A study of otters in the Fingal county area has shown that they have happily colonised many suburban neighbourhoods and have even ventured into the centre of towns, writes Dick Ahlstrom
The Eurasian otter is alive and well in north Dublin and probably living in a neighbourhood unexpectedly close to you, according to a new study. Sightings of the animal are rare however, despite the fact that the otter is Ireland's largest carnivore.
Researcher Eoin Collins completed a Master's degree in environmental resource management at University College Dublin with a study of the otter, Lutra lutra. Collins was far from the wilds of Connemara or Kerry, however, he searched for the elusive otter in streams and rivers in Dublin's Fingal county.
Fingal County Council commissioned Collins last summer to conduct a survey of the otter and he reports he "found surprising evidence of its distribution in the area". The object, he says, was to provide the council with information on the animal and its environs for inclusion in its development plans. "The council is anxious to do its best to protect the otter from any negative impacts associated with development in the area."
The urban fox is probably the most exotic visitor familiar to those living in built-up areas around cities and towns in Ireland, but the otter also seems to be there in numbers, at least in Fingal county, Collins found.
"My survey covered the Ballyboghil, Bracken, Broadmeadow, Corduff, Delvin, Mayne and Ward rivers which flow through a range of habitat types," says Collins.
The otter typically makes its home in holes along the banks of streams or in thick vegetation, he says. Unlike the fox it is extremely secretive, so its presence in an area can easily go unnoticed. It is also nocturnal, spending the day resting and then emerging only at night.
The survey took place from June to August at a time when water levels were at their lowest. This was an important consideration given the primary method used to track down Lutra lutra, not direct observation but by searching for the droppings or "spraints" it leaves behind, says Collins.
"Otters are so difficult to see that spraints are the only main way of identifying their presence in an area."
Spraints are a means of communication between otters so they are left in prominent places - for those with eyes to spot them. Collins found his otters were leaving spraints on large boulders, tree stumps or ledges under bridges, not just along their river bank habitat as is typical of otters outside the city.
"The indications from the survey of the otters' distribution in Fingal are firstly that it seems to be doing quite well in this area and secondly that it frequents the urban as well as the rural areas of Fingal," Collins indicates.
One might expect otters to move about rural areas, but spraint markings were also seen along streams in the centre of busy towns including Balbriggan and Swords, Collins says. "Otters have also been spotted on the Commons Stream in Shankill, south Dublin and otter spraints were seen in places along the west pier in Dún Laoghaire."
He looked at a number of factors affecting otter distribution in Fingal including food supply, water quality, human disturbance and vegetation cover. "The overall conclusion reached by the study was that the otter seems to be doing reasonably well in Fingal and as yet has not been adversely affected by the rapid development of this county area," Collins suggests. The animals seemed capable of surviving in "less than pristine" waters and have tolerated areas of high human activity and development.
The Vincent Wildlife Trust carried out a national otter survey in the early 1980s and recorded otters at 91.7 per cent of the 2,373 sites surveyed, he says. "The recent study of Fingal recorded 86 per cent of sites positive, which compares quite favourably," he adds. Trinity College Dublin is now involved in a fresh national population study of this elusive animal.
The otter seems quite able to adjust to urban living in close proximity to human neighbours, even if the level of interaction is low. The animal has been identified in the centre of cities including Glasgow, Newcastle and Newport in UK studies and one otter was found sleeping in an abandoned car, Collins says.
What the otter cannot tolerate is the devastating effects of pesticides and chemical pollution of the watercourses on which it depends. "As long as the ban on serious agricultural pesticides such as dieldrin and PCBs remains in Ireland, Britain and parts of Europe, the most serious threat to the otter will have been removed," Collins states.
The otter is a protected species under the 1997 Wildlife Act and its 2000 Amendment. It is also an Annex II species under the EC Council Directive 92/43/EEC, Collins points out. Annex II species are defined as "Animal and Plant Species of Community Interest Whose Conservation Requires the Designation of Special Areas of Conservation". This means that human activities must not prove detrimental to the animal.