The remaining population of one of Devon's rarest birds is being boosted by the release of four young barn owls.
Earlier this year, the Barn Owl Trust received the birds from the Gower Bird Hospital via the RSPCA at West Hatch in Somerset. They were originally taken in as owlets that had fallen from the nest. The owlets were reared successfully but the RSPCA lacked the specialist facilities needed to provide each of the owls with a supported release. The Devon-based Trust agreed to release them using their purpose-built mobile aviaries and set about the task of finding release sites with volunteers to feed the birds.
Under most circumstances, barn owls are released as close as possible to the place they were found. This is because they are very site-faithful and will live in the same home range all of their lives, releasing an established bird away from its home range will significantly reduce the chances of it surviving. Because these birds were taken in as nestlings and didn't have a home range to return to, they could be released anywhere. The birds were split into two pairs and two release sites with plenty of good habitat were selected – one in the Teign Valley, west of Exeter and one in the Axe valley close to the Dorset border. The birds are currently confined in mobile aviaries and will be released as soon as the weather improves.
"These mobile aviaries are a fantastic resource," said Stuart Baker from the Barn Owl Trust. "Rather than simply letting the birds go, it is much better to release them from an aviary, where they can be supported in their transition from life in captivity to life in the wild." The problem is that most locations do not have a suitable aviary – hence the need for mobile aviaries. These are large 14-foot aviaries purpose-built onto the back of a trailer with a roof that can propped open. Stuart explained: "Using a mobile aviary allows us to use the best release method in the best place for each individual owl. Once a suitable release site has been identified, the aviary is towed to the site and parked up. The owls are then placed inside for about two weeks before the roof is opened up, allowing the birds to fly in and out. They then disperse into the countryside in search of a home range, just as they would from their parents' nest. Once the owl stops returning for food the aviary is towed away."
The Barn Owl Trust is always on the look-out for volunteers with potential release sites. "We need people who can feed the owls every night at sites with plenty of rough tussocky grassland," said Stuart, "as this is the best habitat for their main prey, the field vole. Sites also need to be at least 1km from the nearest motorway or dual-carriageway." Anyone in Devon, E Cornwall, or W Dorset who is interested in future releases should contact the Barn Owl Trust on 01364 653026 or email email@example.com