Marsh Frog (Non-native)

Pelophylax ridibundus

Marsh Frogs are Europe’s largest frog.  They are considered non-native and were introduced into Kent in the 1930s.  Since then they have become established throughout Romney Marsh and the low lying areas of North Kent as well as becoming common in other areas too.

It is very easy to distinguish the Marsh Frog from our native frog as the Marsh Frog has no eye patch, is generally much larger, has a rounder snout and (in males) two grey air sacs on either side of their mouths which produce their unique call. Their loud call can be heard quite clearly near breeding sites from April to September. Marsh Frog colour varies but they are generally quite green and usually have two parallel lines along their backs with eyes closer together than a native frog.  They form part of what is known as the water frog or green frog complex of species which includes not only Marsh Frogs but Pool Frogs and Edible Frogs.  Although most water frogs in Kent are Marsh Frogs both Edible Frogs and Pool Frogs have also been recorded.  They are not always easily told apart.

They are active both day and night and like to bask in the sunshine.

Some debate and growing concern surrounds whether Marsh Frogs can impact on our native species. They were originally thought to prefer breeding sites which our native amphibians did not favour, such as ditches and dykes, however it is now known that they will readily use ponds and they are now often spotted in the same habitats as our native amphibians.

This frog is a predator and might potentially have an impact on a range of native wildlife over time (as well as potentially carrying diseases to our native amphibians). Due to this concern it is listed under the Wildlife and Countryside Act 1981

Referred to as non native, alien and sometimes exotic, these species are those which do not occur naturally in the UK and have been introduced, accidentally or deliberately, by man.  Many non native species are not able to survive or thrive in this new home and many non natives are of no threat to native biodiversity. However some can thrive and in some cases become ‘invasive’. In general these problem species may potentially carry new diseases which may affect our native wildlife or they may prey on native plants and animals and have an impact on native species abundance or habitat availability.

With reference to non native species in general, please remember not to release any pets or exotic species into the wild as although this has been done in the past, to do so now is illegal and can cause considerable harm to native habitats and wildlife.Be careful also about which plants you purchase or discard from your garden pond. For more information on Invasive Non Natives visit the Non Native Species Secretariat website where you can find out more information about certain non native flora and fauna and read about national campaigns such as Stop the Spread.

We can all play our part in protecting Kent’s herpetofauna by sending in records of native species and also by helping us to monitor the exotic species which are now calling Kent home.

Have you seen a Marsh Frog (Non-native) in Kent?

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Distribution in Kent

Other / Similar Species