Barn Owl nestbox
'Nest' is not really the appropriate word to use in relation to Barn Owls, since they build no nest as such, but lay their eggs on a layer of pellets which has accumulated in their roosting site. Such sites are deep spacious cavities in trees, dark corners of barns, churches and old buildings, or even gaps in straw stacks. With the loss of many old hollow trees and old buildings through modernisation, nestboxes provide a real opportunity for this declining species to re-establish its population.
Owls may accept a nestbox readily, but use it only for roosting for as long as two years before finally breeding. There is no real design for a Barn Owl nestbox - any large box is acceptable if it is at least 18 x 18 x 24 inches (45cm x 45cm x 60cm). For internal use (barns and old buildings) a traditional tea chest can be ideally adapted; but for external use, good quality, heavy, waterproof board must be used. A layer of mini-bark chippings should be placed in the box.
The ideal site for a box is a dark corner on a beam in an undisturbed building near farmland, away from busy roads, and where there is permanent access for the owls through doors, windows or other such holes.
An entrance hole 6 x 6 inches (15 x 15cm) should be cut from one of the top corners, and a lipped tray fitted on the front of the box to provide an exercise area for the young owls.
It is also possible to site boxes in modern, prefabricated farm buildings, using battens, bolts and wire, but the need for a permanent means of access to the building for the owls is vital.