(Frank Greenaway/Vincent Wildlife Trust)

Water Vole (Arvicola terrestris)

With a wide variety of waterbodies in all shapes and sizes, the Weald Moors area is an important bolthole for many aquatic creatures. Surprisingly, one of the most iconic of these is not particularly well-adapted to such a lifestyle, and can even become waterlogged when submerged for too long…

ID: with blunt noses, dark chestnut coats and barely visible short rounded ears, Water Voles have much in common with their Field and Bank Vole cousins in terms of appearance. While they, too, are present on the Weald Moors (inhabiting marginal areas alongside fields, waterways and roads), distinguishing them is not difficult because Water Voles are much bigger and are similar in size to the Brown Rat (which has pointed features and a much longer, hairless tail).
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The Water Vole is Britain's fastest declining mammal (Frank Greenaway/Vincent Wildlife Trust)
In the Field: the ideal Water Vole ‘des res’ will be located within the steep-sided banks of a well-vegetated, slow-moving or still water body, such as a canal, stream, pond or drainage ditch. Here, the profile of the banking is crucial because voles like to excavate extensive burrow systems with entrances at different levels above and below the waterline. Deep within this labyrhynthine maze, the finer points of everyday life are played out in a series of chambers designed for sleeping, nesting and storing winter food supplies. Water Voles are predominantly herbivores, feeding on a range of marginal bankside vegetation and at least 227 plant species have been recorded in their diets. This in itself can sometimes provide a tell tale sign of their presence because Water Voles will cultivate finely manicured ‘lawns’ of closely cropped grass around their burrow entrances.
How Are They Doing? Water Voles are widespread in many lowland areas but are Britain’s fastest declining mammal. There numbers have crashed in recent times and they now occupy less than one of every ten sites where, just a few decades ago, you could reasonably have expected to find them. Predation by the invasive American Mink is regarded as a major factor in their demise but there are many other issues impacting on Water Vole habitat, leaving many colonies isolated and at risk of local extinction. Healthy vole populations require lots of diverse waterside vegetation, with tussocks of grass, sedge and reed to feed on and make dry nests above the waterline. With an average lifespan of around five months, Water Voles are a popular snack for many predators (including Otter and Barn Owl), so plantlife is also vital for providing cover. Indiscriminate dredging (especially where silt is piled-up on the bankside) and the intensive clearance of plantlife from the margins of watercourses are activities that can both serve to cut off and even eradicate local vole populations. Where water supplies become polluted, the growth of algal blooms is another problem that can result in the loss of plant food, while excessive land drainage can also lead to fluctuations in water levels that damage bankside burrow systems.
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Steeply banked watercourses, such as this example at Wall Farm, are often favoured by Water Vole (Gordon Dickins)
On the Weald Moors: Water Voles have been recorded in the Newport Canal but there is a strong probability they are also present in the Strine Brook and other local drainage ditches where favourable ground conditions exist. They maintain fairly small territories of around 70-130 metres of bankside and males mark the edges of their range with latrines of distinctive shiny black faeces. Water voles are most active at night, so a daytime ‘scat-search’ (I never thought I’d find myself writing that!) may prove useful in establishing their presence along the length or breadth of suitable aquatic features.

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