Return of top predators is key to ecological future

Apr 23, 2010
Cristina Eisenberg, a conservation biologist in the College of Forestry at Oregon State University, does field work on the importance of large predators in ecosystem function. (Photo courtesy of Oregon State University)

Sufficient advances have been made about the importance of top predators in ecosystem function that it's time to move from discussing the issue to acting upon it, a conservation biologist from Oregon State University suggests in a new book.

In "The Wolf's Tooth: Trophic Cascades, Keystone and Biodiversity," just published by Island Press, Cristina Eisenberg outlines the many research findings in recent decades about "trophic cascades," or the string of problems that can be created when keystone predators - ranging from to sharks or even spiders - are removed from an ecosystem, allowing other species to disproportionately flourish and cause havoc.

In particular, Eisenberg said, more has been learned about the significance of top predators on terrestrial systems, since their role in was already more advanced. Scientists have now come to understand how wolves, cougars, bears and other leading carnivorous predators, which humans largely eliminated by the early 20th century, served a critical role in ecosystem function.

"The ecological concept of the 1990s was biodiversity, and that's important," said Eisenberg, who is the Boone and Crockett Fellow and a doctoral student in the OSU College of Forestry. "But in the next generation we want the concept of trophic cascades to have that same general awareness, because it's important too and essential to maintaining biodiversity. And we already know enough that it's time to start using these concepts to help ecosystems recover, not just in national parks or wilderness areas but everywhere."

These concepts have gained the most public awareness, Eisenberg said, with the return of wolves to . Wolves have helped to control the overgrazing done by elk, both by reducing their populations and also changing their behavior in what has been identified as "the ecology of fear." As a result, young aspen and willows are beginning to grow along streams for the first time since the 1920s. This will also help control erosion and lead to more beaver dams, researchers believe, and ultimately affect everything from birds to insects and fish, by improving their habitat.

"When we lost most of the large predators in the U.S., along with climate change and other population impacts, we started a hemorrhage of extinction," Eisenberg said. "Streams are being degraded, species are being lost, the function of ecosystems that was once complex and diverse is being severely impaired. But it doesn't have to be that way. There are things we know that can change it."

Many of the obstacles to progress, Eisenberg said, are as much political and social as they are ecological.

In the 1930s, Eisenberg said, the famed naturalist Aldo Leopold once visited some lands in Chihuahua, Mexico that were owned by her grandfather on a huge cattle ranch, and Leopold remarked on how intact and thriving the lands appeared - which, at that time, were still roamed by wolves. Leopold was one of the first to point to the importance of predation in ecosystem function.

"My grandfather still felt he had to get rid of the wolves, so he gave my dad a summer job in which he was supposed to watch the cattle, and kill any wolves he saw," Eisenberg said. "My father later told me that he couldn't bring himself to do it, because he couldn't see that they were really causing any harm."

Eisenberg comes from a ranching background, and now lives in a valley in northwestern Montana where the wolf and grizzly bear population outnumbers humans. In continued research, she's working to understand and demonstrate ranching practices and other techniques that can be used to balance commercial land use with the presence of wolves and other predators. It's both possible and necessary, she said.

"These really are not complicated concepts, they work, and they don't cost much," Eisenberg said. "There can be specific times and situations where predators may need to be controlled. But in many cases all we need to do to bring back predators is to stop killing them. It's all about relationships. I've explained ideas about trophic cascades to third graders and they immediately get it.

"The problems are really more social, because many people have such an emotional reaction to large predators," she said. "But major predators were always a part of balanced ecosystem function, and allowing them to return will be one of the simplest, and most effective ways to restore these lands."

Much of the leading research on these concepts in terrestrial ecosystems has emerged from research at OSU in the past decade, Eisenberg said, in studies done by William Ripple and Robert Beschta in the College of Forestry. They have analyzed the impact of wolves and cougars as key predators in several national parks that, when allowed to recover, are helping restore healthy and vigorous ecosystems.

Eisenberg's new book provides both local and landscape-scale applications of what has been learned about these issues, and ways in which recovery efforts could begin.

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User comments : 7

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fixer
not rated yet Apr 23, 2010
Looks like Humans are still top predator!

"Return of LARGE predators is key to ecological future"
would be a better title!

Apart from that, good article.
marjon
not rated yet Apr 24, 2010
Change laws to allow the top predator, humans, to hunt and take the place of 'top predators'.
A good first step is to allow the hunting/trapping of geese on golf courses.
When protected predators like wolves, coyotes, cougars, bobcats, hawks, owls, etc. continue to attack pets, and children, what should be done?
skybluskyblue
not rated yet Apr 24, 2010
"When protected predators like wolves, coyotes, cougars, bobcats, hawks, owls, etc. continue to attack pets, and children, what should be done?"

Education; often stupid things like humans leaving trash or even feeding or trying to befriends those predators lead to the most problems.
If you believe in absolute safety when humans invade environments filled w other life, then one must live in sterile castles.
The coyote attacks, for example, are in environments where people do not chase off or try to scare the coyotes thus train them to run away rather than approach humans. When that happens a whole new generation of both species needs to be trained.
Let us use the brains we have [ our supposed advantage over coyotes etc.] and be sensible rather than stupid about other life forms.
PinkElephant
not rated yet Apr 24, 2010
Let us use the brains we have [our supposed advantage over coyotes etc.] and be sensible rather than stupid about other life forms.
Do not forget, you're talking to marjon.

Hey marjon the clown, you don't think humans are smart enough to regulate economies, so what makes you think humans are smart enough to regulate ecosystems?
marjon
not rated yet Apr 24, 2010
"When protected predators like wolves, coyotes, cougars, bobcats, hawks, owls, etc. continue to attack pets, and children, what should be done?"

Education; often stupid things like humans leaving trash or even feeding or trying to befriends those predators lead to the most problems.
If you believe in absolute safety when humans invade environments filled w other life, then one must live in sterile castles.
The coyote attacks, for example, are in environments where people do not chase off or try to scare the coyotes thus train them to run away rather than approach humans. When that happens a whole new generation of both species needs to be trained.
Let us use the brains we have [ our supposed advantage over coyotes etc.] and be sensible rather than stupid about other life forms.

Coyotes are wandering around Boston. When animals are not afraid of humans, they will invade and eventually attack.
marjon
not rated yet Apr 24, 2010
so what makes you think humans are smart enough to regulate ecosystems?

The people who regulate ecosystems, hunters, farmers, etc. are usually not liberal socialists.
I drove past Reagan's ranch a few days ago on Refugio road. Lots of lush vegetation just waiting to dry out and catch fire. There were even a few deer. But there should be goats or cattle wandering all over that area eating down the brush to limit the spread of fire. People who live and work on the land know how to conserve its resources.
It was also amusing to watch the latest storm erode the coast on Pacifica threatening the houses stupid people built there. Its too bad so much public money is spent trying to save them.
marjon
not rated yet Apr 24, 2010
"a coyote attack in Jamaica Plain. The host interviewed David Sherris who lost his dog when a coyote came into his well-lit backyard and killed his dog. Sherris approached the coyote causing it to drop his dog and run away (brave man).
"
"For those of you not familiar with Boston, Jamaica Plain is actually near the city’s heart."
"Massachusetts is an asinine state. Massachusetts considers coyotes a “protected species” and won't hunt a coyote down to kill him."
"predators see other creatures in one of three ways: food, threat, and unclassified. The more they’re around us humans and see that we aren’t a threat, the more they start to classify us as food."
http://tenring.bl...ton.html
marjon
Apr 24, 2010
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