The Mourne Mountains situated in the south eastern corner of Northern Ireland are a granite mountain range. The area is popular with tourists, hillwalkers and those interested in wildlife.
The Pine Marten
One of the more elusive mammals present in the region is the pine marten, a species that has increased in range over the last 30 – 40 years. The pine marten was thought to have been made extinct in this area in the 1870’s, but some animals were live trapped in the 1950’s suggesting that a relict population had historically survived in the region, or that new animals had moved in.
Due to the secretive nature of this animal it is often difficult to estimate the population size and density of this species, and it is also difficult to know how pine marten use commercial forestry plantations due to rough terrain and inaccessibility.
Some of these questions have been addressed in a new study published in the European Journal of Wildlife Research by Declan O’Mahony from the Agri-Food and Biosciences Institute, and Peter Turner and Catherine O’Reilly from Waterford Institute of Technology.
O’Mahony and colleagues used a non-invasive approach to remotely collect hair samples from pine marten across a 360 square km study site where forested areas consisted of several areas ranging in size from 56 to 1,325 ha. Plantations consisted of conifer and a mixture of broadleaf and conifer. The area between these plantations mostly consisted of open moorland.
A total of 126 hair-tubes were deployed across the study area, averaging one tube per 26 ha of forest habitat for a total of four sampling sessions. The tubes were baited with chicken and were checked 10 days later.
DNA analysis was subsequently used on the hair samples to identify the species and sex, and to identify individuals via genotyping.
A total of 226 hair samples were collected in this study, with 96% of the hair samples positively identified as pine marten. Some of the other species identified included dog and rat. Using the species identification results, the samples with the highest quality and quantity of DNA were subsequently genotyped and identified to individual (123 samples). One hundred and ten samples provided a full genotype at the nine markers used for individual identification, an overall success rate of just over 48%. Hair samples with 10 or more hairs were the most likely to provide a full genotype.
A total of 31 unique individuals were identified in the study, with one individual genotyped a total of 18 times, while 10 animals were only genotyped once each. O’Mahony estimated that the breeding population consisted of 18 individuals, 11 male and seven females, with the post breeding population consisting of an additional 13 animals.
Statistical population estimates indicated a population abundance of 32 animals, and a breeding and post breeding population of between 23 and 29 animals respectively. Population density estimates suggested an average of 0.5 pine marten per square km of woodland. Some of the re-capture data showed animals moving as far as 6 km between sampling sessions, while the average animal moved only 1 km.
O’Mahony’s data indicated that the pine marten population in this part of Ireland is quite low, with as few as only nine estimated breeding females in the area. The analysis also showed that pine marten only bred in some of the sampled woodlots. O’Mahony warns of the possibility of local population extinctions due to the small number of breeding females, especially as some of the woodlots are small and isolated which may hamper movement of animals across the entire landscape.
The population estimates from this study are lower than recently published work by Emma Sheehy and colleagues where pine marten density was estimated to be approximately three animals per square km in the densely populated Irish midlands, while in the east of Ireland, density was estimated to be approximately one animal per square km.
Previous population studies of Irish pine marten have taken place in small and often fragmented landscapes, with a greater variety of deciduous woodland, and in areas that contain more hedgerows that may facilitate greater movement of pine marten. Indeed, little is known in Ireland about how pine marten might use agricultural landscapes, and as such, these areas could be important for supporting a higher population density.
O’Mahony suggests that the population estimates obtained from this study may be a more realistic view of pine marten populations in Ireland, as commercial forestry plantations are the predominant woodland habitat type found across the Irish landscape.
Within the Mourne Mountains, O’Mahony makes a number of conservation recommendations to protect the pine marten population. For instance, clear felling should be avoided where possible as this reduces the available habitat for the species. In addition to regular harvesting practices, forest disease management also sees large sections of forestry removed, resulting in habitat loss not only for the pine marten, but also other species such as the red squirrel. Future practices should concentrate on managing forests to facilitate wildlife conservation and habitat continuity to avoid habitat fragmentation and possible local population extinctions.
O’Mahony, D., Turner, P., & O’Reilly, C. (2014). Pine marten (Martes martes) abundance in an insular mountainous region using non-invasive techniques European Journal of Wildlife Research DOI: 10.1007/s10344-014-0878-0
Sheehy, E., O’Meara, D., O’Reilly, C., Smart, A., & Lawton, C. (2014). A non-invasive approach to determining pine marten abundance and predation European Journal of Wildlife Research, 60 (2), 223-236 DOI: 10.1007/s10344-013-0771-2