RAUK - Archived Forum - Somerset Green Frog i.d.

I have posted messages relating to Somerset Green Frogs on the 'Naturalised species' and 'What is it' areas of the forum, but if there is an answer to this question in the following exerpt, it may be of interest for indentification purposes:

" I examined a large specimen of a Somerset 'Green Frog' and its heel clearly extended beyond the snout. General opinion considers the Somerset Green Frogs to be Edible or Pool Frogs, and that was my original gut feeling when I saw them. How reliable is the method of determining the three species found in the UK using the length of the hind leg? If it is reliable, the Somerset Green Frogs appear to be Marsh Frogs, or at least, have Marsh Frogs among their number.

Any feedback very welcome! (Particularly literature references to the Somerset colonies and their i.d.)

Peter Sutton

I have stumbled across a report of a past HGBI herp workers meeting where these frogs were part of the discussion - I will dig out the reference which was in the late 1990's I think -

Sound recordings of their mating calls will identify the species - which there are many - the animal you describe is of the 'marsh' type - the name marsh comes from the Romney Marsh introduction - they are known as lake frogs in France -

Are there any pictures of the animals?

Jon

Thanks Jon,

there are images but I need to work out how to reduce the resolution to get them on the site. I have looked again at the pictures, and the heel just clears the snout of the Somerset Green frog, which according to Beebee and Griffiths is a Marsh Frog. However, the diagrams in the Surrey Atlas by Wycherley and Anstis are different. The specimen still appears to conform to the Marsh Frog on account of the fact that it is stated that the heel of the Edible Frog doesn't pass the snout, but in these diagrams, the Marsh Frog's heel is regarded to be "well past the snout", perhaps a case for a note in a journal to discuss the confusion.

Will try to get the picture on the forum. Thanks again,

Peter Sutton

Hi Jon,

I am attempting to attach a picture of a Somerset Green Frog (From Shapwick Heath) which, by measurement, shows the heel just extending beyond the snout.

I am still confused by the differences between the green frog 'heel' diagrams in Beebee & Griffiths, and Wycherley & Anstis. Is the latter an accepted update, and does that make the former diagrams in B&G partially (i.e. with respect to ridibunda)

obselete?

Kind regards

Peter

Peter Sutton

Here are some more pictures of green frogs from the strong colony at Shapwick Heath NNR:

I have just seen Dave Bird's message in the 'naturalised species' section regarding the problems of trying to identify green frogs using morphometrics alone. It would appear that a good sound recording or DNA evidence is required to resolve this matter regarding the true identity and possibly the original source of the Somerset Green Frogs. 

Peter Sutton

I would say that a sound recording would be all that is needed - the heel needs to go well beyond the snout to help id marsh or P ridibundus - so it may well be edible and other species

I remember that someone sent me a frog video from the same area and the animal was definitely not a marsh frog - you need to record them during June and July when they are in full swing breeding mode -

Jon

Many thanks Jon, much appreciated.

Is there a standard or recommended kit for producing high quality sound recordings of these species? I would like to pursue this method of i.d. Who would I send the recordings to?

Peter

I recorded waterfrog calls at Shapwick 5 years ago. Resulting call analyses indicated that this population comprised Edidible frogs. However, this may not be the complete story as I prefer to revisit a site several times in order to ensure that I have recorded all species present...  An Edible frog population rarely survives without the presence of either Pool frogs or Marsh frogs with which they interbreed.

2 years ago I recorded waterfrogs calling at Ham Wall Nature Reserve. These frogs were distinctive from those at Shapwick in that the vocal sacs were unusually dark - even when compared to typical Marsh frogs.

Identification of waterfrog species is never certain by morphology alone but use of leg length can be a useful guide. Diagrams may vary slightly due to the enormous variations within a population and should only be used for adult frogs. The following pictures may be of help.

Marsh frog

Pool frog

Edible frog

Julia