BARN OWL
Photograph courtesy of CJ WildBird Foods Ltd
A ghostly white shape flitting through the car headlights is the most common view of this charismatic owl. Unfortunately this habit of hunting along roadside verges, resulting in fatal traffic accidents, has reinforced the more substantial impacts of habitat loss and destruction of nest sites, which have reduced the population locally and nationally.
Barn Owls have honey-coloured wings and back, and a white face, breast and underparts. The face is shaped like a flat satellite dish, and fulfils the same function – owls locate their food by ear, not eye, and the facial disc reflects and concentrates the sound of prey moving in the grass. They are around the same size as Kestrels, but they usually look much larger because they are seen close-to, with nothing else visible in the dark to provide perspective. They are nocturnal, but are sometimes seen hunting in daylight, when there are young to feed in the nest, or in the depths of winter when food is scarce.
No nest is constructed, and eggs are usually laid in large hollow trees or in farm outbuildings. Barn Owls nest early, and the first clutch, usually 4 – 7 eggs, may be laid anytime between February and May. The eggs are laid at two day intervals, and the incubation period varies between four and five weeks. The male feeds the female at the nest. Like many birds of prey, the nestlings also hatch at two day intervals, so the brood consists of birds of markedly different sizes. However, the oldest, largest chick is fed first, and the second chick only get food when it is satiated. This process continues down the line, so the youngest chick only gets enough food if all its older siblings are already full. In this way one or two young will fledge, even if food is in short supply, but more young will fledge when it is abundant. In this way the species can still produce some young in lean years, but take full advantage of good years. Both parents feed the chicks, which fledge after 8 – 9 weeks, and become independent after about 10 weeks.
In spite of its adaptability, the population declined substantially during the 20th Century, due mainly to agricultural intensification, which removed much of its primary habitat – rough grassland where it can forage for its prey, primarily field voles, shrews and wood mice. The other major contributory factor is loss of nest sites – demolition, enclosure or conversion of old farm buildings and insufficient trees reaching maturity to replace the older ones with cavities as they die off and decay. In common with some birds of prey, poisoning by pesticides also killed some birds and reduced breeding success. This can still be a problem where the present and more toxic poisons such as brodifacoum are used as an alternative to the less toxic first generation poisons such as warfarin.
Nationally, the Barn Owl population fell from an
estimated 12,000 pairs in 1932 to around 4,000 pairs in the early 1980s, and
they have suffered a decline of between 25 and 50% in their breeding range in
Britain in the 25 years up until 2001, so the species is therefore now on the Amber
List in the Population Status of Birds in the UK – Birds of Conservation Concern:
2002-2007. In
Barn Owls are highly sedentary and pairs are very
faithful to nest sites. They range over about three square kilometres in summer
and mainly hunt within one kilometre of the nest increasing to five kilometres
in winter. Although young birds forage more widely during their first winter,
before establishing a territory, it is likely that almost all of the dots on the
2000 – 04 Distribution Map relate to breeding pairs (including the winter records, shown
as small green dots), and that most of the tetrads occupied in 1985 –
90, shown on The Atlas (1992) map,
still hold breeding pairs.
Each pair needs around four hectares (10 acres) of
permanent rank or rough grassland. Tussock grasses such as
The Shropshire Barn Owl Group (SBOG) is combating the loss of nest sites with a nestbox scheme and promoting conservation through advice to farmers and statutory authorities on protection and restoration of habitat. Anyone with sufficient suitable foraging habitat in the vicinity who is interested in installing a nestbox in a quiet outbuilding or on a large mature tree, well away from a road, can contact John Lightfoot (01691 623083) or Glenn Bishton (01952 433949). Click below to read the reports of the SBOG -