The decline coincided with the introduction of cyclodiene insecticidesaldrin, dieldrin and heptachlor – used as seed dressings in agriculture in 1956. The chemicals accumulated in the bodies of grain-eating birds and had two effects on top predators like the Eurasian Sparrowhawk and Peregrine Falcon: the shells of eggs they laid were too thin, causing them to break during incubation; and birds were poisoned by lethal concentrations of the insecticides. Sub-lethal effects of these substances include irritability, convulsions and disorientation.

In the United Kingdommarker, for example, the species almost became extinct in East Angliamarker, where the chemicals were most widely used; in western and northern parts of the country, where the pesticides were not used, there were no declines. The Royal Society for the Protection of Birds bought its Coombes Valleymarker nature reserve in Staffordshire because it was the only Eurasian Sparrowhawk breeding site left in the English Midlandsmarker.

In the UK, the use of cyclodienes as seed dressings for autumn-sown cereals was banned in 1975 and the levels of the chemicals present in the bird population began to fall. The population has largely recovered to pre-decline levels, with an increase seen in many areas, for example northern Europe. In Swedenmarker, the population also decreased drastically from the 1950s, but recovered again once organochlorines were banned in the 1970s.

In the UK, the failure rate at the egg stage had decreased from 17 % to 6 % by the year 2000, and the population had stabilised after reaching a peak in the 1990s. A study of the eggs of Dutchmarker sparrowhawks found that contamination with Dichlorodiphenyldichloroethylene (DDE) – a "very persistent compound" produced when DDT breaks down – continued into the 1980s, though a decline in the number of clutches with broken eggs during the 1970s suggested decreasing levels of the chemical.

Body tissue samples from Eurasian Sparrowhawks are still analysed as part of the Predatory Bird Monitoring Scheme conducted by the UK government's Joint Nature Conservation Committee. Although the average liver concentrations of polychlorinated biphenyls (PCBs) in sparrowhawks were lower in birds that died in 2005 compared to those that died in 2004, there was not a significant or consistent decline in residues between 2000–2005.

Conflict with human interests

The Eurasian Sparrowhawk's adaptation for feeding on birds has brought it into conflict with humans; in the 19th century it was described as "the great enemy of small quadrupeds and birds, and often very destructive to young chicks in poultry-yards in the breeding season" and "very destructive to partridges."

Research carried out in Sussex, England, found that the impact of Sparrowhawk predation on Grey Partridges was highest when the partridge density was lowest (Watson, 2004).

century parish records for Aldworth, Berkshiremarker, in southern England, show that payments were made for 106 sparrowhawks' heads, at the same time as efforts were being made to control the numbers of sparrows. The species suffered heavy persecution by 18th century European landowners and gamekeepers, but withstood attempts to eradicate it. For example, on the estate at Sandringhammarker in Norfolk, 1,645 'hawks' were killed between 1938 and 1950, with 1,115 taken between 1919–1926 at Langwell and Sandside in Caithnessmarker, Scotlandmarker.

The population was able to quickly replace lost birds – there is a high proportion of non-breeding, non-territorial birds able to fill vacant territories. The habitat conserved with gamebirds in mind also suited this species and its prey; gamekeepers' more successful efforts to wipe out the Northern Goshawk and Pine Marten – predators of the Eurasian Sparrowhawk – may have benefited it. The population increased markedly when this pressure was relaxed, for example during the First and Second World Wars.

In the United Kingdom, research into the effect of predators on bird populations has been "a contentious issue," with "perceived conflict between the interests of nature conservationists and those involved in game shooting." Declines in the populations of some British songbirds since the 1960s have coincided with considerable changes in agricultural practices and also large increases in the numbers of Eurasian Sparrowhawks and European Magpies. When the Eurasian Sparrowhawk population declined because of organochlorine use, there was no great increase in the populations of songbirds. In a 1949–1979 study of 13 passerine species breeding in a 16-hectare oakwood at Bookham Commonsmarker, Surreymarker, England, none was present in significantly greater numbers when sparrowhawks were absent from the wood.

Many studies, mostly short-term, failed to find an effect on songbird populations caused by predatory birds such as Eurasian Sparrowhawks. But analysis of long-term, large-scale national data from the UK's Common Bird Census demonstrated that the declines in farmland songbird populations since the 1960s are unlikely to have been caused by increased predation by sparrowhawks and magpies. The results of the study indicated that patterns of year-to-year songbird population change were the same at different sites, whether the predators were present or not.

Racing pigeon owners in Great Britain have said for many years that Eurasian Sparrowhawks and Peregrine Falcons "cause serious and escalating losses" of pigeons and some have called for Eurasian Sparrowhawks and Peregrine Falcons to be killed or removed from areas surrounding homing pigeon lofts.

In Scotland, a two-year study published in 2004, and funded by Scottish Natural Heritage and the Scottish Homing Union (SHU), found there was "no evidence that birds of prey cause major losses of racing pigeons at lofts or during races." It reported that 56 % of racing pigeon were lost each year but that the proportion taken by Eurasian Sparrowhawks – "often blamed for major losses" – was less than 1 %, with at least 2 % taken by Peregrine Falcons. The study was carried out by the Central Science Laboratory; researchers worked with SHU members who provided data, information on pigeon rings found at Peregrine Falcon nests and pigeon carcasses.

In February 2009, the Scottish Government began a trial relocation of Eurasian Sparrowhawks from around racing pigeon lofts in Glasgowmarker, Edinburghmarker, Kilmarnockmarker, Stirlingmarker and Dumfriesmarker. The trial, which cost £25,000, was supported by the Scottish Homing Union, representing the country's 3,500 pigeon fanciers. The experiment was originally scheduled for early in 2008 but was postponed because it would have impinged on the birds' breeding season. The plan was criticised by the government's own ecological adviser, Dr Ian Bainbridge, the government body Scottish Natural Heritage and organisations including the Royal Society for the Protection of Birds and the Scottish Society for the Prevention of Cruelty to Animals.

Falconry

Eurasian Sparrowhawk has been used in falconry for centuries and was favoured by Emperor Akbar the Great (1542–1605) of the Mughal Empire. There is a tradition of using migrant sparrowhawks to catch Common Quail in Tunisiamarker and Georgiamarker, where there are 500 registered bazieri (sparrowhawkers) and a monument to bazieri in the city of Potimarker. Sparrowhawks are also popular in Irelandmarker.

In England in the 17th century, the sparrowhawk was used by priests, reflecting their lowly status; whereas in the Middle Ages, they were favoured by ladies of noble and royal status because of their small size. The falconer's name for a male sparrowhawk is a "musket"; this is derived from the Latin word musca, meaning 'a fly', via the Old French word moschet.

"An austringer [falconer] undertaking to train a sparrowhawk should be in doubt that he is taking on one of the most difficult hawks available." A female Eurasian Sparrowhawk is considered a bad choice for a novice and the male is very difficult and demanding, even for an experienced handler. They have been described as "hysterical little hawks" but are also praised as courageous and providing "sport of the highest quality." Philip Glasier describes Eurasian Sparrowhawks as "in many ways superior to hunting with a larger short-wing [hawk]" and "extremely hard to tame." They are best suited for small quarry such as Common Starlings and Common Blackbirds but are also capable of taking Common Teal, Eurasian Magpies, pheasants and partridges. An 19th century author remarked that this species was "the best of all hawks for landrails," now known as Corn Crakes.

In culture

Good sooth my bones, wheneas they hear thy name

Quail as birds quailed when Nisus o'er them flew



References

  1. Retrieved 28 November 2009
  2. Retrieved 26 February 2009
  3. Lusher, Adam and Welbourne, Peter.
  4. Edwards, Rob.
  5. Edwards, Rob.
  6. Falcons and hawks in British Falconry. British Falconers Club. 2005. Retrieved 9 July 2009


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