The Eurasian otter (Lutra lutra) is a medium sized carnivore that belongs to the Mustelidae or weasel family of mammals; its closest wild relatives in Ireland are the badger, pine marten, stoat and the introduced American mink. It is one of our largest native carnivores, being roughly the same size as a fox or badger. It has a long, sleek body and tail and relatively short legs, as well as brown fur capable of trapping air, all of which are adaptations which help it in swimming and diving in aquatic habitats to hunt for its prey. Otters live in most aquatic habitats available to them in Ireland, from mountain streams, bogs, marshes, lakes, rivers and along the coastline, where they mainly hunt for fish, frogs, crabs and the occasional bird or small mammal.
Otters are territorial and depending on their habitat, they can have territories varying in size from just 2km of river to as much as 20km. They frequently mark their territory with their droppings or “spraints” which they often leave on rocks, tree trunks or other prominent landmarks in their habitat. Since otters are usually elusive and shy animals, these spraints and other signs are the only indication of the presence of otters in an area. For more information on otters, please read this article by Mathieu Lundy.
The Eurasian otter is the only otter species present in Europe and much of Asia, but in many parts of its range, especially in Western Europe, otters have become extinct or extremely rare due to the effects of industrial and agricultural water pollution, hunting, accidental deaths in fishing nets and even road traffic accidents. This has led to the protection of otters under E.U. law. The otter population in Ireland is said to be one of the most stable in Europe. However, we still need to monitor the species as recent surveys by the National Parks and Wildlife Service have shown that the population has declined in some areas.
Thanks to the MISE project, we have been developing DNA techniques to track otters using DNA collected from spraints (poo). DNA can be used for species verification, sex determination and individual identification.
See photos for some tips of how to find signs of otter activity on our Facebook page .
With help from volunteers, we have conducted a number of otter surveys. See our preliminary otter survey report from last year’s survey in Waterford here. We have also been interested in urban otter populations and have been involved in a survey in Cork city with the Cork branch of the Irish Wildlife Trust and University College Cork.
The National Parks and Wildlife Service (NPWS) have an information sheet about otters in Ireland NPWS Otter Factsheet and the Mammal Society also have a factsheet about otters in the UK Otter factsheet.