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Barn Owl Tyto alba

 

The Barn Owl has not only declined dramatically in Britain but also throughout Europe. In 1932 George Blaker estimated that the British population of Barn Owls was about 12,000 and even this estimate revealed a substantial drop in numbers from what was once Britain's commonest owl. A further survey of Britain and Ireland that was undertaken between 1982-1985 concluded that there were approximately 4500 pairs breeding in Britain. Thus a further decline of more than two thirds of the population had occurred between 1932 and 1985. This has prompted it to be amber rated in the list of Birds of Conservation Concern having had a moderate (25-49%) decline in the UK breeding population or range over the previous 25 years. In addition it is afforded Schedule 1 status and this special protection applies to species, which are scarce or are rarely breeding in the UK. Under the Wildlife and Countryside Act 1981 as amended by the Environmental Protection Act 1990, it is an offence, liable to special penalty, to intentionally disturb any wild bird included in the Schedule while it is building a nest or is in, on, or near a nest containing eggs or young or to disturb dependent young of such a bird.
Photo Richard Brooks  
 Barn Owls nest in hollow trees and also in buildings, some reasons for this decline have included the loss of nest sites. Many trees were lost during the Dutch Elm disease outbreak in the sixties and also in the gales of 1987 and 1990, additionally many mature old trees in some cases many hundreds of years old simply died of old age. Traditional sites in old farm buildings have also been lost as barns have been converted to other use including residential occupation or have simply been allowed to deteriorate until they collapsed or were demolished. Tea chests with a front and entrance hole make ideal nest boxes, although sometimes Barn Owls opt to nest in some other places such as disused water tanks or even hoppers! 

Photos John Middleton

 
Most of the barn Owls that we monitor are in nest boxes such as these although some are nesting in natural tree cavities. 
It is important to monitor this species in order that the current population levels can be assessed to determine whether any further declines have occurred. North West Norfolk Ringing Group participate in a national project that was started in the year 2000 and co-ordinated by the British Trust for Ornithology to provide ongoing assessments of the UK Barn Owl population. Monitoring consists of a visit to the nest site by specially trained and licensed bird ringers in the breeding season. Details of occupancy rates, breeding performance and survival are recorded and any young are ringed with uniquely numbered leg rings provided by the British Trust for Ornithology.
Currently we are monitoring over 400 potential nest sites. You can view the nest sites that the Group monitor by clicking .distribution map

 


Naked and helpless


Female and chicks

 

 


These owlets begin to show the facial disc.


Inquisitive youngsters, the bird second from the left is almost certainly a female.

Photos Richard Brooks

If the young are too small or the female is still incubating eggs a repeat visit is made after sufficient time has elapsed for the eggs to hatch or the young to grow sufficiently large to be ringed.

 Photo Richard Brooks

These young owlets have probably already made some exploratory excursions outside the nest box and are almost ready to fledge. The BTO leg rings enable us to keep track of their movements.

This is a recently fledged youngster.
From the spotting on the breast and the pink/buff band we can see this is a young female






Photo Richard Brooks

 

Juvenile Barn Owls remain in the nest for approximately ten weeks but may venture outside the nest box prior to fledging completely, and even when flying strongly they may return to the nest site to roost during the day. However after this time the young owls begin to move away from their natal site to begin the process of finding a territory and a mate of their own. Many young owls die during this time, becoming road traffic casualties or starving and at this time they are very vulnerable and juvenile mortality can be as much as 75%. If they can survive until the following spring by then they have usually ceased to wander, having found a territory and then the mortality rate falls although adults still become victims to road traffic. Most Barn Owls reported dead to the North West Norfolk RG move between 5 and 25 kilometres from where they hatched although some have moved as far as 100 kilometres. 

The preferred prey item of Barn Owls is the field vole Microtus agrestis although they will take a variety of other small mammals including Bank Vole Clethrionomys glareolus, Apodemus spp. (Wood and Yellow-necked Mice Apodemus sylvaticus and A. flavicollis), Common Shrew Sorex araneus, Pygmy Shrew Sorex minutus,  Water Shrew Neomys fodiens, Water Vole Arvicola terrestris, Harvest Mouse Micromys minutus, House Mouse Mus domesticus and Brown Rat Rattus norvegicus. This list is not exhaustive and from analysis of Barn Owl pellets other prey items including Mole Talpa europaea and some bat species have been recorded. The field vole population is cyclic, tending to reach a peak and then falling off and then rising again during the following years. 

Good berry crops and mild winters play their part in this fluctuation of the small mammal population. Barn Owl breeding success (or failure) fluctuates but depends largely on the availability of small mammal prey.

You can click on the picture and expand it to a larger size to view it. Use  your browser 'back' button to return to the page to view more pictures.

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Pole nest box
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Barn owl chicks are weighed and measured 

 

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Nest box in Oak tree
The owners of the Barn Owl 'house' shown in the photos below have had owls nesting in their specially built owl house for many years. 
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A deluxe Barn Owl house! 
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This purpose made nest box complete with viewing window is inside the roof space shown on the left. 

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Barn Owls are a charismatic species and are very useful to capture the attention and imagination especially of children, spreading the conservation word once you have their attention is another aspect of the work that the Group undertakes. You can see just how enthralled these children are by clicking on the picture below.

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Last updated March 2015