Many animals that have learned to live amidst humans benefit from their proximity, but sometimes that relationship goes both ways, as in the case of barn owls that provide a service to their mammalian neighbors. Indeed, there is a long tradition of building “owl holes” to encourage owls to take up residence in barns and hunt vermin.
Historically, barn owl holes have been particularly popular in the UK, and the Yorkshire Vernacular Buildings Study Group has documented a number of such purpose-built niches in their county’s buildings (examples can also be found in mainland Europe, Canada and the US).
Western barn owls often eat at least one rodent per day, making them a boon to farmers trying to keep out rats and mice. The strategy of integrating entrances and nesting spaces for these flying friends dates back centuries. Often, a small opening (big enough for an owl but too small for other large birds) is situated toward the top of a barn with a landing ledge tilting outward to keep water draining from draining in.
With the rise of pesticides, owls have come to play a lesser role in helping farmers with infestations, in turn lessening the popularity of owl holes but also leading dedicated activists to organize species preservation efforts, like The Barn Owl Trust. This non-profit builds nesting boxes, educates the public about owls, and provides resources to help people create and maintain habitats for these synanthropes.
No species exists in isolation — birds (like bees) play vital roles in maintaining larger ecosystems, and the barn owl is no exception. If you want to learn more about these creatures and the history of their architectural niches, The Barn Owl Trust’s website has a wealth of information as well as ways to offer support toward preservation.