17/4/2016

Eagle owls – are they making a comeback in Britain?

Eagle OwlBy Andrew Gilruth, GWCT Communications Director

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?

This top predator is also making a comeback following reintroductions in Norway, Sweden, Switzerland, France, Belgium and Germany. These recovery programmes have received wide acclaim for recovering a species that underwent a significant decline across Europe, along with other top predators such as the wolf and lynx, mainly due to human persecution. Recently, this species has started to colonise urban habitats and is now breeding in several towns and disused quarries in Europe.

Are they a threat to other wildlife?

Eagle owls mostly eat rodents (voles) and Lagomorphs (rabbit and mountain hare, but will also take mustelids, foxes and occasionally fawns. In this country the eagle owl’s main prey appears to be rabbits.

Among birds the most common species eaten are woodpigeons and corvids, and they take a range of water birds. Among the avian predators, though, it is one of the most likely to kill other owls and raptors. The most common raptor in the diet is considered to be the buzzard.

They also take a wide range of other mammals and birds, including raptors; however, the overall impact is unclear. In Bowland, for example, where eagle owls have nested, some other birds of prey continued to nest in the area. In Europe they have been observed killing young and adults of almost all raptors, up to the size of (and including) female goshawks. They are believed to kill for both food and nest defence (they dislike raptors nesting nearby).

Some eagle owls may specialise in killing raptors; one pair in Norway was reported to have killed 13 raptors and owls in one nesting season. In Germany, where the eagle owl has recolonised there is clear evidence of substantive adverse effects on the breeding success of goshawks and buzzards.

In 2010 an eagle owl was caught on film predating a hen harrier. Other species of conservation concern they are known to predate include pine martens, capercaillie, and various raptors and owls

Are they a threat to humans or domestic animals?

They may be aggressive towards people within the breeding territory. This includes some European cities. The species has also believed to take cats and dogs. They have also been known to take lambs, although this appears to be rare

So should we be ‘nipping this in the bud’?

This phrase may be unhelpful. Buzzards are far more numerous than eagle owls in this country, where they are known, for example, to take tawny owls and kestrels. Should we be nipping buzzards in the bud too?

Any studies on gamebird species?

In one particularly detailed study of eagle owl diet, partridges accounted for 8.4% of items and pheasants for 2%, with potential egg predators accounting for over 31% of items. The most important egg predator, the hooded/carrion crow, features in eagle owl diets more than twice as often as in goshawk diets.

Gamekeepers will also be interested to hear that, in the USA, scientists noted that the similarly sized great horned owl had such a great effect on nesting crows that their density is low compared to Britain. These top predators can have other impacts. Scientists in Finland concluded that the golden eagle and wolves could have beneficial effects on small game because they might reduce the need for gamekeepers to control medium-sized carnivore populations including as foxes and mustelids.

Are they prone to disturbance?

Eagle owls are thought to be highly sensitive to disturbance, particularly during incubation, as it may cause adults to abandon eggs and even small young. In Bowland disturbance by licensed raptor workers has been seen by some as the main problem faced by eagle owls.

Does it have any natural enemies?

Only white-tailed eagles and golden eagles are known to kill eagle owls but badgers, pine martens and foxes might predate eagle owl nests. Their populations may be limited by the availability of nest sites. There is some evidence from central Europe to support this.

What next?

This is a species that has had to overcome persecution, the accumulation of pesticides up the food chain, and collisions with vehicles, barbed wire and power lines. The British Trust for Ornithology states that they have bred here for 20 years – so coupled with its expansion across continental Europe, this species appears to be winning against all odds.

Get our FREE weekly newsletter

Stay updated and get all the latest GWCT blog updates and news delivered straight to your inbox.

Free Weekly Newsletter


*You may change your mind any time. For more information, see our Privacy Policy.

Comments

Derbyshire

at 21:22 on 28/03/2018 by Nigel

Eagle owls are nesting in Derbyshire, no matter what the authorities say, or the twitchers. They are in denial about the owls & don't want to believe it, but i know it is a fact.. They are back & that is that!!

Eagle Owls in UK

at 7:15 on 22/02/2018 by Jack fitsgerald

Its clear they belong here, its clear they breed here, its clear they came of their own accord! Its also clear that 40 pairs of Eagle Owls will NOT dent the population of some 2-4 million game birds released every year unless they are savage eaters who will consume upto 4000 pheasants per week! Each! In reality MANY of the thousands of the game birds killed every year actually die on our roads, because they are stupid and have no road sense! So, are we going to cull drivers now because Ian Botham et al are losing out on a meagre profit?! Get a grip! Why does man feel so threatened by mother nature? We have the power to destroy cities yet fossils in flat caps are seriously worrying about a bird with a 6ft wingspan killing a few raptors! Get some bloody perspective!!!! Leave them alone! And whilst you’re at it bring back the Eurasian Lynx & Eurasian Wolf to deal with the thousands of wild herbivores relentlessly stripping our ancient lands of forest and crops!! Man messed it up and man isnt mopping it up! Time to take a step back and let nature decide the balance; she was after all doing a pretty good job before we showed up and created all this mess!

A North American Perspective On The British Eagle Owl

at 4:07 on 26/02/2017 by Steve O'Hara

Please understand, this bird is one of the world's most spectacular birds of prey. For sheer size and prey capacity, there is nothing in North America, South America, Africa, South Asia, Australia, New Zealand or Japan that comes close. Just imagine that this amazing bird has - of its own accord - managed to re-establish a foothold in an ancestral home where is once was a part of your nation's cultural heritage. Yet, despite the fact that it has managed to grab this foothold through its own tenacity - as opposed to a reintroduction program - there are still some among you that would seek to exterminate it. Before you do, let's look at some facts. First of all, Britain's current most important raptor predator is your own goshawk: https://en.wikipedia.org/wiki/Northern_goshawk The eagle owl is the only raptor that can provide any control on your goshawks besides your golden and white tailed eagles. Rather than suppressing the population of your native harriers, I suggest the effect of the British eagle owl would be a net neutral to positive for the harrier by checking its major avian predator, the goshawk. Britons, please realize that this amazing bird has found its own way back to its previous home. How can you contemplate exterminating it a second time?

Eagle Owl

at 7:00 on 22/04/2016 by Terry Pickford

Very well written article. Regarding the claim made that an eagle owl was caught on camera in 2010 predating a hen harrier nest, if this was the video from Bowland, the owl was captured landing on top of a clutch of eggs in a nest. The female harrier was able to fly off but deserted her nest. In I think 2014 two abandoned eagle owl nests containing eggs were located in Bowland. Both nests had been visited during the day by those tasked with looking after these nests. I'm afraid it was a case of irresponsibility. Last year a Bowland resident witnessed three wardens visiting a nest containing eggs , again in the day. It appears the nesting owls then deserted their eggs.

Eagle owls

at 12:36 on 20/04/2016 by Jack hoy

Do they need a large woodland areas to use for hunting and breeding ? here on the Essex coast a lot of the smaller species of owl are relatively common and woodland can be several miles inland. I would love to see one in the wild.

Eagle Owls

at 9:56 on 20/04/2016 by Charles Grisedale

I know it can be a nightmare if they start on your pheasant poults , but if they are sensitive to disturbance I can't see a problem . Anyway pheasants are replaceable . As they control Goshawks , Buzzards and Crows , I think I could live with them . As long as they don't murder Lapwings I am all for them . I did see one on my roof 16 years ago . I thought at first it was a goose flying towards the house in the dusk .

Eagle Owls

at 16:14 on 19/04/2016 by Robert Jones

Whilst the outline about these predators is basically correct they do predate heavily on other Owls. This has been found to be the case in many studies. Our native Owl population is not in a strong position especially the Barn Owl. Whilst there are few in number at the moment the Eagle Owl could become a problem if they find other Owls hunting at night an easy target. Tawny, Little Owl & barn owls could be in trouble. Often problems caused by reintroduction of Species that no longer are part of our ecology are only found out too late.

Eagle owls

at 14:37 on 19/04/2016 by David Dunford

A reasonably balanced article. But I'd like to know who the "some" are in "In Bowland disturbance by licensed raptor workers has been seen by some as the main problem faced by eagle owls.". I can probably guess,

Eagle Owl

at 11:55 on 19/04/2016 by Freddie Wilson

The evidence at present shows that the Eagle owl is posing a minimal threat to the bird community in general. This includes our game bird population as described in your article. Obviously this could change if the Owl were to be present in greater numbers( although this increase appears unlikely in the foreseeable future). I say give this magnificent Owl the opportunity to co-exist with us at present it may help with the control of other far more damaging predators.

Eagle Owl

at 10:53 on 19/04/2016 by Robert Dear

My personal opinion is it's great to have these wonderful birds nesting once again in this country. I would love to see one in the wild. I think it is a great honour to have any species that were once native to this country making a comeback. But in saying that I am not a great fan of re-wilding, I think that needs a great deal more thought e.g. the Beaver where conflicts seem to be appearing already, with fisheries and wildlife factions having different opinions.

European Eagle Owl

at 9:58 on 19/04/2016 by Bryan Benn

A very interesting and well balanced report by GWCT. I think we are still in a "do nothing", phase with these Owls. Monitor them and see if they continue to re colonise parts of Britain, and at what pace. See what impact they have, favourable and adverse, on all other wildlife and all countryside interests. I do have concerns about their impact on other less numerous Raptors and Owls: far from that on such as Buzzards whose numbers seem to be growing at a rate that seems to want to challenge exponential!

European eagle owl

at 17:27 on 17/04/2016 by Lyndon rowland

We should be encouraging thier spread. Lets bring back the balance too many corvids buzzards spars and peregines about. Dont think rspb will agree and provide as much support as they have for the peregine.

Make a comment

Cookie Policy

Our website uses cookies to provide you with a better online experience. If you continue to use our site without changing your browser settings, we'll assume you are happy to receive cookies. Please read our cookie policy for more information.

Do not show this message again