Water Voles on Wilden Marsh Nature Reserve
I am thinking about the Central Drainage Ditch, the work I carried out there in January last year, water voles, and that it is time to see what’s happening there before the start of the breeding season in February.
Water voles are in trouble and have been for quite a while; their numbers have decreased by more than 90% over the last 30 years. Decline of this mammal has and is still being caused by wetland destruction and habitat fragmentation, the American mink, mechanised ditch clearance and intensive farming techniques and processes.
Water voles are usually found within a few metres of water, they 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 as water voles can only travel short distances – moving through dry and open vegetation is extremely difficult for them.
The water vole breeding season begins during February/March and ends in September/October, depending on the weather. Her gestation period is around 3 weeks and she can have a few litters per year, each producing between 3 and 8 babies. The life span of a female water vole is between 5 months and 2 years in the wild.
On Wilden Marsh we see water voles rarely, but we are aware that both water and field voles are using the marsh. I photographed a water vole six years ago and other corroborating evidence has been found recently by Wilden Marsh contractors and volunteers.
My camera traps are seeing increasing numbers of otter and fewer mink; I’m hoping otters are driving them away. We and our contractors have built seven otter holts 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 in a sustainable way.
We have many drainage ditches on Wilden Marsh Nature Reserve and managing them correctly is essential to attracting and maintaining breeding water vole populations. Clearing drainage ditches using heavy machines can be particularly damaging for water voles and will easily destroy their burrows and habitat, as can grazing cattle.
The best time to carry out ditch maintenance is 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 from 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 until it has been established that water voles are using the watercourse or not.
Stage 2 of last January’s Central Drainage Ditch maintenance can be viewed here.