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Pool Frog programme coming up

Printed From: Reptiles and Amphibians of the UK
Category: Herpetofauna Native to the UK
Forum Name: Pool Frog
Forum Description: Forum for all issues concerning Rana lessonae
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Topic: Pool Frog programme coming up
Posted By: Chris Monk
Subject: Pool Frog programme coming up
Date Posted: 02 Aug 2012 at 11:22pm
Just to let you know that this Sunday (5th) the BBC Radio's Living World programme is about the "native" Pool Frog re-introduction conservation project. Interviewer Joanna Pinnock will be talking to John Baker, who was involved in the re-introduction and has been monitoring the site since.
It's being broadcast at 6.35am on BBC Radio 4 but will also be available afterwards on the BBC I player page http://www.bbc.co.uk/programmes/b007qyz3" rel="nofollow - http://www.bbc.co.uk/programmes/b007qyz3 .
Beforehand there's a piece about it with some photos on The Living World webpage http://www.bbc.co.uk/programmes/b01lh96b" rel="nofollow - http://www.bbc.co.uk/programmes/b01lh96b



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Chris

Derbyshire Amphibian & Reptile Group

www.derbyshirearg.co.uk




Replies:
Posted By: Chris Monk
Date Posted: 05 Aug 2012 at 3:07pm
The programme is now available to listen to on the BBC I player for those not up at 6.30 this morning.  Interesting that they are also monitoring the grass snake population on the site to see how many individual snakes are there and whether they are likely to have a significant effect on the frogs. Seems the herons are also hanging around to pick up a meal.
Might be several years still before it's known whether the attempt to re-introduce the species has been a success or not.


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Chris

Derbyshire Amphibian & Reptile Group

www.derbyshirearg.co.uk



Posted By: GemmaJF
Date Posted: 05 Aug 2012 at 3:15pm
Is it not natural that grass snakes will predate any frog population? If they were to be assessed as having some sort of impact what would be the options?

It seems to me that every healthy common frog or common toad population I know has a reasonable number of grass snakes present, one follows the other. If the Pool Frog introduction is actually a success then the fact that they support a grass snake population (perhaps even an increasing one) would in my opinion be ecologically 'normal'.


Posted By: Suzy
Date Posted: 05 Aug 2012 at 4:06pm
Agree with Gemma.
Isn't a natural balance best? Smooth snakes eat sand lizards don't they? Grass snakes eat frogs - not fussy on type presumably.
I hope there is no intention to try and tip the balance in favour of the Pool Frog.



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Suz


Posted By: GemmaJF
Date Posted: 05 Aug 2012 at 8:52pm
My thoughts too, if 'control' of the grass snakes is thought of as an option, it would in my opinion be the ultimate act of 'pet keeping' and in my mind would completely invalidate the 'success' of the reintroduction. 

If the frogs cannot withstand natural predation one would have to really consider if the correct site was chosen or if the project was actually really a 'success' in ecological terms.


Posted By: liamrussell
Date Posted: 05 Aug 2012 at 10:02pm
Of course the population must be able to withstand natural predation in the long-term, but I would assume it would take several years for what is essentially an unnatural population to develop the structure and dynamics of a natural population that would be able to cope with predation.


Posted By: GemmaJF
Date Posted: 05 Aug 2012 at 10:30pm
That is a good point Liam and I understand fully what you are saying.

So would you advocate the 'control' of native snakes to encourage the growth of a non-native population of animals? Not picking a row with you, I'm genuinely interested in peoples views. To me it's seems like just one step too far but that may not be everyone's view on the subject.

I've heard of similar monitoring of grass snakes around natterjack populations but to me if grass snakes (which feed infrequently) are really that much of a threat what hope have these small populations got against heron, rats, foxs natural events etc?

I wonder have there been any cases where grass snakes have been moved away or culled in the process of amphibian conservation that anyone knows of?


Posted By: Suzy
Date Posted: 06 Aug 2012 at 12:23am
What is the biggest gripe on here? Management of sites to benefit particular species (to the detriment of others). When does a leg up for one or two species become very bad news for many others?
If it's a reintroduction then the question is why they died out in the first place. What looks OK habitat to us is irrelevant surely as we can't possibly know all the requirements of of these frogs. With all best intentions I don't think overall, barn owl reintroductions can be considered a success, as an example, because we just don't know.


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Suz


Posted By: GemmaJF
Date Posted: 06 Aug 2012 at 1:24am
Too true, I think it is very fair to say that real ecosystems are in all cases far too difficult to understand or predict and in nearly all cases attempts to modify them fail or backfire. 

For example what happens if the grass snakes were removed and the Pool Frogs then face competition from an explosion of native amphibians?

Should they then also be moved/culled to protect the re-introduced frogs? I've heard that the original reason for the extinction was a lack of management and collection. I guess these issues have been addressed and I'm sure we all appreciated the effort put into the project but it does raise an interesting issue of how far we should go with manipulating things.




Posted By: Caleb
Date Posted: 06 Aug 2012 at 10:44am
The URL to listen to the programme is  http://www.bbc.co.uk/iplayer/console/b01lh96b" rel="nofollow - http://www.bbc.co.uk/iplayer/console/b01lh96b . There was no suggestion in the programme that grass snakes (or heron or otter) were to be controlled, merely that they were being monitored. They did say that the pool frog population is increasing gradually, rather than rapidly exploding. The grass snake population at the site is apparently also increasing.

The reasons for the original extinction are pretty well known- basically drainage of the Fens reduced them to a few isolated colonies, then lowering of the water table during the 1980s and 90s killed them off at the last site.

This is all addressed in the EN reintroduction strategy ( http://publications.naturalengland.org.uk/file/106005" rel="nofollow - http://publications.naturalengland.org.uk/file/106005 ) which is extremely thorough- there's very little to criticise there. Norfolk Biodiversity Partnership have also published an update which includes some of the monitoring data: http://www.norfolkbiodiversity.org/pdf/biodiversityforum/PoolFrogReintroduction.pdf" rel="nofollow - http://www.norfolkbiodiversity.org/pdf/biodiversityforum/PoolFrogReintroduction.pdf



Posted By: liamrussell
Date Posted: 06 Aug 2012 at 11:37am
Thought I'd sleep on this and give it some serious consideration as I was a bit ambivalent before. After thinking about it I came to the conclusion that I would be in favour of controlling grass snakes in this situation for two main reasons. I'm not advocating grass snake control as a permanent situation, but just until the pool frogs can develop the strength and depth of (meta)population structure which would reflect a true natural population. 

Regardless of whether the pool frog reintroduction should have been undertaken in the first place, now that it has been, it should be given every chance of success. Considerable amounts of time, money and effort and good science has been invested in the programme and to let that go to waste now due to problem which could be solved would be an extremely bad use of resources and a shame really.

Secondly, and perhaps more compellingly; in the long-term it will benefit both pool frogs and grass snakes for the pool frog population to be robust. Pool frogs occupy a slightly different niche to other native anurans and I'm told that the site didn't have many amphibians prior to the reintroduction. Therefore if the grass snakes eat all the pool frogs there will be little food left and their population will crash as they either starve or are forced to disperse in to less suitable habitat with a low likelihood of survival. If the pool frog population is allowed to build to a state where it reflects a robust natural population, then you would expect a normal predator-prey relationship to become established which would mean stable populations of both pool frogs and grass snakes would be present on the site with a good long-term likelihood of survival. Given this, I think it would be prudent to control grass snakes at the site whilst the pool frog population is in a vulnerable early stage.




Posted By: GemmaJF
Date Posted: 06 Aug 2012 at 1:27pm
@Caleb yes I agree that nobody has actually put forward that grass snake etc should be controlled in any way - I am just considering if these populations are monitored at what point would someone suggest control. Is there much point monitoring predators if no action at all were to be taken. I originally asked 'what are the options?' and then went on to discuss one possibility.

You are right also regarding the overall decline. I was referring to the loss of the final animals which is also well documented and related to a lack of management and collection at one site. As far as I remember at the time it was only speculation that the population may have been native. I would consider the re-introduction programme is starting at a similar point and working back the other way (i.e avoiding publishing the location, appropriate management etc), I guess the team involved have not persuaded anyone to re-flood the entire fens (yet Wink)

@ Liam - thanks for taking the time to put across your view which I really appreciate. I met an  ornithologist a few years back whilst working on a site. He related to me a project where Magpies were controlled by trapping to encourage rare song birds. After several years it was noted that the target species were actually declining faster. More common small birds had though increased in number. The conclusion drawn was the Magpie 'baddies' were actually controlling the more common species in the past which gave the rarer species a chance at the site. Just one example where what appeared to be a simple solution backfired in reality. Caleb noted that there were few existing amphibians at the site, so they are present. Removing their 'control' predator could for example have the same effect as the Magpie site even in a case where the animals occupy a different niche?


Posted By: Caleb
Date Posted: 06 Aug 2012 at 2:30pm
Originally posted by GemmaJF GemmaJF wrote:

I was referring to the loss of the final animals which is also well documented and related to a lack of management and collection at one site.


It was the final animals I was referring to when I mentioned the water table. That site had dozens of ponds that dried up in summer after summer in the 80s and 90s.

It seems a bit much to blame management when the species became extinct before it was accepted as a native- no-one could have been expected to improve habitat for what was then seen as an  alien.

Is there any real evidence that collection had an effect? No-one knew the Norfolk pool frogs were anything special until after they became extinct, and anyone wanting to catch green frogs had plenty more high-profile sites to choose from.

Originally posted by GemmaJF GemmaJF wrote:

Is there much point monitoring predators if no action at all were to be taken


Well, this is also intended to be the first of several reintroductions, so the data could be applied to the next site(s). The predator data may be able to show if introductions of adults, juveniles, tadpoles or spawn are most likely to succeed, how many individuals should be released, at what time of year, and/or how often.

I'd like to think that this introduction could be allowed to fail and used as a lesson for future efforts rather than 'controlling' other natives or chucking in animals year after year to die off or be eaten. It seems to be generating enough data to make it well worth while even if this does turn out to be the case (which looks unlikely, given that it is already generating a slow increase in the number of pool frogs in the wild).





Posted By: GemmaJF
Date Posted: 06 Aug 2012 at 2:38pm
Well I think you will find Caleb there was one individual who did think they were native and was making a lot of fuss about the final decline, sadly  nobody was listening at the time but then history is written by the victors eh?


Posted By: Caleb
Date Posted: 06 Aug 2012 at 3:37pm
It may have been too late even then. As I understand it, the last sighting of a native pool frog in Norfolk was 1991 or 1992, so they were probably already in terminal decline by the time their native status was being considered. Charles Snell's 'Neglected Native' article was published in 1994.


Posted By: Richard2
Date Posted: 06 Aug 2012 at 6:43pm

The last surviving native Pool Frog was the male who was christened 'Lucky', isn't that right? You probably all know this story well. It makes me think of Waiting for Godot. Didn't Lucky die shortly before the clinching evidence emerged that Pool Frogs were a native species and could therefore be replenished with an imported population? This report, however, suggests that Lucky did breed with some imported females, and that therefore the bloodline was preserved. Is that right? Are some of the introduced specimens genetically descended in part from the native population?

http://www.independent.co.uk/news/species-feared-extinct-as-lucky-the-pool-frog-dies-1046876.html" rel="nofollow - http://www.independent.co.uk/news/species-feared-extinct-as-lucky-the-pool-frog-dies-1046876.html
 


Posted By: Caleb
Date Posted: 07 Aug 2012 at 9:34am
Originally posted by Richard2 Richard2 wrote:

Are some of the introduced specimens genetically descended in part from the native population?


Sadly not. I'm told that 'Lucky' bred with some frogs from the Netherlands, but never with any Scandinavian females. All the animals released originate from specimens recently collected in Sweden.



Posted By: Richard2
Date Posted: 07 Aug 2012 at 10:08am
Thanks - that's interesting. Does anyone know what did happen to Lucky's progeny?


Posted By: liamrussell
Date Posted: 07 Aug 2012 at 3:14pm
@Gemma, I guess that's always going to be a possibility and the only way to find out is to closely monitor the situation and adapt the management as necessary. From what I know about the site (John Baker did a talk about if at the HWM this year) there aren't many other amphibians on the site (newts) but I guess the habitat improvement may have made it more suitable for all species.

@Caleb - I think if the first reintroduction was 'allowed to fail' the chances of obtaining any more funding for subsequent reintroductions would be slim to say the least...


Posted By: GemmaJF
Date Posted: 07 Aug 2012 at 7:19pm
I would agree with that last point Liam. If the purpose of monitoring the grass snakes is also to prevent 'chucking in' animals in the future as Caleb suggests, it also raises the point that perhaps it should of occurred before the reintroduction rather than after it!


Posted By: Richard2
Date Posted: 07 Aug 2012 at 9:50pm
People here are being surprisingly negative about this reintroduction. From the programme, and from what I've read, there is reason to be cautiously optimistic. We do basically welcome it, don't we?


Posted By: GemmaJF
Date Posted: 07 Aug 2012 at 10:12pm
Personally Richard I find it a little hard to get excited about it. 

I suppose it is good PR for EN and in fact I have nothing at all against the team of people who were involved in gathering the evidence, many whom I have met down the years which makes a fascinating detective story even if one is left feeling there might have been some areas overlooked. (such as a very large range of mountains which would have presumably been a little bit of an obstacle to the colonisation of the UK by the Northern Clade) 

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. There are so many issues that remain unaddressed regarding the conservation of UK herpetofauna, I guess if they were not issues I could get more excited about Pool Frogs at a secret site in Norfolk.

Of course their relatives which are very common throughout areas of Kent are supposed to be exterminated during mitigation work because they can't be re-released. So many issues, so much else that could have been addressed.


Posted By: Caleb
Date Posted: 08 Aug 2012 at 9:35am
Originally posted by GemmaJF GemmaJF wrote:

If the purpose of monitoring the grass snakes is also to prevent 'chucking in' animals in the future as Caleb suggests, it also raises the point that perhaps it should of occurred before the reintroduction rather than after it!


According to the report from Norfolk Biodiversity Partnership, grass snakes have been monitored both before and after the reintroduction (and have risen gradually at the same time as pool frog numbers increased).

Originally posted by GemmaJF GemmaJF wrote:

the whole area will be back under the sea in 20 years if some scientists have the calculations right.


Really? The area is about 40m above sea level, so the whole of central London would be underwater first.


Posted By: GemmaJF
Date Posted: 08 Aug 2012 at 12:00pm
Obviously I am referring to the height of the fens which if we are to believe the Pool Frog was once native would have been the natural range. The fens are anything but 40m above sea level, perhaps you are not familiar with the area. If the aim is to have a small population in a tiny area elsewhere it hardly meets the criteria of a real re-introduction. Which must surely relate to an effort to restore the natural range rather than having a single nurtured population at a nature reserve in Norfolk?

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





Posted By: Richard2
Date Posted: 08 Aug 2012 at 12:11pm

True, global warming threatens to make a lot of our hopes and plans futile if nothing is done about it.

But that scale of events apart, what exactly is the problem with this reintroduction? To care about whether the reintroduced species should technically be called native seems pedantic to me. If we're enthusiasts for the presence of wild reptiles and amphibians in our countryside, we should welcome this project. It's an attempt to bring back an animal that was there before. Success at this one site is likely to inspire attempts in others. There doesn't seem to be any real problem of damaging impact on other species, even if a few Grass Snakes do get moved (and no one involved has actually proposed this yet). What's not to like?
 
The policy in Kent that you describe seems sinister and misconceived to me, but that's another argument.


Posted By: Richard2
Date Posted: 08 Aug 2012 at 12:14pm
But I do take Gemma's point about the neglect of other conservation issues.


Posted By: GemmaJF
Date Posted: 08 Aug 2012 at 12:23pm
It's not just a policy in Kent Richard, to make it clearer, it is an offence to release an alien under the WCA. So marsh frogs, alpine newts, midwife toads and more caught in the wild in the UK cannot be re-released. You might have seen the thread recently where Will removed alpine newts from a pond and then had to keep them at home.

But it is OK to put some Pool Frogs in a nature reserve in Norfolk from Europe.. I can't help seeing a little irony when locally we have a massive decline in common frogs and NE couldn't give a fig if local ponds are filled in.


Posted By: GemmaJF
Date Posted: 08 Aug 2012 at 12:31pm
PS I've just realised on that predictive map that my house has gone too! (though we are actually 9m above sea level so I should still be on a tiny island) LOL


Posted By: Richard2
Date Posted: 08 Aug 2012 at 12:55pm
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.
 
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 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.


Posted By: Caleb
Date Posted: 08 Aug 2012 at 1:01pm
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?


Posted By: GemmaJF
Date 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.

Quote

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. 

Quote
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.




Posted By: GemmaJF
Date 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:

http://flood.firetree.net/" rel="nofollow - http://flood.firetree.net/




Posted By: Richard2
Date 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.



Posted By: GemmaJF
Date 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. 


Posted By: Caleb
Date 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.







Posted By: GemmaJF
Date 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:

Quote

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.


Posted By: Iowarth
Date 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

Co-ordinator, Sand Lizard Captive Breeding Programme (RETIRED)


Posted By: Caleb
Date 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.




Posted By: GemmaJF
Date 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.



Posted By: GemmaJF
Date 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'.


Posted By: Caleb
Date Posted: 09 Aug 2012 at 1:40pm
Originally posted by GemmaJF GemmaJF wrote:

Why didn't they colonise the Pingo area as well? We can't blame the draining of the fens or the water table there.


They did colonise the pingo area, as the last known site was a pingo site- and this is where the water table dropped in the 80s and 90s. There are also historical records from other sites nearby.

There was a (slightly) different colonisation route suggested by:
Zeisset I., & Beebee T.J.C., (2001). Determination of biogeographical range: an application of molecular phylogeography to the European pool frog Rana lessonae. Proceedings of the Royal Society, London B, 268: 933-938 (diagram below).

I don't remember David Bird's 'mountain' post, but this route doesn't seem to have any mountains in the way.






Posted By: GemmaJF
Date Posted: 09 Aug 2012 at 2:19pm
So if they colonised the entire Pingo area historically, which we presume was at the time exactly representative of the habitat that would have existed on the 'land bridge' and therefore ideal for dispersal, why not a widespread distribution in the area to this day?

Other native amphibians are still widespread if increasingly becoming discrete isolated meta-populations to this day, but not Pool Frogs? 

You see what I am saying, if they were native there should have simply been more of them as historically there would have been no barriers to their dispersal throughout what is now known as the Pingo area of Norfolk. I think also they would have been far more common in the literature of the past. There are only isolated mentions of what are thought to be references to Pool Frogs always linked with very localised locations.

I might be wrong, but is it not correct that the Norfolk Pool frogs were recorded only from two sites in East Anglia. One being lost in the 19th Century the other being of course the famous 'last site'.

It just doesn't conjure up the picture of immediately post glacial Britain to me, much of Norfolk littered with Pingos and Pool Frogs hopping across a land bridge in a noisy rabble to take up home all over Norfolk.


Posted By: Caleb
Date Posted: 10 Aug 2012 at 12:18pm
Originally posted by GemmaJF GemmaJF wrote:

I might be wrong, but is it not correct that the Norfolk Pool frogs were recorded only from two sites in East Anglia. One being lost in the 19th Century the other being of course the famous 'last site'.


That kind of depends what you mean by 'site'. There are a number of references to water frogs from various places in the pingo area (and slightly further east), as well as a fen area in Cambs. These and other references from the literature relating to East Anglia were summarised in an EN publication:
http://publications.naturalengland.org.uk/file/141025" rel="nofollow - http://publications.naturalengland.org.uk/file/141025

Originally posted by GemmaJF GemmaJF wrote:

It just doesn't conjure up the picture of immediately post glacial Britain to me, much of Norfolk littered with Pingos and Pool Frogs hopping across a land bridge in a noisy rabble to take up home all over Norfolk.


Well, natterjacks were much more widespread over Norfolk, Suffolk & Cambs in the past- and they were reduced to a few isolated sites, including one single inland population in Norfolk.

I think a harder question is why pool frogs disappeared from all the pingos apart from the last site. The reintroduction programme claims that the cause of the final extinction is well understood, but that doesn't really tell us why their range contracted so much during the 20th century. There are lots of good ponds in the area- are they just not quite good enough? Was there a run of poor summers?









Posted By: GemmaJF
Date Posted: 10 Aug 2012 at 6:35pm
Well I guess my answer to the last part is I've yet to be really convinced by the evidence that they were ever there (as in a widespread historically native distribution as opposed to a one two or a few isolated locations). 

I too thought about the Natterjack decline, but I had always considered them to be more specialised in their habitat requirements than Pool Frogs. Kind of more akin to Sand Lizards so to me it is easy enough to understand Natterjack decline in Norflolk and elsewhere, but not so easy to get a grasp on why Pool Frogs would have undergone huge declines particularly in the Pingo area where we can only guess some of the ponds have been filled with water since the last ice age. 

Are Pool frogs in Europe generally not that fussy about the water bodies they use? Certainly it was the impression I had. 

I guess it is possible if the notion of the Northern Clade colonising is correct  (see you are slowly getting me to at least consider they might have been native) that isolation could have led to some evolutionary changes that led them to favour specific habitats. It seems true of Sand Lizards, Smooth Snakes, Natterjacks and even to some extent Adder that they appear more specific in the UK regarding habitat requirements than they do in mainland Europe, perhaps simply temperature/season related but it is a trend that tends to be noted as animals reach the limits of their range. Taking that in to consideration it would seem more possible that subtle factors led to a mass extinction.


Posted By: Caleb
Date Posted: 13 Aug 2012 at 10:21am
Originally posted by GemmaJF GemmaJF wrote:

I too thought about the Natterjack decline, but I had always considered them to be more specialised in their habitat requirements than Pool Frogs


As I understand it natterjacks aren't really that specialised (hence their appearance in odd places like the Cumbrian ironworks) but they do very poorly in competition with common frog and common toad. Their main requirement is a pond for late spring/summer breeding that the common species haven't got to first.

As pool frogs are also late breeders, maybe they have similar issues? The last site supposedly had low numbers of common frogs.

Romney Marsh also has few common frogs or toads- maybe this is part of the reason for the marsh frog's success there?




Posted By: sussexecology
Date Posted: 13 Aug 2012 at 4:39pm

Just an idea Caleb - could this be competition with frog and toad populations (niches etc) if they can't compete with those species

Or is it because being late breeders that the ponds they use have dried out by the time they come round to breeding?  I'm assuming that they return to the same pond each year, as toads do?? If there aren't a cluster of ponds together and so the ponds are isolated, I'm guessing this could make sense.

Just an idea though.

Regards
SE Reptile Ecologist




Posted By: GemmaJF
Date Posted: 13 Aug 2012 at 5:14pm
I would go along with that myself as more likely SE. 

Looking at Marsh Frog populations I know in the UK they will often occupy ponds a little larger than usually used by common frogs, a little smaller than usually used by common toads and drainage ditches not used much by either common frogs or common toads. 

There is much to be said for the idea that they occupying a slightly different niche or perhaps more accurately in my mind a wider one than either common frogs or common toads (at least in terms of the large populations of toads and common frogs I've observed). So direct competition might be a factor at some sites, but not all. Much of the success of Marsh Frogs march across Kent can surely be attributed to the fact that they colonised areas not favoured by the two native species.

Certainly the hypothesis that Pool Frogs being late breeders and ponds drying up during the 80's seems a better model to explain mass decline compared with direct competition with other species. One can only presume that competition had occurred throughout the period after colonisation without previously causing a mass decline.


Posted By: Richard2
Date Posted: 18 Apr 2013 at 3:09pm
Is it possible to make a supervised visit to the Pool Frog site for research purposes? Can anyone give me a contact address for this?
 
With thanks,
 
Richard


Posted By: Katie
Date Posted: 02 May 2013 at 1:08pm
Hi there

I am desperately trying to track down some marsh frogs to be filmed next week and was wondering if anyone knew of hotspots or had any?

Email me  at katie@humblebeefilms.com

Many Thanks 
Katie 


Posted By: Iowarth
Date Posted: 02 May 2013 at 2:31pm
Hi Kate

I have approved your post. There are Marsh Frogs aplenty on the Romney Marshes although I could not give you exact locations. Certainly we have forum members who will be able to do so and hopefully they will see this and respond in time.
I have repeated your plea elsewhere in the forum.
Chris


-------------
Chris Davis, Site Administrator

Co-ordinator, Sand Lizard Captive Breeding Programme (RETIRED)


Posted By: Richard2
Date Posted: 15 May 2013 at 8:10pm
Can anyone give me a contact address for John Baker?
 
With thanks,
 
Richard


Posted By: Iowarth
Date Posted: 15 May 2013 at 8:28pm
Hi Richard

See PM I have just sent you

Chris


-------------
Chris Davis, Site Administrator

Co-ordinator, Sand Lizard Captive Breeding Programme (RETIRED)


Posted By: Suzi
Date Posted: 15 May 2017 at 12:18pm
Maybe this isn't the best place for this post... but here goes.
Went to Ham Wall RSPB reserve near Glastonbury yesterday. Fantastic time as always. Heard the Iberian Frogs in various places, but only individuals. This was good as it meant the 'song' could really be heard, unlike the usual wall of sound which we've normally heard there.
As we left the reserve had the luck to watch a grass snake swimming in one of the drains which hold lots of rudd.




-------------
Suz


Posted By: chubsta
Date Posted: 15 May 2017 at 7:47pm
Here in the South East we have frogs which make an absolute din, sounds like people laughing really loudly and nothing at all like you would expect a frog in the Uk to sound - are they likely to be the same species as these, i never get a chance to actually see them as they are in ponds and dykes which i don't have access to.


Posted By: Suzi
Date Posted: 15 May 2017 at 8:36pm
Others on here will likely be best able to answer your question Chubsta. An absolute din describes them, yes. What was strange yesterday was that in several places just individuals were calling and yes some of the noises did sound human. I'd never been able to see them before this year as they were in hidden ditches, but the RSPB have made viewing places so that was good. They seem to sit on top of water plants instead of just having head and shoulders out, so good views are possible.

-------------
Suz


Posted By: Caleb
Date Posted: 16 May 2017 at 9:39am
Originally posted by chubsta chubsta wrote:

Here in the South East we have frogs which make an absolute din, sounds like people laughing really loudly and nothing at all like you would expect a frog in the Uk to sound - are they likely to be the same species as these, i never get a chance to actually see them as they are in ponds and dykes which i don't have access to.

The Hamm Wall frogs are Iberian green frogs, Pelophylax perezi. Most of the Kent green frogs are Marsh frogs, P. ridibundus (though there are apparently some P. perezi in the Sheppey area).

I'm sure there are lots of places with public access where you could see them. I've seen lots from public footpaths near Appledore (though that was a long time ago).



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