The National Otter Survey 2023-24 aims to assess changes in otter distribution and population status since the last survey in 2010-11.
Why do we need an otter survey?
The Otter and its habitat are protected under the EU Habitats Directive which requires that Ireland reports on the status of the species at regular intervals. Earlier studies suggested a decline, but recent surveys suggest the otter remains widespread. Threats and pressures could include river corridor management such as culverting, canalisation and dredging as well as pollution, oil spillages and road traffic. Consequently, it is important to assess the conservation status of the species regularly.
Submit Otter records
Otters can be seen along rivers or rocky seashores but they are elusive so seeing one is rare. They do leave obvious field signs, however, most commonly their droppings (known as spraint) and footprints. If you see any of these please record it. Submit a photograph of the animal, spraint or tracks with your record if you have any.
Otter – Ronald Surgenor
Sightings
Otters are predominately nocturnal and are most typically seen at dawn or dusk. They may be spotted from bridges swimming in rivers or along rocky shores. Otters are brown, about 80 cm or 30 inches long and are seen gliding along the water surface before diving to show their distinctive long pointed tail almost as long as the body. Not to be confused with non-native American mink which are black, 40 cm or 16 inches long, swim higher in the water and have a short tail. Coypu are another non-native mammal with which otters might be confused but they are rare.
Otter Spraint – Creative Commons
Spraint
Otters mark their territory using droppings known as spraints. Otters deposit spraint conspicuously on boulders along riverbanks, lake shores or the rocky high tide line. The concrete ledge of bridge footings is a favoured spot; so, it’s always easiest to start an otter survey under a bridge. Spraints vary in size (3-10 cm or 1-3 inches long), colour (black through to white but commonly brown), consistency (tarry to powdery) and shape (straight or curved). It’s not uncommon to see fish bones or crayfish shells exposed. Spraints do not have an offensive smell but have a delicate sweet earthy odour that is not unpleasant. Spraint gets washed away periodically by flooding due to heavy rain and accumulate again in dry weather; so, it’s always best to avoid searching if there has been heavy rainfall in the two weeks previous.
Otter Tracks – Creative Commons
Foot-prints
Otters have large webbed (9cm or 3 inches long and 6cm or 2 inches wide) feet. They have five rounded toes which may or may not have claw marks depending on how soft the mud/sand is in which the depression is made. You might also see the distinctive drag of the tail especially if on the beach.
Other evidence
Otters live in holts which are underground dens often among boulders or fallen tree stumps. They are usually within a short distance of the water’s edge with a well-worn path at the entrance. On a slope otters may access the water by sliding on their belly creating a slide, also known as a chute. These forms of evidence are much harder to attribute to an otter unless the animal is sighted.
The National Otter Survey
National Parks & Wildlife Service (NPWS) staff throughout the country will be conducting up to 900 site surveys for otter tracks and signs as part of a formal survey coordinated by Queen’s University Belfast and Giorria Environmental Services. Any records you submit here will contribute to this study and be used when mapping otter distribution. The Atlantic Technological University, Galway will also be testing river water samples for otter DNA to see if this is a feasible way to survey their presence with greater certainty. The final report should be published as an Irish Wildlife Manual sometime in 2025.