Few animals are as adaptable as the wolf, which boasts one of the widest distributions of any land carnivore. Wolves were eradicated from many areas of Europe in the 19th century after prolonged persecution, but they have staged a comeback in recent decades. Today, there are thought to be at least 12,000 wolves roaming the continent, and their numbers are increasing.
Europe’s growing wolf population, often organised in family groups of parents and their offspring of the year, is competing with people for space and resources, occasionally killing livestock, dogs and prized game. Young wolves typically leave after one or two years and try to establish a family of their own. As wolves in central Europe expand their range, they’re increasingly moving into more heavily cultivated rural areas.
One of these is the Jutland peninsula, which is part of Denmark and the northernmost German federal state of Schleswig-Holstein. There are lots of sheep here, mostly kept in fenced enclosures, and very little forest. This means that most wolves entering the area have a hard time finding somewhere to settle. The first wolf in Jutland was recorded in 2007, and there were probably fewer than five entering the area each year until 2014. In 2021, 17 wolves were recorded.
For wolves and local people to coexist, harm to livestock must be kept to a minimum. We investigated where Jutland’s growing wolf population is living and where most attacks on sheep occur, to spot areas where livestock need better protection. But with wolves killing numerous sheep in the peninsula, we also wanted to know why they were doing this in the first place. Were they simply in the wrong place at the wrong time? Or had they developed a preference for sheep as easy prey? The difference is important. Government agencies can only define wolves as “problem animals” suitable for culling if they show a preference for eating livestock.
We found that wolves mainly eat sheep because they happen to be moving through areas with lots of farm animals and little natural prey. Killing such wolves only solves the problem temporarily, usually until the next wolf arrives. For a long-term solution, sheep must be better protected from attack in areas where wolves occur.
Where and why wolves kill livestock
In Schleswig-Holstein in the south of Jutland, most wolf-monitoring is done by inspecting dead farm animals. Bite marks are swabbed to collect traces of saliva which are analysed for genetic confirmation that a wolf killed the sheep. In many cases, it is even possible to identify the individual wolf responsible. In Denmark to the north, where fewer sheep are killed, authorities manage a large network of camera traps and collect faeces. Thanks to this intensive monitoring, wolves in Jutland are recorded on average about once every two weeks.
We found that resident wolves, trying to establish a territory and form a family group, were more likely to settle in places with more forest – important habitat for wild prey such as red deer – compared to surrounding areas, and generally killed few sheep (about eight per year). This suggests wolves generally try to settle in areas with little human influence.
Young wolves on the move also preferred areas with more forest, but they were just as likely to be recorded in areas with lots of sheep, probably because livestock kills are the main way in which people notice these highly mobile vagabonds. They killed way more sheep: more than 40 per year.
Differences in personality were negligible in explaining how many sheep a wolf killed. Instead of there being a few offenders with a taste for sheep, our study indicated that any wolf may predate livestock depending on how the land is managed.
A handful of wolves that killed disproportionately many sheep did so because they stayed a disproportionately long time in landscapes full of sheep and less because they had a special affinity for preying on them. Categorising certain individuals as problem wolves, which is how local authorities deal with wolves that kill lots of livestock, is unhelpful for understanding and mitigating the causes of livestock kills by large carnivores.
How to reduce livestock losses
People must be willing to tolerate the risks of wolves if they are to be allowed to live in the same area. One incentive would reimburse farmers for the sheep they lose to wolves. Yet while it’s crucial that governments support these farmers, this compensation is not a sustainable solution on its own – it doesn’t resolve the cause of the problem.
Instead, the number of farm animals being killed by predators has to be reduced. This is possible in Jutland, where most sheep are kept in fenced enclosures and not herded by a shepherd, by raising fences and adding electric wires to make them predator-proof.
Our results also showed that wolves killed the majority of livestock in a comparatively small area (16% of the total peninsula), probably because many vagrant wolves moved through there. Focusing on improving livestock enclosures here would go a long way to reduce wolf predation overall. The biggest challenge for preventing wolf attacks on livestock is not so much in the forested areas where wolves settle, but in these remaining parts of Jutland where wolves pass by.
Our findings not only show the incredible flexibility of wolves, but also illustrate the increasing challenges of managing them in human-dominated landscapes. As wolf populations continue to increase and expand, there is an urgent need to prepare for their return or temporary visit. Reducing wolf attacks is not only an important part of improving human tolerance, it also lowers the suffering of livestock and economic damage to farmers – as well as their anxiety about sharing space with predators.