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

[jurek]

“the Meare Lake Village Eagle Owl remains described in Stewart (2007) date back to c.2,000 years ago (Gray 1966), making them the latest known archaeological remains of an Eagle Owl in Britain.”

However he fails to mention that Stewart said the Meare Lake record was “perhaps best regarded as unconfirmed. Even when first published, there was doubt over the identification of this specimen.”

It would be very interesting if this record was re-investigated. There are now very good and different methods to identify bird bones.

As I said before, it would be very unusual if Eagle Owl naturally died out in Britain as the climate was warming and becoming more suitable for them. Perhaps the only non-Arctic species to do so!

 

[jurek]

Hello,

Eagle Owls are not loathly to fly over water unlike some forest-dwelling owls.

EO breed on rocky offshore archipelagos in Scandinavia, where they must regularily cross at least sea channels.

Steve Dudley lists crossing sea broader than English Channel: from Finland to Sweden via presumably Aland Islands (minimum ca 40 km contiguous sea) and record on Gotland (90 km). I guess more search in European literature would turn more cases, especially from Asia.

I don't know why Steve concluded they wouldn't fly over English Channel (34 km). I think there is confusion here between average behavior and known distance for vagrants.

 

[jurek]

greater average dispersal distances than 52km and greater overall distances than 528km

I think nobody argues that Britain is within average distance travelled by ringed EO.

Eagle Owls are breeding in CE France and C Belgium slightly less than 500 km from England.

 

[phil baber]

Haven't read the whole of this thread. But spent good hours with the Bristol EO, before it dispatched itself against a window.

The BBC's "Eagle Owls In Britain" gave some good stats on dispersal, etc. Worth getting hold of. I have a copy, but mustn't give any copies to others, as that would contravene certain laws...

Jurek, if you can track down this film, it gives some good info on EOs in Holland.

In Puscza Bialowieska you need a local guide!

I'd rather see them on rooftops in Bristol. Wherever they're from!

 

[PaulD]

With regard to ringing recoveries - these are at best a hit-and-miss affair and where small numbers of birds are ringed (I am assuming that the sample size for EO is small compared to most species) recoveries and the data produced by them should by no means be seen as representative: there is huge bias inherent in recoveries generally, especially where the recoveries are generated from random encounters with dead birds (I presume again that most recoveries relate to corpses rather than retraps). Of course we can make assumptions on the only data we have available, but the average distance travelled within a small sample does really permit us to be entirely confident about those assumptions: the sample mean is not the same as the actual mean. It is surely a rational position to state that these birds are physically capable of reaching our shores and, if our limited recovery sample doesn't fit, we at least admit that our data are insufficient to enable us to make a definitive statement that they do not do so. I read somewhere once "Believe the bird, not the book".

The sample size for Eagle Owl was 1,805, which I think is a large sample. Certainly scientific books and papers are written using much smaller sample sizes; a quick flick through The Atlas of Wintering Birds in Britain and Ireland gives numerous examples (eg comments on Long-eared Owl based on a sample size of 148).

If you don’t feel confident about using evidence from ringing recoveries can I ask what evidence led to your earlier stated belief that “the species is more than capable of making long flights over waterbodies”.

 

[PaulD]

It would be very interesting if this record was re-investigated. There are now very good and different methods to identify bird bones.

As I said before, it would be very unusual if Eagle Owl naturally died out in Britain as the climate was warming and becoming more suitable for them. Perhaps the only non-Arctic species to do so!

This bone has been lost and despite considerable effort it has not been relocated.

For full details the article is in British Birds Vol.100, 481-486

It may be relevant to add that Stewart also noted “It is interesting that no other, more recent, records exist, despite a great deal of work by zoo-archaeologists working on assemblages from the Roman period onwards”.

 

[ed keeble]

Hello,

I guess more search in European literature would turn more cases, especially from Asia.

Asia provides some quite interesting parallels- there was a flurry of records from Hokkaido in the 20th century, including breeding, and some discussion about whether they represented the re-discovery of an old population or some (re)colonisation.

Plus I believe there's a record from Amami-Oshima for anyone accumulating instances of island-hopping.

 

[PaulD]

Hello,

Eagle Owls are not loathly to fly over water unlike some forest-dwelling owls.

EO breed on rocky offshore archipelagos in Scandinavia, where they must regularily cross at least sea channels.

Steve Dudley lists crossing sea broader than English Channel: from Finland to Sweden via presumably Aland Islands (minimum ca 40 km contiguous sea) and record on Gotland (90 km). I guess more search in European literature would turn more cases, especially from Asia.

I don't know why Steve concluded they wouldn't fly over English Channel (34 km). I think there is confusion here between average behavior and known distance for vagrants.

Agreed that EO breed on rocky offshore archipelagos, but I can’t find any references to such birds crossing more than a few kms of water.

If an EO goes island hopping via the Aland Islands from Finland to Sweden then I measure the shortest continuous sea crossing as 23 km (not 40). However it’s certainly possible that it crossed the northern end of the Gulf of Bothnia in winter when it’s frozen and didn’t actually cross water. One other probably less likely possibility is that it went round the northern end of the Gulf of Bothnia (there were 14 years between ringing and recovery so it had time to do that).

With regard to the Gotland record I think it must be possible that bird travelled via Oland, so the sea crossing would be 46 km, not 90.

Up until the end of 2008 the Swedes had ringed 8282 Eagle Owls and had 2285 recoveries. One striking fact is that not one of them had made the sea crossing to Denmark despite the fact that it is less than 10 km at several points.

It’s interesting to note the information on owls given in Gatkes book, The Birds of Helgoland. This was published in 1895 and describes the results of over 50 years observations. The totals Gatke recorded were:-

Tawny Owl 1
Little Owl 1
Tengmalm’s Owl 30
Long-eared Owl well known, up to 4 in a day in autumn.
Short-eared Owl common migrant in spring, very common in autumn.
Scops Owl 1
Snowy Owl 1
Hawk Owl 1
Eagle Owl 0

In over 50 years on an island noted for its migratory birds and just 40 km off the German coast he recorded a host of rare birds, but not a single Eagle Owl. Helgoland now has a bird observatory, but over 100 years since Gatkes book Eagle Owl still isn’t on the Helgoland list.

Of course this is not to deny that Eagle Owls can make sea crossings, but the available evidence indicates that they normally avoid them.

As noted in Melling et al the rising population in Western Europe means the likelihood of wild birds reaching Britain will increase, but even so I believe the sea crossing will be a significant barrier to them.

 

[jurek]

It may be relevant to add that Stewart also noted “It is interesting that no other, more recent, records exist, despite a great deal of work by zoo-archaeologists working on assemblages from the Roman period onwards”.

If you believe this source:
http://www.tha-engliscan-gesithas.org.uk/birdlore/fugellar.html
bird remains are very fragmentary, with just 91 species from Roman times and 21 from Anglo-Saxon times. Although some edible birds are well represented, many birds which must have been common then are lacking or found in one find. So this is no proof of lack of eagle owls.

However, Eagle Owl had own name and there are several mentions of it living in Britain.

 

[PaulD]

Jurek

I agree the archaeological record is fragmentary. Nevertheless Derek Yalden (co-author of the book The History of British Birds) wrote in Birdwatch in July 2009:-

“It has to be admitted though that the sparse British record is in sharp contrast with the archaeological record from Sweden, where Eagle Owl is recorded from at least 20 Viking burial sites, often associated with the remains of hawks or falcons. It was used as a decoy in falconry and survives in the Swedish fauna to the present day, so it is less surprising that there are later archaeological records than in the British Isles. By contrast the absence of later records from Britain must surely be a reliable record of early extinction.”

I’ll happily admit that zoo-archaeology isn’t my specialist subject, but there does seem to be agreement that the Mesolithic Demen’s Dale find is the latest confirmed record.

Similarly I claim no special knowledge of ancient bird names. I seem to recall one author noting that there were more old English names for owls than there were species of owls, but I can’t find that reference.

I can’t really comment on your point that “there are several mentions of it living in Britain” without you detailing what those mentions are.

 

[jurek]

“It has to be admitted though that the sparse British record is in sharp contrast with the archaeological record from Sweden, where Eagle Owl is recorded from at least 20 Viking burial sites, often associated with the remains of hawks or falcons. It was used as a decoy in falconry and survives in the Swedish fauna to the present day, so it is less surprising that there are later archaeological records than in the British Isles. By contrast the absence of later records from Britain must surely be a reliable record of early extinction.”

Different burial traditions in Scandinavian culture, because paper by Steven Dudley et al. clearly describes that Eagle Owls was popular in falconry in Britain, too.

 

[PaulD]

Different burial traditions in Scandinavian culture, because paper by Steven Dudley et al. clearly describes that Eagle Owls was popular in falconry in Britain, too.

No it doesn't. The pdf of that paper is available online:-

http://www.britishbirds.co.uk/Eagle Owls.pdf

The section entitled Eagle Owls in Falconry is on page 6 of the pdf and nowhere does it say that Eagle Owls were popular in falconry in Britain.

The possibility that Eagle Owls were imported for falconry is mentioned, but no specific references to this use were found.

If you do have references to Eagle Owls being used in falconry in Britain then please provide them.

 

[jurek]

About falconry in particular - it was main reason of keeping Eagle Owls.

From the paper: "Ray (1678) included an account of two Eagle Owls in ‘His Majesty’s Park of St James’s near Westminster’ (...) Clearly, the species was held in captivity in western Europe at this time. Edward Fountaine bred Eagle Owls in his aviary at Easton, Norfolk, for the first time in 1849 and continued to do so almost annually until at least 1875. According to Gurney (1849a,b), this was apparently the first account of captive breeding in Britain; he commented that after only five weeks, the young were ‘in the same stage as specimens usually [our italics] imported from Norway at this time of year by the London bird-dealers’. The key point here is that as far back as 1849, Eagle Owls were being imported with sufficient frequency for Gurney to use the term ‘usually’."

So, there were Eagle Owls in captivity from 17. century (which authors suggest to be all imported from the Continent), but they left no bones. So I think there was no tradition to bury Eagle Owls with their masters in Britain. And bird remains in Britain are too fragmentary to claim by extension that if Eagle Owls occured here, their remains would be found.

BTW. Studies of bone finds and historic accounts are interpreted very much using modern fauna. So Eagle Owl bones could be unrecognized, dismissed or doubted precisely because it was not supposed to occur here - creating a circular argument.

Significantly, accounts of Little Egrets breeding in Britain in the past centuries were doubted, misinterpreted and considered to be birds imported from the Continent. British ornithologists for at least a century didn't treat Little Egret as a former breeding bird. Then Little Egrets returned to nest in Britain and proven that they can breed here, and then a British ornitologist rediscovered and correctly interpreted the evidence. European ornithologists made the same mistake, when they didn't believe in Bald Ibises in Central Europe.

 

[Biancone]

I don't know much about falconry but I haven't noticed any reference to use of EOs for that purpose in UK (but plenty to various falcons and hawks). I had the idea that some of the 'gentry' in the 18th-19thC liked to keep them as zoological curiosities or for status. Whatever the purpose, perhaps it's telling that they had to be imported.

The historic bird names issue is puzzling. The article "The Ornithology of Anglo-Saxon England" by Frank Stanford (http://www.tha-engliscan-gesithas.org.uk/birdlore/fugsrc.html), cited in the Melling et al BB paper, states that the EO "...named in Old Latin to Old English glossaries from the 8th century could have occurred in the extensive Anglo-Saxon forests". Note the "could have". The name listed is "Uf" or "Huf" and the author's suggestion that it refers to the bird's deep call is plausible given "Uhu" and similar names current in mainland Europe.

Of course, nobody actually knows if the 8thC name in fact referred to the EO call, but even if it does, perhaps it was added by a scribe who had travelled in mainland Europe (and many had). I may well be wrong but it seems that unless there is a clear descriptive element (eg. "Hwitars" for Wheatear!) there is a huge amount of guesswork involved in assigning these early names to Linnaean species, and I'd prefer to see some more solid reasoning before accepting this as evidence for presence of EOs.

Set against this is the apparent absence of any clear reference to Eagle Owl in folk culture or later descriptive or dramatic literature, and the absence of EO remains from Roman period and later archaeological sites (interestingly, re another debate, there is Sea Eagle material!) Seems a bit implausible that there could have been EOs present here a thousand-plus years ago without anyone anywhere having written down a few words about such a large and dramatic creature.

Whether the EO is a 'native' species or not of course depends on where the time threshold is drawn. Haven't got direct access to the literature on EO bone material but if it is dated to about 10,000 years before present, that would place it near the period the last glacial phase was ending and being replaced by warmer conditions. But given recent findings about the North Sea 'Doggerland', which wasn't submerged until about 6,000 years before present, the EO bones pre-date the latest separation of the British Isles and the European mainland. Whether that weakens or strengthens the case for 'native' status depends on your definition.

Don't think there is any reason to exclude the possibility of a dispersing or storm-driven EO reaching the UK after the species' apparent disappearance. But surely a relatively low probability, and as someone said above, even lower that a single EO would find another ex-mainland mate (or even ex-captive). With so many captive birds in the country it's got to be a much higher probability that EOs now in UK are escaped or released ex-captives.

 

[jurek]

The article "The Ornithology of Anglo-Saxon England" by Frank Stanford (http://www.tha-engliscan-gesithas.org.uk/birdlore/fugsrc.html), cited in the Melling et al BB paper, states that the EO "...named in Old Latin to Old English glossaries from the 8th century could have occurred in the extensive Anglo-Saxon forests". Note the "could have". The name listed is "Uf" or "Huf" and the author's suggestion that it refers to the bird's deep call is plausible given "Uhu" and similar names current in mainland Europe.

Seems a bit implausible that there could have been EOs present here a thousand-plus years ago without anyone anywhere having written down a few words about such a large and dramatic creature.

I see here a self-contradictory reasoning. First, you write that EO was reported and had separate name. Then you wonder why it left no mention.

There were repeated reports that there is an Eagle Owl living in British forests and islands. The paper gives further examples.

I think there is confusion why historic texts don't match the quality of a report to BBRC. This is typical for mentions of wild animals in centuries-old texts. They are often casual and doesn't come with description. Some writers know about the existence of an animal, but themselves cannot recognize it very well. So Eagle Owl was probably sometimes confused with other owls, but likewise, White-tailed Eagle was confused with Golden Eagle or smaller raptors. For me, quality of reports of Eagle Owl is similar to those of other birds.

Sorry, I have to fight here British insular mentality. Ornithologists in Europe are sort of aware of uniformity of European nature, so have little doubt that Eagle Owls and lots of other fauna lived across the whole Europe.

 

[Biancone]

Not really contradictory. I mentioned some 'name' evidence for EO in 8thC and then said I'm not convinced. Then mentioned absence of EO from later writings when might expect some mention if EOs here. Where's the contradiction? The actual reports of observed EOs in wild date from early 19thC and according to BOU cannot be substantiated. Seems to me the probable explanation for all the scraps of evidence is that EOs were here when warmer forest conditions spread across land connection after glaciers retreated, were then lost for most of the past few centuries, and are now back, probably because of releases. As for 'insular' mentality, well, the fact of being a group of islands does have some biogeographic implications, eg. different temporal and spatial patterns of faunal distribution according to how readily species cross water gaps.

 

[alcedo.atthis]

Question(s)
Where did the one which caught a cat and flew with it up onto a twin power line just to be electrocuted when the Owl laid the cat over both the live and the earth on the pole just outside Aberdeen 2 years ago?

Where did the breading pair in lower Speyside come from about 12 years ago. They were there for about 5 years?

None had rings or jesses.

Answers on a postcard to Bird Box number 1

Regards

Malky
ps reportedly, there are prehistoric remains in the Tring museum. (Information came directly from the National History Museum)They were classed as Snowy Owl some many years ago, as it seems that there were/are problems seperating the identification of the remains of the skeletons of the two species. Mmmmmmmmmmmmmmm!!
Wonder if modern methods would work better?
Mind you Roy Dennis is still researching this, I think. I wonder if he will come up with contradictory evidence as to the "official" mmm status quoe!!

 

[Docmartin]

Stable isotope paper published

The stable isotope paper referred to in the World Owl Trust report has been published in April's edition of British Birds.

Kelly A, Leighton K, Newton J. 2010. Using stable isotopes to investigate the provenance of an Eagle Owl found in Norfolk. Brit. Birds 103:213-222.

It shows the juvenile feathers of the Eagle Owl found dead in Norfolk in 2006 were significantly depleted in deuterium compared to its second generation feathers, consistent with a likely change in location. Stable isotope analyses were performed also on a control known captives, and wild birds from Norway and The Netherlands, as well as British wild Tawny Owls. The deuterium depletion of the Norfolk bird was more severe than any of the other birds, very different from the Norwegian and Dutch birds for example and there is no evidence that the bird came from Norway. Unfortunately, captive birds gave deuterium ratios very similar to Norwegian wild birds, offering little hope of a clear result.

The deuterium ratios recorded from the Norfolk bird are similar to those found in Bullfinches of Scottish origin, and it seems quite likely that the Norfolk bird, assuming it was wild-hatched, came from northern England or Scotland. However a definitive answer on where it came from has not been possible.

 

[kr236rk]

European Eagle Owl

This is the European Eagle Owl. Britain was part of Continental Europe before sea levels rose to form the North Sea, consequently this bird is a native species.

 

[Amarillo]

some latest news...

http://raptorpolitics.org.uk/?p=1069