Wolves have personalities that impact their ecosystem


A high-speed chase by a carefully coordinated pack might be the quintessential image of wolves grabbing their meal. But for some wolves in Minnesota’s Voyageurs National Park and beyond, the hunt can involve a long day alone, waiting to ambush their target. For biologists like Joseph Bump, seeing a wolf motionless most of the day often means one thing: it’s beaver hunting time.

Wolves need patience and perseverance to ambush beavers, as semi-aquatic rodents are more likely to swim in a pond or use a densely vegetated path than graze in an open meadow. The new predatory behavior was revealed by researchers from the Voyageurs Wolf Project, who recorded a wolf hunting and killing a beaver for the first time in 2015. Their research revealed that beavers are common prey for wolves, especially during the hottest months. However, not all wolves possess the cunning necessary to score a delicious beaver meal.

A recent follow-up study has now revealed that ambush behavior is an indication of individual personalities. These personal traits can even have an outsized impact on the species and ecosystems around them, finds a new study from the Voyageurs Wolf Project. The results were published in the June issue of Borders of ecology and environmenta peer-reviewed scientific journal, and contribute to a growing body of research on animal personality.

Scientists have long recognized the intellectual capacity of animals, but this research into wolf behavior gives them a window into how personality influences the natural world. Since beavers are ecosystem engineers in their own right, removing them from the landscape through predation means that dams can be abandoned, especially single beaver dams. Once their aquatic abodes deteriorate, the composition of the forest changes.

“A successful ambush trait for wolves requires them to be able to wait in these beaver ponds along foraging trails, and some individuals wait much more often and much longer than others,” explains Bump, a professor in the Department of Fisheries, Wildlife, and Conservation Biology at the University of Minnesota, who led the study.

Waiting wolves may mark their beaver prey, while less patient wolves may feed on other food sources like deer, hare, and even berries, which many turn to during the summer. The project also found that successful beaver-hunting wolves know how to stay downwind of their prey, but often wait in plain sight because beavers have poor eyesight but a keen sense of smell.

The wolves in the study wore GPS collars attached by biologists from the Voyageurs Wolf Project, which is primarily funded by the University of Minnesota and the Minnesota Environment and Natural Resources Trust Fund. Without this technology, it is impossible for biologists to understand what wolves do during the summer, as the forest fills with dense plants that prevent direct observation. The collars are designed to fall off after two or three years, but before that the team receives valuable information about where the wolves go and how they spend their days.

In the personality study, the team combined GPS data and field observations to find out when a wolf has ambushed a beaver. When they watched a wolf stay in one place for many hours, they knew it could be waiting for a chance to catch its prey. Once the wolf had left the place, someone would go looking for evidence to find out what had happened.

“You’re like a forensic unit there,” says Thomas Gable, project manager at the Voyageurs Wolf Project and collaborator on wolf personality research. He has a habit of looking for tiny pieces of evidence to help him figure out what a wolf did in a certain area. “It could be a little piece of bone, it could be a few little tufts of fur. But often it’s very subtle,” he explains.

Wolves also sometimes leave behind a beaver’s skull, jawbone, or even castor glands, Bump says. His best guess is that these bones are too strong for wolves to bite into and that they avoid the scent glands “because they taste bad,” he says, adding, “They can almost remove them surgically.” These types of clues can indicate whether a wolf found a meal in a particular location or simply stopped to rest.

With several years of data from 16 wolves, Bump and his team created eight pairs matched by age, family pack and location. He found that while some pairs hunted a similar number of beavers, other wolves killed double or triple the number of beavers as their pack mate did. Because the level of beaver hunting varied widely for some pairs, even between similar wolves in the same location, factors such as age and beaver density were excluded when examining behavioral difference. This means that the personality of the wolves is the most likely cause of the disparity.

The increased understanding of wild animal personalities has implications beyond simply changing the natural world. In the study, the researchers note that a better understanding of individual behavior has the potential to improve interactions between wolves and humans.

For example, if a wolf kills livestock and harms a ranching business, some may want to wipe out the entire pack, Bump says. This research reveals that hunting traits can be unique depending on each wolf’s personality, so wildlife managers could determine if this extreme measure would be necessary. “But wolves are very social and pack members learn from each other,” Bump points out, so every case will be different.

After decades of research on wolf populations, the next step is to better understand individuals, says Joseph Hinton, senior researcher at the Wolf Conservation Center. “It’s a bit like key individuals – some individuals are going to have a more profound effect on their local communities than others,” he says.

When wolves hunt beavers in the boreal forest ecosystem of Voyageurs National Park, they remove the wetlands that these beavers maintain with their dams. Each year, when young beavers move away from their parents’ lodges, they create ponds in drier areas by building new dams. Without wolves involved, 84 percent of these wetlands remain for at least a year. But when a wolf kills the scattering beaver, the pond dries up, according to project research.

Hinton says the study of wolf personalities contributes to a body of research illustrating how specific predators can have a top-down effect on their ecosystems, known as a trophic cascade. A study in Alberta, Canada, identified a single grizzly bear that specialized in hunting mountain goats, while other grizzly bears in the region were never observed hunting goats. Another Colorado research team found a mountain lion that preferred to hunt beavers, as did some wolves in Voyageurs National Park.

The new discovery about wolf personality comes as no surprise to John Hoogland, a University of Maryland professor who studies prairie dogs. In his nearly 45 years of studying the species, he has observed that each animal has its own personality and it often comes down to being in the right place at the right time to record their unique behaviors. “If I have 150 prairie dogs, I have 150 personalities,” he says.

His research team encountered a strong predatory personality at a prairie dog research station in New Mexico in 2018. In late spring, a mom badger with a unique hunting style moved into the dog colony. of meadow. She killed at least 100 prairie dogs in just over a month, decimating the local population.

“She was just a very impressive and efficient predator,” says Sam Kagel, lead author of the badger study, which the team named Becky. Becky the badger likely killed over 100 more prairie dogs, considering the team only observed hunting during the day and badgers often hunt at night as well.

Like beavers, prairie dogs are a key species, says Hoogland. The burrows they dig impact the circulation of water and minerals in their environment, and their tunnels provide refuge for species like ferrets, salamanders, turtles and arachnids. “Many, many animals depend on it to one degree or another,” he says.

This means that the strong hunting personality of a single badger, much like that of a wolf, can have an outsized impact on an ecosystem.

The heavy predation of a keystone species like the beaver may seem worrying because its wetlands promote biodiversity. But that doesn’t seem to have a negative impact: “We don’t see a decline in beaver density across the landscape, even when we have these strong beaver hunter personalities,” Bump says.

In an ecosystem with a healthy beaver population like Voyageurs National Park, young beavers regularly disperse and create new dams. So, while a persistent wolf can reduce wetlands for at least a year by hunting beavers, new ones can come and replace them. Apparently, Beavers also have a persistent personality.


Comments are closed.