A COUPLE of weekends ago I was on Lothian and Borders Mammal Group’s latest event which was an otter surveying session. We knew we weren’t likely to actually see any otters as the best time to see them is dawn and dusk as they spend most of the day asleep.
What the session was all about was to help the members of LaBMaG know what to look for so they knew whether otters were using the river they were looking at or not.
When I say otter I am meaning the otter found in this country, the Eurasian Otter (Lutra lutra) which is also called the Common Otter. There are other species of otter around the world including the Sea Otter and Giant Otter. The Eurasian otter is one of the most highly protected species in the world.
It is not just the otter that is protected but also anywhere they spend time such as holes in banks, called holts, or ledges where they rest up or eat what they have caught, called hovers. Holts, especially breeding ones, can be quite a distance from rivers. It is illegal to damage or disturb any of these resting places without a special licence. It is also worth pointing out it is illegal to pick up a dead otter from the side of the road, unless you are covered by a special licence and the dead otter is to be used for educational purposes or research.
Male otters can have up to a 40km territory along a river, but if there is sufficient food this could be much shorter. Females have a much smaller territory. Evidence of otter can sometimes be very difficult to find. Holts and hovers can be extremely hard to see without getting into the river wearing waders or looking at the bank from a small dingy or similar. Otter droppings are often a bit easier to find but making sure it is an otter dropping, called a spraint, in your hand and not a dropping from another animal takes a little bit of knowledge.
Hopefully by the end of the session the LaBMaG members were a bit more knowledgeable and able to identify both otter resting places and otter droppings.
Otters grow as long as nearly a metre in length whereas the American mink, a non-native species sometimes mistaken for otter, only grow to about half that length. It was long believed that mink were out-competing the otter and were the main reason for the otter’s decline in the UK in the latter part of the last century. However it looks like the main reason for that decline was habitat loss and river water quality. Now that riparian (riverside) habitat management has improved in many areas and the water quality of most of our rivers is cleaner that it has been in decades the number of otters has been steadily increasing and at the same time the numbers of mink have been reducing. This reduction is in part due to the trapping of mink by gamekeepers and the like as mink can have a devastating impact on game bird and fish stocks. Mink can also wipe out the local songbird population if they are present. However there is also evidence that otters, as long as they have suitable habitat and clean rivers, can out-compete mink which is great news.
Should you find an animal in need of our services, or if you need any advice please phone HQ on (01289) 302882 we are happy to help. You can also e-mail via our website www.swan-trust.org. If you would like to donate to the trust (cheques payable to BSWT) or to become a member please contact the treasurer, Derek Roughton, Yew Tree Cottage, Branton, Alnwick. NE66 4LW. Telephone (01665) 578365.