National Mammal Week 2020: Day 4: Fen marsh, Swamp & Bog
Previous Mammal Society Training & Events Officer Rose Toney tells us about her experience of these wetland habitats
Wetland habitats such as fen, marsh, swamp and bog are characterised by specialised plant and insect communities. However, these natural and semi-natural environments can also support a surprisingly rich mammal fauna. From Chinese Water Deer picking their way through wet woodland to Daubenton’s Bats hunting invertebrates over open pools, a diverse range of species are at home amongst the water-logged ecosystems.
Among these habitat types, bogs are undoubtedly my favourite, from the vast expanse of blanket bog, locking away carbon across much of northern Scotland, to the raised bogs found scattered across agricultural lowlands throughout parts of the UK. This latter habitat has provided some fascinating forays and wildlife encounters for me over the years, particularly at a local site which I have explored and surveyed for over a decade.
Many of the mammals encountered were not unexpected, including Otter and voles. Others were perhaps more of a surprise, including Red Deer and Pine Marten, both utilising a strip of mixed woodland on the periphery of the bog. But perhaps the mammals that most bring a smile to my face are the Sorcidae, and all three of Scotland’s shrew species have been recorded at this site, namely Common Shrew, Pygmy Shrew and Water Shrew. Of these three, the Water Shrew has undoubtedly elicited the most excitement.
My first glimpse of these striking small mammals was some footage from a camera trap looking out across a small pond. The frantic swimming motion of this tiny beast was mesmerising and, when it emerged from the vegetation, the distinctive black coat with pale underside was very clearly visible. Together with the relative size (several times larger than both the Common Shrew and the diminutive Pygmy Shrew), there was no doubting this was a Water Shrew! And thus began a love of this feisty animal, which I have been fortunate to record many times over the years.
As an insectivorous species, Water Shrews are prolific predators, feeding many times over a 24-hour period (especially during the hours of darkness) to sustain their high metabolic rate. But they don’t just eat insects; they have a secret weapon – venomous saliva – which enables them to immobilise and consume lager prey such as amphibians and fish.
Like several other British small mammals, we don’t have a clear picture of the status of Water Shrew. However, we do know they are at risk from the suite of threats facing the wetlands in which they are found; over-exploitation for agriculture, forestry and peat, nutrient pollution, over-grazing and climate change are all severely degrading these valuable habitats.
How Can You Help?
What you can do to help – DON’T BUY PEAT for your garden and ask your local retailer to stock peat-free compost – whilst we have a range of compost materials available to us, the mammals that depend on these habitats don’t. And of course, it you see any mammals, or their signs while you are exploring wetlands, don’t forget to record them on Mammal Mapper