Holes in the map, part 6: Pine Marten

In the sixth installment of the series about specices missing from the Lake District, Site Manager Lee Schofield focuses on one of our most elusive native predators, the pine marten.

At five o’clock in the morning, I crept downstairs with my early-rising son, hoping not to wake my wife and daughter sleeping above. We snuck into the living room of our holiday cottage on the shore of Loch Linhe, keeping the lights low. As we started on our breakfast, the corner of my eye caught a movement outside. A sleek brown creature with a creamy bib flowed onto the picnic table, gently illuminated by the glow through the large windows. Trying not to move or exclaim our excitement too loudly, we watched enthralled as it picked up a piece of bread and jam we’d left out the night before. This was our first glance of a wild pine marten, one of the UKs most elusive mammals. With the bread in its jaws, it scampered back off into the darkness of the woods and the spell was broken.

The Highlands of Scotland is the best place in the UK to see pine martens today, but not too long ago, they were far more widespread.

The evidence for the historical presence of pine martens in Cumbria is stamped onto the map. There are at least half a dozen place names associated with them – Mart Crag, Mart Bield and Martindale all speak of their presence. Like wolves, wildcats and eagles who also gave their names to places, pine martens were a species that were considered vermin and they were vigorously hunted as a result. Hunting pine martens, usually with dogs, was popular sport. So popular in fact that pine martens were nick-named ‘sweet mart’, contrasting with the ‘foul mart’ or polecat as we now call them, which put up a more aggressive defence than the pine martens did.

It is largely their popularity with hunters which led to the pine marten’s current scarcity. The intensity of the ‘sport’ grew through the Victorian period, so that by 1915 pine martens were effectively extinct across most of England, apart from a scattering of small isolated populations in remote areas. They held their own in the Scottish Highlands, where there were less people to persecute them.

Pine martens are the most tree-loving member of the mustelid family, the group which includes otters, badgers, stoats and weasels, though they can also do well in treeless upland areas, where crags and scree can give them the shelter they need to rear their young. They have a broad diet, eating small mammals, birds, eggs, insects, as well fruit and berries. Being a generalist like this is a recipe for success, and before we started knocking their numbers back, pine martens were one of our most numerous predators.

Of all the species I’ve written about in this series, pine martens are probably the most shadowy. They have ranges that cover vast areas which, combined with their nocturnal habits, means that even when pine martens are present, they’re hardly ever seen. The sighting I had in Scotland was my first experience of seeing a live pine marten, and there’s good reason to think that it won’t be my last. As hunting pressure has reduced, pine martens are on the rise, spreading back out from their refuges.

This isn’t just good news for pine martens. There is a growing body of evidence that shows that they might be the ultimate weapon in the fight to save red squirrels. In Ireland, where pine martens are also on the increase, a mammal ecologist observed something fascinating. As the pine martens moved into a new area, she noticed that all of a sudden there seemed to be fewer grey squirrels. As the grey squirrels declined, so the reds bounced back. More research followed which has releveled a fascinating ecological story.

Because red squirrels evolved alongside pine martens, they have had to develop strategies that allow them to withstand pine marten predation. When the researchers spread pine marten scent onto squirrel feeding stations, the red squirrels avoided them, but the grey squirrels didn’t. Red squirrels can recognise that the scent of a pine marten means danger. Grey squirrels, which are native to North America where there are no pine martens, have no such ability so are more easily caught. The fact that red squirrels are daintier than grey squirrels also gives them an upper hand – they can run along branches that are too small to carry the weight of a pine marten and escape to safety.

The deadly squirrel pox virus that grey squirrels transmit to reds is the main reason that reds have vanished from most of the UK. Greys are also a major forestry pest. Living at much higher densities than red squirrels, their habit of gnawing at bark to get at the sap below can kill trees in huge numbers. At present, grey squirrels are killed en masse, to protect both trees and red squirrels. The possibility that the return of a native species might be able to do this grisly job for us seems almost to be good to be true. But as the evidence piles up, even the sceptics are beginning to accept that pine martens really could be the downfall of the grey squirrel and the saviour of the red.

So, how can we get more pine martens back into our countryside? Two recovery projects are already underway, both run by the Vincent Wildlife Trust, a charity specialising in mammal conservation. Translocating martens trapped in the Highlands, they have released them into an area of Mid-Wales, and more recently, into the Forest of Dean. I went with some colleagues to visit these projects a couple of years ago. We were struck by how similar the landscape in the Welsh project was to the Lakes, and it confirmed that pine martens would be very much at home if they could find their way back to Cumbria. The Vincent Wildlife Trust’s opinion was that they’re going to get here under their own steam, and in their view, we just need to be patient. As it turns out, their return has already begun. There are a growing number of trustworthy accounts of people having seen pine martens in Cumbria in recent years. DNA analysis of droppings confirmed that they were present in Grizedale Forest in 2011, and in 2018, one was caught on a trophy camera in the far northeast of the county, close to the Northumberland border, where the population is also growing. With increasing numbers in Dumfries and Galloway, it’s only a matter of time before pine martens properly re-establish themselves south of the border.

Pine martens coming back to Cumbria might not be universally popular. One of the reasons that they were hunted so enthusiastically until fairly recently was because of their occasional liking for chicken. Pine martens can also kill pheasants and other game birds, which doesn’t make them very popular in shooting circles. The Vincent Wildlife Trust have produced a useful guide to show how chickens can be protected from pine martens, and shooting estates generally produce such enormous numbers of bird, that it’s unlikely that pine martens would have much of an impact on them. In my view, we have a moral imperative to accommodate pine martens, a native species which we drove almost to extinction. The fact that they might also help our red squirrels to bounce back, makes them even more worthy of making some small allowances for.

To read the full collection Holes in our Map series, visit our blog.