Northern Ireland is an important area for the enigmatic pine marten, according to the latest research.
A survey of the mammal in NI has been carried out by consultants, the Ecological Management Group (EMG).
In Northern Ireland, more than 80 different forests and 100 miles of trails were searched to find evidence of pine marten.
Evidence of pine marten was found in 55% of the sites visited.
The mammal is one of the rarest and most enigmatic native mammals in Ireland and Britain.
It typically inhabits woodland habitat and is a protected species. It has had a difficult past having suffered from historical exploitation for its fur; habitat loss; and direct persecution as a pest species.
Over the last four years an all-Ireland research project has been undertaken by Dr Declan O'Mahony, a zoologist with EMG.
Thanks to funding from the Mammals Trust UK the survey was able to include Northern Ireland.
The project mapped the current distribution and range of the species throughout the island of Ireland, and investigated what factors are influencing the current distribution of the species.
"Pine marten are difficult to observe in the wild and are extremely shy of people so it is not possible to undertake a reliable survey based on sightings," Dr O'Mahony said.
"Fortunately, pine marten droppings are very distinctive in their shape and odour characteristics and can be readily distinguished from other species.
"Although pine marten scats are variable, typically they are deep black/purple in colour, are often twisted or broken in shape, and have a distinctive sweet smelling odour."
The most important region for pine marten in Northern Ireland is the west, particularly Fermanagh and South Tyrone, according to the survey.
Pine marten are very common in these areas, so much so that they are increasingly being found in houses where they nest in attic spaces which are warm and safe. Pine marten are also relatively common in parts of County Down and Armagh.
Dr O'Mahony said that they were very rare in the rest of Northern Ireland, probably due to historical persecution and habitat loss.
"Right throughout mid-Ulster and the east, where pine marten are present the populations are isolated in fragments of woodland and have little opportunity to spread out to the surrounding countryside," he said.
He said while more was now know about species distribution "very little" was known about pine marten ecology and this should be addressed to provide "a secure future for this rare and important species in Northern Ireland".
A previous pine marten study was carried out by David Tosh of Queen's University in 2003.