Wolves spur rebirth of Yellowstone ecosystems

Study documents new tree growth and improving riparian ecosystem

A wolf in Yellowstone National Park. (Photo courtesy of Yellowstone National Park)
Young aspen trees are now recovering in Yellowstone National Park, after wolves that were re-introduced in 1995 helped to limit elk browsing that had been killing young trees. The older trees seen here date to the last time there were wolves in the park 70 years ago. (Photo by William Ripple, courtesy of Oregon State University)

By Summit Voice

SUMMIT COUNTY — The reintroduction of wolves has resulted in profound ecoystem changes in the Greater Yellowstone region.

For the first time in 70 years, the over-browsing of young aspen and willow trees has diminished. Trees and shrubs are recovering along some streams, providing improved habitat for beaver and fish.

“Yellowstone increasingly looks like a different place,” said William Ripple, a professor in the Department of Forest Ecosystems and Society at Oregon State University, and lead author of a recent study documenting some of the changes.

“These are still the early stages of recovery, and some of this may still take decades,” Ripple said. “But trees and shrubs are starting to come back and beaver numbers are increasing. The signs are very encouraging.”

The findings of this report are based on a recent analysis done by OSU researchers and a review of other studies. They were published recently in Biological Conservation, a professional journal. They outline an ecosystem renaissance that has taken place since wolves were restored toYellowstone after being extirpated in the 1920s.

Among the observations in this report:

  • Since their reintroduction in 1995-96, the wolf population generally increased until 2003, forcing changes in both elk numbers and behavior due to what researchers call the “ecology of fear.”
  • The northern range elk populations decreased from more than 15,000 individuals in the early 1990s to about 6,000 last year, and remaining elk now have different patterns of movement, vigilance, and other traits.
  • By 2006, some aspen trees had grown tall enough they were no longer susceptible to browsing by elk, and cottonwood and willow were also beginning to return in places.
  • Improved willow growth is providing habitat that allows for a greater diversity and abundance of songbirds such as the common yellowthroat, warbling vireo and song sparrow.
  • The number of beaver colonies in the same area increased from one in 1996 to 12 in 2009, with positive impacts on fish habitat.
  • Increases in beaver populations have strong implications for riparian hydrology and biodiversity – Wyoming streams with beaver ponds have been found to have 75 times more abundant waterfowl than those without.
  • The coyote population decreased with the increase in wolf numbers, potentially allowing more small mammals that provide food for other avian and mammalian predators, such as red foxes, ravens and bald eagles.

Evidence of improved ecosystem health following the return of wolves is “becoming increasingly persuasive,” the scientists said in their report, though they also note that an increasing population of bison is continuing to impact young woody plants in the Lamar Valley.

“The wolves have made a major difference inYellowstone,” said Robert Beschta, a professor emeritus of forestry at OSU and co-author on the study.

“Whether similar recovery of plant communities can be expected in other areas, especially on public lands outside national parks, is less clear,” Beschta said. “It may be necessary for wolves not only to be present but to have an ecologically effective density, and mechanisms to deal with human and wolf conflicts also need to be improved.”

But at least in America’s first national park, the return of this large predator is having an impact.

“Predation and predation risk associated with large predators appear to represent powerful ecological forces,” the researchers concluded in their report, “capable of affecting the interactions of numerous animals and plants, as well as the structure and function of ecosystems.”


12 thoughts on “Wolves spur rebirth of Yellowstone ecosystems

  1. One small step by mankind, a big leap for the environment. Somehow, the destructiveness of the human element needs to be replaced, as this shows that taking that destructiveness out of the picture, recovery does become a reality. It also shows, that humans who decry the wolfs value, are narrowly short sighted.

    1. Norman, man has always been a predator and part of the foodchain, all over the world for hundreds of thousands of years. To try and take man out of it creates this imbalance that you are so passionate to protect. There is a place for wolves and for man, but like man and other species, wolves must be managed to maintain balance or all species suffer. The Province of Alberta recently announced that 6,000 wolves will need to be culled to protect ungulates, curb wolf starvation, and to minimize conflict with other species and man. Their past inaction with regards to managing wolves and the feely good attitude of let them alone and nature will take over has ultimately hurt the wolf and sealed their fate. The provincial government must now kill 6,000 wolves by shooting, aerial gunning, trapping, and poisoning. Other animals will be trapped and poisoned by mistake, as a result.

      It’s one thing to feel good about the return of the wolves. It’s another altogether to be foolhardy and unrealistic, trying to erase man from a thousand milenia as part of predation and the food chain. Our impact on nature is constant and to ignore that fact of our existence and interaction with other nature with grand ideas of removing man from the picture is to hurt the very animals you seek to protect. That’s what happened in Alberta and it’ll happen here, too.

      1. John, your input about Alberta is interesting. Though it doesn’t seem fair to compare that to the situation here in the States. As for your take that I would eliminate humans from the environment, you missed the point I made, which was the destructiveness of the human element needs to be replaced. That’s quite a bit of a leap you make saying I would replace human[s]. After all, it’s humans who have reintroduced the Wolf back into the environment. So human[s] are important. I take issue with the idea that because there are 100, 200, 300, wolfs, then they have to be killed because of: take your pick of reasons, ranchers, livestock, elk, etc. Their environment has steadily shrunk here in the U.S., so to think that their numbers will grow to what is up in Alberta, is a stretch. Besides, the way they are destroying the environment up there with the Tar Sands project, well, wouldn’t you agree that their habitat is being reduced by human[s]? I might add that this is taking place in less than the thousands of years you mentioned in your reply.

  2. nice article Bob, I just read a great story this morning on this very topic on High Country News, on this place called the High Lonesome Ranch, http://www.hcn.org/issues/42.3/prodigal-dogs/article_view?b_start:int=0&-C= which is definitely a managed hunting/dude ranch type of place, but it seems like they are managing it in a conservation/environment sort of mindset.
    Really intriguing stuff on wolves in Yellowstone, and maybe Colorado in the very near future. Thanks!

  3. Good to see the NPS revising their “predators as an non-essential adjunct” to their former “Natural Regulation” paradigm. A lot of formerly vilified non-NPS ecologists have finally been affirmed.

    Now if we can only continue working on restoring another expatriated keystone predator to the ecosystem,… aboriginal man’s influences.

  4. Prof. Charles Kay(Utah StateU) authored a comprehensive study of wolves in the Yellowstone area. He says(historically) there never were wolves living there. They are there now but the term “re-introduced” is false. Man has created this eco system(think “TREE HUGGER) to makes us feel warm and fuzzy. Were the settlers wrong to not want to live with wolves? Probably not. So rather than knee jerk reactions to this comment get a copy of Prof. Kays report(his group did 700 man days) of digging in the dirt. Look deeply into why any one would want to reduce great elk herds in number. Re-introduction may be as phony as anthropogenic global warming. Have a good day. Gary.

    1. I think it’s rather absurd to say wolves never lived in the Greater Yellowstone ecosystem when hunting and trapping records from the settlement era show quite clearly that wolves were widespread across the West. And I don’t think it’s so much about huge reductions in elk and deer herds as it is about trying to restore some kind of naturally balancing and sustainable ecosystem.

      1. Google, Prof. Charles E. Kay. download his article “Wolves in the yellowstone eco-system” and while there have a look at ” the article “the politics of wolf recovery”. He is a wildlife biologist and has some credibllity in the field. He also states that his interest in seeing science used honestly by policy makers. (a refreshing thought). Don’t argue with me…argue with him. come back with comments when the report has been read, Gary.

  5. Goodness, Mr.Jones reads like those climate deniers, cites one expert as being the last word. Perhaps. . . . . . . . . . oh well, such is life at the beginning of this 2012 season. Can the name calling be far behind?

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