In 1935 it was estimated there where 12,000 pairs of breeding Barn Owls in Britain. The
BTO Survey of 1972 - 76 gave a figure of up to 9,000 pairs, while our own survey between
the years 1972 - 79 suggested a more realistic 6,000 pairs. Inspired by our findings the
Hawk Trust carried out a most thorough and detailed study of the population between
1983 - 85, the results of which were published in October 1987 (The Barn Owl in the British
Isles, by Colin R. Shawyer, £6.95, from the Hawk Trust, Freepost, Beckenham, Kent).
This reveals a further decline to only 5,000 pairs in the whole of the British Isles, of
which only 3,000 bred every year, 2,700 breeding sites were identified.
The conclusion is that the population of this beautiful owl has fallen by a staggering 70% in the last 50 years. Changes in weather patterns and farming methods have now been identified as the two most important factors responsible for the Barn Owl’s decline since the 1940’s. The decline has been caused mostly by the reduction in the availability of food, which means the Barn Owls have not been in good enough condition to breed or, if they have, then there has been insufficient prey to feed their young.
Severe winter weather in itself does not seem to cause high mortality, but prolonged periods of snow cover limit their ability to find small rodents which are their staple diet. Twenty days of snow cover in a year appears to be the critical level. This occurred only once in the forty years prior to 1940 but, since then, no fewer than 21 winters have reached this level. Continuous rain and drought also seriously affect breeding success.
More intensive farming methods (combine harvesters, prairie farming, high levels of livestock and silage-making etc.) have resulted in larger and larger fields, with the consequent loss of hedgerows and field margins - the rough grassland of which was the favourite hunting ground for the Barn Owl. Even where small areas of suitable habitat have been retained, the fragmentary nature of the resulting countryside has isolated small Barn Owl communities and restricted their ability to expand into the surrounding farmland.
Another major killer is road traffic. Between 3,000 and 5,000 Barn Owls are killed in this way every year. Motorways have now wiped out all adjacent populations and less than 0.05% of Barn Owls now nest within 1Km. of any motorway. Less than 2% are within 3Km. - the distance generally considered to be the limit of the bird's hunting range.
Since the end of the Hawk Trust Survey in 1985 the British isles have suffered from yet more years of appalling weather, i.e. cold winters with heavy snow and cold, wet springs and summers. The loss of rough grassland and prey has continued.
Only the restoration of rough grassland and the erection of nest boxes in favourable habitat can help save the Barn Owl for posterity and the WORLD OWL TRUST intends to be at the forefront of this campaign.
|World Owl Trust
Registered Charity Number: 1107529
Limited Company Number: 5296745
The World Owl Trust is a member of the British and Irish Association of Zoos and Aquariums (BIAZA) and the European Association of Zoos and Aquariums (EAZA). The Trust relies on a dedicated membership, visitors, donations and legacies.