Eagle Owls in Britain, Scientific Paper by The World Owl Trust (1 Viewer)

[terry pickford]

The world Owl Trust have today (16 February) published their long awaited Scientific Paper dealing with the issue of eagle owls in Briatin, native or allian?

The document has been published in full on the raptor politics web site as a Pdf file.

You may need an hour or so to read the full 40 odd pages.

Follow the attached link. http://raptorpolitics.org.uk/wp-content/uploads/2010/02/EAGLE-OWLS-IN-BRITAIN-DOSSIER.pdf

 

[Sy V]

Very interesting indeed, Terry.

The summary states:

"In eastern Finland Mikkola found that although paired Eagle Owls will change actual nest sites from year to year, they usually retain the same territory throughout. This also seems to be the pattern in Bowland, as well as the former Yorkshire pair. For the reasons given, we believe that any future spread (if any) within the UK will be small – possibly <100 pairs – though this is impossible to quantify at the present time due to lack of sufficient data, especially of the claimed release programmes.
Given the probable mortality problems listed above, plus the large size of their territories (variable according to prey and nest site availability) it seems unlikely that the Eagle Owl will ever become a serious problem in Britain, and we would cite the fact that the Yorkshire birds nested virtually unknown to all but a few, as did the Bowland pair until the birding network and media drew attention to their presence.
We can find no evidence that Eagle Owls breeding in the UK either in the past or in the present have caused any environmental problems or seriously affected the numbers of other species sharing their environment. Nor have we found records of any of the ‘species of conservation concern’ listed in the DEFRA Risk Assessment, being taken as prey in Britain.
We have found no evidence of attacks on farm livestock, and believe that apart from one or two attacks on dogs taken too near to active nests, allegations that they are a threat to domestic pets are largely based on ‘sensationalist’ media hype.
Like many other organizations and individuals, the World Owl Trust has submitted its response to the Risk Assessment’s conclusions, outlining in brief why we oppose its findings and contend that most of the answers given by CABI are either conjecture or represent data taken from European and Fennoscandia studies that are not relevant to Eagle Owls breeding in Britain. This response can be seen on our website www.owls.org
We believe that in this report we have given sufficient evidence to suggest that the European Eagle Owl Bubo bubo bubo is a legitimate candidate for listing as a native British species. The BOU’s arbitrary interpretation of what does or does not constitute a native species, is at odds with archaeologists, palaeontologists and mammal scientists’ interpretations (see Stewart 2007 and Yalden 2003), and also that published by DEFRA. Furthermore, their claim that the European Eagle Owl is an invasive alien originating solely from escapes or deliberate releases is unsubstantiated. We therefore now call on DEFRA, FERA, the RSPB, BTO and Natural England to scrap the Risk Assessment document and it’s conclusions until first-hand accurate data is collected from pairs nesting or present in Britain.
We also call on the British Ornithologist’s Union to remove the Eurasian Eagle Owl from Category E* of the British List and place this species in Category A unless they can validate their claim that all Eagle Owls currently in Britain originate from captive stock."

 

[Richard Klim]

The world Owl Trust have today (16 February) published their long awaited Scientific Paper dealing with the issue of eagle owls in Briatin, native or allian?
The document has been published in full on the raptor politics web site as a Pdf file.

Interesting stuff, but the Raptor Politics website needlessly undermines the report's credibility by describing it as a 'Scientific Paper'. Such an overtly political, opinionated and anecdotal document would never be considered for publication by a respected peer-reviewed scientific journal. For example, just try counting the number of exclamation marks...

Richard

 

[Farnboro John]

Frankly I think the authorities should address the question of whether any species protected under European Law to which the UK has committed itself, can be legally controlled or eliminated from the UK. The evidence for problems arising from Eagle Owls Bubo bubo is thin at best, but the evidence for economic damage resulting from the presence of Edible Dormice Glis glis is considerable yet the issue has not been gripped. One wonders why not, presumably principles are applicable across the range of species. A legal opinion devoid of application to a particular species is what is needed here before any scientific or political group can opine on the desirability or otherwise of action.

John

 

[TwoDipsfromAmsterdam]

Interesting stuff, but the Raptor Politics website needlessly undermines the report's credibility by describing it as a 'Scientific Paper'. Such an overtly political, opinionated and anecdotal document would never be considered for publication by a respected peer-reviewed scientific journal. For example, just try counting the number of exclamation marks...

Richard

That was my initial reaction too. I haven't had chance to read it through but a quick glance suggested it was far from "scientific".

David

 

[Strandman]

You may need an hour or so to read the full 40 odd pages.

Not sure it deserves an hour. Try this for a bit of science:

"If a Scops Owl can make it to Orkney, why should anyone doubt that an Eagle Owl can?"

 

[Stephen Fletcher]

Interesting stuff, but the Raptor Politics website needlessly undermines the report's credibility by describing it as a 'Scientific Paper'. Such an overtly political, opinionated and anecdotal document would never be considered for publication by a respected peer-reviewed scientific journal.
Richard

Exactly, as it is plain english for everyone to understand, not unnecessarily designed to baffle with scientific jargon unless you are, as you say, one of the few "peers" able to understand its language. Was it ever intended to be published in a scientific journal ? If not, then plain english, for plain englishmen to understand would make perfect common sense, surely ?

 

[AlanCh]

Not sure it deserves an hour. Try this for a bit of science:

"If a Scops Owl can make it to Orkney, why should anyone doubt that an Eagle Owl can?"

Obvious where you stand in the arguments - perhaps you should have included the full quote:

"The west coast of Norway (a stronghold of the species) lies some 350km from Shetland, and c.400km from the Scottish mainland, which at first glance seems a very long way for such a heavy bird to travel. However, anyone who has witnessed at first hand the majestic wing and gliding powers of this bird could surely have no doubts about its ability to make such crossings – a fact accepted by the late, great Chris Mead of the BTO, as well as Roy Dennis, former Highlands Officer for the RSPB, who knows the bird well. What is more, the low wing-loadings (0.71) of the gigantic Eagle Owl and that of the tiny Scops Owl are virtually the same and indicate a high level of flight efficiency as well as the Eagle Owl’s ability to glide easily and fly slowly for long periods at a time (Mikkola 1983). The Scops Owl does in fact arrive in Britain from time to time without ever being questioned as a genuine vagrant (nor should it be, for one individual even made it to Papa Westray, Orkney in 1996). If a Scops Owl can make it to Orkney, why should anyone doubt that an Eagle Owl can?"

There is, of course, much more discussion on the dispersal movements of young Eagle owls in Europe. Well worth reading.

 

[Steve Dudley]

Having read this article and noted the misrepresentation of the BOU and the Melling et al paper (an official paper of the BOU), I will repeat my offer (made on other EO threads) to provide anyone with a PDF of -

Melling, Tim., Dudley, Steve & Doherty, Paul. 2008. The Eagle Owl in Britain. British Birds 101: 478-490.

Please PM me your email address and I will gladly send.

The Melling et al paper will correct many of the inaccurate statements attributed to the BOU (and some of the other inaccuracies) in this article and it clearly sets out the BOU's position on the status of Eagle Owl in Britain.

Steve Dudley
British Ornithologists' Union

 

[jurek]

Steve, thanks for the paper.

However I am of opinion that there is a high probability that wild continental Eagle Owl can occur as natural vagrants and can join British feral breeding population.

As you pointed in your paper, there are cases of crossing sea - eg. Gotland. Continental population is growing and, what you omitted from your paper, significantly spreading from the historic strongholds in the mountains in the centre of the Continent and colonizing lowlands and farmland closer to the Channel.

The possible way to check it would be analysis of stable isotopes (carbon and nitrogen, not hydrogen) between British captive and wild Continental eagle owls, and of corpses found in Britain. Since the diet of captive EOs is based on rats and chicks fed commercial diet, isotope composition might be clearly different from wild birds eating natural prey. The analysis of bones might also discover the place where the bird was born, even after it spent some years elsewhere. This is more promising than analysis of hydrogen isotopes and feathers used for the certain Siberian duck.

I have no time to write details, but i hope somebody will want to follow the thread.

 

[jurek]

Follow the attached link. http://raptorpolitics.org.uk/wp-content/uploads/2010/02/EAGLE-OWLS-IN-BRITAIN-DOSSIER.pdf

I do not agree with everything what Raptor Politics says, but British authorities didn't make a good job.

First, there are draconian punishments for something so arbitrary and difficult to judge by a layman lawyer as "letting the falconry bird escape by negligence". This is natural that falconers are worried and furious. I am certainly no fan of falconry, but this is a bad law.

Second, DEFRA forgot the precautionary principle - heaps of secondary evidence although no single 100% proof is very different from the claim that Eagle Owl didn't occur in Britain since the last Ice Age. This potentially opens the way for wiping out the native species.

Third, treating Eagle Owl as a potential pest is incredible. Any conservationist in Europe knows it is low density, shy species with slow breeding rate, which required conservation programs to keep it from going extinct. Something of a symbol of endangered wildlife.

 

[Richard Klim]

Also tabled in 'the other place', I see:
http://www.surfbirds.com/forum/showthread.php?t=6494

Richard

 

[James Lowther]

Exactly, as it is plain english for everyone to understand, not unnecessarily designed to baffle with scientific jargon unless you are, as you say, one of the few "peers" able to understand its language. Was it ever intended to be published in a scientific journal ? If not, then plain english, for plain englishmen to understand would make perfect common sense, surely ?

i've not read the original link so as far as i know it may well be a very sensible and well-written document, however if it's not "intended to be published in a scientific journal" then by definition it's not a "scientific paper"

and richard's reservations were because it was "overtly political, opinionated and anecdotal", not because it was written in plain english

 

[Tony Warburton]

The report was not written as a 'scientific paper' intended for a scientific journal. As we made clear, it was written in response to the recent Defra (fera) Risk Assessment for the Eagle Owl and I am sorry if some readers are unable to discern the difference. As a co-author of the first ever monograph on the Barn Owl (Poyser 1982) and papers in 'British Birds', rest assured that I do know the difference. Nor do we regard the BOU statement that "members (of the Rare Breeding Birds Panel) were equally united in believing (i.e. unsubstantiated) that the possibility of escapes, releases and confusion over the provenance of skins could not be dismissed" and "There is no evidence that this species has occurred in the wild state in Britain and Ireland for over 200 years" as 'scientific'. All our quotes of BOU (inc. Melling et.al.) and other statements are taken from their own actual documents, so why our words are regarded as overtly political and anecdotal we simply do not comprehend. The answers given by CABI in the Risk Assessment made the World Owl Trust realise that there was a pressing need for an 'all-in-one' document which lists the facts about Eagle Owls in Britain as we and others see them (not just the BOU) and others have recorded them, all of which are documented - see the list of c.70 references which detail the true facts recorded by first hand observers/researchers of this species, including the World Owl Trust with over 30 years experience of the species.

The paper was peer reviewed by 13 proof readers and ammended according to their comments. These reviewers included Maj. Tony Crease who researched and managed the ill-fated Yorkshire breeding pair as well as others in Germany, Dr Andrew Kelly who carried out the isotope tests on the dead Norfolk bird, an ex-RSPB Reserve Warden who is lucky enough to have a pair breeding on his doorstep, and three fieldworkers with vast experience of Eagle Owls in the wild, both in the UK and in Europe. These are the people we regard as 'peers'.


We are pleased to see that Steve Dudley has read our report. Could he now, for the sake of 'scientific accuracy' now inform us who the person was(representing the BOU) whose comments in the film 'Return of the Eagle Owl' resulted in the the following statement (in a BOU report in 'British Birds' 100 Nov.2007 - Mark Holling & the Rare Breeding Birds Panel) "The programme stated that, since the Eagle Owl is classified as by the BOU as a non-native species, it does not carry full protection, but this error was corrected in repeat showings of the programme". Readers of our report will know just what the effect of this comment was on the Yorkshire breeding pair.

We fully expected to receive criticisms regarding our report, but we can live with this in the knowledge that now people will know the real truth about Eagle Owls in Britain, and not just repeated 'facts' gleaned from research carried out in Europe and Fennoscandia. To quote Pertti Saurola (a scientist) "Bad or good judgements are just subjective personal opinions and not a universal 'truth' of conservation". So there we are, we admit to being opinionated - and our opinion is that the European Eagle owl is a genuine British native, and as such should be on Category A of the British List, not Category E* on the whim of a Panel of 'experts'.

Tony Warburton

 

[Biancone]

In blissful ignorance of the personalities involved, here's my tuppence worth.

The WOT paper isn't as bad as some above have suggested. Yes, it's clearly partisan and unconstrained by the protocols of 'scientific' reporting, but there are plenty of poorly supported assertions and opinions in refereed journals too.

The report presents no positive evidence that any of the reports of Eagle Owl in recent history refer to other than escaped or released captives (or to different owl species). Unfortunately, it doesn't matter how many intriguing but undocumented or unverifiable records are available; they cannot add up to a solid case. Given that since at least the late seventeenth century some of the gentry have kept eagle owls, and that birds escape from aviaries, the simplest hypothesis is that UK records relate to former captives. Until someone finds a dusty stuffed owl sitting in a provincial museum storeroom, labelled "collected as arrived off the North Sea, October 1849", or until some feather isotope data are available, the case for a natural wild eagle owl population in the UK remains unproven.

Interesting that gaelic names seem to exist for the species, but I think one would need to see evidence of actual use, and that whoever used these names was also using a popular taxonomy that distinguished eagle owls from other owls, and more importantly that the names weren't just made up by someone populating a database.

However, nobody can exclude the possibility that a dispersing juvenile or vagrant adult Eagle Owl has arrived here naturally from time to time. This seems quite a plausible explanation for the claimed Shetland and Orkney records. Must admit I'd be interested to see the evidence the BOURC assessed and rejected in 1996 and form my own views.

What I find most perplexing is that bones attributed to Eagle Owl are known from around the Pleistocene-Holocene boundary in the UK, and perhaps into the Mesolithic (haven't tracked down the original sources), confirming that it is a "native" species as usually understood, but such species can only be categorised in BOU category F which is not treated as part of the British List.

 

[jurek]

Actually, I have less and less faith in such historic restorations of past birdlife.

Breeding records of Little Egrets were long attributed to Lapwings, and only when Little Egrets recolonized Britain, ornithologists reinterpreted correctly the historical texts. White-tailed Eagles were clearly historic breeders, but were also confused with Golden Eagles and other raptors. Eagle Owls had their own name, but were also confused with other owls.

I can only say that researchers are so much influenced by current fauna, and records are so fragmentary, that there is a room for historic breeding o Eagle Owls.

What I find most perplexing is that bones attributed to Eagle Owl are known from around the Pleistocene-Holocene boundary in the UK, and perhaps into the Mesolithic (haven't tracked down the original sources), confirming that it is a "native" species as usually understood, but such species can only be categorised in BOU category F which is not treated as part of the British List.

Actually, I find this rather unlikely, that Eagle Owls colonized Britain in subarctic climate immediately after the Ice Age, but died out when the climate was warming and becoming more suitable for them. This is not arctic species like Snowy Owl.

I suggest either:
1) These Eagle Owl remains come from the previous warm period (Eemian), and not immediately after interglacial.
2) Eagle Owls lived in Britain much longer, but their presence became confused by other owls and imported birds (BTW - is there evidence of massive trade of captive Eagle Owls from the continent or they were locally sourced?)

 

[jurek]

Out of interest. Why Eagle Owls were so popular in falconry?

They were not flown at game. Instead, people used the behaviour of other birds to mob Eagle Owls.

Tame Eagle Owl was taken to the forest or moor and put on a pole. The hunter hid in a blind nearby. Falcons and other raptors in the area were soon attracted and started mobbing the owl. Sometimes, raptors were caught alive in snares or nets set nearby and used for falconry. Elsewhere, it was effective way to shoot raptors and corvids as vermin and some small birds for food. This hunting with Eagle Owl was still widely used in Europe in the first half of 20. century, until bird protection laws were commonly introduced.

 

[wolfbirder]

The "future of Englands Hen Harriers" post states that an adult Hen harrier was taken by the dunsop bridge Eagle owls in 2007.

Either way, this single killing does not really affect the argument IMO.

 

[Amarillo]

The "future of Englands Hen Harriers" post states that an adult Hen harrier was taken by the dunsop bridge Eagle owls in 2007.

Either way, this single killing does not really affect the argument IMO.

This WASN'T proved.

 

[rokermartin]

Out of interest. Why Eagle Owls were so popular in falconry?

They were not flown at game. Instead, people used the behaviour of other birds to mob Eagle Owls.

Tame Eagle Owl was taken to the forest or moor and put on a pole. The hunter hid in a blind nearby. Falcons and other raptors in the area were soon attracted and started mobbing the owl. Sometimes, raptors were caught alive in snares or nets set nearby and used for falconry. Elsewhere, it was effective way to shoot raptors and corvids as vermin and some small birds for food. This hunting with Eagle Owl was still widely used in Europe in the first half of 20. century, until bird protection laws were commonly introduced.

Some people use Eagle Owls to hunt foxes.