Chesham Directory 2021_HR 15/09/2021 14:28 Page 19
Will Ratty Move Back to Chesham? Water voles used to be common across Britain, living alongside rivers, ditches, lakes and ponds. Tragically, the national population of this charming mammal declined by 95% over the last century and Chesham’s water voles suffered the same fate. Water voles were once a normal sight along the River Chess, but they were last seen in the town centre (in Meades Water Gardens) in the 1980s. As urban pressure grew, the population retreated downstream into the countryside. But even there, the voles were not safe. Between 2001 and 2003, the population on the Chess crashed by 97% and the Chess water voles were teetering on the brink of extinction. Their decline in the Chess Valley was largely the result of American mink, an invasive species that has established over here after escapes/releases from fur farms. A water vole is a perfect snack for a hungry mink, and mink can easily outfox a water vole’s normal antipredator behaviours such as diving under water. As a result, mink can rapidly eat their way through a population. A further problem was the loss of good places for water voles to live. Water voles like earthen banks where they can create their burrows, and wide expanses of bankside vegetation – they are enthusiastic herbivores, nibbling on the stems and leaves of at least 227 plant species! Suitable habitat was lost from the valley as people put in artificial banks, tidied up areas, or changed how they used the land on the river’s edge.
In the nick of time, the Bucks, Berks and Oxon Wildlife Trust (BBOWT) launched a recovery project in 2004. There was a two-pronged approach; to remove mink from the valley and to improve habitats along the river. The project was a great success, and by 2011, the population had recovered back to its 2001 size. However, water voles did not return to Chesham. BBOWT, the Chilterns Chalk Streams Project and the River Chess Association (RCA) have worked together to survey the Chess water vole population every two years since then and the results show that we cannot be complacent. The population fluctuates a lot, and mink keep venturing into the valley and doing a lot of harm. The Chess water voles are isolated from any other water vole population, which means that a poor breeding season, flooding, drought or mink predation can easily plunge the population towards extinction. The last survey was carried out in 2019 and showed that vole numbers are holding fairly steady, although it is only at 66% of the 2001 population size. Habitat improvement work has helped water voles to recolonise areas of the river where they’ve been missing for years, and there were even signs of small numbers of water voles exploring parts of the river at the southern end of Chesham. The next survey is being carried out over the summer of 2021 and this will reveal the most up to date population information and whether any of the voles have made their home in Chesham. The RCA would like to hear from you if you have seen water voles, or their field signs in Chesham. Whilst it is easy to confuse water voles and rats, rats have a more pointed muzzle, larger ears and eyes and their tails are naked, whereas a water vole has a fur-covered tail. The RCA is also interested in sightings of mink locally. All reported sightings will help to conserve the Chess voles. You can contact the via their web site: www.riverchessassociation.co.uk.
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