In this blog RSPB Scotland's Senior Species Policy Officer Keith Morton shares lots of amazing facts about lovely pine martens - they're more than just a cute face!

All about pine martens

Martens are small to medium-sized mammals, relatives of the (larger) badger and otter and of the (smaller) stoat and weasel. These are all part of a wider group of animals called mustelids.

Various different sorts of martens – eight in fact – live across much of the northern hemisphere. These include such creatures as the Japanese marten and the American marten, both with obvious clues in their name as to where you might look for them. But the only marten that lives in the UK is the pine marten. In fact, within the UK it is still mostly restricted to Scotland and within Scotland still mostly found in the Highlands, although that now seems to be changing. We will come back to that below. While it is the UK’s only marten species, it is common and widespread across most of Europe and into the western fringes of Asia. There it shares a lot of its range with yet another sort of marten, the beech marten (aka stone marten) which has never been a UK species.

If the pine marten’s name – unlike its Japanese and American relatives – doesn’t tell us which countries it lives in, it does give us a strong clue about its habitat (well, up to a point, as we shall see!) All the martens are indeed associated with trees and woods. In fact, their ecology is often described as ‘semi-arboreal’. So, although they do use scrubby and more open places quite readily, more often than not a typical pine marten’s territory will contain a significant patch of woodland at its core. The name is nevertheless still a bit misleading. For they are not just restricted to pine woods.

pine marten curled up on some sticks
Image by Hebi B. from Pixabay 

Pine martens are often described as ‘domestic cat-sized’. This is both helpful and unhelpful in getting an idea of what they look like. Their general dimensions are certainly similar to those of a small domestic cat, but their shape is far from cat-like. They have the typical long body and proportionately shorter legs of many of their fellow mustelids (stoats, weasels, otters). If that shape suggests a certain ungainliness, then the very opposite is true. Pine martens are very agile both when on the ground and up trees. This is essential for them to function effectively as a predator.

Pine martens are mainly nocturnal and go after a wide range of small creatures. Small rodents, i.e. mice and voles, are probably their main prey but they will also take birds and their eggs and even hunt invertebrates. Nor are they just carnivorous. Fruit and berries can form a significant part of their diet at certain times of year and they are famously attracted to gardens when such delicacies as jam sandwiches and peanut butter are offered. In fact, several Highland ecotourist businesses rely on pine martens’ willingness to turn up reliably and regularly for a nightly peanut fix in order to show the animals to their clients.

Pine martens are also predators of squirrels for which their agility in trees is essential. Over recent years a fascinating story has emerged about the pine marten’s relationship with both species of squirrel, the red and the grey. It is a story we do not yet fully understand.

We said earlier that pine martens are mostly missing from the Lowlands of Scotland and from most of England and Wales. Historically they were far more widespread but 19th and early 20th century persecution by game shooting interests eradicated pine martens from all but the remoter Highland areas. Legal protection from the latter part of the 20th century has allowed a slow recovery and there has been a gradual re-occupation of most of the Highlands, parts of the Scottish Lowlands and around areas of England and Wales where perhaps a few animals may have hung on in isolated groups. This has been helped by reintroduction projects in south west Scotland and in Wales.

Red squirrels, of course, have been pushed out of large parts of their former British range by the invasive, non-native grey squirrel, introduced by us humans from the eastern parts of north America. As pine martens slowly returned and started to move into areas where grey squirrels had replaced reds, it was sometimes observed that the grey squirrels declined, and the reds started turning up again.

This was first noticed in Ireland and now seems to have happened in parts of Scotland. It is very important to stress that, although some high-quality research has been focussed on trying to understand exactly what is going on, we cannot yet categorically say that the pine marten is definitively the red squirrel’s saviour. Apart from anything else, pine martens are more than happy to hunt both species, so it is somewhat counter-intuitive that this could benefit one sort of squirrel but not the other. Nevertheless, there are various credible explanations that would fit the pine-marten-as-red-squirrel-saviour scenario. These are theories, so we must be careful not to present them as facts. They focus on the evolutionary history of the species concerned and on the significant weight difference between red and grey squirrels. See what theories YOU can come up with on that basis!

pine marten on forest floor
Image by Th G from Pixabay

It is certainly well established that predators, in some circumstances, can have a net benefit on some of the species they predate (though, clearly, NOT on the actual individuals that get eaten!) In fact, one of the most famous examples of this is from another mustelid, the Californian sea otter, which provides a net benefit to the various shellfish it preys on by keeping one of the invasive ones in check. In doing so, it also maintains the health of the kelp beds where the otter and the shellfish all live. Google it. It is one of the classics of ecological research.

Whether of not pine martens really are inadvertent red squirrel conservationists, we should celebrate them in their own right and continue to enjoy them as they gradually reappear over more and more of Scotland. An RSPB Scotland colleague was recently amazed to see one on his back garden fence in Glasgow! It is certainly still a huge thrill and a privilege to get even a brief glimpse of one.

Header Image of pine marten photographed at a hide specially adapted to attract and view them in Strathspey. Credit: Keith Morton.

Anonymous
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  • I remain unconvinced that Pine Martens have colonised or recolonised some parts of England. The finding of a dead male (known to roam far) Pine Marten from Wales in England suggests to me that until we have evidence of breeding or female Pine Martens for instance in Northern England we should assume that there is no viable population there. This may well be the case in most of Southern Scotland. I have not found literature which purports to give an accurate picture of their spread. Pine Martens are likely to be caught in traps, which would limit their spread, as well as not being a fast breeding species.

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  • I remain unconvinced that Pine Martens have colonised or recolonised some parts of England. The finding of a dead male (known to roam far) Pine Marten from Wales in England suggests to me that until we have evidence of breeding or female Pine Martens for instance in Northern England we should assume that there is no viable population there. This may well be the case in most of Southern Scotland. I have not found literature which purports to give an accurate picture of their spread. Pine Martens are likely to be caught in traps, which would limit their spread, as well as not being a fast breeding species.

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