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House sparrow |
BreedingHouse sparrows nest in loose colonies of 10-20 pairs. Since they don't defend a proper territory, nests can be as little as 20-30cm apart. Colonies spread over a quarter to half a hectare, separated by empty spaces of apparently identical habitat. Sparrows prefer to nest in holes in an occupied building but they regularly use other kinds of holes and nestboxes, even house martin nests. If there is a shortage of holes, they can build a free-standing nest in a thick hedge or conifer, although this is infrequent in the UK. Pairs are faithful to their nest site and to each other for life, although a lost mate of either sex is normally replaced within days. A hole is filled with dry grass or straw with a nesting chamber lined with feathers, hairs, string and paper. Feathers may be plucked from a live pigeon! The main nesting season is from April to August, although nesting has been recorded in all months. Most birds lay two or three clutches, but in a good year fourth attempts are not uncommon. The female lays two to five eggs at daily intervals and often starts to incubate part way through egg-laying. Both sexes incubate, and the chicks hatch after 11-14 days. The parents share nesting duties equally. Chicks are brooded for 6-8 days, but can control their own body temperature only when 10 or 11 days old. The chicks are fed on aphids, caterpillars, weevils and grasshoppers, but seed and grain are the most important foods by the time they fledge. The young fledge 14-16 days after hatching. They are unable to feed themselves for a week after leaving the nest and are cared for by their parents for a fortnight. Post-fledging care is normally left to the male; the hen prepares for the next brood. She starts to lay about a week after the previous brood fledged. Newly independent young gather in large flocks, outside the breeding area where there is an abundance of seed and other suitable foods. These are often areas of wasteland and hayfields rich in grass and weed seeds. Later, flocks move on to grainfields to feed on the ripening grain. Here they are joined by adult birds, once they have finished nesting. Between August and October many colonies are abandoned in favour of the temporary abundance of grain. Once the flocks break up in October, nesting colonies are re-occupied. Any birds that don't return, will soon be replaced by juvenile birds. |
Bird guide |
Dilapidated barn, Norfolk - Theresa Knox
Juvenile house sparrow profile - Steve Round
Bird illustrations by Mike Langman (RSPB)