My final post concerning the WWT London Wetland Centre is all to do with one of the noisiest amphibians I think I have ever come across. Whilst walking around the site I kept hearing very peculiar, and very deep, croaking noises. Initially I put these down to over amorous Coots but the sound just wasn't right. After a bit of investigation I found the culprits in the reeds to the side of one of the board walks. Happily displaying and mating were around ten Marsh Frogs. I was lucky enough to get a short video of the display.
The Marsh Frog is not a native species and was originally introduced in 1935 to Walland Marsh in Kent. Since then its population has spread to other areas of Kent and East Sussex, and they clearly have a good foothold at the London Wetland Centre. Currently the species is not thought to be causing any harm to the native amphibians, mainly due to its niche habitat of dyke's and ditches that the other species tend to shy away from. More information can be found here.