HOMEWARD BOUND
Pine martens are back in the Forest of Dean, after one of the most exciting reintroduction projects of recent years.
The faint ‘blip blip blip’ is all we needed: ‘FD09’ is alive and well. To the three of us straining our ears, this signal on our little black box is as thrilling as a message beamed back from a distant space probe, though it has travelled only a couple of kilometres rather than many millions. “She’s probably lying up in this quiet valley,” explains Josie Bridges of the Gloucestershire Wildlife Trust, pointing out an area of tight orange contours bunched around a stream on an OS Map. “That’s a good choice – she’s doing well. It’s where I expected her to be.”
A lot rests on the sleek shoulders of FD09, one of 18 adult pine martens set free this autumn in the Forest of Dean. Just a few weeks earlier, the elegant, bushytailed carnivore was roaming a forest in north-east Scotland. After being caught and driven south, she forms part of the advance guard in what is hoped will be her species’ triumphant recolonisation of this wild and beautiful corner of England, after an absence of probably at least 150 years.
I’m being given a tour of the exciting project by Josie and the manager of the Wildlife Trust’s ‘Team Marten’, Dr Cat McNicol. Both are fresh from the translocation of pine martens from Scotland to Mid Wales (a Vincent Wildlife Trust scheme), where, after five years, there are now 80–85 animals – the first Welsh-born kits were reported in 2017. Their latest marten mission, 90km to the south, aims to replicate that success.
We bump along muddy forestry tracks on a drizzly day in mid-September, stopping occasionally for Josie to hold up what looks like a battered old TV aerial, to get fixes on the radio-collared martens’ current positions. The foul weather can’t dampen our mood; we know we’re witnessing something big.
“Our dream result is for this marten population to join up with the one in central Wales, leaving both stronger,” Cat says. “We have an army of people with trailcams in the Brecon Beacons, halfway between the two areas, waiting to monitor the martens’ progress. We really think this is going to work.”
A long time coming
Until the 1800s, pine martens could still be found in small numbers throughout much of Britain, including lowland English shires as far south as the Channel, but a toxic combination of deforestation and ruthless extermination saw them wiped out almost everywhere.
In her 2018 book A Richness of Martens, Polly Pullar describes the “Victorian killing fields” in chilling detail, citing the example of a Cairngorms estate that slaughtered 246 “marten cats” in only three years. Pine martens retreated to the remotest Highland glens, their stronghold until the 1970s, when they began a gradual recovery and southward expansion through Scotland. In 1988 – amazingly late in the day for a nation that proudly invented nature conservation – the species was given an extra boost with full legal protection.
Back in the mists of time, pine martens were – incredible as it may seem now – the second most numerous carnivore in the British Isles (with the weasel in top spot). That’s over 5,000 years ago, when vast swathes of these islands were still forest and fen, meadow and mire. And that sort of mixed terrain suited the martens just fine.
“Pine martens love a habitat mosaic,” Cat says. “Around half their diet is field voles, which are most abundant in rough grassland.” Martens may be woodland gymnasts, with semi-retractable claws and super-flexible ankles that rotate their hind feet 180 degrees, enabling them to streak up trees in a flash of chestnut. But they hunt on the ground, and often venture into clearings and meadows and onto open hillsides in search of small-mammal prey.
The Forest of Dean is perfect. Covering 110km², it is one of the largest wooded areas in the southern half of Britain, with many fine old oak, beech and hornbeam trees. But, crucially, it’s also a working landscape. Once a royal hunting forest, it then supported a thriving coal-mining industry, and today much is managed by
“I've never seen so many wild animals. The forest is busy with people, but also with wildlife.”
Forestry England ( formerly the Forestry Commission) for timber, recreation and wildlife. Where the close-packed ranks of Douglas fir have been felled for timber, the scrubby regrowth that springs up – a mix of long grass, bramble, gorse and hazel and birch saplings – is an ideal hunting ground for martens.
While out radio-tracking in the forest, I’m surprised how many people we meet, despite the ‘dreich’ conditions: mountain bikers, a forestry team, dog walkers, joggers. “It can get busy, especially at weekends” agrees Cat. This makes life difficult – Josie points out that with all the background noise, it’s much harder to hear signals on VHF (very high frequency) tracking equipment. “We do get some strange looks,” Cat says. “Some people think we’re TV licence detectors!”
Technical problems
Aren’t GPS tags the norm nowadays? “Not always,” replies Cat. “For one, they’re 10 times as expensive. Also, there is no GPS signal in much of the forest.” This is something I can confirm by my mobile phone’s near-total lack of signal. “VHF is far more precise,” Cat continues. “Basically, GPS is really unreliable for tracking small or medium-sized terrestrial mammals in this type of landscape.”
The leather radio-collars are designed to wear away and fall off naturally next spring, and have a ‘mortality sensor’ that indicates if its owner has died by changing the pulse rate of the bips. The collars don’t bother the martens, though Cat says that some individuals prove very good at getting
With Scottish pine martens heading south under their own steam, I wonder why this reintroduction is necessary.
rid of their fancy neck-wear. “Yet another reason for not using pricey GPS tags,” she says with a grin.
Another occupational hazard of mammal-surveying in the Forest of Dean is more alarming. Cat and Josie often work at night, when pine martens are most active – and when Forestry England rangers are out culling deer and wild boar using nightsights and high-calibre rifles.
I’ve written about the controversial ‘boar war’ for BBC Wildlife before; suffice to say, most ecologists agree that it is vital to control the forest’s feral boar population, recently estimated at 1,600. Boar are native and their energetic snuffling and rootling opens up habitat for some species, but since these chunky omnivores breed yearround and have no natural predators left in the UK, their numbers soon spiral.
“We liaise with the rangers to see where they are shooting,” Cat says. “But there are poachers in the forest, too. So, we have to be careful.” Undeterred, Cat enthuses about spending time in such a wildlife-rich place. “I’ve never seen so many wild animals as here,” she says. “In a typical night, I’ll spot something like eight deer, a group of boar, a fox or two, a badger, some owls. The forest is busy with people, but also with wildlife.”
Cat explains that the 100 days after the martens’ release are critical. The experience of the Welsh reintroduction showed that they spend their first two weeks of freedom exploring their new surroundings. During this initial phase, they range widely, covering up to 10km in a couple of nights.
Team Marten can’t afford to lose track of even one tagged animal. “If we don’t know where it is at this early stage, the chances
of us re-finding it later are slim,” Josie says, “Our job is a bit ‘needle-and-haystack’ as it is!” To keep tabs on martens, Josie adds, you have to think like martens. It turns out that they tend to follow linear features – streams, valleys, hedgerows.
Keep your friends close
After a fortnight or so, the martens settle down, establishing home ranges. At first, they can be living quite close together, but as they begin breeding, the juveniles disperse to fill vacant space. “The population expands outwards in concentric rings,” says Cat. “One of our key findings in Wales was that martens like to have neighbours. It’s the law of attraction. So, you need a certain density of individuals for a project to work. You can’t just release a small number, which is why we’re trying to create a neighbourhood of martens.”
With the Scottish pine marten population heading south under its own steam, confirmed sightings in northern England, and the Mid Wales population well established, I wonder why this latest reintroduction is necessary. I talk to mustelid expert Johnny Birks, author of the 2017 monograph Pine Martens. A freelance ecologist, Johnny used to work for the Vincent Wildlife Trust, which carried out the preliminary research into the feasibility of pine marten reintroductions and which has been heavily involved in both the Welsh and Forest of Dean projects.
“If we had been willing to wait many decades, the English population might have recovered in its own time,” Johnny tells me. “But unlike other mustelids – polecats, say – pine martens are a very slow-breeding species. Not only that, the landscape has changed since it was last home to martens. There are many more sheep, so it’s too heavily grazed, altogether less suitable. We also have a high fox population, and foxes can kill pine martens. On the plus side, the spread of commercial forestry plantations since World War II has created new habitat that wasn’t there before.”
Meanwhile, some people have taken the law into their own hands. Johnny describes how “covert dumpings” of pine martens – taking them from the wild is illegal without a licence, and so is releasing them without the landowners’ permission – have led to a spate of records from Shropshire, the New Forest and even, ironically, the Forest of Dean. A marten was camera-trapped there this April, a full five months before the first ‘official’ batch of Scottish martens arrived.
Help or hindrance?
Who is behind the secret releases? One intriguing theory is that landowners or foresters are responsible. Perhaps, Johnny says, they have been encouraged by studies, widely reported in the media, that suggest pine martens could help to control grey squirrel populations by predating the invasive rodents. Barkstripping grey squirrels cause significant damage to British forests, while preventing the comeback of native red squirrels, so “releasing a few pine martens on the quiet” might seem an excellent idea.
But both Johnny and Cat question the extent to which pine martens can push back Britain’s grey squirrel population. “There may be some impact,” Cat says, “for example, the martens may create a landscape of fear that, alongside some predation, reduces the squirrels’ breeding success. But it would not be enough on its own.”
I ask Cat what her hopes are for the Forest of Dean project. “Pine martens belong here,” she says, smiling. “Yes, they will be brilliant for tourism, but we’re doing this because it’s the right thing to do, not just to boost the local economy. Martens’ recovery across the country is dependent on creating connected habitats, and this project is a small, yet valuable, part in that larger puzzle.”
FIND OUT MORE Read more about pine marten projects at bit.ly/GlosTrust and bit.ly/VWTproject.