Identifying priority areas for Barn Owl conservation in Britain
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A collaborative research project between the Barn Owl Trust, Environment Agency, English Nature, Central Science Laboratory and the University of York carried out by Nick Askew PhD. Principally funded by BOT.
There are numerous Barn Owl volunteer groups and individual enthusiasts in the UK helping to conserve this most popular of bird species. However, one of the difficulties faced by Barn Owl workers until 2006 was the lack of information on the species' habitat requirements. Although rough grassland was well known as the species' optimum foraging habitat, the simple question "how much do they need?" could not be adequately answered. Whilst many Barn Owls seem to depend on the availability of prey-rich rough grassland, in some areas they appear to do well without any. In the absence of dedicated research, assessing landscape suitability for Barn Owls and for nestbox schemes was a major challenge. With these problems in mind, Nick Askew asked the Barn Owl Trust to support his PhD thesis research.
Nick was already well known for his work in the Lower Derwent Valley where he had researched Barn Owl foraging behaviour and prey selection, along with the diet and habitat requirements of Field Voles. His new research proposal hade two main aspects; Barn Owl habitat requirements and landscape suitability. The specific aims were to:
- Produce landscape suitability maps to aid targeting of conservation effort.
- Quantify habitat requirements within different landscape types.
- Produce a new Barn Owl advisory leaflet.
- Publish the results on the BOT website
A rough grass field margin or 'buffer' strip in Yorkshire
Nick now takes up the story…
“To produce the landscape suitability maps I linked 1,521 nest-sites with information already known about their location. For example, for each nest-site I knew the altitude, winter climate, slope, distance to major roads, amount of different habitat types available etc. I could then look for differences between successful Barn Owl breeding nests and sites never used for breeding. This allowed me to better understand what determines the suitability of a location for Barn Owls. More importantly, it allowed me to then predict the suitability of all British locations for Barn Owls – a “landscape suitability map”. I have now produced landscape suitability maps for ten British regions – all of which can be downloaded from the BOT website.
It is hoped that these maps may prove useful for Barn Owl conservation groups wishing to find new locations to target their nest-boxes. By simply downloading a map from the BOT website, you can open an image of your region and zoom in to your area. Each 10 km OS square is clearly labelled and each coloured cell represents a 1 km square. Land within 1km of a trunk road (where Barn Owl nestboxes should not be erected) are also shown (yellow hatched areas).
I also split Britain into three different landscape types: Arable, Pastoral and Mixed. This allowed me to compare habitat associations of successful nests between different agricultural areas and thereby quantify habitat requirements. So what did I find?
The results show that Barn Owls are primarily associated with lowland areas of arable and horticultural usage, but also occur in pastoral habitats. These relationships were strongest in England and Wales. If you have arable or horticultural landscapes in your area they could be some of the best locations for Barn Owls. Of course, it is unlikely that Barn Owls hunt directly where crops are grown or where livestock are grazed. I suggest instead that lowland landscapes indirectly provide hunting opportunities for Barn Owls in the form of prey-rich rough grass margin habitats. I then compared the quantity of rough-grass available around Barn Owl breeding sites in the three different landscape types.
Arable Landscapes - Barn Owls require 14 to 21 ha of rough grassland within 2km
Pastoral Landscapes - Barn Owls require 31 to 47 ha of rough grassland within 2km
Mixed Landscapes - Barn Owls require 17 to 26 ha of rough grassland within 2km
These results help us better answer some fundamental questions relating to Barn Owl conservation. How many times have we been asked, “how much habitat do Barn Owls need?”. It seems that the landscape type may be an important part of the answer.
The results of this groundbreaking work are now available. The landscape suitability maps, and more information relating to habitat requirements in different landscape types, can be downloaded (see link>) and a free RSPB/BOT leaflet is available (see link>). Information from this study has since been incorporated into the Barn Owl Conservation Handbook.
I wish to thank David and Frances Ramsden (Barn Owl Trust), Roger Martin (Environment Agency) and Richard Saunders (English Nature) for financial support.
For academic guidance I would like to thank Prof. Jeremy Searle (York University), Dr Barb Anderson (UKPopNet).
For spending time collating and sending data I would like to thank: David Ramsden (BOT); Colin Shawyer (WCP); Jenny Holden (World Owl Trust); Helen and Matthew Cottam (Staffordshire Barn Owl Action Group); Bernard Wright and John Wild (Cheshire Barn Owl Action Group); Duncan Brown, Rhodri Dafydd & Sian Whitehead (CCW); Gordon Ellis (Broxtowe Project); Howard Broughton (Rushcliffe Barn Owl Project); John Lightfoot and Glen Bishton (Shropshire Barn Owl Group); David Hodgson & Peter Wilkinson (Cambridgeshire); Pawl Willet (North Yorkshire); John Middleton (North Norfolk Barn Owl Group); Judith Smith (Greater Manchester Bird Recording Group); Alan Levitt & Nick Atkinson (Northumbrian Barn Owl Group); Roy S Leigh (Cheshire); Geoff Shaw (The Forestry Commision); Steve Harris (Wirral Barn Owl Trust); and Steve Huddleston (Wheater.biz). Thanks also to Jason Ball (BOCN), Dr Dave Leach (BTO), Dr Richard Winspear (RSPB), Craig Ralston (EN), Dr Niall Moore (CSL), and David Tate."