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

bluechaffinch · Mar 3, 2010

I have to say this is all rather ridiculous. Are we to dismiss the expert views of Mr Warburton and the extremely persuasive arguments and, let us not forget, evidence that he presents within this article? Does the presence of some exclamation marks indicate that it is not somehow 'serious'? Please...

There is archaeological and historical/cultural evidence that this species has been around in Britain for an awfully long time; the species is more than capable of making long flights over waterbodies; the species can and does move long distances regularly; and the species is not the child- and pet-devouring anti-Christ.

I for one am inclined to take Mr Warburton at his word and bow to his greater expertise on this matter - his posts here have been informative and persuasive and I really just cannot see why this species in particular seems to be the subject of so much negativity in regard to its 'expertly appointed' status.

Richard Klim · Mar 3, 2010

Tony Warburton said:
One for Richard and Graham who apparently object to my many exclamation marks (I didn't realise their use was illegal!!!). Another dictionary definition: 'Eclamation mark' = "indicating anger, pain, surprise etc". Believe me - I feel all of these things with regard to the Eagle Owl controversy, and if they upset you so much, you should feel grateful that I chose not to put in many more! What does grieve me is that in the face of this important discussion, and having apparently waded through all 50 pages of the report, the only comment you both can make is about the number of exclamation marks! Very sad.

Of course exclamation marks aren't illegal - I use them myself, far too often! But it's unusual to see them used so liberally in a 'scientific paper'. To quote the Oxford Dictionary of English:

An exclamation mark shows in writing what you would normally say loudly or strongly in speech, to attract attention or to tell someone what to do. In ordinary writing, you do not often need to use the exclamation mark in this way. Avoid using it just to add a false sense of drama or sensation to writing that is otherwise routine or unexciting.

Or, more pointedly, from The Guardian Book of English Language:

exclamation marks - do not use!

Scientific papers present and discuss evidence, and draw evidence-based conclusions - this shouldn't require the protracted use of emotive language. I'd picked on this one aspect to illustrate my point, but the report is littered with distinctly unscientific language. Just one other random example:

It is also worth noting that France, the Netherlands... and Belgium..., all now have breeding Eagle Owls and are a mere stone's throw away from southern and eastern England - well within the capabilities of a dispersing Eagle Owl.

For such a key point, one would expect a scientific paper to provide some discussion of the over-water distances involved. Instead, the report unhelpfully resorts to hyperbole (again, unusual in a scientific paper), quantifying the distances to all three nations as "a mere stone's throw".
[Incidentally, elsewhere in the report a random mix of imperial and metric distance units is used - very unusual practice in a scientific paper...]

My original comment was restricted to Raptor Politics' counterproductive hyping of the report as a 'scientific paper'. Given the unscientific presentation and language immediately apparent on reading the document, this unnecessary claim seriously reduced its credibility for me, despite starting with an open mind (and I'm sure that many others with a science background will have formed similar impressions). Why not simply present the report as a 'review' or 'discussion paper'?

Richard

kr236rk · Mar 3, 2010

hooray!

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".

We're politically part of Europe now so the 'Euro BB' is in. We were physically part of Europe prehistorically so it's nonsense to assert that this bird hasn't lived here: it's a Brit!

Ric

kr236rk · Mar 3, 2010

i mean it's a Brit as much as it is anything else

nirofo · Mar 4, 2010

Gary Jenkins said:
'Only a handful in the area' is a little bit blase Amarillo. I realise that they are not on every fence post, but Bowland is the breeding stronghold in England. Im sure you'll agree, if the EO had chosen to breed in the middle of London, then the future of the HH would be a little more secure.
The EO is a magnificant bird, but its just in the wrong place totally.(IMO)

So, would you say the Hen Harriers are more secure from the gamekeepers and so-called Wildlife Liaison Officer than they are from the Eagle Owl ???

nirofo.

PaulD · Mar 4, 2010

bluechaffinch said:
There is archaeological and historical/cultural evidence that this species has been around in Britain for an awfully long time; the species is more than capable of making long flights over waterbodies; the species can and does move long distances regularly

Archaeological evidence

On page 9 of his paper Warburton writes “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.”

The last confirmed record is the Demen’s Dale bird from about 10,000 to 5,500 years ago.

Sea Crossings

Ringing recoveries indicate that sea crossings are a rare event for Eagle Owls. The furthest movement I can trace for an Eagle Owl is 528km, but that was overland and it can’t be assumed that crossing the English Channel is “a mere stone’s throw.”

The furthest movements I can trace for Little and Tawny Owls are 600 and 725km respectively. Nevertheless the Channel was enough of a barrier to prevent Little Owls colonising Britain and Tawny Owls have never even occurred in Ireland despite a sea crossing of only 20km at one point.

Obviously these are different species, but it does prove that overland movements of hundreds of kilometres are no indication that a species will readily make sea crossings of even a few tens of kilometres.

Farnboro John · Mar 4, 2010

PaulD said:
Archaeological evidence

On page 9 of his paper Warburton writes “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.”

The last confirmed record is the Demen’s Dale bird from about 10,000 to 5,500 years ago.

Sea Crossings

Ringing recoveries indicate that sea crossings are a rare event for Eagle Owls. The furthest movement I can trace for an Eagle Owl is 528km, but that was overland and it can’t be assumed that crossing the English Channel is “a mere stone’s throw.”

The furthest movements I can trace for Little and Tawny Owls are 600 and 725km respectively. Nevertheless the Channel was enough of a barrier to prevent Little Owls colonising Britain and Tawny Owls have never even occurred in Ireland despite a sea crossing of only 20km at one point.

Obviously these are different species, but it does prove that overland movements of hundreds of kilometres are no indication that a species will readily make sea crossings of even a few tens of kilometres.

On the other hand both Short- and Long-eared Owls regularly cross the North Sea, and Snowies navigate the North Atlantic, so you kind of pays your money and takes your choice on the water-crossing issue. Does our dear old Bubo bubo have more in common with a Tawny or a Long-ear? Are the "ears" clues to water-crossing ability - after all Scops Owl pitches up in Britain effortlessly - by George I'm onto something here!

John

dantheman · Mar 4, 2010

Farnboro John said:
Does our dear old Bubo bubo have more in common with a Tawny or a Long-ear? Are the "ears" clues to water-crossing ability - after all Scops Owl pitches up in Britain effortlessly - by George I'm onto something here!

John

In the style of Dumbo you mean?? :eek!:

Definitely worth writing up in a scientific paper!!!

(And yes, your use of the familiar 'our' above has been noted - unless you are of course speaking from a European point of view.

)

PaulD · Mar 4, 2010

Farnboro John said:
On the other hand both Short- and Long-eared Owls regularly cross the North Sea, and Snowies navigate the North Atlantic, so you kind of pays your money and takes your choice on the water-crossing issue. Does our dear old Bubo bubo have more in common with a Tawny or a Long-ear? Are the "ears" clues to water-crossing ability - after all Scops Owl pitches up in Britain effortlessly - by George I'm onto something here!

John

Thanks for the comments John but I don’t think it is a case of you pays your money and you takes your choice. You look at the evidence (primarily ringing recoveries) and see what they tell you.

Here’s a table of European owls showing the average distance of movement after ringing (primarily based on BWP data)

Ranking from most sedentary to most migratory

Based on average distance moved by ringed birds (primarily based on BWP data)

Tawny Owl – 15km
Little Owl – 15km
Ural Owl – 30km
Eagle Owl – 52km
Great Grey Owl – 100km
Pygmy Owl - 150km
Tengmalm’s Owl – irruptive movements of over 1000km noted
Snowy Owl – 830km
Hawk Owl – few figures, but recoveries are long distance (eg Sweden to Russia). One moved 1860km.
Long-eared Owl - Migratory in parts of its range with movements of over 2000km recorded.
Short-eared Owl - Migratory and nomadic. One movement of 3345km.
Scops Owl – Few figures, but wholly or partially migratory and eastern birds travel 7000–8000 km to their wintering areas.

That tells me that Eagle Owl is one of the more sedentary European owls and in that respect does indeed have more in common with Tawny Owl than Long-eared Owl.

King Edward · Mar 4, 2010

Farnboro John said:
On the other hand both Short- and Long-eared Owls regularly cross the North Sea, and Snowies navigate the North Atlantic, so you kind of pays your money and takes your choice on the water-crossing issue. Does our dear old Bubo bubo have more in common with a Tawny or a Long-ear? Are the "ears" clues to water-crossing ability - after all Scops Owl pitches up in Britain effortlessly - by George I'm onto something here!

John

Leaving aside ear lengths, Long-eared, Short-eared and Snowy Owls are all migrant or irruptive species, for which long distance movements and sea crossings of adults are part of normal behaviour. Likewise for the Scops Owl, also a migrant species. Tawny and Eagle Owls, though, are both resident, non-migratory species which do not normally make long (or short) sea crossings. That's not to say it's impossible for an individual owl to make such a journey, but it's much less likely (and even more unlikely that enough individuals would make it across to establish a viable population).
Edit: missed PaulD's post, making the same point in better detail.

Mike Price · Mar 4, 2010

There is plenty of evidence showing displaced juv Eagle owls are travelling far greater distances than those listed. It's far from being impossible that they have or would eventually cross the channel from France.

I think we must accept that much don't we?

From things I have read and watched it seems that the UK is close to ideal for Eagle owls so my thoughts would be that it would only be a matter of time before they found their way here and established a viable population, who can say if that has already happened or not?

Everyone seems to interpret the parts that support their own arguement for or against Eagle owls occuring naturally in the UK, to me it seems irrelevent given that once a pair breed that offspring is a wild bird.

It's not a case of naturally occuring = good, otherwise = bad.

I believe a more thorough funded evaluation of the potential damage or lack of damage seems to be the correct way forwards, the current FERA risk assessment seems woefully inadequate so where does that leave us?

nirofo · Mar 4, 2010

I fail to see how it can be assumed that the Eagle Owl could not have made it's own way to the UK, in fact it probably never left it, it's natural distribution covers Asia, Scandinavia, Europe, Northern parts of Africa, the Middle East, the short hop across to the UK would pose it no problems whatsoever. Are we so arrogant in this country as to believe that we know more about the birds abilities to decide for itself where it wants to live and breed. I think there is more likely an hidden agenda for the anti Raptor brigade, (keepers/estate owners etc), where it would suit them if they could have this super predator removed officially, rather than have it added to the Schedule one breeding list. Having seen the multi strokes that are being pulled to eliminate the Hen Harrier and other Raptors on Bowland by the keepers and so-called "Wildlife Liaison Officer", and the indiference shown by the owners, then it's obvious they will stop at nothing to have the superb Eagle Owl removed at any cost.

nirofo.

PaulD · Mar 4, 2010

Mike Price said:
There is plenty of evidence showing displaced juv Eagle owls are travelling far greater distances than those listed. It's far from being impossible that they have or would eventually cross the channel from France.

New or overlooked information is always welcome. If you have information that shows greater average dispersal distances than 52km and greater overall distances than 528km then please post a link to it or detail the source.

Tony Warburton's paper made no mention of average dispersal distances and the longest movement he noted was 480km, so if there "is plenty of evidence showing displaced juv Eagle owls are travelling far greater distances" than I listed then Tony missed it as well.

I should stress that I am not suggesting that Eagle Owls are incapable of making sea crossings (the paper by Melling et al details a 40km sea crossing to Gotland). However the available evidence clearly indicates that sea crossings are a significant barrier to Eagle Owls and that they normally avoid them. Which makes it makes it extremely unlikely that they will get here in sufficient numbers to colonise.

But as noted above, new or overlooked information is always welcome so please post a link.

Farnboro John · Mar 4, 2010

dantheman said:
In the style of Dumbo you mean?? :eek!:

Definitely worth writing up in a scientific paper!!!

(And yes, your use of the familiar 'our' above has been noted - unless you are of course speaking from a European point of view. )

I am a good European - of course I am a better Englishman!

Its clear I think that what we have referred to as "ears" are in fact "water wings".

John

Mike Price · Mar 4, 2010

PaulD said:
New or overlooked information is always welcome. If you have information that shows greater average dispersal distances than 52km and greater overall distances than 528km then please post a link to it or detail the source.

Tony Warburton's paper made no mention of average dispersal distances and the longest movement he noted was 480km, so if there "is plenty of evidence showing displaced juv Eagle owls are travelling far greater distances" than I listed then Tony missed it as well.

I should stress that I am not suggesting that Eagle Owls are incapable of making sea crossings (the paper by Melling et al details a 40km sea crossing to Gotland). However the available evidence clearly indicates that sea crossings are a significant barrier to Eagle Owls and that they normally avoid them. Which makes it makes it extremely unlikely that they will get here in sufficient numbers to colonise.

But as noted above, new or overlooked information is always welcome so please post a link.

The numbers you quoted showed the mean of the distances and didn't include the extra details you have added in this post.

That was exactly the point I was making, you choose what you wish to share to support your arguement.

PaulD · Mar 4, 2010

Mike Price said:
The numbers you quoted showed the mean of the distances and didn't include the extra details you have added in this post.

That was exactly the point I was making, you choose what you wish to share to support your arguement.

Sorry I must be a bit slow this afternoon, but are you suggesting that I used mean distance travelled rather than longest distance travelled because that suited my argument better?

If you compare mean distance travelled then Eagle Owl comes out as less sedentary than Tawny and Little Owls (52, 15 + 15 km respectively).

If you compare longest distance travelled then Eagle Owl comes out as more sedentary than Tawny and Little Owls (528, 725 + 600km respectively).

It follows that if I was intent on showing that Eagle Owls were sedentary birds I would only have quoted longest distance travelled. But I didn't, I used mean distance travelled because I felt that was a more appropriate figure (it helped even out differences in sample sizes).

If I've misunderstood you, then apologies - please clarify.

Mike Price · Mar 4, 2010

My point was and is that EO can do travel vast distances, there are always exceptions and no realistic determination of whether they could fly to England from say France can be judged from the figures you gave.

It is highly possible that they could make it to England, just because no-one has proven it yet doesn't mean it has never happened does it?

Equally just because a bird makes has made it to the UK naturally does not make it a good thing and neither do wild birds 2-3 generations removed from Escaped/released birds make them a bad thing.

The point is that the risk assessment was worded in a way that made it seem like that was exactly the point they were trying to make.

The whole argument is pointless at this point as the RA is finished and is woefully inadequate and evenin my opinion misleading.

Richard Klim · Mar 4, 2010

The arguments in support of the feasibility of colonisation by genuine wild Eagle Owls from the continent usually focus solely upon the physical possibility of a vagrant successfully making the over-water crossing to Britain. It's clear that such a possibility cannot be ruled out. But given that an individual does arrive in Britain, the probability that it encounters a second wild vagrant of the opposite sex within its potential breeding lifetime must surely be extremely low – perhaps an order of magnitude less than the (already very low) probability of mating with an escaped/released individual of potentially indeterminate race.

There are more than 30 globally threatened owl species, and I acknowledge the value of the conservation work performed by the World Owl Trust to help some of them. But given the Trust's global mission, and having read its report, I still fail to understand the rationale for devoting so much energy to campaigning for the establishment and protection of a British population of a species of Least Concern, derived from the interbreeding of individuals of unknown provenance – even if it can be proven that there are no significant negative impacts on other species. Surely there are many more worthwhile causes.

Richard

Mike Price · Mar 4, 2010

I must say I agree with that, in the UK I would like to see the Barn Owl conservation given priority.

bluechaffinch · Mar 4, 2010

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".

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

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