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Pool Frog programme coming up

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GemmaJF View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GemmaJF Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 2012 at 1:19pm
Originally posted by Richard2 Richard2 wrote:

And my old university trembles on the edge.
 
But Marsh and Edible Frogs, as they used to be called, were introduced long ago and are in all the old wildlife books. Do you really think they should now be rounded-up and extirpated? I don't get this. I can understand wanting to remove introduced species if they really threaten native ones (grey squirrels because of the danger to reds, for example), but it isn't because of Marsh and Edibles that the Common Frogs are declining.
 

I don't think they should be extripated, I love Marsh frogs and have many happy memories of splitting my sides listening to them cackling away. 

Unfortunately if you ask NE what to do with them if they are caught up in mitigation works, they will say you cannot release them again. 

In Kent where they are widespread they no doubt also support a huge number of grass snakes, so I'm all for them. Further more they tend to be found in areas where common frogs would not thrive so I really think now they should just be 'adopted' as naturalised. 

It's just a technical issue under the WCA regarding release of aliens into the wild though one would hope the local NE team would be more pragmatic their responses to me in the past they have stated that marsh frogs should be destroyed if caught. Of course one always has one worker who is rubbish at holding marsh frogs in reality, so personally I have never been involved in any executions!

My point is that on the one hand NE can sanction a 're-introduction' of Pool Frogs yet on the other have the policy that marsh frogs accidentally caught up in mitigation works cannot be re-released.

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The basic idea here seems to be that we should try to freeze natural processes at a particular moment. It was OK, presumably, for prehistoric Pool Frogs to cross from the land that became Scandinavia, but movement of species is not OK now. That seems inconsistent to me. Shouldn't biodiversity rather than an arbitrary concept of nativeness be the fundamental principle?
 

I actually totally agree. My own view is people are a natural phenomenon, if they introduced animals to an area either by mistake or by design it is part of a natural process. On the other hand I would not encourage people to introduce aliens for the obvious reason that we simply don't know what might happen particularly in terms of impacts on natives species. 

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I quite agree with you about the inconsistency between the reintroduction policy and the weakness over habitat-destruction, but the answer isn't to stop the reintroduction policy so as to achieve consistency with the weakness.

That is a fair point but the money and resources could have been placed elsewhere. Lets just say the project has more in my opinion to do with the ability of a handful of people to influence NE rather than a lot of merit as a ground breaking conservation exercise.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote GemmaJF Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 2012 at 1:25pm
Originally posted by Caleb Caleb wrote:

Originally posted by GemmaJF GemmaJF wrote:

Below is a predictive map showing the effect of a 7m rise in sea level. The blue area above Cambridge is (was) the Fens.


I am familiar with the Fens- I lived there for some time. There were fields below sea level within a couple of miles of our house.

No-one's seriously predicting a 7m sea level rise- most estimates seem to be more like 1m in the next century. How does the map look with a 1m rise?

40m / below sea level you don't seem too sure Caleb, actually with a 1 m rise in sea level the fens are still predicted to be flooded by sea water, take a look for yourself:



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richard2 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 2012 at 1:32pm
I think we agree on just about every point, really; perhaps a difference of emphasis only.
 
Of course, a free-for-all policy on introductions would be very dangerous to native species - I can see that. The recent Signal Crayfish thread gives us a prime example. But where an introduction has occurred without causing a significant problem, we should celebrate it rather than fetishizing nativeness. Alpine Newts are beautiful and exciting. As far as I know they constitute no serious threat to anything. I want them here. A policy that demands they should be killed on sight is a symptom of bureaucratic callousness, in my view.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote GemmaJF Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 2012 at 2:06pm
It is subtle though I guess Richard, I think alpine newts are really lovely and tend to exist in small populations. Yet on the other hand one 'could' consider the Italian Crested Newt as a serious threat. Deliberately introduced and able to hyrbridise with native Great Crested newts they do pose a threat to the genetic integrity of native newts and are therefore regarded as a fairly serious issue when they are discovered.

One could though say does it actually matter much? I'm sure the grass snakes in Epping Forest have a little bit of foreign blood in them. (and dare I say Chris so might some of the early Sand Lizard re-introductions??) If one considers that as a species ourselves we seem to generally be moving as far away from genetic integrity of races as possible and find any other concept (such as the Nazi ideal) abhorrent it does seem a little odd we will still apply the same logic of genetic purity to wildlife. At the end of the day where we are now does any of it matter at all, the bigger issues seems to be whether or not any species of amphibian is going to survive with the global declines of previously unseen proportion. What the exact genes are of those hopping about in the UK seems only a small point in comparison. The genetic make-up of these different races of animals only formed through a series of chance natural events in any case. 

I guess at the end of the day if the Pool Frog re-introduction is anywhere near as successful as past Marsh Frog introductions I can have egg on my face and we all will have something to smile about. For some reason though I'm struggling to identify the vast tracts of suitable habitat where the Pool Frogs will eventually expand into. 


Edited by GemmaJF - 08 Aug 2012 at 2:44pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Caleb Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 2012 at 2:59pm
Originally posted by GemmaJF GemmaJF wrote:

40m / below sea level you don't seem too sure Caleb, actually with a 1 m rise in sea level the fens are still predicted to be flooded by sea water, take a look for yourself:


The Thetford area (including the last pool frog site and the reintroduction site) is about 40m above sea level. The lowest parts of the Fens are below sea level, but they are not underwater, as they're pumped dry. If water levels increase, either pumping will have to be stepped up to keep them dry, or they will flood.

The site you mentioned generated the map below for a 1m rise in sea level. As the flooded areas of the Fens are not directly connected to the sea, they wouldn't necessarily be 'flooded by sea water'.

Either way, your suggestion that 'the whole area will be back under the sea in 20 years' is clearly a vast exaggeration.





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Post Options Post Options   Thanks (0) Thanks(0)   Quote GemmaJF Quote  Post ReplyReply Direct Link To This Post Posted: 08 Aug 2012 at 3:11pm
keep it accurate Caleb

It was not my suggestion that the area would be under the sea in 20 years I stated:

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I guess my negativity is that the reintroduced animals are not native and the whole area will be back under the sea in 20 years if some scientists have the calculations right.


You see it states if some scientists have the calculations right. In other words a worse case scenario. We already very nearly had a breech of the sea wall locally during the spring high tides. So thinking this is not some sort of possible reality is a little blinkered. You yourself stated that a 1m rise in sea level is predicted in 100 years so where is my vast exaggeration? Is a factor of '5' vast in terms of predictive calculation?

I think also you will find the predictive map is just representative. It might not appear directly connected to the sea but would this not depend on spring high tides etc rather than a predictive snap shot?

If it is fresh water then the problem is solved eh. Perhaps you cannot address the issues that the Northern Clade could not have actually colonised the UK naturally and also the fact there isn't now any large areas of suitable habitat in the area for the Pool Frogs to colonise in the future as you seem to be spending too much time worrying about the maps.

It clearly shows what you asked, what is the result of a 1m rise in sea level. The result is the fens become the sea again. Simple isn't it. To prevent the flooding would require a 1m rise in the sea defenses would it not rather than increased pumping exercises? I think you should look at the environment agencies polices regarding sea defense in East Anglia. You will find the policy is to accept that some areas will be reclaimed by the sea in future years rather than raising the sea defenses around the entire coast line.


Edited by GemmaJF - 08 Aug 2012 at 3:23pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Iowarth Quote  Post ReplyReply Direct Link To This Post Posted: 09 Aug 2012 at 5:32am

Hi Gemma

Addressing your point re Sand Lizards, according to our records every re-introduction has been from animals either taken directly from wild UK populations or bred from such animals. Obviously, this does not guarantee they are British animals (a male was found in Northants a few years ago - where did that come from?) but it is, to say the least, highly probably.

I also note later that you say "the Northern Clade could not have actually colonised the UK naturally". Can I ask what you base that statement on, considering that a) they are known from post-glacial but pre-introduction fossils and that the North Sea landbridge would have given them comfortable access (remembering that it was somewhat similar to the fenlands). Or am I misunderstanding/taking out of context your statement?

I do agree that Grass Snakes should not be controlled but currently their effects are simply being observed and no such proposals have been made. And I also agree that the movement of species by man is as natural an event as any other - also, that condemning captured naturalised animals which have no negative impact on natives to death or captivity because they are not native is ridiculous. I might change my mind on this score should NE decide that all pheasants should be extirpated!

Chris

Chris Davis, Site Administrator

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Caleb Quote  Post ReplyReply Direct Link To This Post Posted: 09 Aug 2012 at 9:30am
Originally posted by GemmaJF GemmaJF wrote:

Perhaps you cannot address the issues that the Northern Clade could not have actually colonised the UK naturally and also the fact there isn't now any large areas of suitable habitat in the area for the Pool Frogs to colonise in the future


OK, ignoring the Fens. There's the rest of the Pingo area of Norfolk for them to colonise- roughly the same size as Romney marsh, and with hundreds of ponds.

The natural colonisation was addressed in:

Snell, C., Tetteh, J., & Evans, I. H., 2005. Phylogeography of the Pool frog (Rana lessonae Camerano) in Europe: evidence for native status in Great Britain and for an unusual postglacial colonization route. Biological Journal of the Linnean Society, 85(1), 41-51.

As Chris said, they suggested migration via the north sea land bridge, and pointed out that there are other species in Norfolk that are most closely related to Scandinavian specimens of the same species. I've attached the diagram of the suggested migration route below.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote GemmaJF Quote  Post ReplyReply Direct Link To This Post Posted: 09 Aug 2012 at 12:35pm
Originally posted by Iowarth Iowarth wrote:

Hi Gemma

Addressing your point re Sand Lizards, according to our records every re-introduction has been from animals either taken directly from wild UK populations or bred from such animals. Obviously, this does not guarantee they are British animals (a male was found in Northants a few years ago - where did that come from?) but it is, to say the least, highly probably.

I also note later that you say "the Northern Clade could not have actually colonised the UK naturally". Can I ask what you base that statement on, considering that a) they are known from post-glacial but pre-introduction fossils and that the North Sea landbridge would have given them comfortable access (remembering that it was somewhat similar to the fenlands). Or am I misunderstanding/taking out of context your statement?

I do agree that Grass Snakes should not be controlled but currently their effects are simply being observed and no such proposals have been made. And I also agree that the movement of species by man is as natural an event as any other - also, that condemning captured naturalised animals which have no negative impact on natives to death or captivity because they are not native is ridiculous. I might change my mind on this score should NE decide that all pheasants should be extirpated!

Chris


Hi Chris,

I must have been given duff information, as I have been told in the past that the early Sand Lizard breeding included animals of unknown origin. That no 'stud book' was kept and that it is more than possible that some of the animals originate from the pet trade. I certainly remember sand lizards being common in pet shops back in the 70's and these were European imports on the whole. But really it is an academic point because as I have stated above in my own mind genetic purity really doesn't matter much on the balance of things.

Regarding the colonisation, I can't find it now on the archived forum but David Bird put up an excellent post regarding his doubts of the Northern Clade colonising the UK. I accept the land bridge existed. Unfortunately to use it the Northern Clade would have also had to negotiate a Mountain range. The issue in my mind that has never been fully addressed. Having looked into it for myself it would appear to be a feat of such proportion that they may as well have swum across the North Sea. Wink

Though there is much talk of how the animals 'might' have colonised the UK (with some points that make me doubt it) it seems to me just as likely to this day that they resulted from human introduction. Even if the evidence goes back over 1000 years because people were already by then crossing the North Sea, who knows if they had a few Pool Frogs with them for whatever reason, perhaps Viking kids kept them as pets!

Really I would be much happier about the whole thing if the UK Marsh Frogs and other low impact naturalised herp species in the UK had their death penalties removed. You know how I get about NE and glaring double standards.



Edited by GemmaJF - 09 Aug 2012 at 12:47pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GemmaJF Quote  Post ReplyReply Direct Link To This Post Posted: 09 Aug 2012 at 1:04pm
Originally posted by Caleb Caleb wrote:



OK, ignoring the Fens. There's the rest of the Pingo area of Norfolk for them to colonise- roughly the same size as Romney marsh, and with hundreds of ponds.


I addressed my doubts regarding the potential colonisation which does not question the existence of the land bridge but rather the ability of Pool Frogs to have used it in my reply to Chris.

The Pingo area of Norfolk seems to me to be a whole can of worms in itself. 

Would the intention be to transport the frogs around to each remaining isolated area from the initial site? It isn't much like Romney Marsh to me. Many of the Pingo ponds are heavily neglected, isolated, silted up or just depressions in the ground and in all there is very poor connectivity in terms of suitable habitat throughout the entire region.

I am not saying that transporting the spawn or tadpoles is necessarily a bad thing as obviously disease monitoring is within the capability of those involved. I just wondered if this was part of the plans as fully natural colinisation of the area seems pretty unlikely to me.

Of course I then also have the reservation whether or not the Pingo area is actually representative of their 'natural' historic range? Wouldn't some native Pool Frogs still be surviving along with the GCN etc if that was the case? 

It actually sparks off another doubt too. Lets say there were native pool frogs all over the Fens before they were drained. Why didn't they colonise the Pingo area as well? We can't blame the draining of the fens or the water table for 'extinction' there. Some of the ponds still exist and one would expect a distribution of pool frogs along the lines of the current GCN distribution of modern times of isolated but stable meta-populations. 

It kind of makes me think the Pool Frogs were always in tiny little populations, almost as if someone put them there in the past.. Confused (Which if it is true also sets of the alarm bell of 'why was this theoretical historic introduction not as successful as Marsh Frog introductions in Kent???)

I suppose in all I've talked myself into admiration for the task the team involved took on. It is really something to work back from a handful of records and decide 'was this a representation of a native species' or just the remnants of an  'isolated historic introduction'.


Edited by GemmaJF - 09 Aug 2012 at 1:42pm
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