A camera trap in an ancient Polish forest has captured extremely rare and unexpected footage of wolves attacking a bison herd made up of adults, youngsters and a newborn calf, a new study shows.

The event took place on Sept. 15, 2025. Five wolves (Canis lupus) enter the camera frame, closely followed by three bison cows and the newborn calf. In the footage, the cows chase after the wolves, leaving the calf alone and exposed. The wolves then surround the calf, bite its neck and try to drag it away, but two cows come to its rescue. The wolves return and seize the calf a second time in the background of the video — however, this time the entire bison herd comes to its defense to end the attack.

The clip is from the Bialowieza Primeval Forest, the oldest and best-preserved temperate lowland forest in Europe, which hosts the world's biggest population of European bison (Bison bonasus). The forest covers 350,600 acres (141,900 hectares) on the border between Poland and Belarus. There are more than 870 bison on the Polish side, according to the new study, while the Belarussian side has roughly 730 bison.

Also known as "the king of the forest," the European bison is typically considered a non-prey species, meaning it has no predators except humans. But the footage calls this into question.

"To our knowledge, we present the first video-recorded evidence of wolves attacking a European bison herd in the Białowieża Primaeval Forest," researchers wrote in the study, published May 29 in the journal Ecology and Evolution. "Although the video did not capture a direct kill, it suggests that other attacks on European bison could potentially be successful."

Historical documents show that wolf attacks on European bison used to be more common, with about 8 kills recorded annually in the Bialowieza Primeval Forest between 1840 and 1849. The forest was a popular hunting ground for monarchs from the 14th century onward, explaining why such detailed records exist.

European bison went extinct in the wild in 1919, but they were reintroduced in the Bialowieza Primeval Forest in 1952. The first confirmed bison kill since then dates to the mid 1990s, and after that, it seems as though wolves stuck to a diet of roe deer (Capreolus capreolus), red deer (Cervus elaphus) and wild boar (Sus scrofa), likely because these are much easier prey than bison, the researchers wrote in the study.

But now, "our observation demonstrated that the European bison is in fact a potential prey for wolves," they wrote. "This raises questions about why predation attempts are so rare, whether the bison can still be described as a non-prey species, and what this could mean for conservation and management of the species."

An intriguing trend in the Bialowieza Primeval Forest is that wolf packs are growing in size, possibly thanks to a late 1980s hunting ban. This shift could increase wolf predation on bison in the future, because bigger packs can handle bigger prey.

"If predation on European bison, specifically young animals, occurs more frequently than previously assumed, wolves could play a small but potentially important role in the natural regulation of bison numbers," the researchers wrote in the study. "In turn, such regulation could possibly lead to mitigation of human-bison conflicts."

Never-before-seen fossils of newly hatched crocodile-like creatures are shining new light on how our aquatic ancestors conquered land.

Early four-limbed vertebrates (tetrapods), which would eventually give rise to humans, took their first steps on land in the Devonian period, some 419 million to 359 million years ago, marking one of the most important periods in the evolutionary history of animals.

Now, a new study published Thursday (June 18) in the journal Science has revealed that these early tetrapods were less like amphibians and more like us. Rather than having a tadpole phase in their development, as many amphibians do today, new evidence suggests that they were direct developers — growing from smaller to bigger versions of themselves, like their ancestors, humans and many other animals.

The study is an important contribution to our understanding of early tetrapods' reproductive developmental biology, said Tim Smithson, a visiting academic at the University of Cambridge who specializes in early tetrapods but was not involved in the study.

It suggests that the "earliest tetrapods that took those first steps on to land were able to rely on the successful reproductive and developmental strategies of their forebears," Smithson told Live Science in an email. "Direct development made life easier — one less thing to worry about!"

The new research was based partly on fossils from early land-dwelling predators called embolomeres. These animals looked like a cross between a crocodile and an eel and ruled river, lake and swamp habitats 350 million to 280 million years ago, during the Carboniferous and Permian periods. While these creatures could grow to more than 10 feet (3 meters) long as adults, the study unveils rare fossils from Mazon Creek, near Chicago, that preserved embolomeres as hatchlings that were days to a couple of weeks old.

"These are intimate details of the first moments of these animals' lives, and we've never seen that before for this entire part of the evolutionary tree," study co-author Jason Pardo, a postdoctoral fellow of evolutionary biology at Vilnius University in Lithuania and a research associate at the Field Museum in Chicago, told Live Science.

These fossils didn't show evidence of external gills and other tadpole-like features that the researchers would have expected from an early land dweller. The researchers then checked other fossils from before and during the "fin-to-limb transition" but found no evidence of an amphibian-like life cycle in those, either.

"For as long as we've understood evolution, we've assumed this story of how we made that transition from water to land," Pardo said. "We in fact have a completely different story."

Science upended?

A statement released by the Field Museum claimed that the study upends scientists' understanding of how animals conquered the land. However, the experts Live Science spoke to disagreed with this assertion.

"The Mazon Creek material is wonderful, the study is interesting and the interpretation of the fossils is sound, but I don't think the results are terribly surprising," Per Ahlberg, a professor of evolutionary organismal biology at Uppsala University in Sweden, told Live Science in an email.

Ahlberg, who was not involved in the new study, specializes in the early evolution of tetrapods. He noted that scientists knew some early tetrapods had a larval stage similar to that of modern salamanders ‪—‬ namely, those belonging to the group Temnospondyli, which he described as the ancestral stock of modern amphibians. However, he contends that this didn't mean scientists assumed every early tetrapod was the same.

"Nobody has been arguing in recent years that ALL early tetrapods had such a larval stage or that this was essential for enabling the transition to land," Ahlberg said. "I mean, I have been working right at the core of this research field for 40 years and I have never given it any thought."

In response, Pardo agreed that specialists in the field recognized that the data didn't support that early tetrapods had an amphibian-like development. However, he argued that even among specialists, assumptions were still made about metamorphosis — a major developmental transition, like a tadpole transforming into a frog — and amphibian-like bodies.

"Onto something big"

Study co-author Arjan Mann, an assistant curator of early tetrapods at the Field Museum, first saw the study's first baby embolomere fossil during a 2016 trip to the Field Museum while working on his doctorate. At the time, the fossil was a mystery.

Mann and Pardo mused over the fossil's identity for years before high-resolution scans with scanning electron microscopy at the Canadian Museum of Nature confirmed that the ancient creature was an embolomere, according to the museum's statement.

"I think Jason and I both knew we were onto something big, since fossils of this kind of animal and from this phase, and developmental state in early tetrapod evolution have never been found or studied before," Mann told Live Science in an email.

Along with the embolomeres, the researchers looked at megalichthyid fish from before the land transition and limbless, snake-like creatures known as aistopods from during the land transition. All showed signs of direct development, they said.

"I think the take home message of this study is that we should always challenge conventional wisdom in science, especially when these older ideas do not have substantial backing," Mann said.

Camera traps from inside the Chernobyl exclusion zone reveal how the occupation of Russian forces at the site in February and March 2022 altered the behavior of wildlife living in the area.

After the invasion, which involved significant armed conflict inside the exclusion zone, mammals like deer and horses became less active and spent less time moving around at night, a new study reports.

Researchers discovered the changes by comparing footage from camera traps collected during the early months of Russia's 2022 invasion with recordings from the same period a year earlier, before the conflict began. The findings, published Thursday (June 18) in the journal Science, offer a rare glimpse of how animals respond to the immediate disruption caused by warfare.

"I wish the opportunity to analyze how the unfolding invasion affected wildlife ha[d] never happened," Svitlana Kudrenko, who conducted the study as part of her PhD at the Albert Ludwig University of Freiburg in Germany, told Live Science in an email. "Unlike in preindustrial times, current interstate conflicts are highly detrimental for wildlife because of a long list of warfare, often operated remotely."

The study took place in the Chernobyl exclusion zone, a roughly 1,000-square-mile (2,600 square kilometers) area surrounding the site of the 1986 Chernobyl nuclear disaster. Following the reactor explosion, authorities evacuated the region and restricted most human activity. Over the decades, with little to no human activity, wildlife populations have flourished, turning the zone into a natural laboratory for scientists studying ecosystem recovery and animal behavior.

But in February 2022, Russian forces seized control of the region during the beginning stages of the invasion of Ukraine. Military vehicles, troop movements, weapons being fired and other wartime disturbances suddenly transformed one of Europe's most unusual wildlife refuges into an active war zone.

To investigate the impact, researchers analyzed data from camera traps already operating in the exclusion zone from 2020 to 2022. Studying the ecological effects of armed conflict is difficult because war zones are dangerous and often hard for researchers to access.

By using the existing network of automated cameras, the scientists captured wildlife responses that would have been impossible to record otherwise. In total, the team analyzed almost 2,000 photographs and videos from the exclusion zone to build a picture of behavioral changes in response to the conflict.

The images and footage revealed responses from 11 wild mammal species, ‪showing that some animals changed their behavior during periods of heavier fighting.

Several mammal species — including roe deer (Capreolus capreolus), red deer (Cervus elaphus), moose (Alces alces) and red foxes (Vulpes vulpes) — were less active during the occupation than before the conflict, especially at night, the team reported.

The findings suggest that the impact of conflict can ripple through entire ecosystems. While Russia no longer occupies the Chernobyl exclusion zone, the authors highlighted that this study still shows how animal behavior can adapt to warfare.

Camera traps could become a valuable tool for measuring the environmental costs of conflict and understanding how wildlife copes with sudden human disturbances across the globe, the researchers added.

"Our study highlights the need to develop and implement research and conservation strategies focusing on armed conflict impacts on wildlife and environment in general, especially in areas of conservation importance," Kudrenko said.

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Corvids, including ravens and crows, have earned a reputation for being some of the smartest birds on Earth. They can recognize human faces, use tools, solve multistep puzzles and even hold funerals.

In recent years, scientists have added another surprising skill to the list: a grasp of numbers. Research suggests that corvids can distinguish between different quantities and, in some cases, even perform statistical analysis.

These discoveries have raised a provocative question: How deep do the roots of mathematical thinking go? While modern humans are the only known species to develop formal mathematics, studies of crows, monkeys and other animals suggest that the cognitive building blocks of math may have evolved hundreds of millions of years before people began doing calculations.

Few researchers have done more to uncover these abilities than Andreas Nieder, a professor of animal physiology and the director of the Institute of Neurobiology at the University of Tübingen in Germany. By examining the neural activity of both monkeys and crows, Nieder has found evidence that very different animal brains can process numerical information in surprisingly similar ways. Live Science spoke with Nieder about how these findings may reveal that the origins of mathematics are far older than our species.

Kenna Hughes-Castleberry: How did you get into researching crows and primates?

Andreas Nieder: After studying the auditory and visual systems for several years as a student, I realized that I wanted to focus on the neuronal foundations of intelligence and cognitive control functions. How does the brain give rise to abstract concepts, working memory, or the ability to follow complex rules deliberately? Of course, to study intelligence, you need intelligence specialists. I therefore began working with primates ‪—‬ more specifically, rhesus monkeys, arguably among the most intelligent mammals. They are closely related to humans, possess relatively similar brains, and share many cognitive abilities with us.

However, as a trained biologist, I was always interested in a broader evolutionary question: Are sophisticated cognitive abilities unique to mammals, or can they emerge in very different brains? Crows provided an ideal comparative species. Birds diverged from mammals more than 360 million years ago — roughly six times longer ago than the extinction of the dinosaurs. Yet despite this immense evolutionary distance, corvids display remarkably flexible behavior; in many ways, they are the feathered primates of the air.

KHC: Are crows difficult to study? Are they fun? Do they have personalities?

AN: Both primates and crows are demanding to study. Because they are highly intelligent, they require special housing and care. Since we investigate cognitive abilities under tightly controlled experimental conditions, they also require extensive behavioral training by skilled personnel. And, of course, the regulations governing research with these species are particularly strict.

At the same time, they are fascinating research subjects. Individual monkeys and crows differ noticeably in temperament and behavior. Some are curious and adventurous, others are cautious and reserved, and some learn new tasks much faster than others.

Their qualities can be quite striking. Some are reliable, highly motivated workers that perform consistently day after day. Others are sensitive divas who seem to require special treatment before they are willing to cooperate. Researchers generally avoid anthropomorphizing, but there is little doubt that individual animals exhibit stable behavioral traits that we would reasonably describe as distinct characters.

KHC: You've found that crows understand the concept of zero. How do we know this?

AN: We trained crows to recognize different numbers — sets containing one, two, three, four objects, and so forth. We then included trials in which no items appeared at all. The remarkable finding was that the birds treated an empty set as a quantity and as part of the numerical continuum. They behaved as though the empty set belonged before "one." Their error patterns were particularly revealing: They confused zero more often with one than with larger numbers, exactly as one would expect if zero were mentally represented as a numerical quantity next to one. In addition, recordings from neurons in the crow brain showed cells that responded selectively to empty sets. This suggests that zero is not merely a behavioral trick but is represented neurally as a meaningful numerical category.

KHC: To play devil's advocate, is the ability to recognize the difference between something and the lack of something really that surprising? Is it akin to the human concept of zero?

AN: That's an important question. Simply recognizing that nothing is present or absent is not surprising. Many animals can distinguish between the presence and absence of objects. The key issue is whether they treat "nothing" as a quantity that can be compared to other quantities.

Our experiments suggest that crows do more than detect absence. They position empty sets within an ordered numerical sequence, at the low end of the number line, and show distance effects similar to those observed with other numbers. For example, they find it easier to distinguish zero from two than zero from one.

That said, we should not claim that crows possess the full human mathematical concept of zero. Humans use symbolic zero in arithmetic, algebra, calculus and formal mathematics. What we have demonstrated is a foundational precursor: a nonsymbolic numerical representation of zero. This may represent an evolutionary building block from which more sophisticated human concepts eventually developed.

KHC: You've also found that crows can perform statistical analysis. Tell me more about these findings and what you showed.

AN: We trained carrion crows [Corvus corone] to associate a series of arbitrary visual signs, colored geometric images displayed on a touch screen, with different reward probabilities. One sign might yield a food reward 90% of the time, another 70%, another 50%, and so on down to 10%. Importantly, the signs themselves carried no inherent meaning; the birds had to learn these probabilities through experience.

Once the birds had learned these sign-probability associations, we presented them with pairs of signs and asked them to choose one. To maximize their rewards, they should select the sign associated with the higher reward probability. The crows did exactly that. Even when confronted with many novel pairings, they reliably chose the statistically more favorable option.

This does not mean that crows perform formal statistics in the human sense. They are not calculating percentages or solving probability equations. However, the results show that they can extract probabilistic regularities from experience, store this information in memory, and use it flexibly to make reward-maximizing decisions under uncertainty. These are fundamental ingredients of statistical reasoning and are highly valuable in natural environments, where animals constantly have to make decisions based on incomplete information.

KHC: Have researchers tried similar tests on babies or young humans, and if so, how do we stack up?

AN: Yes. Developmental psychologists have conducted many related studies with infants and young children. Even before learning language, infants show sensitivity to quantities, numerical differences and simple probabilistic information. By around 4 years of age, children also display an intuitive understanding of empty sets.

What is striking is that the behavioral signatures observed in crows resemble those seen in preverbal human infants and nonhuman primates. Of course, human children eventually develop symbolic mathematics through language, education and culture, which takes them far beyond the abilities observed in animals.

KHC: Can these findings tell us anything about how the human understanding of math evolved?

AN: They suggest that some foundations of mathematics may predate humans by a very long evolutionary timescale. Humans did not invent numerical intuition from scratch. Rather, we appear to have inherited ancient cognitive systems that allow brains to estimate quantities, compare numbers, and represent concepts such as zero approximately.

The fact that crows and primates — two distantly related groups — show similar numerical abilities suggests that these capacities may emerge whenever evolution favors flexible intelligence. Human mathematics likely built upon these ancient cognitive foundations and then expanded dramatically through language, symbols and culture.

KHC: What's something a general audience might be surprised to learn about crows?

Many people are surprised to learn that crows are songbirds. Most people associate songbirds with melodic singers such as nightingales or blackbirds, not with the harsh cawing of a crow. Yet crows do learn a significant part of their vocal repertoire and are even known as apt imitators, even of human speech sounds — the internet is full of funny videos in which crows imitate human speech.

What makes this particularly interesting is that their vocalizations are not merely reflexive calls. In our experiments, we found that crows can exert volitional control over their vocal behavior. They can learn to produce vocalizations in response to arbitrary cues and withhold them when required, demonstrating a level of cognitive control over vocal output that is considered an important prerequisite for complex communication and, ultimately, language.

More recently, we showed that crows can even use their vocalizations to count. In a recent study published in [the journal] Science, we trained crows to produce a specific number of calls — between one and four — in response to visual or auditory cues. Remarkably, they not only generated the correct number of vocalizations but also appeared to prepare the intended number before they started calling. This suggests that they can represent numerical information and use it to guide a self-generated sequence of vocal actions.

Taken together, these findings show that crow vocalizations are far more sophisticated than most people assume. Their characteristic "caw" is not just a simple call — it can be brought under deliberate cognitive control and even used to express numerical information. For a bird, that is a remarkably advanced ability.

This interview has been edited for length and clarity.

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An elusive dwarf fox that was feared extinct has been photographed for the first time, after being spotted near a highway in Cozumel, Mexico.

The tiny animal was part of the mysterious Cozumel fox population, a potentially undescribed species that had not been officially sighted in more than 20 years.

Cozumel foxes live only on Cozumel, an island near Cancún. Researchers know very little about these mysterious predators, which are roughly 20% to 40% smaller than their gray fox (Urocyon cinereoargenteus) cousins that live on the mainland.

Park and museum officials spotted and captured the fox in 2023 and, after a health assessment, released it back into the wild. Researchers have now shared the photographs and documented the encounter in a new study published May 4 in the journal Neotropical Biology and Conservation.

Although the rediscovery confirms that Cozumel foxes are still alive, they are likely on the brink of extinction, the study authors noted; the photographs highlight the need for focused research and conservation efforts.

"The biggest challenge facing the Cozumel fox is that we still know almost nothing about it, including its remaining population size, distribution, or ecology," study first author Travis Bayer, executive director of the conservation organization Pathos Wildlife, said in a statement. "That uncertainty alone is dangerous, because it makes effective conservation extremely difficult."

Cozumel foxes are an example of insular dwarfism, an evolutionary process in which larger animals, including fox-sized mammals, evolve to be smaller after colonizing islands, where there are limited resources and less space than on the mainland. The foxes aren't the only mammals that have shrunk on Cozumel over time; other examples include the island's critically endangered pygmy raccoons (Procyon pygmaeus) and dwarf coatis.

Archaeological evidence suggests that Cozumel foxes have lived on the island for at least 5,000 years, likely since before the arrival of the Maya within the past few millennia, and potentially for tens of thousands of years before that. Prior to this rediscovery, the last confirmed sighting of a Cozumel fox was in 2001, according to the study.

The rediscovery began with reports of a disoriented animal wandering near the highway on the southeastern side of the island. Officials with the Parks and Museums Foundation of Cozumel located and captured the fox, an adult male, on Sep. 14, 2023. They checked its health and later released the fox in the Laguna Colombia State Reserve, a protected area just south of where it was captured.

Recent and historical sightings suggest that Cozumel foxes could have an extremely restricted range in the island's South, where nature is increasingly threatened by development, land-use change, invasive species and natural disasters, the study authors noted.

The researchers recommended surveys to determine the current distribution and size of the Cozumel fox population, along with morphological and genetic assessments to establish its evolutionary status and conservation efforts to protect its assumed habitat in southern Cozumel and minimize human-wildlife conflict.

"Ultimately, we hope this work helps move the Cozumel fox from a little-known, uncertain presence on the island to a better-understood key part of Cozumel's ecosystems," Bayer said. "We also hope it demonstrates that conservation is often most urgent when certainty is lowest and that uncertainty itself can be a call to action."