Lancs Eagle Owls (1 Viewer)

[DGRW]

Brian -

DRGW: accepting this argument would give carte blanche to the introduction of a feral population of any actual or potential vagrant. It just won't wash.

I'm sorry but I fail to understand the casual approach to killing natural vagrants along with feral populations when a little common sense might resolve the issue.

It isn't carte blanche to allow all feral invasive populations to thrive at the expense of UK ecologies, it's carte blanche to get our sums right rather than allowing 2+2 to equal 5 for no better reason than that the additional effort, investment and forethought is lacking.

It won't wash because very few people are particularly interested in washing it; to much effort to get it right, so much easier to get it close, a one size fits all solution.

 

[DGRW]

John -

Sounds almost like carte blanche for the hunting fraternity.

My thoughts exactly but I didn't want to descend into a hunting debate.

 

[Amarillo]

Just re-read this more carefully. Are you really suggesting that there is no connection between the hordes of easy to raise Red-legged Partridges infesting farmland from Farnborough to Speyside and the disappearance of native more difficult to maintain and rarely bred for release Grey Partridges? Define threat!

John

Well its maybe not the best example because gamebird populations are not natural anyway, but I don't think red-legged partridges directly affect grey partridges. their decline is due to farming practices.

 

[Farnboro John]

Well its maybe not the best example because gamebird populations are not natural anyway, but I don't think red-legged partridges directly affect grey partridges. their decline is due to farming practices.

Farmer decides to raise partridges sp for him and his green-wellied, barbour-clad mates (hang on that sounds like us!) to shoot and (presumably) eat, although excess may be sold at farmers' market or to trade. Albeit slaughter is al fresco, this is basically livestock farming, kind of PYO.

Farmer discovers by reading/is told by mate who's tried, that Red-legged Partridges are easy to raise (well easier than Grey). Buys in x young uns (and I mean large values of x, coveys of 60+ per field, every field, where I never used to see more than 30 Greys in a few fields in a good year) and releases as appropriate. Some breed, using nest sites, eating insects, attracting elil and therefore putting pressure on native Greys.

When in season farmer and mates drive the 4WDs down the lane, hop out, local peasants drive partridges over them (I'm a bit shaky on this - are partridges driven game?) bang go the Purdeys and x-some RLPs and half a dozen Greys fall to the ground for later consumption.

Next spring farmer repeats process, naturally releasing only RLPs, again in nonsensical quantities for the habitat. More pressure on fewer Greys and sooner or later they vanish.

This has happened around me. In less than ten years we've gone form coveys of 30 odd Greys to this year, not being able to find one pair within 10 miles radius of home. Simultaneously numbers of RLP have rocketed.

Believe you me the connection is direct.

John

 

[ColinD]

Well its maybe not the best example because gamebird populations are not natural anyway, but I don't think red-legged partridges directly affect grey partridges. their decline is due to farming practices.

That's my understanding as well. Last thing I heard, Red-legs were in no way to blame for the decline in Greys. Greys have declined due to farming practices.

(Edit, though I can see sense in what John said later as well)

 

[Amarillo]

Believe you me the connection is direct.

John

Well it sounds indirect from your post.

 

[PaulD]

Well there seems to be general agreement that:-

A. It is possible that Eagle Owls could reach Britain naturally.
B. The majority of current records are down to escaped or released birds or their offspring.

As has already been pointed out the public relations side of things will probably mean that no conservation body will call for selective removal or extermination, and anyway the shooting fraternity will apply their own unofficial controls so the owls may struggle anyway (see the stories already circulating about the Dunsop Bridge Eagle Owls being on a hit list).

I have posted previously saying that I feel natural colonisation is unlikely, and to be honest the more I think about it, the less likely it seems. BWP gives Tawny Owl as having a broadly similar dispersal range to Eagle Owl, and there are recorded sea crossings by Tawny Owls (but none for Eagle Owls). Yet Tawny Owls don’t occur in Ireland and have never colonised (SW Scotland to NE Ireland is actually shorter than the distance from Dover to Calais). If wild Eagle Owls do occur here the numbers are probably so low that natural colonisation won’t take place now or in the foreseeable future.

If a land bridge suddenly appeared between Britain and the Continent then I bet Eagle Owls would colonise and I believe they would cause some local problems by eliminating some other birds of prey in some of their territories, but overall wouldn’t cause major problems. Monitoring of the birds at Dunsop Bridge may provide some very interesting information!

 

[Big Phil]

well yes, to a point, but my point is that there isn't apparently anything even suggestive of eagle owl. And as they are such bird mysterious birds, like eagles, then remains would have been concentrated at human settlements, as they'd have been sought after (just as the eagles etc were), so we WOULD have found them if they existed.

There's no 'WOULD' about it. You choose to assume that our predecessors would have been aware and in some way obsessed with EO. You then choose to assume that anything that came their way would be represented in recovered remains. The first is wild speculation. The second flies in the face of common sense - the physical record will always have gaps and ommisions.

I heartily agree that there is no evidence for EO occuring naturally in Britain. But that is as far as it goes. Stating as fact that they have never occurred is wrong.

 

[lewis20126]

"....the majority of Goshawks breeding in Britain are larger than the Continental Goshawks which one would expect to colonise Britain naturally by immigration. To judge from the lengths of moulted feathers found at nests, most are approximately the size of those breeding in the north and east of Europe, from whence came most imported Goshawks in the 1970s. Thus, there is nothing present evidence which is inconsistent with the view that recent British Goshawks have been derived entirely from falconry sources."
(BB75, p247)

We have the wrong Goshawks - I trust they will be removed along with the Eagle Owls and Ruddy Ducks?

 

[nirofo]

"....the majority of Goshawks breeding in Britain are larger than the Continental Goshawks which one would expect to colonise Britain naturally by immigration. To judge from the lengths of moulted feathers found at nests, most are approximately the size of those breeding in the north and east of Europe, from whence came most imported Goshawks in the 1970s. Thus, there is nothing present evidence which is inconsistent with the view that recent British Goshawks have been derived entirely from falconry sources."
(BB75, p247)

We have the wrong Goshawks - I trust they will be removed along with the Eagle Owls and Ruddy Ducks?

You are assuming that all Uk Goshawks originated from falconers stock, not so, although admittedly many did !!!

nirofo.

 

[lewis20126]

You are assuming that all Uk Goshawks originated from falconers stock, not so, although admittedly many did !!!

nirofo.

Eh? - the ref says "the majority.." - so why would I assume "all"?

Another point - as they are somewhat larger than the previously native birds, they will presumably take somewhat larger prey (on average)? Like Honey Buzzards and Hen Harriers? Just a thought...

Now I like Goshawks - I really do - but they are totally plastic, of a non native form..rather like the eagle owls.

 

[PaulD]

"....the majority of Goshawks breeding in Britain are larger than the Continental Goshawks which one would expect to colonise Britain naturally by immigration. To judge from the lengths of moulted feathers found at nests, most are approximately the size of those breeding in the north and east of Europe, from whence came most imported Goshawks in the 1970s. Thus, there is nothing present evidence which is inconsistent with the view that recent British Goshawks have been derived entirely from falconry sources."
(BB75, p247)

We have the wrong Goshawks - I trust they will be removed along with the Eagle Owls and Ruddy Ducks?

It's not a valid comparison. Goshawks have a natural place in our avifauna, Ruddy Ducks certainly don't and in the 1990s the BOU carried out a review of Eagle Owl records and decided there were no acceptable records. So if you want to argue that Eagle Owls have a natural place in our avifauna you have to go back hundreds and hundreds of years to the last Ice Age, and even then it's my understanding that the evidence is inconclusive or lacking.

As you are probably aware Mick Marquiss who co-authored the article you quote also wrote the Goshawk account in the New Atlas of Breeding Birds, and in there he said "The Goshawks which started breeding in the 1960s were mainly small birds from Central Europe, whereas those which started breeding in the early 1970s were much larger birds from Finland. In places those populations are now close enough to mix". The New Atlas was published 12 years after the article you quote so it seems we may have a more mixed population than your isolated quote suggests.

Put it another way British Goshawks had been persecuted to extinction, so in more enlightened times (if there hadn't been the escapes mentioned above) we might seek to reintroduce them and we would use continental stock which happen to be a slightly different size. If you insist that only similarly sized British stock can be used for a reintroduction then you're into a Catch-22 situation because they've been exterminated.

In a rather similar vein the Red Kite releases in Britain used birds from Spain and Sweden, one advantage of which was a widening of the gene pool.

 

[lewis20126]

..In a rather similar vein the Red Kite releases in Britain used birds from Spain and Sweden, one advantage of which was a widening of the gene pool.

My personal view on red kites is that we should have facilitated natural recolonisation from Wales (or artificial releases from the admitedly limited Welsh stock) - despite the issues of potential inbreeding depression (cheetah's managed it!). I'm not too up on the genetics of red kites but I presume we now have a somewhat homogenized red kite widespread in the UK. "Widening of the gene pool" can be seen as a benefit from some perspectives (i.e. total UK population) but not at the ultimate expense of the ancestral native stock. From the more recent text it appears that our Goshawks are of similar mixed (non-native) origins. As presumably are Eagle owls.

The botanists amongst us are concerned with local provenance of seed sources in road schemes (Lotus corniculatus var sativa anyone?!) and on preserving small native plant populations of isolated populations at the edges of their ranges (most of those on Schedule 8 for a start) in order to preserve the totality of intra-species genetic diversity across native ranges - why do we treat charismatic fauna so differently?

 

[Himalaya]

whatever the situation is - we cant prove how these eagle owls arrived here. thery are not o the yorkshire pair as their offspring were ringed.

whatever the case is - numbers of eagle owls are building up and if this happens it will become a part of the islands ecosystem - for better or for worse.

there is alot of secrecy and im guessing there are more breeding within the british isles - most maybe escapees but some would be natural vagrants. we roughly know how many golden eagles, peregrine pairs we have so why not eagle owl? if these birds are from a feral stock and many are released/escape then surely more would be joining the bowland and yorkshire dales pair in mating and breeding. i hope we get atrue figureof how many pairs ad possible individual birds there are in the country.

 

[Farnboro John]

My personal view on red kites is that we should have facilitated natural recolonisation from Wales (or artificial releases from the admitedly limited Welsh stock) - despite the issues of potential inbreeding depression (cheetah's managed it!). I'm not too up on the genetics of red kites but I presume we now have a somewhat homogenized red kite widespread in the UK. "Widening of the gene pool" can be seen as a benefit from some perspectives (i.e. total UK population) but not at the ultimate expense of the ancestral native stock. From the more recent text it appears that our Goshawks are of similar mixed (non-native) origins. As presumably are Eagle owls.

Before the reintroduction programme began there was genetic work done that established the Welsh Red Kites were just part of the overall European gene pool and not an island race in their own right. Significantly there was at least one record of recruitment from Europe (Germany I think) to the Welsh population before the reintro prog. So the "widening of the gene pool" was not thinning out of different genes from the rest of Europe.

John

 

[PaulD]

My personal view on red kites is that we should have facilitated natural recolonisation from Wales (or artificial releases from the admitedly limited Welsh stock) - despite the issues of potential inbreeding depression (cheetah's managed it!). I'm not too up on the genetics of red kites but I presume we now have a somewhat homogenized red kite widespread in the UK. "Widening of the gene pool" can be seen as a benefit from some perspectives (i.e. total UK population) but not at the ultimate expense of the ancestral native stock. From the more recent text it appears that our Goshawks are of similar mixed (non-native) origins. As presumably are Eagle owls.

The botanists amongst us are concerned with local provenance of seed sources in road schemes (Lotus corniculatus var sativa anyone?!) and on preserving small native plant populations of isolated populations at the edges of their ranges (most of those on Schedule 8 for a start) in order to preserve the totality of intra-species genetic diversity across native ranges - why do we treat charismatic fauna so differently?

I'm certainly not up on genetics, but my understanding is that the Welsh Red Kite gene pool was uncomfortably small (traceable back to a single female!), so widening the gene pool was seen as a positive thing.

With the Goshawks the native stock had been exterminated, so if they were replaced it had to be with non-native stock. Similarly with the White-tailed Eagles and their Norwegian replacements.

I am not aware of any practical consequences of the presence of non-British Goshawks (and White-tailed Eagles), but if there are any it would be interesting to have them noted.

Incidentally unlike Eagle Owls, Goshawks do make sea crossings, so there is a good chance that at some stage we would have been re-colonised from the Continent (there are far more Goshawks than Eagle Owls in the Netherlands etc).

 

[PaulD]

whatever the situation is - we cant prove how these eagle owls arrived here. QUOTE]

I'm baffled as to how people can people ignore the probabilities, point out that we can't be 100% certain and then feel that we should treat the current breeding birds as if they were part of a vaguely natural colonisation.

There are many, many things we can't be 100% certain of. Persistent pesticides such as DDT were banned in the UK years ago, but some still say they weren't responsible for eggshell thinning in birds of prey, and they argue we are not 100% sure. If we only take conservation action when we are 100% sure them I'm afraid very little will get done.

So lets consider the probabilities again:-
1. Escape likelihood very high. Over 400 license applications per year and we know that significant numbers are lost or released every year (ball park figure of 25% in the first year), so potentially 100 escapes or releases every year.
2. Vagrancy potential very low. The BOU review in the 1990s didn't accept any records, I'm not aware of any accepted records since then, nor am I aware of any evidence of sea crossings by Eagle Owls.

Balance those two points and it seems to me that the only logical conclusion is that the chances of a pair of wild Eagle Owls meeting up and breeding in the UK are very, very slim.

If you have actual evidence or information that contradicts that then it would be very interesting to hear, but a simple opinion that we can't be sure really isn't a positive contribution.

I do agree with you that it would be good if more were published about these birds. It's certainly my understanding that the Catterick and Dunsop Bridge birds are of captive origin and note that the caption in Birding World (20:183) describes them as "of captive origin" and that Lee Evans (who is generally agreed to be keen on a tick) treats them as captive origin and therefore not tickable.

 

[Amarillo]

I'm baffled as to how people can people ignore the probabilities, point out that we can't be 100% certain and then feel that we should treat the current breeding birds as if they were part of a vaguely natural colonisation.

Its not that anyone thinks that they have colonised naturally - but the fact that they could have, means that to some of us they are viewed as "less alien" than species from further away.

 

[DGRW]

All very valid points Paul.

You know what, I'll stick to my guns for as long as I'm certain that I'm correct, in this instance though, I've seen some very good arguments that pursuade me that I may be mistaken.

I still feel however that the book should not be entirely closed on the subject, I most definately feel that we must continue to question our conservation strategies.....but that obviously goes without saying doesn't it?

PS: For some reason I am still very uncomfortable with the idea of a total eradication programme.

 

[PaulD]

Amarillo, I guess the problem for the authorities who have to consider any practical issues which might arise is that they are either native or non-native, there isn't a third category of "non-native, but less alien".

DGRW, no problem with modifying your views as there's no question I have modified mine. A while ago I was sitting on the fence on this issue, but the more I consider the available evidence the more obvious it is that if we get any wild Eagle Owls they are at best rare vagrants and are heavily outnumbered by escapes and releases.

I heartily agree about keeping an open mind - who knows what surprising information could pop up in the near future.

I would be very surprised if there was an eradication programme. These owls are so high profile that it would be a public relations nightmare. The media would certainly take an interest in it and would get many of their facts wrong (hardly surprising when some birdwatchers think the Dunsop Bridge birds are part of an RSPB re-introduction programme).

Where I do think it would get tricky for the RSPB is if studies at Dunsop Bridge and elsewhere reveal the Eagle Owls are taking significant numbers of prey we would rather they didn't. Hopefully we will get to hear more about what's happened in Bowland this year. With all those Hen Harriers nearby it's an interesting area for Eagle Owls to set up shop!