The otter is a long, slender semiaquatic mammal, usually coloured brown above and cream below.
Otters has an adaptable diet of mainly fish. In winter, when there are less fish available, the otter will also eat amphibians, crustaceans, insects, birds and sometimes small mammals. This means that otters can be found in any body of fresh water including lakes, streams, rivers and ponds - as long as there is sufficient food available. They may also live in salt water but in this case need access to a source of fresh water to clean their fur.
Otters are strongly territorial, so they live alone most of the time. Territories are held against members of the same sex only, so males and females may have overlapping territories. Mating takes place in winter with females giving birth to between one and four pups. The babies remain with the mother for about 13 months.
In Ireland the otter population declined by 20-25% between 1980 and 2006 for reasons which are not entirely clear. One possibility is a decline in numbers of eels due to pollution incidents and habitat removal. Due to this decline, the otter is categorised as near threatened in Ireland.