I photographed a water vole on Wilden Marsh in 2013, when the American mink population was at its zenith and before the dramatic increase in River Stour otter numbers. I have not seen evidence of water voles on the marsh since then. Recently, though, audio recordings have been made, verified by two independent sources, of water voles on Wilden Marsh. We are implementing our water vole attraction program this year, so this is exciting and timely news.

Water voles numbers have decreased by more than 90% over the past 30 years. The decline of this mammal is a consequence of wetland destruction and habitat fragmentation, the American mink, mechanised ditch clearance and intensive farming techniques and processes.

Water voles, usually found within a few metres of water, need to eat around 80% of their body weight every day, are semi-aquatic, and rely on wetland vegetation for food and shelter. They don’t hibernate, are diurnal, and are less active and more vulnerable in winter and early spring. Interconnecting wet habitat is important because water voles only travel short distances – they find moving through dry and open vegetation difficult.

The water vole breeding season is February to October; there is a gestation period of around three weeks with a few litters possible per year, each producing between three and eight babies. The life span of a female water vole is between five months and two years in the wild.

My camera traps are seeing increasing numbers of otters and fewer mink; Otters may be responsible for driving mink away. Seven otter holts have been built on the reserve over the past eight years.

Managing water vole habitat requires in-depth knowledge and an understanding of this mammal’s breeding, feeding and habitat requirements and how best to provide and maintain these sustainably.

We have many drainage ditches on Wilden Marsh Nature Reserve, and managing these correctly is essential to attracting and maintaining breeding water vole populations. Clearing drainage ditches using heavy machines can be particularly damaging for water voles, as can grazing cattle.

The best time to carry out ditch maintenance is in October when water voles are still active and not hidden away in their burrows. Breeding starts in early February, and females will not want to move out of their burrows when they have young. It’s important to thoroughly survey an area before developing a maintenance implementation and ongoing ditch management plan. Practical groundwork should not begin without knowing whether water voles are using the watercourse or not.