Sparrowhawk
Accipter nisus
Accipter hawks are short-winged birds of prey, perfectly designed for rapid manoeuvring amongst the heavily vegetated areas in woodlands which are their main habitat. Many birds of prey exhibit sexual dimorphism – differing sizes of male and female – the largest difference of all is Sparrowhawk, where females can be 25% larger than the males. It is believed that this ensures both birds can hunt different prey, and not come into conflict over limited prey, especially in winter. Particularly in the early stages of pairing up in the spring, males must be cautious, as they are well within the range of female prey and it is not unknown for males to be taken, although they are more agile than the heavier females.
Although well-known as a visitor to garden bird feeding stations, only 10% of Sparrowhawk hunting flights are successful. They use a variety of hunting techniques, but perhaps the most characteristic one is to fly low on the far side of a hedge or fence, before flipping over the top and surprising the birds on the other side. Some small birds, such as Blue Tit have a specific warning call they give if they spot a Sparrowhawk. Other birds, including other species, can understand this call and also seek cover. The call will also alert us to the near-by presence of a Sparrowhawk!
The colouration, size and even flying style of Sparrowhawks is very similar to that of Cuckoo, and it is believed that Cuckoos have evolved this, as other small birds see them as predators, rising off the nest to ‘mob’ a potential predator and, in the process, revealing the location of their nests which the female Cuckoo will be looking for to lay her eggs in.
Males are blue-grey above with fine orange barring beneath, females are grey-brown and white. Young birds are browner with coarsely barred chests. The only likely confusion species is Goshawk.
VITAL STATISTICS
Size: Average 33cm (male) 37cm (female); wingspan 62cm (male), 74cm (female). Females (260g) much heavier than males (150g).
Status. Resident breeder and passage/winter visitor.
Population size. 33,000 pairs.
Conservation status: GREEN (Least concern).
Lifespan: Typical lifespan of 4 years, with an adult year-to-year survival rate of 69%. First year survival is just 34%. The oldest known wild bird was just over 17 years old (ringing recovery).
Nesting: Sparrowhawks nest in messy stick nests in trees, often deep in forested areas, although they will nest in parks, large gardens and small wooded patches. They are quite shy whilst breeding, but when they have well-grown chicks in the nest, their incessant begging can give the location away.
Number of eggs: 4-5
Incubation: 33 days
Fledging time: 27-31 days
Sparrowhawks are single-brooded and will breed in the year after hatching.
Habitat and Distribution: One of our most frequent and familiar birds of prey, Sparrowhawks are birds of woodland, but they have adapted to life in our mosaic habitats, including gardens, farmland and even urban areas. Sparrowhawks occur over the whole of the UK, although they are scarcer in the north and west. Numbers crashed in the latter part of the 20th Century, due to pesticides used as seed dressings accumulating in their bodies through eating contaminated prey. This poisoning caused thinned egg shells leading to breakage in the nest. From the 1970s, after these chemicals were banned the population slowly recovered, leading to stability in the 1990s. Numbers have dropped slightly in the last decade.
Movements: Most British Sparrowhawks remain rather sedentary, although young birds can move significant distances in the search for a territory. Birds from northern Europe migrate here for the winter and can often be encountered in the east.
Feeding: Reliant on small birds, which are often caught in a twisting, agile flight. Despite their name sparrows are not particularly sought, but any small bird is a potential target. In gardens tits are frequent prey, and males will frequently hunt birds up to the size of a Blackbird. Females tend to target larger prey, and commonly tackle Collared Doves and Wood Pigeons. Prey is usually dispatched with their very long toes and talons, but distressingly plucking can often begin before the prey is dead. Larger prey, such as Magpies, is often drowned.