BY CALUM CAMPBELL
Let’s be honest—if you’ve been following the latest rewilding headlines, you’ve probably had that sinking feeling in your gut. The one that says: here we go again. Right now, there’s a huge push to release pine martens into parts of the country where they haven’t set foot for centuries—if they ever even lived there at all. And while the PR machine is working overtime, I can’t help but ask: am I the only one absolutely staggered by the blind spot here? Because when you look at the rock-solid evidence of what happens when you drop a predator into an unprepared ecosystem, the secondary damage to other vulnerable species isn’t just a risk—it’s a guarantee. And the worst part? We’ve literally just done this. And it failed. Spectacularly.
Let’s rewind. Not that long ago, stoats turned up in Orkney. And no, they didn’t hitch a ride in a bale of hay—that story was always laughable. The official line was “accidental introduction,” but however they got there, the damage was instant and devastating. The idea—if you can call it that—was that they might help control rats. Sounds sensible on paper, right? Predator eats pest. Problem solved. Except it wasn’t. What actually happened was a textbook case of ecological backfire. The stoats didn’t just go after rats. They tore through the native Orkney vole—a subspecies found nowhere else on earth—and then turned their attention to ground-nesting birds. Curlews, hen harriers, short-eared owls; you name it. Within a few years, conservationists were watching breeding numbers tank. The RSPB recorded a steady drop in hen harrier fledglings from 2011 onward, and stoats were squarely in the firing line (Fraser et al., 2015). One study even predicted that this invasion would “profoundly change the ecology of Orkney” with impacts of “national and international significance.” And they weren’t exaggerating. So let’s get this straight: a predator introduced to solve one problem ended up creating a much bigger one. The stoats caused more damage to native species than the rats ever did. That’s not a hypothesis. That’s a fact. And it’s right there in the data.
Fast forward to today, and we’ve got pine martens being released in Cumbria, Dartmoor, and even being talked about for the South East. The South Cumbria project has already dropped 13 healthy adults into Grizedale Forest. Devon’s Two Moors Project followed suit with 15 on Dartmoor. The argument? Pine martens will eat grey squirrels, which will give red squirrels a fighting chance. And to be fair, there is genuine science behind that—studies in Scotland have shown that where pine martens thrive, grey squirrel numbers drop and reds bounce back (Sheehy et al., 2018). On that front, it makes a kind of sense. But here’s the bit that keeps me up at night: nobody seems to be asking the obvious question. What else are they going to eat? Because if the Orkney stoat saga taught us anything, it’s that predators don’t read the management plan. They don’t stick to the menu we’ve assigned them. They eat what’s available. And in an ecosystem that has evolved for generations without pine martens, there’s a whole lot of vulnerable prey that hasn’t adapted to avoid them. Ground-nesting birds? Check. Small mammals that aren’t grey squirrels? Absolutely. Other at-risk species that conservationists claim they want to protect? You’d better believe it. Amy Fitzmaurice from Kent Wildlife Trust has rightly pointed out that we need to understand “what the ecosystem is like now before pine martens get put back.” And that’s a fair point—but even the best baseline survey can’t predict complex food-web chaos. You can’t model every ripple effect in a lab. And when you’re dealing with species already on the edge, you don’t get a mulligan.
I’m not saying we should never rewild. I’m not anti-pine marten. But for goodness’ sake, we’ve got a live case study sitting right there in Orkney showing exactly how this plays out when it goes wrong. And we’re walking into the same trap, just with a fluffier, more charismatic animal. Here’s a simple question for anyone cheering on this “tsunami” of rewilding: after everything that happened in Orkney—the vole crashes, the bird declines, the millions spent on containment—do you genuinely believe there won’t be a negative side to releasing pine martens into an environment that isn’t ready for them? I’ll accept the stoat experiment for what it was: a well-intentioned gamble that failed. What I can’t accept is pretending it never happened and charging ahead anyway. That’s not rewilding. That’s repeating the same mistake and expecting a different result. And in conservation, that kind of stubbornness costs species their futures.
References
RSPB Orkney (2021). Hen harrier breeding survey data. Internal report.
Fraser, E.J., et al. (2015). The impact of stoats on Orkney’s native wildlife. Scottish Natural Heritage Commissioned Report.
Sheehy, E., et al. (2018). Pine marten predation of grey squirrels – a natural solution to an invasive species? Proceedings of the Royal Society B, 285(1876).
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Calum Campbell is a commentator on rural and environmental issues in Scotland.