Abstract
ONE of the outcomes of the census of barn-owls (Tyto alba alba) in England and Wales (Blaker, Bird Notes and News, 15, 7) is substantiating the fears that this useful bird is on the decline in Britain. Northumberland, Cumberland and Durham were the only counties to report an increase. The areas of maximum population (41-50 pairs per 100 sq. miles) appear to be Anglesey, Devon, Durham and parts of Essex, Suffolk and Hertford, and that of minimum population (0-5 pairs per 100 sq. miles), a mountainous area of north-east Lancashire and north-west Riding. About 4,000 naturalists took part in this census, organised by the Royal Society for the Protection of Birds, and found about 12,000 breeding pairs for England and Wales in the summer of 1932, non-breeding birds averaging one per 50 sq. miles. Some 45,000 eggs were laid in 1932, of which 35,000 hatched and 33,000 owlets left the nest, when the country would contain 55,000 barn-owls, which, by the following spring, would be reduced to 24,000. The species seems to have declined 50 per cent in the past ten years, and is declining at about 1,000 a year, or four per cent. Of 214 nests examined, 807 eggs were laid, 174 of which failed to hatch, and of the 633 owlets, 594 left the nest. There is a marked spreading over the countryside at the end of the nesting season, which accounts for the presence of the birds in areas otherwise rarely inhabited. Mr. Blaker considers that the decline of the species could be averted if four per cent of the death-rate was stopped. The Royal Society for the Protection of Birds is to issue the complete census results in pamphlet form. The barn-owl, which was once the commonest owl in “Britain, is nowhere now so numerous as the tawny-owl, nor in many places as the alien little owl. The food of the barn-owl consists of 69 per cent voles and mice (Collinge).
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Decreasing Barn-Owls. Nature 132, 889 (1933). https://doi.org/10.1038/132889a0
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DOI: https://doi.org/10.1038/132889a0