Froglife volunteer, Victoria L, has taken the time to look into Marsh Frogs, one of the non-native frog species that you could come across in ponds and ditches across the UK, Most commonly spotted in South-eastern areas of England.
What are Marsh Frogs and where do they come from?
Marsh frogs (Pelophylax ridibundus) are a species of frog which are native to continental Europe and Western Asia. They are not a native species in the UK and were introduced in the 1930’s from eastern Europe. They are Europe’s largest native frog species, growing up to 15cm in length. In the UK, they are most frequently found in the Southeast of England, particularly in marshland areas.
Where do Marsh Frogs like to live?
Marsh Frogs are most prominent in the South-east of England due to having been imported from Hungary in 1935 and introduced to the Walland Marsh in Kent, already making it the main location of the species in the UK. Marsh Frogs prefer to spend most of their time either at the edge of or inside a body of water. They have an affinity towards wet, humid habitats such as lakes, ponds, and rivers. When they are not in the depths of these water bodies, they bathe in the sun.
This aquatic preference makes Marsh Frogs differ from other species, like the common frog, which travel around the landscape without much need to be in a constantly wet environment.
What makes Marsh Frogs unique?
Marsh Frogs may seem like any ‘typical’ frog, yet they have some unique features in plain sight. Marsh Frogs are bigger than the usual frog, usually being 13cm long but have the potential to reach 15cm. This contrasts with other frog species which are usually smaller, around 8cm. Another special identification detail about Marsh Frogs is that males have two grey vocal sacs on either side of their head which produce their call. Marsh Frogs have an interesting call which sounds like a cackle or a laugh, which can be produced by both females and males. Their calls travels far and can be used to attract mates.
Marsh Frogs have the ability to have hybrid offspring with other frog species, the green frog group. They can also easily adapt, for example them being able to survive in salt marshes.
Although Marsh Frogs are not native to the UK, their close relative, the pool frog, is. They belong to a group called ‘Green Frogs’ along with their hybrid, the edible frog.
What do Marsh Frogs look like?
They have large heads, males having the two grey vocal sacs on either side. Marsh Frogs also have textured skin along with folds on either side of their body. They come in a variety of colours, be it green, brown or grey.
What is the diet of Marsh Frogs?
Like any other frog, Marsh Frogs consume insects such as worms and spiders. Yet, they may also consume other frogs and even mice, contributing to the threat of native species in the UK.
What impact do Marsh Frogs have in the UK?
With Kent having a rise in the invasive, non-native, Marsh Frog population there has been a simultaneous decline in the populations of common frogs and native newts. Studies have shown that this is likely due to the Marsh Frog species preying on the common frogs and native newts while also bringing them diseases such as chytridiomycosis which they carry and is a threat to native species.
Other studies have shown a decrease in common frogs occurring in habitats which do not contain Marsh Frogs. This is likely due to the changes in habitats caused by pollution and climate change. This has led researchers to believe that the cause of this decline in common frogs is caused by both factors, which also affects other native species as well.
The affect of climate change on Marsh Frogs and other Herpetofauna:
Climate change also plays an important role on the future of Marsh Frogs and UK native frog species. Reptiles and amphibians are sensitive to the changes in precipitation of their environment, being two animal groups which are highly affected by climate change. As climate change and other severe events increase, research and monitoring of vulnerable species become even more important to drive effective conservation efforts.
Warmer temperatures have an unforeseen affect on herpetofauna, impacting their behaviour, reproduction and distribution traits. With climate change and global warming, this is currently affecting them.