Breeding and nesting habits
Sparrowhawks require woodland, or at least a small clump of trees, for nesting.
Their territories are well spaced - pairs do not tolerate another nest close by. The distance between each nest varies ranges from 0.5 km to 2.1 km. This is determined by the local food supply - the better the food supply, the smaller each territory will be.
The nest is usually built in lower parts of the canopy, close to the trunk of a tree and usually concealed from view. It is a sturdy platform of twigs, lined with bark flakes. A central 'cup' prevents the eggs from rolling out. Nest building can take several weeks and is often completed long before the eggs are laid.
Sparrowhawk chicks hatch when there are plenty of fledgling small birds around, in the same way that blue tits synchronise their breeding to coincide with the peak availability of caterpillars.
Three to six eggs are laid at two-day intervals during May. Incubation lasts for 32-35 days and the eggs hatch in succession over two or more days, so that the chicks are different sizes. The female helps the chicks to break out of their shell. They are covered in pure white short down, and their eyes are already partly open when they hatch.
Succesive hatching is an adaptation to cope with an unpredictable food supply. If food is short, the youngest chick will die and reduce the brood to a manageable size.
The chicks are very vulnerable in the first week of their lives as they cannot control their body temperature. They are therefore brooded almost constantly at this time, and then progressively less until they are able to do so.
The female has sole care of the eggs and young, while the males' role (from egg-laying through to fledging) is to provide all food required by the female and the chicks. The female will hunt as the chicks get older, but only if the male is unable to catch adequate food by himself.
Flying the nest
The chicks are ready to fledge when they are around four weeks old. Initially, they leave the nest for brief periods, but continue to return to it to be fed - and to sleep at night.
Over time, they venture farther and spend longer periods away from the nest. Once their feathers are fully grown, they begin to chase other birds and practise the skills that will make them efficient hunters, able to feed themselves.
Three or four weeks after fledging, the young will have learned to hunt, and then disperse establish their own hunting territories and begin independent life.