When a pack of wolves kills prey, crows are often the first to appear. Even before the wolf begins to feed, these birds gather nearby and try to steal any scraps that are available. The timing of crows has long been considered almost spooky, leading many to believe that crows were simply following wolves in search of food.
A new study that tracked crows and wolves in Yellowstone National Park over two and a half years reveals a more sophisticated strategy. Rather than chasing wolves, crows memorize locations where kills are likely to occur and return to those locations, even from a distance. “They can fly non-stop for six hours and go straight to the scene of the kill,” said Dr. Matthias Loretto, lead author of the study.
Published in scienceresearch shows that crows rely on spatial memory and navigation to find food spread across the landscape. “Ravens can cover long distances by flight and seem to have good memories, so they don’t have to constantly chase wolves to benefit from predators,” Loretto said.
The project was led by the Institute of Wildlife Ecology at the University of Veterinary Medicine Vienna and the Max Planck Institute for Animal Behavior (Germany), together with several international partners, including the Senckenberg Center for Biodiversity and Climate Research (Germany). Department of Environmental and Forest Sciences, University of Washington (USA). and Yellowstone National Park (USA).
Tracking Crows and Wolves in Yellowstone
The study was conducted in Yellowstone National Park, where wolves were reintroduced in the mid-90s after a 70-year hiatus. Currently, about a quarter of the wolf population wears tracking collars each year. Dr. Dan Stahler, a Yellowstone biologist who has been studying these wolves since their return, notes that crows often seem to be closely associated with them, saying, “You’ll see them flying right over the traveling pack or leaping right behind the wolves to take down their prey.”
This behavior makes sense because wolves create reliable food opportunities for scavengers. “We all thought birds had a very simple rule: Just stay close to wolves,” Stahler said. However, the idea was never directly tested. “We didn’t know what crows were capable of, because no one had ever focused on crows, no one had taken a scavenger perspective,” he says.
To better understand crow behavior, researchers fitted 69 birds with small GPS tracking devices. This is an unusual number for this type of research. “Ravens are very observant of their surroundings, so they don’t fall into traps easily,” says Loretto. In order to successfully capture them, the team carefully blended the trap into its surroundings. For example, traps near the campsite were disguised with garbage and fast food. “Otherwise, the crows will suspect that something is wrong and will not approach it,” says Loretto, who is now at the University of Veterinary Medicine in Vienna.
In addition to the crow data, the researchers analyzed the behavioral patterns of 20 collared wolves. They focused on winter, when crows most frequently interact with wolves, and recorded crow positions every 30 minutes and wolves every hour. They also recorded when and where wolves killed prey, primarily elk, bison, and deer.
Ravens remember productive hunting locations
Over two and a half years, researchers found only one clear case of a crow chasing a wolf for more than a kilometer or an hour. “I was confused at first,” Loretto said. “Once we found out that crows don’t chase wolves over long distances, we couldn’t explain why birds would arrive so quickly to kill wolves.”
A closer look at the data revealed the answer. Instead of tailing wolves, crows repeatedly returned to certain areas where killings were more common. Some birds could travel up to 155 kilometers a day, sometimes flying directly toward locations where carcasses were likely to appear, even though the exact timing of the kill was unpredictable.
Wolf kills tend to be concentrated in certain parts of the landscape, such as flat valley floors, where hunting is more successful. Ravens visited these high-yield areas much more frequently than locations where kills were rare. This pattern suggests that they are learning and remembering what researchers call a long-term “resource landscape.”
“We already knew that crows remember stable food sources, such as landfills,” Loretto said. “What surprised us is that they seem to be learning in which areas wolf kills are more common. One-time kills are unpredictable, but over time some parts of the landscape become more productive than others, so the crows seem to be using that pattern to their advantage.”
What this reveals about animal intelligence
Researchers say crows may track wolves over short distances even when they are nearby. “Crows may be using short-range cues, such as monitoring wolf behavior or hearing wolf howls, to locate local wolf kills,” Loretto says. But on a larger scale, memory plays a leading role. Ravens decide where to search first based on past experience, sometimes traveling tens or even hundreds of kilometers.
Lead author John M. Marzluff, a professor at the University of Washington, said: “Our study clearly shows that crows are flexible in deciding where to feed. They do not remain tied to a particular wolf pack. “Memory allows us to choose from a wide range of many foraging opportunities. This changes the way we think about how scavengers find food and suggests that we may have underestimated some species for a long time.”
