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|Feathered Friends - July 2010|
|Written by John Keeling|
By John Keeling
The house sparrow is not only a common resident here, but it is also the most widely distributed wild bird in the world. Its spread has been closely related to human expansion in the world. In the countryside if you come across a house sparrow, you know there is a human dwelling or farm close by.
It is a stocky bird, six inches long, with white cheeks, grey crown, black bib, and rich brown feathers on the wings and back. The size of the black bib increases with age. The female is plain mid-brown in color with a pale buff line over the eye.
Originally from northern Europe and northern Asia it has spread widely over the last 150 years, both on its own and as a result of introduction by humans. Birds on the American Continent are descended from fifty pairs released purposely in 1852 by the commissioners of Central Park in New York City.
They are social birds, joining together in flocks for eating and roosting at night; and may build nests quite close together. They feed mainly on the ground, foraging for seeds of all kinds – note the heavy beak which is adapted for crushing seeds. They are required to eat small quantities of grit to help grind up the broken seeds in the stomach. They are adaptable however, switching when necessary to berries, fruit, beetles, caterpillars and earthworms.
In the early spring when there are enough insects around to feed the future offspring, the male will pick out a nest site and start singing incessantly to call females. When a female comes, the male displays by shivering its wings, raising its tail and head, and displaying its black bib. The female then attacks the male and flies away. He follows and displays some more. When she sings a soft acceptance call, the male mounts the female repeatedly.
The male builds the nest with some help from the female, in any kind of hidden or semi-hidden cavity. It is an untidy mass of plant material, generally domed with an opening in the side. The female lays four spotted, bluish eggs and sits on them for 15 days until they hatch. Both sexes feed the young in the nest for 15 days, and also after they leave the nest for many more days until the young can fend for themselves. Up to four nesting cycles may occur in a year.
The young have a high mortality rate – only 20% survive the first year. Adults are subject to an annual survival rate of 50%. Many are eaten by domestic cats, and also hawks and crows. Some are killed by avian diseases. House sparrows are the most common road-kill in Europe.
Currently there is a decline in the population of house sparrows in England, and it has almost disappeared from the center of London. Naturally, ornithologists in England are investigating each of several possible causes. A similar decline was seen a hundred years ago when cars were first introduced.
(John Keeling and his wife lead the ‘Lake Chapala Birding Club’ which is a group of people interested in birds. To receive notices of bird walks etc., leave your e-mail address at avesajijic.com.)