The English Marsh frog invasion


What fun we've all had, discussing corpses and decomposition. Thanks to all who participated. I'm going away for a couple of days. For no good reason other than that it looks good, find here a slide from a talk I do called 'Britain's changing herpetofauna'. I think it's pretty self-explanatory! The pic of the Marsh frog Pelophylax ridibundus is by Neil Phillips - thanks Neil :)

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Where are marsh frogs from originally? Mainland Europe, or North America (or Asia)? On a similar note, how many of Britain's "microfauna" (e.g. rodents, reptiles, small passerine birds) are endemic, and how many are found both in Britain and in the rest of mainland Europe. It would sure be interesting to know, since wasn't Britain part of the mainland during the last ice age?

By Metalraptor (not verified) on 10 Mar 2009 #permalink

Central Europe east of northeastern France, north to southern shore of Baltic Sea (and extreme southern Finland), south to extreme northeastern Spain, northern Italy and the Balkans including eastern Greece; east to ca. 81° E in Asiatic Russia and Xinjiang (China), south to Afghanistan and Pakistan. Isolated populations in the high Asir region of of western Saudi Arabia, and oases of eastern Saudi Arabia; introduced into England and Italy

Reminds me a bit of the bloody American bullfrog (Lithobates catesbeianus) invasion that's going on in many parts of Asia. =(

Oh, by the way, Great Britain apparently does not have any endemic species mammals and reptiles, although there are apparently endemic rodent subspecies that are found on some of the surrounding smaller islands.

Thanks YOU for using the photo :)

Its funny you should be posting on marsh frogs, as Ive been re-reading up on them for a post im writing (its amazing how many half finished blog article you can amass in such a short time!) and was going to see the Rainham marshes colony tommorow until I saw the forecast.

One thing I still cnat find an answer either way is their effect on our native fauna. All I can find is ancedotal evidence, some saying they displace common frogs, otehr saying the inhabit areas that had very few or no native amphibians. I thinkt he latter is mostly true, based on North Kent and Rainham (in Essex) marshes. I found something on all the amphibians populations increasing in the London wetland centre (Barnes) and of course the herons and Grass snakes seem to do well feeding on marsh frogs, but I'm yet to find any scientific work on their impact in the UK

You definitely need a few Xs on South Essex (Rainham especially) on that Powerpoint map. Pretty sure they're on Sheppey and Hoo (Kent) now, too...

By David Callahan (not verified) on 10 Mar 2009 #permalink

<clearing throat>

Pelophylax ridibundus.

Reminds me a bit of the bloody American bullfrog (Lithobates catesbeianus) invasion that's going on in many parts of Asia. =(

And Germany.

BTW, you might like to try Aquarana catesbeiana. Or not. :-)

By David MarjanoviÄ (not verified) on 10 Mar 2009 #permalink


On a similar note, how many of Britain's "microfauna" (e.g. rodents, reptiles, small passerine birds) are endemic

Among birds, there is one recognized species of passerine endemic to the British Isles, the Scottish crossbill Loxia scotica. There are also a few species with distinctive British subscpecies, for example white (pied) wagtail Motacilla alba, yellow wagtail Motacilla flava, coal tit Periparus ater and willow grouse Lagopus lagopus. The latter (which, incidentally, is the 'famous grouse' on the label of the eponymous whisky brand) is sometimes treated as a distinct species, the red grouse Lagopus scoticus.


there are apparently endemic rodent subspecies that are found on some of the surrounding smaller islands.

Such proposed and traditionally recognized endemic British subspecies include the St Kilda field mouse Apodemus sylvaticus hirtensis and the (extinct) St Kilda house mouse Mus musculus muralis. But it should be noted that many modern authorities, e.g., Wilson & Reeder (2005), no longer recognize these as valid taxa.

Regarding American bullfrogs in Europe: They are not only found in Germany, but also in Italy, France, Belgium and Greece (Ficetola et al., 2007). There have also been temporary populations, which were apparently successfully eradicated, in Spain, the Netherlands and the UK (Kent and Sussex).


Ficetola, G.F., Coïc, C., Detaint, M., Berroneau, M., Lorvelec, O. & Miaud, C. 2007. Pattern of distribution of the American bullfrog Rana catesbeiana in Europe. Biological Invasions 9, 767-772.

Wilson, D.M. & Reeder, D.A. (eds.) 2005. Mammal Species of the World. A Taxonomic and Geographic Reference. III ed. Johns Hopkins University Press.

Supplementary information to my previous comment: Wilson & Reeder (2005) do recognize separate Scottish (scoticus) and Irish (hibernicus) subspecies of the mountain hare Lepus timidus. I'd guess that these populations of L. timidus, which is something of a relictual species in this part of Eurasia, are the closest things there are to endemic British* mammal species.

* 'British', in this biogeographical context, of course means including Ireland.

We've found a couple of escaped frogs here in Jersey too. The island naturally has Agile Frog Rana dalmatina which is sadly very rare and survives through direct conservation. We turn up lots of R. temporaria as thoughtful people don't like to see wet areas with no frogs and bring them back from their holidays!I'd guess that we've had other frogs through the same route.

By Glyn Young (not verified) on 11 Mar 2009 #permalink

You think you've got problems? What about us? Hawaii is being taken over by Puerto Rican coqui frogs that are louder than chainsaws and never eat mosquitoes, but eat the other bugs that used to eat the mosquitoes. (Let's not get too deeply into who brought the mosquitoes. Or the flies. Or the rats. At least you-all didn't bring snakes.)

Of course the Puerto Ricans say, "You think you've got problems? What about us?" It's hard to argue with them.

By Nathan Myers (not verified) on 11 Mar 2009 #permalink

I have a few off topic questions about ancient (or medieval) people discovering fossils:

(a) Are there any extant fossils known to have been discovered before the 17th century? If so, please turn up some links.

(b) I recall reading in many different places that fossils in ancient China were so commonly found that an industry of 'dragon-bone hunters' existed, which sold them as curios, and sold them to apothecaries, who ground them up for use in traditional Chinese medicine. If this is true, can anyone provide references?

(c) I turned up this review of First Fossil Hunters . Can anyone provide a link to online available material on ancient Greeks or Romans finding fossils, other than said book review?

The context of this question is Steven Novella's comment:

... if ancient cultures found dinosaur bones, then where are they? We have many artifacts from ancient cultures, the absence of a single dinosaur fossil is significant (of course, the absence of evidence is never conclusive).

My first thought was that some dinosaur bones known to have been found by ancient cultures were currently in museums somewhere, but my google-fu failed to turn up any evidence, other than reviews of the above mentioned Adrienne Mayor book (also already mentioned in the thread.)

(Note: I don't think the Cambodian carving discussed in the thread requires fossils to explain it; it looks like a mythical creature to me.)

Any answers much appreciated.

Thanks to Dartian and Hai~Ren for the info.

And you people think you have it bad? Two words: Sea Lamprey. Little jawless fish have been crawling into our lakes and shredding our fish. Come to think of it, the entire Great Lakes region is crawling with invasives, zebra mussles, gobies, loosestrifes, alewifes, etc. And nutria...don't forget nutria.

By Metalraptor (not verified) on 11 Mar 2009 #permalink

As somebody raised in a country which still has almost all historic fauna, I always wondered: why legitimate reintroductions are so rare, cautious, slow, expensive, while establishing alien species goes like puff!

Wouldn't mind some terrarium entusiast travelling with a bucket and re-establishing colonies of native British amphibians wherever they went extinct. Anyway, there is a good evidence that 1) many historic colonies of small animals are result of accidental transport by man, 2) natural expansion of species goes by trial and error - random attempt of colonizations, most of them failed.

Chris: Hawaii has Bufo too. But Puerto Rico has snakes, and Australia has vipers — oh does it ever! But both came by them honestly, so (how is it you say that?) no worries.

Jerzy: Reintroductions fail for the same reason the original population died out: conflict with introduced species, and habitat destruction. Invaders have the advantage that local predators, prey, and parasites aren't adapted to them. The solution is to introduce the locally threatened species somewhere else where they have the invaders' advantage. This solution is not very popular with naturalists, despite the alternative. Ordinarily this would not matter, but it's only the naturalists who would care enough to do it in the first place.

By Nathan Myers (not verified) on 11 Mar 2009 #permalink

"But Puerto Rico has snakes, and Australia has vipers "

Which die upon attemtping to eat said Bufo marinus

By Metalraptor (not verified) on 11 Mar 2009 #permalink

"You think you've got problems? What about us?"

Bufo marinus, Herpestes javanicus, Casuarina equisetifolia, Hypostomus plecostomus, Iguana iguana, Rana catesbeiana, Macaca mulatta, Caiman crocodilus

"Puerto Rican coqui frogs that are louder than chainsaws"

Come on, they can't be that loud ;) There are about 17 species of coqui in Puerto Rico and they are anything but bothersome; in fact a night in the countryside without listening to a coqui is just wrong!!


Agreed in part. But also trying to reintroduce in the same place often makes sense. Amphibians might be extinct due to past events (eg. pollution) but cannot recolonize naturally because of man-made landscape fragmentation.

Bufo marinus has now been Rhinella marina for a few years. Bufo in the old sense was multiply paraphyletic, and huge.

By David MarjanoviÄ (not verified) on 12 Mar 2009 #permalink


Bufo marinus has now been Rhinella marina for a few years.

What, is it not Chaunus marinus anymore? Damn, I lose track of all these herpetological name changes!

David: It's a mistake ever to change genus/species names we learn in our youth. Taxonomy at that level should be let to drift free from phylogeny. I'll continue calling them Bufo. Everyone will know what I mean.

By Nathan Myers (not verified) on 12 Mar 2009 #permalink

i always found it hard to distinguish marsh frogs to the green frogs (rana sp) eny tip on how to tell them apart?

By Zach Hawkins (not verified) on 12 Mar 2009 #permalink

It was Chaunus marinus for a couple of months. Frost et al. (2006) had simply neglected to consider the type species of Rhinella.

Taxonomy at that level should be let to drift free from phylogeny. I'll continue calling them Bufo.

Then the term Bufo will be drastically misleading. I prefer to eat my cake.

By David MarjanoviÄ (not verified) on 13 Mar 2009 #permalink

And this, my friends, demonstrates the value of standardized "common" names. The catesbiana part would have been a tip off for the frog (there being relatively few species bearing that moniker), but out of context I would have had no idea what Rhinella marina is. Having fallen so hopelessly far behind in herp taxonomy, I think I'll just stick to calling them the American Bullfrog and the Marine Toad.

I feel a bit responsible for the presence of marsh frogs at Lewes. In the late 1960's I collected no more than about half a dozen adult/subadult marsh frogs, and some tadpoles, from Walland Marsh and released them in drainage ditches west of the Ouse and, I think, between Lewes and Iford. A year or two later I returned to the same place and heard marsh frogs calling. These days I would be very much against moving frogs around, because of disease problems, but at the time it seemed harmless. Are they still not present on Pevensey Level?

By Julian Dring (not verified) on 15 Mar 2009 #permalink

Hell, Tz'unun is right. They're just all just toads now.

By Nathan Myers (not verified) on 16 Mar 2009 #permalink

Having fallen so hopelessly far behind in herp taxonomy, I think I'll just stick to calling them the American Bullfrog and the Marine Toad.

Refer to the "Marine Toad" here in Australia, and no-one will have a clue what you're talking about. Just saying.

Nathan: or the ants. Hawai'i had a whole ecosystem that had evolved without needing to defend itself against ants.

Um, caffeine kills frogs. Just saying.

Was going to comment re Dartian's reference to Lepus scoticus and L. hibernicus being distinct from L. timidus, but that's just splitting hares.


By Graham Shortt (not verified) on 19 Mar 2009 #permalink

Graham: Ouch, what an atrocious pun! I wish I had thought of it!

There are Marsh Frogs in the forest pools in north Hampshire. However, one rarely sees the indigenous frog; so I assume the Marsh Frog competes with and eventually replaces the indigenous species.

By Robert Gray (not verified) on 20 Jun 2009 #permalink

There are Marsh Frogs now in the New Forest,I photographed one.Its on Wild about Britain.

By Jason Claxton (not verified) on 23 Sep 2009 #permalink