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Tuesday, March 20, 2012

Owls - Barn Owls of England

Here I post a FDC of England on Barn owls. Date 20-5-1986 - species at risk

The barn owl is a very beautiful bird with pale golden buff coloured upperparts laced with silver grey and white under-parts. It has a distinctive white heart shaped face and when seen in flight the overall impression is of a large white bird. Adult birds of both sexes are between 33-35cm from head to tail and have a wing span of approximately 85cm. Many people will recognise a barn owl from pictures, but in the wild the species is generally very elusive. The birds are most active just after dusk and just before dawn, and as a result it is not unusual to find that people living close to an occupied site can be unaware of the birds’ presence. Contrary to popular belief barn owls are not woodland birds and do not hoot. They do however have a considerable vocabulary of calls including screeches, hisses and snoring sounds.

In Britain the field vole (Microtus agrestis) is the barn owl’s main prey species; shrews and mice are also significant. During an average year a breeding pair of barn owls and their young may consume as many as 5,000 small mammals. In the breeding season most foraging occur s within about 1km of the nest. However, during the winter birds have been recorded at up to 4.5 km from their former nest sites. Food supply is the predominant factor governing barn owl survival and breeding success. The ideal habitat for barn owls is rough grassland supporting a high density of small mammals. This can be in the form of linear features such as drainage ditches or woodland edge, or non-linear features such as young tree plantations or fallow pastures (see picture 13 on page 20). Intensively grazed pasture, silage and arable fields yield little prey and the birds are not adapted to hunt within woodland. Nevertheless, Barn Owl Trust studies have shown that breeding barn owls are sometimes found with less than one acre of rough grassland within 1km of the nest. Thus even in areas of intensive grazing and cultivation the possible presence of resident barn owls cannot be discounted.

I post here under FDC of GB dated 20-5-86 under "" Nature Conservation - species at Risk - Slimbridge Gloucester

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