In summer 2016, Gloucestershire Wildlife Trust, Forestry England, Forest Research and Vincent Wildlife Trust (VWT), supported by Forest Holidays and the Woodland Trust, began a collaborative project investigating the feasibility of reintroducing pine martens to the Forest of Dean and lower Wye Valley. The project draws on international reintroduction guidelines to help us ensure any reintroduction is of the highest possible standard. Pine martens are one of Britain’s rarest mammals (our second rarest carnivore), and are mostly found in Scotland and central Wales. They are a member of the weasel family, the mustelids that live over large areas at low density (range sizes can vary from around 1 to 30km2)1,2. They live predominantly in woodlands 3,4 and their main prey are small mammals, but they have a broad and varied diet, for instance eating large quantities of berries when in season1,5.
Reasons for a reintroduction
The European pine marten, Martes martes, declined throughout much of the UK as a result of habitat loss and predator control, particularly in the 1800’s6. They survived in a stronghold in the north east of Scotland and have slowly recovered across much of the country. However, in England and Wales the population was thought to be too small to recover. From 2015 to 2017, VWT successfully moved 51 pine martens from Scotland to central Wales. It is now essential to build on the success of this project to ensure that a population of pine martens in Wales and west England becomes established. Translocation of similar species in the UK and overseas has shown that to give the reintroduced population the best chance of survival, the more animals that are released together, the better their chance of establishing2,7,8.
We assessed the suitability of the habitat in the Forest of Dean and lower Wye Valley for pine martens and studied whether a stable population of pine martens could live in this area. Find the full reports at the bottom of the page. Research, carried out by Dr Andrew Stringer, showed that the region could support nearly 200 pine martens. Due to geographical barriers, these pine martens would predominantly expand to the west and north, towards where pine martens are already established in Wales.
It was thought that in this region, pine martens may be at risk of being killed by foxes and road traffic. However, road density in the Forest of Dean and lower Wye Valley is comparable with areas of the Netherlands which have healthy pine marten populations.
Pine martens are known as “generalist predators” meaning they eat what is most common and available9. Restoring predators to ecosystems has been shown to restore balance to environments, controlling prey species and their impact on other flora and fauna10. One of the most recent interest in pine martens stems from their impact on grey squirrels (a non-native species in the UK)11,12. Grey squirrels have a number of negative effects including tree damage via bark stripping as well as outcompeting and spreading disease in red squirrels13. Pine martens may drive a reduction in the grey squirrel populations in Gloucestershire, however it is not the focus of this project and any effects are likely to be many years away.
Pine martens are opportunistic predators and before translocating any animals we also assessed any risks pine martens may pose to rare and protected wildlife. The only high risk we identified was the potential disturbance of bat roosts within buildings by pine martens looking for den sites. We are working closely with VWT who are experts in both pine martens and horseshoe bats, the key bat species group in the Forest of Dean. VWT have previous experience mitigating against this type of disturbance and we continue to work on and monitor any species interactions closely.
Social and economic impacts
Pine martens are a joy to watch. They can help to engage people with nature. They may also bring more tourists to the region in a bid to see this rare and elusive creature. The potential impact of martens on grey squirrel numbers may also enable a greater number of broadleaf trees to be planted and grow into high quality timber. While infrequent, predation of enclosed poultry can and does happen. A variety of measures can work in preventing livestock losses, which are often the same techniques used to prevent foxes. The project team will be on hand to help discuss, monitor and reduce the likelihood of any impacts. We recommend the following links:
https://www.vwt.org.uk/ - Vincent Wildlife Trust’s page with further information about pine martens.
https://pinemarten.ie/ - Useful information for gun clubs and poultry keepers, foresters and farmers.
Community support was essential for the reintroduction to proceed. An on-street survey was thought to be the most robust methodology for surveying local opinion, and showed 71% in favour of the reintroduction, 3% against, and 26% undecided. This was further supported by an online opinion survey and feedback collected at community events, which both showed a broad backing for the project. We also had detailed discussions with representatives from a variety of groups. There was clear support for the principal of reintroducing a native species. Many suggested that their concerns could be addressed if the impact of pine martens is monitored in detail. We thoroughly support this approach, and the reintroduction project will have 5 years of detailed monitoring alongside it. The full report for this study can be found at the bottom of the page.
Find all of the reports and documents mentioned at the bottom of this page.
- Caryl FM. 2008. PhD Thesis: Pine marten diet and habitat use within a managed coniferous forest. University of Stirling
- McNicol, C.M et al. 2020. Postrelease movement and habitat selection of translocated pine martens Martes martes. Ecology and Evolution 10:5106-5118.
- Balharry D. 1993. Factors affecting the distribution and population density of pine martens Martes martes in Scotland. PhD Thesis. University of Aberdeen
- Manzo E et al. 2012. Estimation of population density of European pine marten in central Italy using camera trapping. Acta Theriologica 57:165–172.
- Lockie JD. 1960. The food of the pine marten Martes martes in West Ross-shire, Scotland. Proceedings of the Zoological Society of London 136:187–195.
- Sainsbury KA et al. 2019. Recent history, current status, conservation and management of native mammalian carnivore species in Great Britain. Mammal Review 49:171–188.
- Armstrong DP et al. 2013. Using radio-tracking data to predict post-release establishment in reintroductions to habitat fragments. Biological Conservation 168:152–160.
- Fischer J & Lindenmayer DB. 2000. An assessment of the published results of animal relocations. Biological Conservation 96:1–11.
- McDonald RA. 2002. Resource partitioning among British and Irish mustelids. Journal of Animal Ecology 71:185–200.
- Ripple WJ & Beschta RL. 2003. Wolf reintroduction, predation risk, and cottonwood recovery in Yellowstone National Park. Forest Ecology and Management 184:299–313.
- Sheehy E & Lawton C. 2014. Population crash in an invasive species following the recovery of a native predator: The case of the American grey squirrel and the European pine marten in Ireland. Biodiversity and Conservation 23:753–774.
- Sheehy E et al. 2018. The enemy of my enemy is my friend: Native pine marten recovery reverses the decline of the red squirrel by suppressing grey squirrel populations. Proceedings of the Royal Society B: Biological Sciences 285: 20172603.
Rushton SP et al., 2006. Disease threats posed by alien species: The role of a poxvirus in the decline of the native red squirrel in Britain. Epidemiology and Infection 134:521–533.