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March 17, 2005

10th Birthday for Yellowstone's Wolves

Wolfpic4 Next Monday will mark precisely 10 years since wolves re-appeared in Yellowstone National Park, from where they had been absent since the 1920s. The re-introduction program was a smashing success, far exceeding even optimistic predictions.

On March 21, 1995, federal biologists finally opened the acclimation pens holding 14 gray wolves, sometimes called timber wolves, brought from Alberta. Earlier that year an additional 14 wolves had been set free in central Idaho's mammoth wilderness. And the following year, 17 more wolves were released into Yellowstone and 20 more into Idaho.

WolfchartjpgA decade later, Yellowstone's wolf population has grown more than five-fold and expanded into adjacent areas of Wyoming and Montana. Idaho's wolf population expanded even more spectacularly--by thirteen-fold--with an estimated 452 animals in the Gem State at last count in 2004. All told, over 850 wolves now roam the US Rocky Mountains. It's only a matter of time until they begin returning in numbers to Washington and Oregon, where they are now only rare visitors. [Click on the chart at left for state-by-state trends.]

Even better, the return of the native wolf has meant a return to healthier ecosystems. (Perhaps the best study of the effects of wolves on Yellowstone's ecosystems appeared in the Journal of BioScience in 2003.) Because wolves are a dominant predator, the effects of their presence or absence are felt on many levels--biologists call this effect a "trophic cascade." For example, wolves preying on beavers can mean more streamside trees--because beavers are fewer in number and fear to linger in the open--which in turn means more shady habitat for trout.

Prior to European contact, wolves ranged across almost all of North America. Wolfpic3But by mid-century ill-advised and relentless programs of hunting, trapping, and poisoning extirpated wolves from their entire American range, with the exception of Alaska and a small remnant population in the wilderness of northern Minnesota and Isle Royale, Michigan. (The wolves in the upper Midwest are actually a different subspecies of Gray Wolf, the Great Plains Wolf, from the Canis lupus of the western US and Canada, which are Rocky Mountain Wolves.)

But wolves are tenacious creatures, and by the 1980s a few wolves had crept back over the Canadian border and had begun recolonizing parts of northwestern Montana. By the early 1990s, wolves were reported in remote areas of northern Washington, also Canadian immigrants. Then, in the mid-1990s the US Fish and Wildlife Service began a reintroduction program that catapulted wolf populations to viable sustaining numbers and also into the limelight.

The US National Park Service estimates that over 100,000 visitors to Yellowstone have observed wolves there; and visitors continue to throng the park in the hopes of glimpsing a wild wolf.Wolfpic2_2 But wolves have also bred a fever pitch of controversy--a controversy I don't fully understand. Certainly, a few ranchers and herders have, I suppose, justifiable concerns about predation of stock, though many of these concerns are addressed by compensation programs.

What's bizarre, I think, is the amount of attention paid to wolves' purported lethality to humans. Wolves are not actually dangerous to humans in any meaningful way. Healthy wild wolf attacks on humans are exceedingly rare and are usually the result of human stupidity. In a typical year, 50 Americans die from bee stings, 7 from snakebites, and 25 from dog bites. But in the entire 20th century there's not been a single documented case of a wolf killing a human in North America, including Canada and Alaska where wolves are relatively numerous. [For more on this subject, and sources for my claims, click here.]

But whether wolves are dangerous seems to fundamentally miss the point. They are a cornerstone to their entire ecosystem--essential for maintaining balance. Their return to the Northwest signifies not only a return to wild-ness, but the beginning of a return to healthy and thriving natural systems. And on the 10th anniversary of their reintroduction, their story is a heartening one because it suggests that we can play a hand in restoring our native ecology. 

Posted by Eric de Place | Permalink


In my opinion the greatest damage caused by wolves being moved into Yellowstone is that these wolves will spread worms and parasites over large areas. The wolves will also spread diseases and create "hot spots" of diseases. The damage these worms, parasites, and diseases cause wild animals, and also spread to domestic animals is the main reason the "local people" do not want wolves. Wolves can also spread worms and parasites to pet dogs which can then bring these damaging worms/parasites to humans. Having wolves anywhere near domestic animals raises the cost of animal products to the human consumers.

Will Graves

Posted by: Will Graves | Mar 18, 2005 4:55:33 PM

The removal of wolves, the top predator, from the ecosystems of the lower 48 states has led to exlosive and nuisance growth in populations of their natural prey. Contrary to popular myths, wolves are not wasteful and wanton killers, nor are they carriers of horible diseases or parasites. Restoring wolves to reasonable ranges will not harm nature's balance, it will help to restore it!

Posted by: Henry J. Bennett | Mar 18, 2005 10:04:00 PM

A couple of things: first- you have the relationship between wolves and beaver in Yellowstone wrong...Beavers in Yellowstone prior to wolf reintroduction were becoming more and more scarce...

This was because the Elk were eating all of the willow tree shoots and not letting any willow trees mature- willows are an essential tool of beavers in their lodge building and diet...

After Wolf reintro- Elk no longer feel safe enough to forage in constricted areas- like riparian habitat where willows grow- feeling vulnerable to wolf attack...this in turn is allowing willows to mature and creating an environment where beavers are now returning and working their natural engineering magic...

As for Will Graves- the vast majority of opposition to wolf reintroduction was because of fear of wolf depredation of livestock and hunting stock (Elk/deer) ...not because of parasites and disease...

However....something for all to think about...that the "balance" of nature in in fact a myth....life on Earth is never static...any perceived "balance" is but a snapshot in time of a forever changing and dynamic process.

Posted by: Carter | Mar 22, 2005 3:29:50 PM

I would love to know where Will Graves obtained the info that the greatest damage caused by wolves in Yellowstone is the spreading of parasites to domestic animals! I have spoken with many YNP biologists, and this is simply not true. Who, in YNP, would the wolves spread these parasites to??? Elk? Bison?

I would also like to know what diseases he is referring to. I have not heard of any incidents of wolves spreading any diseases to domestic dogs, even mange. These animals are usually not in any close proximity to domestic dogs anyway, and, if they are, the dogs are in danger of being killed by fighting - not by parasites or disease. I have not heard one incident of a domestic dog dying of parasites or disease through contact with wolves.

Carter is correct - the main reasons local residents do not want wolves is the fear of loss of livestock (and the irrational fear of attacks on humans).

Posted by: Jill | Mar 23, 2005 5:04:19 PM

this is a very informative paper. It is my belief that wolves in yellowstone was a great idea. I love the fact that scientists came to realize that they need wolves in yellowstone, and what they did was wrong. Thank you yellowstone biologists and everyone who participated in this reintroduction.

Posted by: Jessica Petty | Apr 28, 2005 6:52:01 AM

Awsome! You all are acually not fearing wolves! You are helping them! I am glad that other people besides me care about animals. The reintroduction program was a awsome idea! I would so much like to see a wild wolf for once but I don't have the money to. I think whoever gets to see one is a lucky person.

Posted by: Adellia | Feb 28, 2006 1:49:23 PM