Press Releases - January/February 2007
Item 3

No. 2007/01/10
January 2007

Is double-glazing to blame?

With reports of Tawny Owls being absent from many areas where they used to be frequently heard, and national bird monitoring schemes suggesting that the population may be undergoing a decline, the British Trust for Ornithology sent out volunteers to find out what was going on.

The last time a survey of Tawny Owls was carried out was in 1989 and this showed that they were both widespread and abundant in Britain, with the exception of the Scottish and English uplands and the Greater London conurbation. The latest survey aimed to see if this was still the case, or to see whether the species really was declining and, if so, by how much.

Between 15 August and 15 October 2005, bird enthusiasts visited 2,652 sites across the country in a bid to count their local owls. Responding to a rallying call of ‘Who gives a hoot?’ volunteers were asked to undertake counts within two hours after sunset, listening for ten minutes to record any observations of calling Tawny Owls, ‘hoots’ (males) and ‘kew-wicks’ (females), or birds that they saw.

It was previously estimated that there were 19,000 pairs of Tawny Owls in Britain. Analysis of the the 2005 results, published in the latest BTO News, showed that 63% of the areas surveyed were used by Tawny Owls. This was almost identical to the 1989 results, showing rather encouragingly that the British Tawny Owl population had maintained its earlier range and abundance. Paul Stancliffe, Promotions Officer at the BTO, said. “There were concerns that up to one third of Tawny Owls had disappeared in recent years, so it is great news that they are still to be found in most of the areas in which they were encountered in the previous survey. It may just be that, with modern houses and more and more double-glazing, we just aren’t hearing them as much as we used to”.

With their very sensitive hearing and vision, Tawny Owls are well adapted to hunt at night, and their truly nocturnal habits make them difficult to see. By standing outside during the winter months, when they are at their most vocal, you are more likely to hear their characteristic territorial calls, the ‘Tuwit-Tuwoo’ of children’s stories, as they proclaim their territory and advertise for a mate. Hunting in woodlands, parks and gardens between dawn and dusk, Tawny Owls feed mainly on small mammals, but will take earthworms and small birds.

If you would like more information on the BTO and its surveys, visit the BTO website, www.bto.org, or telephone 01842 750050 or write to BTO, Room 10, The Nunnery, Thetford, Norfolk, IP24 2PU

Notes for Editors

1. The Tawny Owl survey was generously funded by the BTO Owl Appeal with the help of Anglian Water and several charitable trusts, including the D’Oyly Carte charitable Trust, the Hobart Trust and the Cooper Charitable Trust.
2. Tawny Owls set up their territories in the autumn and it is at this time that they are at their most vocal. The well known ‘hoot’ call is mainly given by the male and the ‘kew-wick, kew-wick’ call by the female. Tawny Owls normally lay 2-3 eggs, which are brooded entirely by the female. They are early nesters, laying their first egg from mid to late March. Tawny Owls typically live for five years but the oldest recorded wild individual was 21 years and 5 months old.
3. The 2,652 sites surveyed were 2km x 2km squares.
4. BTO News is the Trust’s newsletter, which keeps all members informed about the latest results from surveys and topical issues concerning birds and the environment. It is published six times a year (at two monthly intervals) and is posted to all members of the Trust free of charge.
5. The BTO runs a number of national and annual surveys through its volunteer network, to monitor the status of many of our bird species across a range of habitats. See www.bto.org/survey
6. Images of Tawny Owls are freely available for use in association with this press release. Please contact images@bto.org to request an electronic version. Please quote reference number 2007/01/10
7. Bird Information. For lots of facts and figures about birds go to www.bto.org/birdfacts
8. The BTO has an ISDN line available for radio interviews.

For further information please contact:

Paul Stancliffe on 01842 750050 or e-mail: (during office hours)