As gray wolves continue to make a strong comeback in Washington state, their presence can’t help but impact other animals — particularly the ones these large carnivores target as prey.

White-tailed deer and mule deer, two distinct species common in Washington, are among wolves’ favorite catch. Wolves will chase deer great distances — sometimes upwards of 6 miles (10 kilometers) — in search of a satisfying meal. How these two deer species respond to the threat of being pursued by wolves in the early years of this predator’s return could shed light on changes to their behavior and numbers.

To help answer this question, researchers from the 91̽»¨ and other institutions monitored the behavior and activity of wolves and deer in Washington for three years. They found that mule deer exposed to wolves, in particular, are changing their behavior to spend more time away from roads, at higher elevations and in rockier landscapes.

“In any particular ecosystem, if you have a predator returning, prey are unlikely to all respond similarly,” said senior author , an associate professor in the 91̽»¨School of Environmental and Forest Sciences. “We show that wolves don’t have a uniform effect on different deer species.”

Their were published in December in the journal Oecologia.

Wolves were completely wiped out from Washington early last century, but began returning to the state from Idaho, Montana and Canada about a decade ago. The now show about 200 wolves in packs across eastern Washington.

Both white-tailed and mule deer are important food for gray wolves. While they might look similar to an untrained eye, white-tailed deer and mule deer are very different animals: Mule deer are bigger, with large, dark ears and a black-tipped tail. White-tailed deer are smaller animals, boasting an unmistakably long tail with a white underside that stands straight up when alarmed.

Aside from their physical characteristics, the two species differ in how they escape from predators. When chased, mule deer “,” a quick bound with all four legs touching the ground at the same time. This bounding gait helps them negotiate all types of terrain and can give them an agility advantage over predators in rocky, uneven areas where it might be hard to run.

By contrast, white-tailed deer sprint away from predators and rely on spotting them early enough to try to outrun them.

Keeping these known escape tactics in mind, the research team focused on the “flight behavior” of deer living in areas where wolves have returned and in areas without wolves. The researchers chose four distinct study areas, all near the small town of Republic, Washington. All four areas are home to both species of deer, but only two were occupied by known wolf packs at the time of the investigation.

In partnership with the Colville Tribes and the U.S. Forest Service, researchers set up wildlife cameras, captured and put collars on wolves and deer, and monitored the data from all of the collars over three years, from 2013 to 2016. This endeavor involved complex coordination and a dedicated team of 91̽»¨students who were always ready to respond should an animal enter one of the traps.

“That part of eastern Washington is really special,” said lead author Justin Dellinger, who completed the work as a 91̽»¨doctoral student and now works at the California Department of Fish and Wildlife. “There is huge diversity of large mammals, including all of the native prey populations like big horn sheep, moose and deer. And now we’re starting to see a full complement of native predators, like wolves, here as well.”

Overall, the researchers found that mule deer in gray wolf areas changed their behavior to avoid wolves altogether — mainly by moving to higher, steeper elevations, away from roads and toward brushy, rocky terrain. Alternately, white-tailed deer that favor sprinting and early detection as ways to escape from predators were more likely to stick to their normal behavior in wolf areas, sprinting across open, gently rolling terrain with good visibility — including along roads.

“Mule deer faced with the threat of wolves are really changing their home ranges, on a large scale,” Wirsing said. “They appear to have shifted kilometers away from where they had been prior to the return of wolves, generally going up higher where the terrain is less smooth and where wolves are less likely to hunt successfully.”

These larger shifts among mule deer could affect hunting opportunities. Indeed, some hunters in eastern Washington have already reported seeing mule deer higher on ridges where they are less accessible than in past years, Wirsing said. Hunting for white-tailed deer likely won’t change to the same degree with the presence of wolves, the results suggest.

Long term, changes among mule deer in wolf areas could affect other parts of the ecosystem, and perhaps reduce the number of deer-vehicle collisions. These possible impacts are tantalizing fodder for future studies, Wirsing added.

Other co-authors are and , both 91̽»¨graduate students; Michael Heithaus of Florida International University; and William Ripple of Oregon State University.

This study was funded by the National Science Foundation, the Safari Club International Foundation, Conservation Northwest, Washington Department of Fish and Wildlife and the 91̽»¨.

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For more information, contact Wirsing at wirsinga@uw.edu or 206-543-1585 and Dellinger at Justin.Dellinger@Wildlife.ca.gov or 916-261-3610.

That’s the main finding of a appearing May 23 in Nature Communications that analyzed the relationship between top predators on three different continents and the next-in-line predators they eat and compete with. The results were similar across continents, showing that as top predators’ ranges were cut back and fragmented, they were no longer able to control smaller predators.

“Our paper suggests it will require managing for top predator persistence across large landscapes, rather than just in protected areas, in order to restore natural predator-predator interactions,” said co-author , an associate professor at the 91̽»¨’s School of Environmental and Forest Sciences.

Gray wolves historically lived across vast swaths of North America, particularly in the western states and Canadian provinces. Coyotes, a smaller predator kept in check by wolves, appear to have been scarce in areas once dominated by wolves. As human development shrank territories for wolves, however, the wolf populations became fragmented and wolves no longer had the numbers or space to control coyotes, whose populations in turn grew.

The same story is at play in Europe and Australia, where the researchers examined the relationship between gray wolves and golden jackals, and dingoes and red foxes, respectively. As with America, when the top predator’s range was slashed, the second-tier predators ballooned and ecosystems became imbalanced.

“This research shows that apex predators like dingoes and wolves need large, continuous territories in order to effectively control the balance of their ecosystems,” said lead author of Deakin University and the University of Sydney in Australia. “Humans need a greater tolerance of apex predators if we want to enjoy the environmental benefits they can provide.”

Only in the northern regions of Canada and parts of Alaska do wolves still roam across the large landscapes they once occupied. Elsewhere in North America, patchwork conservation efforts have brought wolves back in areas such as Yellowstone National Park, the northern Rockies, and eastern Washington and Oregon. Though wolves are on the upswing in these regions, their populations are likely too isolated to control the pervasive coyote and other small predators.

In some areas, the increase in wolves is actually helping some predators that might be a couple of rungs lower on the food chain, like the red fox. But regardless of whether the presence of more wolves helps or hurts other predators, that effect is likely dampened when wolf populations are fragmented.

This calls into question what makes for effective conservation. At least for wolves, Wirsing said, prioritizing activities that connect landscapes and attempt to rejoin isolated populations should be considered, he said.

“This reframes the debate ― what we really need to do is connect areas if we want predators to play their historical roles,” he said.

The researchers used bounty hunting data from all three continents to map the top predators’ historical ranges. They then mapped the range over time for the three smaller predators, looking to see where they overlapped. The researchers found that top predators such as wolves and dingoes could suppress coyotes, red foxes and jackals only when the top predators lived at high densities and over large areas. Additionally, wolves and dingoes exert the most control closest to the core of their geographic range.

In places like Yellowstone and eastern Washington and Oregon, however, smaller wolf populations are too far removed from the remaining core of the species’ distribution to really make a difference in controlling coyote numbers.

Fewer wolves aren’t the only reason coyotes have proliferated everywhere in North America. Coyotes are generalists that can live almost anywhere and have basically followed humans, eating our food and, in some cases, household pets. There have even been sightings in many metropolitan areas, including downtown Chicago.

“Coyotes have essentially hitched a ride with people,” Wirsing said. “Not only do we subsidize coyotes, but we also helped them by wiping out their predators ― wolves.”

The researchers plan to test whether similar patterns occur for other species pairs that compete strongly. They also call for more research comparing the ecological role of top predators on the edge of their geographic range, especially in human-modified environments.

“It will be interesting to see the influence of large predators on smaller predators in other parts of the world, especially the role of the big cats such as jaguars, leopards, lions and tigers,” said co-author of Oregon State University.

Other co-authors are from the University of Sydney, the University of Belgrade, the University of Tasmania, the University of Ljubljana, the University of New South Wales and the University of Forestry, Sofia in Bulgaria.

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For more information, contact Aaron Wirsing at 206-543-1585 or wirsinga@uw.edu.

“Promoting tolerance and coexistence with large carnivores is a crucial societal challenge that will ultimately determine the fate of Earth’s largest carnivores and all that depends upon them, including humans,” write the co-authors of a , in the Jan. 10 issue of Science, about the largest carnivore species on Earth.

Despite their scary reputation, carnivores deserve credit for all kinds of ecological services, among them, helping fight climate change (they eat the grazers that gobble down young trees and other vegetation that could be holding carbon), improving streams and stream banks,  helping other smaller predators cope with climate change, eating diseased deer, elk and other wild animals that might otherwise contaminate livestock and, possibly, helping ranchers achieve sustainable pasture lands.

Lead author of Oregon State University has done work in the Pacific Northwest’s Olympic National Park and in Yellowstone National Park revealing carnivores’ roles in those ecosystems. The UW’s co-author on the paper is , an assistant professor of , who studies how prey animals react when large predators such as wolves are present.

This paper takes a global perspective to look at the status of 31 of the largest carnivores on Earth, three-quarters of which have declining populations. These are charismatic animals like wolves, tigers, leopards and bears – but also hyenas and, interestingly, sea otters. Otters eat sea urchins that would otherwise graze on kelp. Fewer sea otters mean kelp beds are eaten down and no longer take up as much carbon dioxide.

As lions and leopards decline in West Africa, another example in the paper, olive baboons have increased eating forest animals including smaller primates and raiding livestock and crops on farms.

Here in Washington, deer populations have thrived and likely over-browsed plant communities for decades in the absence of gray wolves, Wirsing said. Eating small trees and other vegetation to the ground along streambeds means less habitat for birds, and streams are more likely to be filled with sediments from soil erosion and overheated because of lack of shade. Now with wolves back in the state, Wirsing is leading a study sponsored by the National Science Foundation to document changes to deer populations and forest landscapes.

The co-authors write that the classic conception of carnivores’ role in ecology is that they deplete resources such as fish, wildlife and domestic livestock, That is now outdated and in need of fundamental change, they write.

The 14 co-authors from the U.S., Australia, Italy and Sweden call for an international initiative to conserve large predators in coexistence with people. They suggest that such an effort be modeled on the , a nonprofit scientific group affiliated with the .

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For more information:
Wirsing, 206-543-1585, wirsinga@uw.edu
Wirsing will be conducting field work near Republic, Wash., between Jan. 8-11, ask Sandra Hines, 206-543-2580, for cell phone number.