Bison Used to Roam Eastern Europe Before They Neared Extinction. Now Researchers in Poland Want to Create a Suitable Home Where They Can Thrive

Once nearly extinct, wisent adapted to life in the Bialowieza Forest. Human intervention kept them from disappearing, and now humans are trying to return them to their true habitat

By Marta Zaraska

Photographs by Kasia Strek

November 2026

A branch snaps under Rafał Kowalczyk’s feet as he pushes through a tangle of trees, tracking a herd of wisents though a dense part of the Bialowieza Forest, a stretch of pristine lowland woods at the eastern edge of Poland. He can’t see the animals, but he can hear them: the grunting, the snorting. “Follow me,” he says. “Unless you are scared?” 

It’s hard to imagine that several dozen wisents, a European species of bison, could make themselves invisible among the trees. “They can disappear in the forest like ghosts,” Kowalczyk says, taking a few steps toward the thicket. It’s quite warm for December, about 40 degrees Fahrenheit, and his rubber boots squelch against the boggy soil. The air smells of decay. 

Kowalczyk hoped to study the animals’ herd structure and assess their health. An ecologist at the Polish Academy of Sciences, in his mid-50s and sporting an unshaven look of someone who spends a lot of time outdoors, he has been studying wisents in Bialowieza for more than 20 years. This time, however, he has to give up and turn back to his car. “They are too deep inside,” he says.

The day before, I’d met a group of rangers in a different part of the forest, where the trees were more widely spaced. I saw several dozen bison there, and they were majestic. The European bison is a different species from the American one. It’s lankier, taller, harder to tame. Some scientists think that the two species’ most recently shared ancestor lived in the Pleistocene era, before some ancient bison migrated across the Bering Strait and others wandered through Europe, mating with the ancestors of domestic cattle. Compared with its American cousins, the wisent has a smaller hump on its back, and its head sits higher. It’s also less shaggy. As I stand watching the herd, a sound scares them off, and they run away with a surprising speed and agility, deeper into the forest. 

Kowalczyk first visited this area from central Poland many years ago. At the time, he wasn’t interested in studying wisents. He remembers the train pulling into the town of Bialowieza, at the edge of the forest, close to midnight, snow piling so high against the station’s doors that they wouldn’t open. “I thought: Is that Siberia or what? But then I saw the forest and I fell in love.”

At first, Kowalczyk wanted to study wolves, lynx; the predators. Instead, his supervisors pushed him into a project on wisents. For Polish people, the wisent is emblematic. You see it on logos everywhere: on one of the largest Polish banks, on popular beers, on Zubrowka vodka (“zubr” means wisent in Polish). It was here, in Bialowieza, that the last of the species disappeared from the Polish wild in 1919. It was also here that scientists brought the species back in 1952. But pulling a species from the brink made it extremely vulnerable. It had to be intensely managed, fed in winter, practically domesticated. This was the image Kowalczyk had in mind as he resisted taking on the wisent project: a herd of bison standing in a forest around a feeding rack full of hay, slowly chewing. “Like cows,” he says. 

The Poles call the wisent the “king of the forest.” There are about 9,500 in the world, and about 900 of them live in the Bialowieza Forest—the largest free-ranging population in the world. Others were introduced to countries including Russia, Germany, Ukraine, Romania and Spain. While the numbers have been growing, the species is still listed as “near threatened” by the International Union for Conservation of Nature. “It could go fast,” says forest ranger Mirosław Androsiuk, one of the people tasked in Bialowieza with taking care of wisents. A virus or a parasite could sweep through a population, he says. Whole herds could disappear in a matter of weeks.

The wisent is especially vulnerable because it is inbred. After the last European bison died in nature, only 54 were left in zoos and private parks around the globe. Twelve became the ancestors of the current population, and most of their genes came from a single pair called Planta and Plebejer. “Luckily, they had good genes,” says Katarzyna Daleszczyk, vice director of nature conservation at Bialowieza National Park.

The wisent disappeared from England in the 12th century, from France in the 14th. As a large animal, it was valued not only for its meat but also as a symbol of power. Medieval elites hunted the wisents with abandon, decorating their castles with the bison’s impressive heads. The horns were used as chalices said to possess magical powers: Pour a drink into such a cup and any potential poison will bubble to the surface. 

In the beginning, the wisent lived in wide-open areas like grassy meadows and arid steppes. As the human population spread across the continent, the wisent was pushed into the forest. By the 18th century, the range of the wisent was limited to a few spots across Poland and Prussia. By the 19th century, it found refuge solely in the Bialowieza Forest. (Its cousin, the Caucasian bison subspecies, survived in the Western Caucasus until 1927, when it was hunted to extinction.) The dense, primeval Bialowieza Forest was a perfect place to hide. The surrounding region was sparsely populated and, for centuries, lorded over by the kings of Poland who wanted to keep the forest’s resources, from timber to meat, to themselves. When the Russian czars seized control of central and eastern Poland in the late 18th century, they turned Bialowieza into their private playground. Anyone who hunted wisents without the czar’s permission faced exile to Siberia.

World War I changed everything. In 1915, German troops took over the region. They were poorly provisioned—and hungry—and here was this large, meaty animal, easy to shoot. So the 20th-century hunting began. There were still about 730 wisents in Bialowieza, but by 1918 only a quarter remained. After the war, emaciated Polish villagers came home from the front. The wisent was doomed. It was a snowy winter, too, so the animals were easy to track: just follow the hoofprints across the white. In 1919, the last wild wisent was killed in Bialowieza.

It didn’t take long for scientists to realize what had been lost or to set up efforts to bring the species back. In Poland, which had just regained its independence, restoring the wisent was part of the nation’s revitalized patriotism. After all, the animal was a symbol of Polish cultural heritage. In 1932, the European Bison Pedigree Book began tracking and observing all pure-blooded wisents to make sure no unwanted traits got mixed into the species. This mixing was possible because the animals were being shipped to Bialowieza’s breeding reserve from outside the country. (One came from a circus.) In one case, wisents bred with American bison that escaped from a farm where they were being raised for meat. On September 13, 1952, the first two wisents were released into the Bialowieza woodlands. The king had returned to the forest.

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Today, Bialowieza smells of sticky spruce needles, old leaves and damp soil. Somewhere high up, a woodpecker rat-a-tat-tats a hollow tree trunk in search of bugs. European forests tend to look tidy: deadwood cleaned up, everything utilized and managed. Bialowieza, one of the continent’s last wild places, looks messy, with a tangle of dead trees covering the ground. “You can see right away that it’s a different type of forest,” says Andrzej Keczyński, a conservation specialist at the Bialowieza National Park.

The messiness is Bialowieza’s treasure: centuries of uninterrupted cycles of life and death, with no humans trying to take the resources for themselves. The unspoiled forest, a UNESCO World Heritage Site, boasts about 12,000 species of animals (about a third of all the species found in Poland), including lynx, wolves and moose, as well as the rare smooth snake, European pond turtle and masked shrew. The forest is also one of Europe’s hot spots for fungi: A single plot, less than half the size of New York City’s Central Park, was once found to contain 1,380 species of fungi and 166 species of lichen.

And then there are the massive, ancient trees: the oaks, the hornbeams, the lindens. The largest of all is a particular oak tree named Maciek, which measures about 25 feet in circumference. Such old trees are precious because of their hollows, which may take centuries to develop, yet are vital to many species, including Eurasian pygmy owls and Leisler’s bats. Once, when Keczyński was walking home through the forest, he got caught up in a storm. Fearing toppling trees, he rushed to hide in a hollow of a giant oak. “I was already bending down to go in, but I thought, ‘No, no, no: I need to check first.’ So I picked up a stone, threw it inside. There was a stir, and a raccoon dog jumped out. Well, that could have ended badly!”

Raccoon dogs are a sign that not all is well with the forest. The invasive species, a fox-like canid about the size of a Jack Russell terrier, came to Bialowieza in the 1950s from eastern Asia. By now, it has outcompeted all midsize native carnivores. There are other issues, too, most of them brought on by humans. The Bialowieza Forest was long famed for its wetlands, yet climate change means the forest is drying out. “You see that lowering of the terrain? There should be water standing here,” Keczyński says. “But there is nothing. There is not much rainfall.” Locals tell me I could walk across the forest in my slippers. It’s that dry. Research confirms their observations: Across the region, temperatures are rising and groundwater tables decreasing. It’s one of the reasons that the bark beetle, a wood-boring pest, is now ravaging Bialowieza. 

Keczyński kneels down and gently lifts the bark off a dead Norway spruce. “There you go,” he says, pointing at the maze of shallow corridors tunneled through the wood—signs of bark beetle damage. Healthy trees produce enough resin to fight bark beetles, trapping the insects in the sticky substance. Not so during drought. Spruces also require three months of freezing weather to produce enough resin, and cold spells are getting shorter. “If there is no resin, the spruce is helpless,” Keczyński says. 

Now a new issue threatens the forest: An 18-foot-tall border wall with Belarus, erected in 2022, may isolate habitats, leading many species to lose genetic diversity. The wall was Poland’s response to a wave of illegal human migration. Thousands of migrants and asylum seekers escaping conflict zones as far away as Syria, Iraq and Afghanistan have trudged through Bialowieza. After flying into Belarus, they headed toward Poland, hoping to settle in the European Union. Many were pushed back, over and over again, from the border and across the forest. Many died. 

Kowalczyk tells me about a group of asylum seekers he encountered in Bialowieza. He was doing research, hiking through the boggy forest hoping to find hiding wisents; instead, he stumbled upon hiding people. There were nine of them. Two families with children, some still infants. “They were completely unprepared, with no proper shoes, and it was a cold October,” Kowalczyk says. “They stepped out onto a meadow to warm up in the early morning sun. I went to my car to get them some water. As I was walking back, I cried.”

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In a presentation that he gives sometimes, Kowalczyk talks about two refugee species in the Bialowieza Forest: Homo sapiens (the migrants) and Bison bonasus (the wisents). Both are there because they’ve run out of choices. Kowalczyk introduced the concept of “refugee species” of animals in a 2012 paper he co-wrote with Joris Cromsigt, an ecologist at the Swedish University of Agricultural Sciences, and Graham Kerley, a zoologist at Nelson Mandela University in South Africa. Like human refugees, a refugee species can no longer access optimal habitats and becomes confined to low-quality niches. As it is cut off from the best resources, its fitness suffers. The population begins to decline. According to one study, this is what has happened to wisents since the early Holocene around 11,700 years ago, first due to climate change, then due to humans. The refugee species concept has been applied by different groups of researchers to such animals as the giant panda, the kakapo and the Cape mountain zebra, among others. 

Kowalczyk explains to me why the wisent belongs in the steppes and meadows, with just a bit of forests thrown into the mix. We are standing in the archives room of the Mammal Research Institute of the Polish Academy of Sciences, in the town of Bialowieza, as Kowalczyk picks up a skull of a female wisent off a shelf. In his other hand, he takes the skull of a moose, a known forest specialist. “The moose has a narrowing muzzle, and its lips are very soft, well-adapted for eating shoots and leaves. In contrast, the bison has a broad muzzle,” he notes. Kowalczyk and his colleagues did a 3D-dental microwear texture analysis of ancient wisent teeth, studying tooth-wear patterns to reconstruct the animals’ diet. They found that in the past, the animals used to eat more grass. 

Stable isotopes from early Holocene bones indicate that thousands of years ago, the European bison lived in more open habitats. Data from wisent feces also indicates that even within a single forest, the animals still choose to dine in roomier spaces, such as clearings and river valleys. 

If the wisent is a refugee in the forest, and its optimal habitat is more open, then the species should be managed differently, Kowalczyk argues. A major issue here is supplementary winter feeding, a management strategy that has been going on with few changes since the 1700s. But as Kowalczyk’s research suggests, too much supplementary feeding may be leading to diseases. Research he published in 2023 showed that due to crowding at feeding sites, bison may have loads of dangerous parasites almost four times higher than those whose diets aren’t supplemented. He supports supplementary feeding but says it should account for a smaller part of the animals’ diet.

To feed the bison, four rangers arrive at dawn at a clearing, their truck’s engine roaring through the forest. The hay, piled high in a stack, is still covered in a thin layer of dew. Two of the rangers grab pitchforks and start turning the hay, filling the air with the scent of wet grass. I follow the others to the back of the truck and grab several dirt-covered sugar beets, the wisents’ favorite treat. We throw the beets far, toward the forest, and soon, the bison appear. “They can tell our car by the sound of the engine,” says Androsiuk, the forest ranger. About 60 of them start approaching, slowly, stepping out into the clearing one by one.

While Androsiuk and his team are proud of the quality of feed they provide—fresh hay of the highest grade, he says—he admits that outside of the national park, the feeding, done by private contractors, often consists of poor-quality hay, provided indiscriminately, without taking into account how much supplementation the animals in different places really need. This oversupply of low-quality food could indeed make the bison sick. One goal of supplementary feeding is to keep the wisents in the forest—otherwise they come out onto the surrounding farms and damage crops by eating and trampling them. When I drive around with Kowalczyk, we see a pair here, a small herd there, standing among the vibrant greenery of winter rapeseed. 

Kowalczyk is big on the meadows idea. He and his colleagues have already put it into action as part of a European Union project, providing some local farmers with grants to keep meadows open for wisents. At first, there was little local interest, but after a series of workshops, a couple dozen farmers signed up. “They stopped chasing the wisents away and instead became proud of them; started talking about them as their wisents,” Kowalczyk says.

Kowalczyk stops his car at the edge of a meadow near Lewkowo village. The border wall is several miles away; the forest, with its ancient oaks, and lynx and raccoon dogs, just a couple of steps ahead. You can smell it from here: the moist bark, the mushrooms. Out on the meadow, a herd of bison feeds on a pile of hay that has been left behind, wind rustling the vast sways of surrounding grass leaves. As we approach, the wisents slowly lift their heads, all 19 of them, and calmly, they observe. Kowalczyk puts down a tripod topped with a long-lensed camera and starts taking photos. This is how he likes to portray the wisents: with plenty of space around them, out in the open, as wild as they can be on a continent filled with humans.