This week, we are profiling three types owls in the RSPB Geltsdale blog, as we have Barn Owls nesting at the visitor centre, as well as Tawny Owls and Short-Eared Owls nearby. Barn Owls (Latin name: Tyto alba), with their heart-shaped face, buff-coloured back and wings and pure white underparts are both beautiful and distinctive. They measure between 33 and 39 cm in length, weigh 250 to 350g and have a wingspan of 80 to 95 cm. They are widespread across the UK, with between 4,000 and 14,000 breeding pairs in the UK and 110,000 to 220,000 pairs across Europe. They are largely nocturnal, but may be seen before dusk and around dawn in open countryside, along the edges of fields, rivers and roads, where they hunt for food. In winter they may even be seen hunting in daylight. They eat small mammals such as voles, shrews and mice, some larger mammals and small birds. They have amazing hearing and can find their prey by sound alone. Prey is usually swallowed whole, and indigestible parts such as fur, bones and teeth are then regurgitated in large, smooth, dark pellets which can be found around nesting sites.
Barn Owls usually nest in holes in trees or in undisturbed buildings, such as barns and ruins. Normally they lay between four and seven eggs each breeding season, but this varies according to the availability of prey, so can be between three and 11. The eggs are laid at intervals of two to three days and incubation lasts 30 to 31 days, before the young, known as owlets, hatch – again at intervals of two to three days. They fledge 50 to 55 days after hatching. Barn Owls may raise two broods in one season, but about 75 percent of the young die within the first year – the survivors usually live another one to three years, although the oldest known Barn owl was more than 21 years old, and there are several records of them living to between 12 and 17 years old.
Barn Owls are listed under Schedule 1 of the Wildlife and Countryside Act 1981 (and the Wildlife Order 1985 in Northern Ireland), meaning they, their nests and their eggs are protected. It is an offence to intentionally or recklessly disturb an active nest. Barn Owls are also listed under Schedule 9 of the 1981 Act, which means it is illegal to release them into the wild in Britain without a licence. It is also illegal to take Barn Owls from the wild, although they can be kept in captivity if they are wild birds which are injured and undergoing treatment or have been bred in captivity.
Short-eared Owls (Latin name: Asio flammeus) are similar in size to Barn Owls, but with long wings, mottled brown bodies, yellow eyes, and pale under-wings. Their short ‘ear tufts’ give them their name. They are often seen hunting for voles and small birds during the day, which is unusual among owls. In winter, their numbers increase as birds arrive from Scandinavia, Russia and Iceland to northern, eastern and some parts of central and southern England, and they can be seen over moorland and saltmarshes. Short-eared Owls measure between 34 and 42 cm in length, weigh between 260 and 350g and have a wingspan of 90 to 105 cm. There are between 620 and 2,200 breeding pairs in the UK and they can be heard around their breeding grounds, where males perform display flights ang make a series of fast, deep hoots and short, fast wing claps. They eat small mammals, especially voles, and nest on the ground, unlike Barn Owls and Tawny Owls, making scraped-out hollows lined with grass and downy feathers. They are, in fact, the only UK owl to build their own nest, rather than using an existing structure. The male Short-eared Owl has a song which is made up of ten or more hoots, sometimes delivered alongside an elaborate flight display, which includes wing claps and can last for up to an hour. Short-eared Owls are on the Amber List of Birds of Conservation Concern in the UK, largely because their breeding range had decreased, so they are now considered a rare breeding bird.
Meanwhile, Tawny Owls (Latin name: Strix aluco) are Britain’s largest common owl, about the same size as a Woodpigeon, with a rounded body and head, a ring of dark feathers around their face, a hooked beak and dark eyes. They measure between 37 and 39 cm in length and weigh 330 to 590g, with a wingspan of 94 to 104 cm. They have reddish-brown upperparts, with paler feathers underneath, and are widespread across England, Wales and Scotland, but are not found in Ireland. They are mainly resident in the UK, forming pairs for life which never leave their territories, although juveniles disperse from breeding grounds during the autumn. Breeding pairs, of which there are 50,000 in the UK, will defend their shared territory from other owls all year round. After mating, females lay their eggs in a hole in a large tree. They may also use old crows’ nests and squirrel dreys. They usually lay two to three eggs in the spring, which hatch after about a month. The owlets leave the nest and spend several days in the surrounding branches before fledging, and the parents spend a few weeks caring for and feeding their young before they are fully independent at the end of autumn.
Tawny Owls’ diet consists of small mammals, birds, frogs, fish, insects and worms. Their finely tuned sight and hearing allows them to locate their prey on the forest floor, while their feathers have a soft edge which makes their flight soundless. They are nocturnal, and often heard calling at night, but are rarely seen. They make the recognisably ‘too-wit, too-woo’ sound, which is made by the male and female calling to one another – the female calls ‘too-wit’ and the male answers ‘too-woo’. The male’s hooting call is easy to mimic and owls will often respond to impersonators. Tawny owls’ pellets are often found below roosting places, in woodland against tree trunks, in hollow trees or among creepers such as ivy. UK numbers of Tawny Owls have declined by more than a thirds since the 1970s, possibly due to a loss if woodland habitat and suitable trees for nesting. Like Short-eared Owls, they are on the Amber List of Birds of Conservation Concern in the UK.