The "disappearing" Tawny Owl
Photo: Jill Pakenham/BTO

A LEADING conservation organisation that set out to discover why the Tawny Owl - thought to be a common inhabitant in many areas across Britain, including the Yorkshire Dales - has not been sighted quite so often in recent years - and they came up with a surprising answer.

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 just what was going on.

The Tawny Owl population was last surveyed 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 their distinctive calling.

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.

with modern houses and more and more double-glazing, we just aren't hearing them as much as we used to

Paul Stancliffe, - BTO

It was previously estimated that there were 19,000 pairs of Tawny Owls in Britain. Analysis of the 2005 results, published in the latest edition of BTO News, showed that 63% of the areas surveyed were used by Tawny Owls. This was almost identical to the 1989 results, showing that the British Tawny Owl population had maintained its earlier range and abundance.

So, the question remained, why have sightings fallen and why is their distinctive call rarely heard anymore?

The BTO suggests that 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.

Paul Stancliffe, Promotions Officer at the BTO, added another simple explanation: "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".

• For more information on the BTO and its surveys, visit the BTO website, www.bto.org, or telephone 01842 750050.

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