Wolves And Elk Revisited...

[Al Agnew]

So we know the elk population in and around Yellowstone Park has declined considerably. Lots and lots of people in the area and elsewhere have blamed the re-introduced wolves, believing they've killed off a large percentage of the elk.

The latest issue of Discover magazine has a great article on the subject. Here is what it says:

Researchers have known it wasn't quite as simple as wolves eating lots of elk, but a study done in 2007 by Scott Creel, an ecologist at Montana State University, suggested that the presence of wolves stressed the elk, leading to poor female health and fewer pregnancies. However, Creel's paper was based on indirect observations--he didn't document how often elk were exposed to wolves, for one thing.

So starting in that same year, Arthur Middleton, then a Ph.D. student in biology at the University of Wyoming, began a three year study, including fitting 90 female elk and 15 wolves with GPS collars, which recorded their movements every three hours, resulting in detailed maps of long term elk and wolf movements. He also counted the number of calves that survived each summer and recaptured the females trice a year for health check-ups.

The pregnancy rate among elk in the migrating Yellowstone herd was 19% lower than non-migrating herds nearby, and compared to the last study in 1989, by 2009 the survival of calves to adulthood declined 74%!

So were wolves the main culprit? Middleton spent months in the wild observing the elk...and both the GPS data from the collars and his own observations showed that the elk rarely encountered wolves, and when they did, the elk ignored the wolves as long as they were no closer than a half mile. And he could find no correlation between the number of wolf encounters and the declines of elk pregnancy rates or levels of body fat.

So what IS the problem? At the same time, another team of researchers led by wildlife biologist Shannon Barber-Meyer from the University of Minnesota followed 151 elk calves in Yellowstone for three years.

Almost 70% of the calves died before they were a year old. Wolves killed only 15% of them.

Bears, mostly grizzlies, killed a whopping 60% of the calves! That was three times the bear predation found 20 years earlier. Yet grizzly populations had not increased nearly enough to be the reason for the greatly increased predation. So why were grizzlies killing so many more elk calves?

Jennifer Fortin, then a Ph.D. student studying bear nutrition at Washington State University, conducted long term monitoring of grizzlies in the Yellowstone area, and found that historically they had fed heavily on spawning and migrating cutthroat trout around Yellowstone Lake, slapping them out of the water just like Alaska bears eating salmon. But the illegal introduction of lake trout into Yellowstone Lake in the 1980s resulted in drastic declines in the cutthroat populations (and lake trout don't swim or spawn where they are within reach of grizzlies). So the bears turned to stalking elk calves.

So that explained the increased mortality of elk calves...but not the decline in pregnancy rates. What did explain it, as it turns out, were the severe droughts that have occurred most years since 2000 (possibly correlated with climate change). The droughts reduced grass production on the elks' summer feeding grounds, forcing the elk to eat less nutritious plants, resulting in females that were undernourished and unable to conceive.

So the reasons for the elk decline were many, with wolves being only a small part of it. I doubt that you'll convince all the wolf haters in Montana and Wyoming of that, but the evidence is pretty indisputable...large scale changes in the entire ecosystem, many brought about by human activities, is the real reason for the elk decline.

[ozark trout fisher]

So apparently the introduction of a non-native trout can lead to a reduction in the elk population in a massive national park. It makes sense when you break it down, but it also shows how little we actually understand about all the complex ways we can royally mess up these types of ecosystems. Because (even if lake trout had been stocked intentionally, by someone who gave a darn) no one was going to predict that they would become a factor in the decline of a major big-game species. No one thinks in those terms before we make any kind of decision that could make such an impact however many years down the road.

It makes you wonder how many of these types of things go unnoticed, while we blame something else that has little to do with the problem. Because it would take a pretty good mind to even bother thinking to test something that (seemingly) far-fetched.

[Tim Smith]

So the reasons for the elk decline were many, with wolves being only a small part of it. I doubt that you'll convince all the wolf haters in Montana and Wyoming of that, but the evidence is pretty indisputable...large scale changes in the entire ecosystem, many brought about by human activities, is the real reason for the elk decline.

So why are Defenders of Wildlife suing the National Park Service for refusing to consider introducing wolves into Rocky Mountain National Park to reduce the overabundant elk population there? And why do the people who managed the reintroduction of the wolf take credit for the regrowth of willow and forests in Yellowstone due to reduced overgrazing?

No picture is ever simple but the Yellowstone elk herd is just now returning to the size it was when wolves were removed. Even a 15% take of calves added to the pre-existing background mortality is a pretty big bit out of the population of an animal that can only replace itself once a year. And does the presence of another predator make it easier for bears to capture elk calves? Facilitation between predators is pretty common, but no one has looked at that. These numbers also don't take into account the adults elk that are taken by wolves.

I don't see the point of apologizing for wolves to people who think elk are the functional equivalent of cattle. Yes, the wolves contributed to the elk decline. They were supposed to do that. There are still plenty of elk. And ranchers.

[ScottK]

.. it also shows how little we actually understand about all the complex ways we can royally mess up these types of ecosystems.

My sentiments exactly. To think that we(humans) "know best" how to maintain natural balance is, for lack of a better word,arrogant on the part of the "experts" and morons alike(the line between which is which is pretty blurry IMO). Mother Nature will fix things back up just fine after we're long gone and have stopped jacking with it.

[Al Agnew]

So why are Defenders of Wildlife suing the National Park Service for refusing to consider introducing wolves into Rocky Mountain National Park to reduce the overabundant elk population there? And why do the people who managed the reintroduction of the wolf take credit for the regrowth of willow and forests in Yellowstone due to reduced overgrazing?

No picture is ever simple but the Yellowstone elk herd is just now returning to the size it was when wolves were removed. Even a 15% take of calves added to the pre-existing background mortality is a pretty big bit out of the population of an animal that can only replace itself once a year. And does the presence of another predator make it easier for bears to capture elk calves? Facilitation between predators is pretty common, but no one has looked at that. These numbers don't take into account the adults elk that are taken either.

I don't see the point of apologizing for wolves to people who think elk are the functional equivalent of cattle. Yes, the wolves contributed to the elk decline. They were supposed to do that. There are still plenty of elk. And ranchers.

You're right. Absent the predators, the prey tend to go beyond the carrying capacity of their habitat. Put predators back into the mix, AND reduce the carrying capacity, and you see large declines in prey. That's what's happening here, and it goes farther than just droughts, wolves, and grizzlies. There may now be fewer elk than there were before the wolves were removed in the first place, though, because so much of the land outside the park is grazed by cattle and sheep. Yellowstone is an ecosystem that doesn't stop at the park boundaries, and the elk traditionally used a lot of land outside the park that is now nearly useless to them because of the numbers of cattle on it. It never ceases to amaze me when I'm hiking in the backcountry of the Absarokas north of the park to find so much evidence of cattle way back in what is supposed to be wilderness. When we owned a cabin with a terrific view of Emigrant Peak and would glass the whole area, including a major elk refuge, looking for elk from the cabin porch, we saw far more cattle, often way up on the peak where you'd think it would be more likely seeing a mountain goat, than we ever did elk.

[Wayne SW/MO]

I think another consideration is short term evolution, if there is such a term. My point is that wolves were introduced into a population of elk that had evolved free of them as a predator. I would think it would take many generations to evolve an elk population better suited to survive. I doubt that true historical numbers of elk versus bears and wolves are available and if the estimate is off then the effect would be in new territory.

[Mark]

Just a couple nights ago there was an interesting NOVA on PBS that I had not seen about the effects of the reintroduction of wolves in Yellowstone. As mentioned, the wolves started the much needed thinning of the elk herds, which in turn led to the reforesting of Yellowstone as not as many elk to eat the small aspen and willow shrubs, which has led to something no one expected - an increase in the beaver population of Yellowstone, which has led beaver dams slowing down the run off in rivers and creeks, which has led to less erosion and an increase of fish habitat along streams, which has led to more fish, which will lead to bears having more fish for their diets, which will lead to less stress on the elks as a bear food source, which will lead to more elk for the wolves to eat, which will lead to......on and on and on.

And not to mention the effect on all the other critters, plants, and environment around Yellowstone. It is truly amazing what the effect was of the elimination of wolves 70 years ago, and the effects of Yellowstone with the reintroduction of wolves. And we are just now realizing some effects we never expected, i.e. the beavers, and who knows what else has been affected further down the food chain.

Notwithstanding Yellowstone, it is truly amazing the effects on an environment man can cause with one simple addition or subtraction from the natural order of Mother Nature.

[Tim Smith]

My sentiments exactly. To think that we(humans) "know best" how to maintain natural balance is, for lack of a better word,arrogant on the part of the "experts" and morons alike(the line between which is which is pretty blurry IMO). Mother Nature will fix things back up just fine after we're long gone and have stopped jacking with it.

Managers definitely make mistakes and the world is always more complex that we realize, but without those "morons" we would have already lost wild turkey, white tailed deer, ozark trout, bison, every fishery in the eastern US (and most of them in the west)...and a limitless list of other resources.

The options are to intervene or watch the natural world decline to little more than rats, raccoons and cockroaches. Go to China and see if you like what they've settled for in their country.

You may be right that it's arrogant to want to avoid that. If so, thank God for arrogance.

[Wayne SW/MO]

Marks post simply strengthens the argument that we really don't know what normal is and probably never will. We're establishing new ones all the time and will hopefully reach a balance that is both sustainable and acceptable.

We also find new evidence all the time that changes the equations. The passenger pigeon is a notable one. The idea that huge flocks always existed before the white man came is in question now. many now think that there numbers weren't that high until man started farming grains. They base this on the fact that very few of their bones are found in native American refuse dumps. The thinking is that if they were always that abundant they would have been an important food source, but apparently they weren't. their numbers were apparently created and then wiped out because they were never abundant beyond agriculture.

[Tim Smith]

Marks post simply strengthens the argument that we really don't know what normal is and probably never will. We're establishing new ones all the time will hopefully reach a balance that is both sustainable and acceptable.

That says it pretty well, although that idea of "balance" has just as many limitations as "normal".

At least by preserving some parts...especially the ecologically influential parts like top predators....we give what's there a chance to behave and interact in a way that managed to get us this far at least.

It takes longer than the age of civilizations for nature to come up with "new" norms...and the blink of an eye for us to wipe out the old ones. We may decide to completely rewrite the rules of nature, but I would hope that in places like Yellowstone we can at least agree the old rules should be given the best possible chance to play themselves out.

Here's a bit of data: http://www.cascwild.org/wp-content/uploads/2013/11/Northern-Yellowstone-Elk-Herd-Trends.jpg

I don't see the original citation for that.

Loved the NOVA program as well.