Ireland's Biodiversity Awareness Campaign

Species of the Month

Below is a list of our previous 'Species of the Month'

Common Yew Tree
Witches' Butter
Hen Harrier
Eurasian Otter
Harbour Porpoise
Butterfiles of Ireland
Barn Owl

Eurasian Otter

Eurasian Otter – Lutra lutra – Dobharchú / Madra Uisce

Description & Behaviour

The Eurasian otter is the only otter native to Europe and is one of Ireland’s oldest mammals with record of habitation stretching back to the end of the last ice age (c. 10,500 years ago). It is extremely well adapted to water life and is an excellent swimmer. It has webbed feet and a long stream-lined body between 80-90 cm long from the tip of its tail to the top of its head. The otter has a thick coat of fur which is dark brown on its back and grey-brown on its underbelly. This layer of fur keeps the otter warm by trapping air and keeping its skin dry. Otters have small black eyes and ears and long whiskers which are important sense organs for finding food underwater or in the dark.

Their large lungs allow them to stay under water for several minutes, although most dives last for just one minute. They swim low in the water, with only their eyes, ears and nose above the surface. Otters are very playful animals and even solitary otters have been spotted playing catch with pebbles.


The Eurasian otter can be found in lakes, rivers, marshes, estuaries and coastal waters. While mostly confined to water areas, they will occasionally travel overland, crossing bogs, farmlands, or upland areas. Coastal dwelling otters need to visit freshwater sources often in order to rinse the salt from their fur.

Holt Sweet Home

Otters dig burrows called ‘holts’ into riverbanks, or in the root system of trees where they rest during the day. These holts often have many different entrances, some of which may open underwater. Otters will choose secluded or vegetated areas in which to build their holts and they sometimes use vacant fox earths or rabbit warrens instead of building their own holt from scratch.  


Spotting Otters

Otters are quite difficult for humans to spot, as they are shy and are mainly active at dusk and after dark. Worn-away pathways used by the otters to enter the water, or collections of fish remains are common signs of an otter’s presence. Look out for black droppings called ‘spraints’ which mark an otter’s territory. These are commonly found on boulders or in other prominent positions along otter paths, in an otter’s fishing spot, or near holts or resting places.


Otters are carnivores and predominantly feed on fish such as stickleback, salmonids, eels and crayfish. They also sometimes eat small mammals and dead animals or water birds. Otters dwelling by the coast eat molluscs, crabs and sea urchins. The otter holds its food in its front paws when eating. 


The otter breeding season is in spring and summer. The female will give birth to 2 or 3 otter cubs in a quiet breeding holt following 9 weeks of pregnancy. The mother feeds the cubs until they are about 4 months old and the cubs will stay with their mothers for between 6 – 12 months. Otters begin breeding in their third year and will last about 5 years in the wild.


The Eurasian otter has suffered decline in recent years and is now one of the most threatened mammals in Ireland. Recent survey work has shown that the otter has declined by approximately 18% in the last 25 years or so. This is mainly due to poor water quality, loss of habitat and roadkill. The otter has been protected in Ireland since the 1976 Wildlife Act and is listed on Annex II and Annex IV of the European Habitats Directive. Because of this listing,  40 Special Areas of Conservation (SACs) have been designated for the otter. Despite decline in the otter population in recent years, the otter remains relatively common on Irish waterways, inland water bodies, and in coastal habitats. Ireland’s population of otters is of unique conservation importance as the Eurasian otter has become extinct in much of Europe.

©2007 Department of the Environment, Heritage and Local Government