Barn Owl roosting and nesting places

Barn Owls don’t only live in barns! Historically, they lived in many different types of rural buildings and tree hollows. These days, they mainly roost and nest in:

• Nestboxes in modern agricultural buildings.
• Nestboxes on isolated or hedgerow trees.
• Nestboxes on poles.
• Old barns.
• Hollow trees and cavities.
• Converted barns with built-in provision.

…and to a lesser extent in old churches, castles, dovecotes, derelict cottages, chapels, chimneys, bridges, walls, sea cliffs, quarry faces, mine buildings, mine shafts, disused factories, bunkers, observation towers, and water towers. Basically they will use anything that provides what they need: somewhere that gives them shelter from rain and wind and where they ‘feel safe’. Unless the site is extremely isolated, Barn Owls generally roost and nest at least 3 metres above ground level.

Roosting in warm straw bales helps conserve energy, especially in winter.

What did Barn Owls live in before there were barns?

The answer must be tree hollows and rock crevices and, in some areas, natural sites like these are still used today. Farming in Britain started around 3,500 BC and as soon as haystacks, animal shelters and houses were created Barn Owls almost certainly moved in. Indeed, the remains of Barn Owls have been discovered during the excavation of several ancient human settlements including the iron age village of Glastonbury (Somerset) and a Roman site at Woodcutts, Cranbourne Chase, Dorset.

Many old barns have long since disappeared.

Barn Owls have absolutely no sense of architecture!

To a Barn Owl, an ugly steel shed surrounded by concrete can be just as attractive as a lovely old stone barn surrounded by wildflowers. Although the majority of recorded nest sites are now in purpose-made nestboxes, Barn Owls still use a very wide variety of site-types and there is enormous variation in their suitability. Not every old barn is a potential nest site and even some purpose-made Barn Owl nestboxes are far from ideal!

About poor nestbox design.

Suitability and availability of nesting places for Barn Owls – facts and figures

To use any site, the owl has to be able to get in, but the absolute minimum hole size required is only 70 x 70mm. The minimum width of a nest ledge is around 250mm and the minimum floor area of a nest cavity is about 300mm x 300mm. If you are thinking of creating a suitable access hole, nestbox, or built-in space for nesting please don’t use these minimum figures as a guide!

Watch the videos on how to build your own box for inside a building & how to erect, how to build a box to go on a tree & how to erect and the best nestbox design.

Our Barn Conversion Research Project (carried out in SW England) quantified the number, type, suitability, and rate of loss of potential Barn Owl sites.

• 48% of traditional farm buildings were suitable for Barn Owls to nest in but…
• Only 4% of modern farm buildings had a potential nest-place (unless a nestbox was provided).
• 76% of traditional farm buildings were suitable for Barn Owls to roost in but…
• Only 41%  of modern farm buildings were suitable for roosting in.
• Only 2% of all potential nest places were tree hollows.

In the UK, the types of sites used by Barn Owls for nesting show a clear east-west difference. In the western half of Britain, the vast majority of recorded nest sites are buildings, whereas in some eastern areas, about 70% of sites are tree hollows. Our research in SW England suggested that there was no positive selection – that the type of sites used by the birds was simply a reflection of the types of sites available to them. This disproved the idea that Barn Owls in the west select buildings rather than trees because of the higher rainfall in western areas and extra shelter they provide. Scientific research in SW Scotland by Dr. Iain Taylor later supported our view.

Barn Owls have nested in the roof of this occupied farmhouse for many years – directly above the bedroom.

The ‘universal appeal’ of traditional Barn Owl nest sites

Once settled into their home range (after post-fledging dispersal) Barn Owls generally use the same nest and roost sites for the rest of their lives. In areas where there are plenty of suitable-looking sites for the owls to choose from, it is often unclear why they choose the sites they use and ignore others. Interestingly, when a home range is vacated for a period (because the owls have died) and later re-occupied by new owls, the sites they choose to use are often the same ones the previous residents used. This suggests that occupied sites not only have a certain appeal to individual owls, they also have ‘universal appeal’ to Barn Owls as a species. This fascinating aspect of Barn Owl site-selection behaviour warrants further investigation.