Nav: Home

Wolves need space to roam to control expanding coyote populations

May 23, 2017

Wolves and other top predators need large ranges to be able to control smaller predators whose populations have expanded to the detriment of a balanced ecosystem.

That's the main finding of a study 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 Aaron Wirsing, an associate professor at the University of Washington'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 Thomas Newsome 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 William Ripple of Oregon State University.
-end-
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.

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

University of Washington

Related Predators Articles:

Herbivores, not predators, most at risk of extinction
One million years ago, the extinction of large-bodied plant-eaters changed the trajectory of life on Earth.
Bugs resort to several colours to protect themselves from predators
New research has revealed for the first time that shield bugs use a variety of colours throughout their lives to avoid predators.
Jellyfish contain no calories, so why do they still attract predators?
New study shows that jellyfish are an important food source for many animals.
'Matador' guppies trick predators
Trinidadian guppies behave like matadors, focusing a predator's point of attack before dodging away at the last moment, new research shows.
The European viper uses cloak-and-dazzle to escape predators
Research of the University of Jyväskylä demonstrates that the characteristic zig-zag pattern on a viper's back performs opposing functions during a predation event.
Predators help prey adapt to an uncertain future
What effect does extinction of species have on the evolution of surviving species?
To warn or to hide from predators?: New computer simulation provides answers
Some toxic animals are bright to warn predators from attacking them, and some hide the warning colors, showing them only at the very last moment when they are about to be attacked.
Dragonflies are efficient predators
A study led by the University of Turku, Finland, has found that small, fiercely predatory damselflies catch and eat hundreds of thousands of insects during a single summer -- in an area surrounding just a single pond.
Predators to spare
In 2014, a disease of epidemic proportions gripped the West Coast of the US.
Red-winged blackbird nestlings go silent when predators are near
If you're a predator that eats baby birds -- say, an American crow -- eavesdropping on the begging calls of nestlings can be an easy way to find your next meal.
More Predators News and Predators Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.