Recent news (here and here) that a pair of eagle owls are preparing to nest in North Yorkshire has restarted the controversy around one of the largest owls in the world.

Eagle owls - in Britain?

The Scots Gaelic, Manx, Welsh, Cornish and Irish Gaelic languages all have words for them and it is generally agreed that fossil records indicate eagle owls were present in Britain from some 700,000 years (to at least 10,000 years ago but the evidence for more recently presence is inconclusive). – ten times longer than anatomically modern humans.

There are currently claimed to be 12-40 pairs of eagle owls nesting in Britain but no one is certain how many of these have escaped from captivity (eagle owls were used as decoys to catch birds such as the magpie for centuries) and how many have naturally immigrated here from Europe.

We know that the smaller long-eared and short-eared owls regularly migrate to Britain from Scandinavia and either pass through or stay for the winter (especially the long-eared owl). Owls have been seen resting temporarily on oil rigs in the North Sea. This would explain why some ornithologists were not surprised that isotope analysis of an eagle owl found in Norfolk ten years ago indicated overseas origin.

Are eagle owls native to this country?

The historic records from Orkney (1830), Shetland (1863, 1871) and Argyll (1883) seem likely to be genuine, but the British Ornithologists’ Union (BOU) concluded that these and other records were not strong enough (to reach a balance of probability which is overwhelmingly in favour of natural immigration) and so have classified it as non-native. The World Owl Trust has called for the BOU ruling to be reversed and offered supporting evidence as to why it believes the eagle owl is, and always has been, a true native British species.

Are they protected by law?

All wild bird species (native or non-native) are fully protected by the Wildlife & Countryside Act (remember that offspring of birds that have escaped from captivity are considered wild birds). Any intervention (to cull or remove them to captivity to protect native species, etc) may require a licence from Natural England, if they felt eagle owls were protected by the Act.

Such a licence might be issued more swiftly if it is to control a non-native species – so the status of eagle owls is important. The RSPB has previously said it would not support any cull of eagle owls in Britain, but some will be wondering why the RSPB has begun comparing them to escaped American mink, which are controlled.

Should they be compared with American mink?

American mink were brought here by man relatively recently and can have a devastating effect on local wildlife. On the other hand, eagle owls have lived alongside our other native species for hundreds of thousands of years, so many might consider it alarmist to compare the two. Some may compare them to beavers, which have been reintroduced to this country, but this could also be unfair because eagle owls may be arriving here naturally – just as they are believed to have done in Holland and Belgium.

Where else are they making a comeback?