A water vole, which is the UK’s fastest-declining wild mammal, has been spotted in Croxley Green and volunteers say this is the first time one has been spotted in the River Gade for more than 20 years.

The mammal was discovered by Michelle Prater and Robin Adair, volunteer surveyors for Herts and Middlesex Wildlife Trust and they monitor the River Gade in Croxley Green. 

The pair are two of a 75 strong team that monitors rivers and lakes in the two counties and they were carrying out routine checks when they discovered the water vole.

Martin Ketcher, Wildlife Trust’s Water Vole conservation officer said: "Our volunteers are trained to look out for the telltale signs of water vole activity - which is also a great indicator of a healthy river - and we’re delighted that Michelle and Robin have been able to spot signs that this rare, endangered creature is making its home here on the Gade."

He added: "We know that water voles have suffered a 90 percent decline both nationally and locally, so this is a very exciting discovery."

The Wildlife Trust said the decline in water vole numbers is mostly down to the impact of predation by American Mink and as a result water voles are absent from most rivers in Hertfordshire.  

They added the nearest known populations are on the River Chess and this is the most likely source of the newly discovered water voles on the Gade.