After our previous sightings of exotics in our garden, we have been talking with neighbours about where they might come from. In doing so, we discovered some more exciting residents of a pond two doors down.

The photos show 2 of about 8 that appear to be resident there. Each is around 6-8cm long, with a green back with a pronounced brighter green stripe down the middle. The underside is very pale, almost white. The rear big toe is very elongated. It makes a very lound 'rark' (RAUK?) sound when calling. Our neighbour says they puff out their cheeks at the same time. This all suggests either a Pool Frog Rana lessonae or possibly a Marsh Frog Rana ridibunda. Can anyone positively identify from the photo (as always, more photos can be found at http://www.soi.city.ac.uk/~jwo/frog - http://www.soi.city.ac.uk/~jwo/frog ) I am not sure what can be used to distingish between the two species.

The next question is where they have come from. We are about half a mile or so from the edge of Hackney Marshes where we have previously spotted what look like Pool/Marsh frogs. Could they have travelled from there? The fact that they have sucessfully spawned this year is itself interesting. Does anyone else know of any sightings in the area?

Jo.

According to a recent article published in the herpetological journal Green Frogs are still extent in the Lee Valley Navigation system though the actual species present have not been confirmed.

I hope Jo that the leaflet drop in the area goes ahead and we find the extent of the exotic introductions in the area. I fear it would be all to easy for them to use the Lee Valley system to spread as far as Essex and Hertfordshire and any effect on native populations will need to be monitored if this is the case.