Tracking the Wild Big Cats of Britain

by Brian Dunning
September 21, 2021

Some refer to them as ABCs — alien big cats — black panthers and similar big cat species, completely out of place in the British Isles, most particularly the Welsh countryside. Not only is it trivially easy to find photos on the Internet taken in recent years, it's just as easy to find old stories that go back farther than we would reasonably expect people to be importing them into the Isles. They prey on deer and livestock, leaving carcasses that we can test for DNA and for identifiable tooth marks. ABCs are captured on film and in digital images, and they photograph much better than Bigfoot — that is, the pictures are often good enough to tell that this is no blob or misidentification. By any reasonable assessment of the evidence, ABCs in Britain are no fantasy.

Britain does have one native cat species, the Scottish wildcat, which looks a lot like a regular tabby house cat but is slightly larger. They're also critically endangered, with only a few thousand individuals remaining in northern and eastern Scotland. Although it's a certainty that some ABC reports are misidentification of native wildcats, the phenomenon we're talking about today is clearly distinct from these. We're talking about full-size predatory cats, on the scale of cougars, leopards, even lions. Particular ones have even been given names: the Surrey Puma (1960s), the Stratford Lyon (1960s), the Sheppey Panther (1970s), the Beast of Exmoor (1988), the Beast of Bodmin (1992), the Fen Tiger (1994), the Galloway Puma (1999), the Beast of Barnet (2001), the Essex Lion (2012), the Cotswolds Big Cat (2012).

It should come as no surprise that sometimes big cats do escape from private collections and are just as often turned loose when they get too unwieldy for their owners' taste, and some of these have made it into the wild to live on their own. We know for a fact that this has happened any number of times, as some escapees have been caught; in other cases, hairs, tracks, droppings, and other remains have been conclusively identified as coming from known non-native species of big cat. The amateur British Big Cats Society website gives plenty of specific cases, as does zoologist Darren Naish on his blog, and both of these sources are perfectly well cited. In short, it's a fact that leopards, lynxes, jungle cats, and probably others have been in the British countryside, and have wrought havoc among sheep and deer populations accordingly.

Since private ownership of such animals is usually illegal, giving owners a reason to get rid of them, we can be sure that such releases have happened a lot more times than we know about. Way back in 1976, the UK passed the Dangerous Wild Animals Act which required that anyone owning such an animal had to have their premises inspected, and since very few would have passed such an inspection or failed other provisions of the act, many exotic animals were simply released and abandoned into the wild. During those years, other laws have been passed making ownership even more restrictive, so abandonment has continued.

Big cat species have lifespans from 8 to 15 years (most nearer the lower end of that range, especially in the wild), so of those that are reportedly spotted but never captured, they probably didn't have more than a few years left to live before they ceased being seen. And that would be the end of any such individual; it's not like they were liable to encounter a mate to breed with. However this remains a theory popular among some cryptozoologists: that escaped individuals of large exotic cats have managed to multiply into a self-sustaining breeding population. This is extremely unlikely. Big cat species are highly susceptible to inbreeding depression, the reduced survival and fertility of related individuals. Achieving a sustainable breeding population requires that you start with an MVP (minimum viable population). For big cats, these numbers are way out of reach. Historically, biologists have called this the 50/500 rule, which is where the MVP requires about 50 individuals in order to reach an effective population size of 500 to keep the population going in perpetuity. Today, this number has been revised upward, as 50/500 has been show to still produce too much inbreeding depression, and 100/1000 is the current wisdom. Having one or two, or even ten, escaped big cats, is light years away from what would be needed.

The legend became something that a small fringe of people started to take seriously in the early 1980s with the publication of a series of books. First up in 1980 was Alien Animals by Janet and Colin Bord, which claimed that the big black cats in the UK were paranormal phenomena; followed in 1983 by Cat Country: The Quest for the British Big Cat by Di Francis, which hypothesized that the cats are an actual undiscovered species, or perhaps surviving individuals of prehistoric big cats erroneously believed to be extinct. Though Francis was not the first to put this idea forward, her book played a role in raising awareness of this possibility among the mass market. As a result, quite a few cryptozoologists take this proposition quite seriously.

According to this school of thought, a probable explanation is that ABCs represent a relict population of the Eurasian cave lion. This was an actual species of large predatory cat, Panthera spelaea, known from ample paleontological evidence, which lived throughout Eurasia until its extinction at the end of the Pleistocene epoch — the same mass extinction responsible for the loss of so many other species of megafauna around the world, including woolly mammoths, dire wolves, sabre-toothed cats, and giant ground sloths.

The evidence that the cave lion did not survive that extinction event is hard to argue with. This comes from the permafrost throughout northern Eurasia, in which we find evidence that's both fossilized and frozen, giving us skin samples plus bones and teeth, all of which contain genetic material. We know a great deal about the cave lion, including that it was very big, bigger than the modern lion from which it split half a million years ago. It had no mane, or perhaps a very short one, and so would indeed look very much like the ABCs in the photographs. Throughout the permafrost from the Pleistocene, we find the cave lion along with all the other plentiful species — until suddenly, we don't. All the megafauna that fell victim to the mass extinction event are completely absent from newer permafrost, and yet the surviving species are found just as plentiful as ever. Is it possible a population could have escaped this line of evidence? Well, no. It's not. Not in any practical sense. All animals that survived the extinction are still found, in abundance, in the newer permafrost. To claim the Eurasian cave lion was an exception to this otherwise unbroken law — with no corroborating evidence of any kind — stretches credibility just too far.

In our quest to identify the ABCs, there's one clue we've mentioned a few times but that warrants a moment of focus, and that's that the cats seen are often black. Photos you find on the Internet are likely to show a large black cat, regularly described as "black panthers". Now, for whatever relevance it may or may not have, the only big cats that have all-black individuals are jaguars and leopards, and they're usually not completely black. It's a genetic trait called melanism, and it runs around 10% in both species, give or take. No other big cat species have ever been confirmed to have melanistic individuals. So if melanism is that rare, why do such a high majority of the sightings and photographs show black cats? Is this evidence nudging us toward some unknown all-black species, or might there be another explanation?

There are two simple facts that favor black cat sightings. First is that the black cats are more greatly prized by zoos and collectors, and so are found in those environments more often than in the wild, and so are correspondingly more likely to be those that escape or are abandoned. Second is the simple fact that a black cat is really easy to see, while the common colorations of these animals are incredibly well camouflaged. A cougar can be three meters from you and you'd never see it. If there were one of each in the English countryside, the black one is the one far more likely to be spotted. So, reasonably, little can be concluded from the propensity of black cat reports.

Let's return to the native species of cat in Britain, the Scottish wildcat mentioned earlier. In 1984, a gamekeeper snared a large black cat near the village of Kellas. As interest in British big cats was relatively high at the time due to the popular books, the cat was studied and found to be a genetic hybrid of the Scottish wildcat and domestic house cats. It's what we call a landrace, not quite a breed, not quite a subspecies. Landraces are morphologically distinct from other members of their species — in this case, being large black cats of a particular build — and are genetically adapted to an isolated environment. It was named the Kellas cat. Their numbers are not exactly known, but they are considered to be the rarest mammal in Britain. Kellas cats are all black, are about the size of the very largest domestic cats, are distinctively long and gracile, and — except for the scale being wrong — look very much like a large predatory cat species stalking its prey.

Scale often becomes a sticking point in these conversations, just as it does with UFO witnesses. When we see something at a distance, it's not possible to judge its size and scale, unless there is something of known size for reference and it's known for a fact that that object is the same distance away — this is never the case for UFOs up in the sky, and for these long distance photos of big black cats, the only objects for scale are usually trees and shrubs, which come in all sizes. So no matter how insistent an eyewitness is that they were accurately judging the scale of one of these animals, when it comes to its usefulness as data, such a judgement is unfortunately too unreliable. It could be a Kellas cat, or it could be a melanistic leopard.

And really, that's the best place to leave this story. Reports of big cats in Britain do appear to be completely consistent with what we already know: that there are occasional big exotic cats out there, and that sustained species like the Kellas cat are too. The photographs look about as we should expect, and the numbers of deer and livestock killed by big cats are in line as well. So if you find yourself in the forests of the British countryside one night, and your flashlight returns the eye shine from an apex predator stalking you... you can relax. It's probably not a paranormal entity.

Correction: An earlier version of this incorrectly referred to the Pleistocene epoch as the Pleistocene era. —BD

By Brian Dunning
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