Male sparrowhawk © Jill Pakenham/BTO
1 Bouncing back
While the sparrowhawk is now one of the most widespread birds of prey in Britain, until a few decades ago it was more or less extinct in many eastern counties. This was partly due to persecution, but also due to pesticide use in agriculture. As well as killing individuals, the accumulation of harmful compounds thinned their eggs, which increased breakages during incubation. This led to a population decline.
2 Conflict with twitchers
Since bouncing back, sparrowhawks have spread into many suburban parks and gardens. Due to their efficiency at catching small birds, they have come into conflict with some garden birdwatchers, and have been blamed for the widespread decline of many songbirds. However there is little scientific evidence that supports this and other factors, such as habitat degradation, are more likely to be causing the declines.
3 Devoted parents
Sparrowhawks prefer to nest in dense woodland and breed between May and July. Until the chicks are old enough to be left alone, the male does all the hunting, feeding the young and the female. Then both parents hunt for the juveniles, and continue to do so up to a month after the young have left the nest.
4 Ambush hunters
Sparrowhawks rely on the element of surprise and as such will often follow a regular route to get close to potential prey, which in gardens means using the cover of a hedge or shed. By moving feeding stations around your garden and keeping them close to cover, you can reduce the chance of a sparrowhawk attack.
A sparrowhawk’s eye colour changes with age. © Jill Pakenham/BTO
5 Big is beautiful
Female sparrowhawks are about twice the weight of males, one of the largest differences between sexes in any bird of prey. While this enables her to carry extra body reserves needed for reproduction, and to go for several days without a meal, it does mean she is a less agile hunter than the male.
6 All in the eyes
The colour of a sparrowhawk’s eye depends on its age and gender. Typically younger birds have greenish-yellow eyes which become brighter yellow within the first couple of years of their life. In some older males, the eye colour can become orange or, occasionally, red.
Sparrowhawks are small, broad-winged raptors with long tails and long, thin yellow legs. Adult males have slate-grey upperparts and fine rufous barring underneath. Females have brownish-grey upperparts and less rufous barring than the male. They have a more prominent white line above the eye.
The British Trust of Ornithology (BTO) works in partnership with over 40,000 volunteer birdwatchers to chart the fortunes of UK birds.
Among the surveys that we coordinate is our popular Garden BirdWatch, the largest year-round survey of garden birds in the world.
Each month we highlight a bird for you to look out for in your garden.
For more information about Garden BirdWatch or to speak to the Garden Ecology Team please email email@example.com
Read previous BTO Garden Bird of the Month blogs.