The adaptable golden jackal could soon be spotted all over Europe
Meet the golden jackal – the charismatic carnivore whose adaptability is enabling it to quietly conquer Europe, reports Stuart Blackman
When photographer Janez Tarman set up a camera-trap at a fox den near his home in Slovenia in October 2012, he got a lot more than he bargained for. He achieved a picture of a canid, as he had hoped for – but this was no fox. What Tarman had photographed was a golden jackal, a carnivore that most people associate with Africa or perhaps Asia – but not central Europe.
“At the time there were only rumours,” says Tarman. “We didn’t know if these animals were establishing territories in this region, or just passing through. We didn’t know much at all.”
Tarman’s photograph was further evidence that the species is indeed on the move – spreading north and west from its refuges in the south, and east into territory it has never previously occupied. “Ten years ago, the animals hadn’t got much further than Austria and Italy,” says Miha Krofel, a carnivore biologist at Slovenia’s University of Ljubljana. “Since then, though, they have turned up as far north as Estonia, Latvia and Lithuania. And in 2016 we had the first records for the Netherlands and Denmark.”
So, it seems, this is the day of the jackal. And Krofel and his collaborators are hot on its trail, trying to work out just what is driving its rapid and remarkable rise.
The golden jackal (or more strictly, the Eurasian golden jackal, to distinguish it from its African counterpart that has recently been declared a separate species) is smaller than a wolf but bigger than a fox, and has much in common with both canids. “Genetically and taxonomically, the golden jackal is closer to the wolf,” says Krofel. “Ecologically, it is more similar to the fox.”
Take its hunting niche. It is well established that there is a size threshold for predators, above which they are able to focus on prey bigger than themselves. Typically, the cut-off is around 20kg – about the size of a Eurasian lynx. At 40kg-plus, wolves come in well above it. But jackals (14kg) and foxes (7kg) are significantly below, and are therefore considerably more reliant on much smaller mammals, such as rodents.
Socially, the are somewhere in between. they howl like wolves, for example, but largely shun pack-life in favour of fox-like nuclear family groups.
The fact is that while Europe’s other charismatic carnivores – the brown bear, lynx, red fox, and, of course, wolf – are among the most intensively studied animals on the planet, golden jackals remain shrouded in mystery. According to Krofel, they were virtually ignored by researchers until about five years ago – and, even then, the little data that existed turned out to be virtually useless. “The majority of studies into behaviour and sociobiology were carried out in Africa. So what we thought we knew about the European animals actually applies to a completely different species,” says Krofel.
MANY A MEAL
What is clear is that golden jackals are more than a simple pick-and-mix of fox and wolf characteristics. According to Tarman, it’s the jackal’s character that sets it apart from either of its relatives. “It’s really its own animal,” he says. “Once you get to know it, you couldn’t say it is similar to a fox or a wolf. It’s completely different.”
What stands out for him is the golden jackal’s adaptability. “Whatever situation the animal finds itself in, it makes it work,” he says. For jackals, rules are there to be broken. Their body size may incline them towards small prey, but they are also able to work cooperatively to bring down larger animals such as roe deer. They are browsers and scavengers too, eating insects, vegetation and human refuse. “Their dietary niche is one of the widest known in the animal kingdom,” says Krofel.
In Serbia, the single largest component of a jackal’s diet is the remains of animals slaughtered for human consumption. The country has just a single carcass processing plant, and most waste is dumped in unofficial middens close to towns and villages. If it wasn’t for the
jackals – which are estimated to remove more than 3,000 tonnes of discarded meat annually – this practice could pose a serious hazard to human health. “It’s an ecosystem service that was originally provided by vultures,” says Krofel. “But in most of Europe, the vultures are basically gone, and the jackals are taking over.”
BULLETPROOF DOGS
Other signs of jackals’ flexibility include their willingness to adopt a nocturnal or diurnal existence according to circumstance. Likewise, they are equally at home in a forested wilderness or a town rubbish dump.
They are also apparently highly adaptable reproductively. “In south-east Europe, where we have the most jackals, they are hunted in huge numbers,” says Krofel. In Bulgaria, some 30,000 per year are shot. “But unlike wolves, jackals seem to be very resistant to hunting.” Indeed, a study in Israel has shown that it’s possible to shoot more than 50 per cent of the population without affecting the density of animals. “We suspect that they respond to being hunted by increasing their reproductive rate and producing bigger litters,” says Krofel. In which case, even large-scale culling is unlikely to hamper the jackals’ current advance.
Such adaptability – known as ‘behavioural plasticity’ – is likely to be one of the keys to their current success. “Species that have wide ecological niches and high plasticity are the very ones that are pre-adapted to take advantage of changing, human-dominated landscapes,” says Krofel. “We could have predicted that the jackal would prosper. And this is exactly what’s happening now.”
Adaptability is only part of the story, though. For one, it doesn’t account for the sheer speed of the jackal’s progress across the Continent, which might have something to do with its knack for long-range dispersal. “Jackals can suddenly show up without warning, 300 or even 400km from the closest breeding pair,” says Krofel. “And if they show up somewhere one year, they appear with greater frequency the next. If they reached Holland in 2016, why not France in 2017? Or Finland?”
Since most initial sightings are of single animals either shot by hunters, caught in camera-traps or killed on the roads, it’s hard to see how long, speculative migrations undertaken by individual animals could lead so quickly to new breeding populations. It’s possible that these journeys are not always undertaken alone. The first jackals ever recorded in Slovenia, in the 1950s, consisted of a group of at least three animals, 200km from the nearest breeding population in Croatia. Unfortunately, the visitors were immediately shot by hunters, and on this occasion the jackals did not return until the 1980s.
Not everyone is comfortable with the species’ dramatic and rapid grabbing of territory. In 2011, when jackals turned up out of the blue in the Baltic States, the governments of Estonia and Latvia declared them an invasive species and planned a complete extermination. However, genetic detective work soon revealed that the newcomers had originated from the Caucasus Mountains in Russia, arriving under their own steam via a route to the east of the Black Sea.
“If you look at the definition of invasive species, the first requirement is that it is an alien,” says Krofel. “Native species cannot be invasive species, no matter what happens to their population dynamics. Alien species can only be brought from abroad by humans. These jackals walked to the Baltics, so they are not aliens. And if they are not aliens, then they cannot be invasive.”
Fortunately, the Baltic States came round to that way of thinking and dropped the designation. But the case still serves to highlight the fact that in this age of ecological shifts and re-shuffles, we have no term to describe species that colonise new ground by natural means.
FORSEEING THE SPREAD
The potential for conflict arising from the sudden appearance of a breeding population of a novel carnivorous mammal on your doorstep might be minimised if only we had an indication of where the
animals might pop up next. “All that’s certain now is that there will definitely be further expansion,” says Krofel. “One of the big projects currently underway is to collect and examine data from jackal surveys all over Europe in order to analyse which habitats are good for jackals, and which are not. We can then use this knowledge to predict the areas that are prone to colonisation.”
Another crucial question is this: why are golden jackals only making their moves now? It’s probably safe to assume that these canids have always been adaptable and capable of long-distance dispersal, and man-made landscapes have dominated Europe for centuries. In which case, what has been stopping them?
A clue might be found in the vicinity of Krofel’s home in the Dinaric Mountains to the south of Slovenia’s capital, Ljubljana. “I live inside the northernmost wolf territory in Slovenia,” he says. “We can hear wolves howling at night, and they have come to within 20m of my house.”
What he doesn’t see, though, are jackals. To do that, he must leave the wolf territory, a journey of about 10km as the crow flies, since the two species rarely
THE SPREAD OF THE JACKAL COINCIDES NEATLY WITH THE DECLINE OF WOLVES IN SOUTHERN EUROPE.
overlap. This is unlikely to be due to mutually exclusive habitat requirements – the jackal certainly doesn’t seem particularly picky in that respect. Neither is it a simple case of the wolves killing the jackals (though they can, and do) because we already know that jackals can sustain a high mortality rate.
AFRAID OF THE BIG BAD WOLF?
Krofel believes that, for jackals, there’s a significant difference between wolves and human hunters. Eons of aggressive interactions between the two canids have instilled jackals with an overriding fear of their larger cousins. “The spread of the jackal coincides neatly with the decline of wolves in southern Europe,” he says. As wolves have been progressively exterminated, the jackals have been free to fill the vacuum. Most convincingly, perhaps, Krofel’s team has identified eight regions in southern Europe where wolves have re-colonised old haunts. In seven of these, the jackals were driven out once the wolves re-established themselves.
That said, after a long history of being overshadowed, dominated and suppressed by its nemesis, it seems that the golden jackal is now having the last laugh.
STUART BLACKMAN is a science writer who regularly contributes to the Discoveries (see p14) and Q&A (see p100) sections of BBC Wildlife Magazine.