The barn owl (Tyto alba) is a widely distributed raptor sought after by landowners for its quiet, highly effective natural rodent control. Known for its pale, heart-shaped face and silent flight, this nocturnal hunter is a welcome resident on farms and large properties. Attracting barn owls requires providing safe nesting sites and a consistent, robust food supply. Specific, practical steps to modify your property can attract this beneficial species and support its long-term presence.
Providing Suitable Shelter
Installing an artificial nest site is the most direct action a landowner can take to attract barn owls, compensating for the loss of natural tree cavities and old barn structures. A well-designed nest box provides a safe, dry, and predator-resistant location for breeding and roosting. The internal floor area should be 0.2 to 0.4 square meters.
The entrance hole should be square, optimally 130 by 130 millimeters, positioned with a minimum depth of 450 millimeters from the bottom edge to the floor to contain the young. Use exterior-grade plywood or treated timber for construction, including a hinged panel for future cleaning access. To prepare the box, line the floor with a 1- to 3-inch layer of untreated wood mulch or large wood shavings, avoiding fine sawdust or cedar.
Placement is a major factor in the box’s success, with a height of 3 to 5 meters (10 to 16 feet) above the ground being suitable. When installing the box outside, position the entrance facing away from the prevailing winds (often west or southwest). If placing the box inside a building, such as a barn or silo, ensure the access hole is clearly visible to a flying owl from the building’s entrance point.
Cultivating a Healthy Prey Base
A consistent food supply is necessary for owls to establish a territory, as a single breeding pair and their young can consume over a thousand rodents annually. Barn owls primarily feed on small mammals like voles, shrews, and mice, with field voles often making up the largest percentage of their diet. These prey species thrive in dense, undisturbed ground cover, which offers them both protection and a food source.
Creating and maintaining rough grassland is the most effective way to support a robust prey population. This habitat consists of grass that is left uncut and ungrazed for at least one year, allowing the thick litter layer to develop. Strips of this rough grassland, even a buffer zone of 2 to 6 meters wide along field margins or hedgerows, can significantly increase the abundance of small rodents.
Owls hunt by flying low over open ground, relying on their exceptional hearing to locate prey moving beneath the dense vegetation. Maintaining these rough, unfertilized areas provides the necessary cover for the rodents and accessible hunting territory for the owls. Establishing these patches near the nest box increases the likelihood of successful breeding and year-round residency.
Ensuring Safety and Longevity
Protecting barn owls from hazards is as important as providing them with shelter and food, particularly by eliminating the threat of secondary poisoning. Anticoagulant rodenticides (ARs), especially the highly toxic Second-Generation ARs (SGARs), pose a significant risk. These poisons interfere with the rodent’s blood clotting mechanism, causing fatal internal hemorrhaging when an owl consumes a poisoned rodent.
High percentages of wild barn owls are found to have residues of these poisons, confirming widespread exposure. Property owners should immediately stop using any rodenticides on their land, relying instead on the owls for natural pest control.
Physical hazards also need attention, such as open water troughs, which can lead to drowning. A simple solution is installing a floating platform made of plastic mesh and treated timber to provide an escape ramp for any bird that falls in. Other risks include entanglement in netting, especially fine garden or sports netting, and collision with vehicles near major roads. Minimizing human activity and domestic pet presence near established nest sites is helpful, as owls are sensitive to disturbance that can cause nesting failure.
Monitoring and Long-Term Stewardship
Once owls have established residence, long-term stewardship involves respectful monitoring and necessary maintenance. Barn owls are protected under wildlife laws, and in many regions, they are a Schedule 1 species, which affords extra legal protection against intentional or reckless disturbance while they are nesting or have dependent young. Approaching or inspecting a nest box during the breeding season (typically February through September) is illegal without a special license.
Annual nest box cleaning should be scheduled for the off-season, ideally between late October and early December, after the young have fledged and before the next breeding cycle begins. The nest box accumulates a large amount of compacted debris, mostly composed of regurgitated pellets, which are indigestible masses of fur and bone from their prey. This debris must be removed to maintain sufficient depth in the box for future nesting.
When cleaning, wear protective gear, such as an N95 mask and gloves, due to the low risk of exposure to pathogens like Hantavirus from rodent droppings. Use a small hand tool to scrape out the material, replacing it with a fresh layer of wood mulch. Analyzing the collected pellets can confirm occupancy and provide insight into the owl’s diet, helping to gauge the success of your rough grassland management.