Eurasian Sparrowhawk - Food, Feeding and Predation

Food, Feeding and Predation

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:

• Short-stay-perch-hunting
• High soaring and stooping
• Contour-hugging in flight
• Still-hunting
• 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 ".

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.