This Will Shatter Your View of Apex Predators: How Wolves Change Rivers

Have a look at this amazing video showing how one species can have a massive cascading effect on the entire ecosystem in which it lives… and even alter the geography of the area. 

UPDATE: Here is an alternative view of the story and research expressed in the above video – Is the Wolf the new American Hero? 


This may be one of the most important conservation concepts to come out of natural science in the last half century. The thing about this case study is that the same can be applied to apex predators around the world: lions in Africa, tigers in Asia. Sharks, bears, and wild dogs are all species sitting at the top of their respective food chains, creating stability amongst the species they prey on and maintaining the health of plants and animals right down the trophic ladder.

The sad part is that some of these apex predators are in decline, sometimes jeopardising ecosystems on which they and other species rely.

With all this in mind, it’s time for us humans to adjust our perception of predators in general. We can’t be agreeing to mass culling of sharks as has recently been sanctioned in western Australia. (Also see: Western Australia’s Controversial Shark Cull Claims First Casualty)

Human/wildlife conflict is a reality of growing populations around the world, and the fact is that we need to learn to live beside wildlife if we are to maintain our wonderful thriving ecosystems in the future.

Follow Paul Steyn on Twitter and Instagram @steynless

Paul Steyn is a widely-published multi-media content producer from South Africa, and regular contributor to National Geographic News and blogs. Having guided throughout Africa for some years, he went on to edit a prominent travel and wildlife magazine, and now focuses on nature storytelling in all its forms. In 2013, he joined a team of researchers and Bayei on a 250km transect of the Okavango Delta on traditional mokoros. In 2016, he accompanied the Great Elephant Census team in Tanzania and broke the groundbreaking results on National Geographic News . Contact: paul@paulsteyn.com Follow Paul on Twitter or Instagram
  • George

    I never see any reference to any original scientific peer-reviewed publications of this work. The voice over is a imitation of David Attenborough, but not sure it was him. I wonder if this is a fiction with slick videograpghy written by someone with a lot of imagination. It’s hard for me to imagine serious, rigorous scientific work would come to such a conclusion without striking evidence.

  • Paul Steyn
  • George Monbiot

    George: It wasn’t David Attenborough, or an imitation of him. It’s an excerpt from my TED talk. You can find references fro everything I say in my book Feral, where this story and many others are fully sourced.

  • Sarah

    This is only ONE protected ecosystem. Protected from what, you ask? The ultimate predator, man. There is no hunting allowed in Yellowstone, just as people are kept in only certain areas of the park. Man can do the same “job” as the wolves by controlling the numbers of deer and elk…and we humans are carnivores, so the kill by man benefits mankind. God put us here on the earth to be “stewards”. It is our job to take care of all God has given us.

  • Peter Faletrs

    One thing is certain, humans have managed to displace and/or unsettle every ecosystem on earth. The interactions of preditor-prey are far from completely understood. To think that humans can take the place of this complex interaction with our crude hunting or culling programs, to me, is pure arrogance.

  • Edward Emerson

    Conversely, overfishing of sharks and tuna (apex predators) will have disastrous consequences in the oceans.

  • A.J. Tarnas

    It’s worth noting that this is exactly what Allan Savory advocates with cattle grazing. Timed, bunched, cell grazing (rotation through paddocks according to pasture growth cycle) by hoofed animals in areas where no apex predator is managing the terrain (inevitably due to humans killing those predators one way or another). In the video, Monbiot mentions that wolves drove deer away from the river banks, allowing them to “regenerate”. A more accurate view is that the wolves drove the hoofed animals into movement patterns which severely trampled small areas (animals bunched and moving nervously in response to predators) then, having left that small patch in ruins, it was well fertilized and cultivated for the plant life to move in aggressively. This pattern repeats itself especially at water edges, being choke points in animal migration.

  • Peter

    I’m looking forward to your TED talk, Sarah.

  • Jessica

    Sarah from Idaho: Yes, we are stewards OF ALL GOD HAS GIVEN US. That includes WOLVES! GOd created the world in perfect working order, to say that you cold do a better job than GODS OWN DESIGN AND PLAN is the most ignorant and blasphemist thing you could imagine saying. Hunters DO NOT MIMIC WOLVES. They hunt the biggest, strongest, healthiest animals. The ones a healthy population needs to reproduce to be a healthy herd. Wolves take the small, the weak, and the sick. There is a HUGE difference. Besides, the whole POINT is that it is WHERE and HOW wolves hunt that changes the behavior of the deer and elk which then transformed the entire system. Hunters do not hunt that way. Hunters lie in wait. Wolves give chase. BIG DIFFERENCE. Do not talk about things you do not understand one iota even after it is explained to you, especially when it comes to God. You do not know better then God. You do not understand His plan. Nor do you comprehend what He has given you.

  • Gary

    What a load of junk science to further spread the introduction of wolves by wolf lovers. Wolves don’t just cause animal populations to move, they obliterate them. Wolves don’t just kill what they need to survive, they slaughter bands of animals and leave the carcasses to rot just for the pleasure of killing. They maim and leave animals to die a slow death. They are very efficient in what they do and leave entire areas void of animal populations.

    Contrary to the uninformed anti-hunting crowd (aka enviromentalists and wolf repopulationists), hunters do not take only the largest and strongest of an animal population. If people were informed, they would know that hunting is closely regulated with intense studies by biologists to leave the correct numbers of breeding populations of target species that the ecosystem can support, including mature males. The right amount of browsing is critical to maintain the health of an ecosystem and can best be controlled by man, not a bunch of vicious unchecked carnivores. Our wild places are much healthier today than they were when we arrived in this country. Don’t believe all the junk science hype that you hear.

  • Greyfur

    Lol, Gary, I haven’t read such a pile of crap in a long time. I would like to see a hunter, who gets a capital elk infront of his gun and says: “No, this one’s healthy and great looking, I will kill that starved, ill-looking with twisted antlers instead.”, pardon me to laugh. I bet you think what luck mother earth has, that humans came, as the populations of wild animals would be completelly eradicated by the vicious wolves without proper human management. The truth is, Gary, that wolves, elk, bison and other animals were in USA before “white man” entered the lands and the fact, that elk, bison and other prey animals still were there shows, that the populations were stabile and self-managing. Don’t choke on your human ego, Gary.

  • John

    George M and Paul S. have you read any of the research contradicting the above claimed behaviorally mediated trophic cascade? In addition, have you read other literature examining trophic cascades in different systems? I ask, because elk behavioral and diet studies do not line up with the claims being made. Nor do more general papers addressing theory (the expected interactions of mobile versus immobile predators and their prey). Specifically, wolves and elk are highly mobile, and wolves are a coursing predator, not ambush hunters. The very notion that they create permanent risky places is hard to swallow, and based almost entirely on unsubstantiated assumptions (which have been heavily criticized). When the hypothesis is challenged with real risk data, it fails (see Kaufman et al 2010). Even the Fortin et al paper referenced above, only made the coarsest of generalizations about elk distribution on the landscape and did not address risk at fine scales, nor did they show, or infer, that there was indeed a change in elk diet in relation to risk. Wolves probably are saving some plants, but they are probably doing it the way many carnivores do – by eating herbivores.

  • Ted

    It’s interesting to read the comments from people on this posting. Scientific research by biologists that do not have a reason to scue their research for hunters, the NRA or for alterior purposes have real research that proves that eco systems benefit from Apex predators. Since reintroducing the grey wolf to the northern rockies, elk heards have increased in numbers and the herds are more healthy. Hunters seem to want to kill anything and everything they can get their guns pointed on.

  • Gary

    So many comments from those who no nothing about hunting. Take a look at the Lolo pass area in eastern central Idaho, once a thriving area with healthy managed herds of deer and elk. After introduction of wolves, the deer and elk have all but disappeared, and no, they didn’t move on, but the wolves did.

    In answer to the comment about hunters only killing the biggest animals with the largest antlers, hunts are regulated, and when deemed necessary by biologists, limit the number of branched antlered elk taken, sometimes only allowing spikes to be taken. There are also cow elk harvests to keep the balance.
    Wolves take everything, sick or healthy, until there is very little left, then move on to destroy other herds in other areas. We’ve seen the evidence first-hand here in Idaho. What is this with the absolute love affair some people have with these vicious killers?

  • Mike

    The piece could be re-titled “How unmanaged ungulate herds can alter ecosystems” whether they are managed by predators or humans through hunting or active management. However, the piece reminds me of the essay entitled “Thinking Like a Mountain” that wildlife conservationist and hunter, the great Aldo Leopold wrote and included in A Sand County Almanac back in 1949.

  • John

    Ted, I agree that ecosystems benefit from apex predators, but sorry, you are wrong about elk herds increasing. Across Montana, Wyoming and Idaho, wherever wolves have shown up, elk numbers have declined. For example on Yellowstone’s Norther Range, elk went from just under 17,000 the year wolves were reintroduced, to around 4500 today. Similar declines have occurred elsewhere in the Greater Yellowstone Ecosystem and in Idaho where wolves were also reintroduced. In places where there are no wolves, elk populations have remained stable to slightly increasing. I would argue that these declines in elk numbers are good for both plant communities and other herbivores that compete with elk, and overall, good for ecosystem health.

  • lisa

    the web of life is so intricate…we have much to learn from it. Maybe we can stop trying to figure it out, stop trying to put our stamp on it, stop trying to use it for our own gain and just learn from it…just observe and learn.

  • annette

    to John Montana
    I know plenty about wolfs
    some of the elk problems crated over grassing. some of the laws of hunting have also changed.. Overall, the wolves have helped to put the Ecosystem back in balance, when the wolves where reintroduced. The reason: the Ecosystem we changed by killing all the wolves was out of balance. We thought it was good, but know the balance is our ecosystem is back.
    A lot of people should stop blaming the wolves for everything and get informed. PS. wolves do kill people, hybrids do. Untrained eyse will have difficulties to see the difference.

  • rick

    so basically wolves are awesome, and deers suck

  • Jared

    I find these hunter’s comments disgusting. I was raised in a hunting family and spent a lot of time in the woods with my grandfather. He taught me to respect and enjoy seeing all animals in their natural habitat. Are we really trying to justify killing off wolves so hunters have more animals to hunt because that is what those arguments come down to. My grandfather and grand-uncle had a big falling-out because my grand-uncle ran down and killed a coy dog “because they kill the deer”. Yes, the deer population in the Adirondacks was in decline but in the St. Lawrence Valley where we lived, it was on the rise. Harsh winters and a lack of food moved the deer out of the woods… Not the coy dogs. When will people realize that we share this planet and all of these creatures are what makes it beautiful AND there is a natural order of things. Without humans, this planet did quite well managing itself. We have come along and ruined so much in the name of progress. I’m not in support of the environmentalists who get in the way of reasonable expansion…. Moderation is the key.

  • Keli Hendricks

    Simply replace the word ‘wolf’ with the word ‘man’ and you actually have a point.

  • Dave Robertson

    The major problem facing earth is the unchecked and exponential growth of human population.

  • Anita

    The impact of wolves is complex, and I live in a state where the wolf controversy gets a lot of media coverage. This is the first time I’ve ever heard such expansive claims about resurgent wildlife and stabilizing river courses and rebounding songbird populations all being brought about by wolf predation. It’s also weird that the narrator of these miracles keeps talking about “deer,” while the video shows only elk, with a moose and a few bears thrown in. And why isn’t there any video of the river-stabilizing, beaver-attracting willow groves? The last 25 years have seen a lot of fires in Yellowstone, so in large areas of the park, new deciduous trees have replaced the old climax forest of lodgepole, and that causes changes in the fauna, too. Bottom line, if I’ve got to take sides, l’ll be a wolf supporter–I miss the steady supply of elk meat, but mule deer aren’t bad. But this wolf story seems less like biology, more like a bedtime tale.

  • dimitri

    This is propaganda. The agenda is Agenda 21. The very first image on this video is captioned: “sustainable man”. After that it’s all innuendo. The wolf was “reintroduced” by… man. Then “nature” responded to this genius-level manipulation. Man needs to stay out of nature’s way. He should stay in the cities and leave Yellowstone to the wolves (and their alter egos, the elites) to enjoy.

  • Michael

    The wolves, and the elk, and the deer where all here for thousands of years. Along with large tribes of American Indians. They co-existed in balance with nature. It was only after ‘man’ arrived and eliminated the wolf that anything changed. But now we are stuck. Man is here. The damage is done. We can’t go back. And where ever this has happened, man has had to have hunting quota’s to keep the balance. YES, keep the wolves, of course. But also yes, at some point, if the balance is out of whack, then you have to allow the culling of the heard. Elk, Deer, …or wolves. Man has required himself to now be a part of the balance.

  • Mike

    “What a load of junk science” says Gary, totally avoiding/disregarding the salient point Greyfur brought up, because it destroys his entire line of reasoning.

    North America, before the coming of Europeans, was TEEMING with wildlife (deer, elk bison, caribou etc.) AS WELL AS wolves. This directly contradicts your claims. Admit to being a liar or a fool.

    (Personally, I suspect you are both).

  • Christian D. Bannister

    Absolutely brilliant! I love it! Apex predators: “mother natures antibody cures biodiversity, and health”, sustainability in moderation at its best!

  • Spellcheck

    Anita, George Monbiot is British, and they are among those europeans who call the elk, Red Deer, the closest related species to the North American Wapiti.
    George makoored in Zoology at Oxford, but with such a political family, he bacame a well-versed commentator and observer of that and various other subjects, for which a scientific education prepared him very well.
    He was a journalist/writed.
    Ecology appears to be far too complex for those with agendas to understand as does any science.

    There needs to be considerable moderator activity on this site’s comment columns to help eradicate the most ridiculous and inflammatory of the antiscience and antiknowledge comment.

    Studying wolves, ecology, field biology, I have read quite a number of the studies upon which this video is based, some everal years ago.
    I strongly recommend that the comment column of National Geographic gains close and healthy moderators, in order to reduce the purposeful obfuscation of strong scientific developments.

  • Damien Gibson

    Mike from SC was EXACTLY right. Post of the year nominee. The man has ‘inserted’ himself into the fabric of North America. The stain appears to permanent.

  • Todd Palmer

    wolves arent the problem greedy asz humans. we take EVERYTHING for our own.we will be our own demise . nature can take care of itself without us. IF we quit messing around with it. humans isnt the only species on this planet that matters.industrial progress is KILLING the earth we live on. STOP. quit being so darn selfish. elk deer… bs. we GROW cows for meat eaters so get used to it. no more hunting for anyone.the population cant support it anymore. do the math. too many people

  • Bob

    Hunters are the first ones to pound on the the desks of the managers, asking for restrictions when certain specific game populations are reduced. They are out there and very observant, it is in their best interests to maintain a balanced game population and they insist on it.

  • Brandon

    In response to Todd Palmer: I used to feel much the same way as you do. I thought that hunting was (for this country’s relatively high standard of living) largely unnecessary considering the availability of food. Then I started realizing how much crap they put in our food.
    Taking away my ability to hunt is like saying that you can’t have a garden. Sure, I could go to the co-op and get boutique beef and organic produce, but that removes me from my food chain.

    We are part of the ecosystem for as much as we have screwed it up. What is really wrong here is people who think that meat comes from the store on a styrofoam plate. There is a lot to be said for knowing firsthand where and how your food is processed.
    Sustainable living is not just for vegans. Omnivores can do it too. I have a garden and a gun, and I use both to make my ecological footprint smaller.

  • Tim

    Sarah, if people were allowed to hunt in Yellowstone, then not only would we not be able to do the “job” of the wolves, we would kill off everything else. Beavers would be killed, and that would drastically reduce the quality of the rivers, but we would kill off the healthy elk, leaving the remaining population weak and susceptible to disease. It would be the equivalent of a ranch, with only the animals that could live on the scraps of humanity to survive. And also, if you want to argue about it, do you really think that God would be pleased if we killed off His creatures because we could do their job?

  • buckroy

    What garbage…… Wolves forsooth…… Has this idiot ever seen a pack of wolves ripping apart a calf even as it is being birthed?

  • Zsofie

    I just studied this issue in my Environmental Sciences class at University and the claims that the narrator makes are in fact true. How can anyone say that the wolves hardly made any impact when there is observable proof that they stabilized the Yellowstone ecosystem? Sure, all they had to do was eat the herbivores but because of that it started a chain reaction that led to the growth of the ecosystem and eventual peace was sustained.

    If you guys want to start talking about human impacts on the environment I think you should look past the hunters and see the bigger picture. The more pressing matters at hand are the problems that our growing technology and resource-dependence has created. Did you know that with the rise and rapidly increasing numbers of cell phone towers the bird population was dramatically decreased? It is estimated that about 1 million birds are killed each year by these towers because they cannot see the wires that hold them up. This has a huge negative impact on the environment because birds are necessary to combat pest control on the ground as well as the insects in the air, etc. Another huge problem is climate change caused by the U.S and China (the top two CO2 emitting countries). These are causing detrimental effects on every environment in America. For example, the extreme winter conditions in the Midwest, Coastal regions (Polar vortexes, snowing in Georgia) and the extreme drought in the southwest of the U.S. The issue of hunters pales in comparison to just two of the many negative impacts that we as a species have on this earth and if we want any chance of sustaining the human race for longer than a couple centuries then we need to act now.

  • Jeff Free

    Hunters need to hunt each other. Only a coward or a sadist shoots a defenseless animal for fun. Hunt something that has a fighting chance against you – another hunter.

  • Brandon

    So here we see Jeff as a proponent of cannibalism. Well put.

    To add a little to my previous comment, sustainable living does not include killing for fun. I eat what I kill. I don’t shoot wolf, coyote, or varmints because I imagine they wouldn’t be good to eat. I don’t go tearing out half my garden when I know I won’t be able to eat the veg before they go bad.
    Killing is no fun. Processing even less so.

    You ask what about that poor defenseless deer, I say what did that carrot ever do to you.

    And there’s the curt response you were fishing for with your incendiary comment.

  • alex

    So the wolves kill coyotes which allows the number of rabbits and mice to increase. This then leads to an increase in hawks, weasels ,foxes and badgers that all prey on the smaller mammals.
    Sounds to me like the rabbit and mouse population would be under much more pressure than it ever was with only the coyotes to worry about. They now have a number of different ways of attack to avoid , so why did their numbers increase exactly?
    It seems that our cause and effect relationship is being stretched just a tad too far.
    By the way , I think wolves are a truly majestic and awesome animal that ought to be allowed a place in this world.

  • Reed Dils

    Good story but he is talking about elk, not deer. I assume this is because the red deer in Europe are closely related to our Elk.
    He needs to correct this in future talks.

  • Kara

    The conservation of wildlife in our country is revered by the entire world. It’s due in large part because the biologists understand the connections….to everything.

  • John

    While the video portrays a scenic and picturesque story of the wolf’s reintroduction ‘success’ story, I encourage people to dig a little deeper. Studies (http://onlinelibrary.wiley.com/doi/10.1111/ele.12133/abstract) have been done investigating the limited effects wolf presence has on elk behavior, as well as the limited impact apex predator reintroduction can have on riparian restoration following the absence of the apex predator, the wolf, for several decades (http://rspb.royalsocietypublishing.org/content/280/1756/20122977). Another study published in the journal Ecology in 2010 discusses behaviorally mediated trophic cascades (BMTC), which is the effect discussed in the video. However, the study detailed in this paper explains that elk browsing on trembling aspen stands is not significantly diminished in sites where elk are at higher predation from wolves. Further, the study shows that the relative survivorship of young aspen indicates that they are not recovering in Yellowstone, despite the large wolf population (http://www.wyocoopunit.org/index.php/archives/2010/kauffman-m-j-j-brodie-and-e-s-jules-2010-are-wolves-saving-yello/). However, other studies such as this one (http://www.cof.orst.edu/leopold/papers/RippleBeschtaYellowstone_BioConserv.pdf) published in the journal Biological Conservation indicate that a BMTC is occuring favorably for riparian vegetation such as trembling aspen, cottonwoods, and willows. I am stressing the fact that it is not a foregone conclusion that wolves have had this incredible effect on the ecosystem. There have been so many more factors at play since 1995, including climate change, fungus and beetle infestations, resource development, and other ecosystem changes. And let’s not forget the other side of the story, that the wolf reintroduction has been for many a great hardship, particularly livestock ranchers whose livelihoods are at stake as their animals are easy prey for a pack of wolves.

  • max

    We humans are just another apex predator … no?

  • ScienceIsReal
  • John Falcone, Phd, Animal Behavior

    NG should be ashamed of itself for including such hogwash as the wolf story. This propaganda is riddled with errors, absent serious research methodology and artificially staged events. Author failed to mention that the wolves introduced were never native, rather they are the huge aggressive grey wolves. Author never shows film of a pack of wolves ripping flesh off live animals as they suffer a painful and agonizing death. Didn’t bother to show a favorite of the wolves where they rip apart a newborn calf while it is birthing. the people who made this idiotic decision to put this breed, or any breed, of wolves into the environment in this age should be in jail. This represents animal cruelty at its worst! SHAME ON NG FOR PROMOTING THIS PROPOGANDA DESIGNED ONLY TO COVER THE STUPIDITY OF THOSE INVOLVED IN THIS CRUEL AND UNJUSTIFIABLE DECISION.
    John Falcone

  • KC

    I have to agree with some of the previous posts about NG needing to thoroughly update their sources before posting. Here is a link to a very well known study by Matthew J. Kauffman, et al. , “Are wolves saving Yellowstone’s aspen? A landscape-level test of a behaviorally mediated trophic cascade”
    ( http://www.esajournals.org/doi/abs/10.1890/09-1949.1) that sets the information straight.

  • KC

    Sources need updating. Here is a link to a very well-known study by Matthew J. Kauffman, et al. , “Are wolves saving Yellowstone’s aspen? A landscape-level test of a behaviorally mediated trophic cascade”
    ( http://www.esajournals.org/doi/abs/10.1890/09-1949.1) that sets the information straight.

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  • D. Kelly

    Why are you quoting a 5-year old article (Kaufmann etc.) when much more recent studies have indicated exactly the opposite… that the aspen are regenerating as evidenced by widespread sampling? The Kaufmann study was a very short-term study, and has now been disproved.

  • isak

    We have no business manipulating nature by either adding or removing species, not belonging. But if the matter is about reintroducing an extinct specie, then it is a totally different matter, and should be considered as healing a wound that we earlier have inflicted upon nature.
    I am a norwegian, and we have wolves in the forest stretching into our capitol, Oslo. And I am really proud that we have come this far! About calfs getting eaten during birth: of course!!! that is the way of nature. Do you really think humane moral and ethics should rule nature, you gotta wake up or seek advice. That is not how this world works. Sorry.

  • Amanda

    I have been researching the affects of wolves on trophic cascades as a university student. As even some researchers have written about I have discovered a polarized area of study for or against wolves. Some studies attributing super hero forces to wolves and some demonize them. I believe after reading through the literature over the past 3 years that the answer is in the middle. Wolves are essential apex predators that do effect many other aspects of ecosystems. We need to find balance. However asserting that reintroducing wolves because they tear apart baby calves of ungulates is outside the realm of science. Food webs are essential and many predators behave like this. Even a house cat will tear apart a mouse or bird. Should we eliminate all non herbivores? This kind of reasoning is illogical and a recipe for ecosystem collapse.

  • Amanda

    KC: That is ONE research study. Here is a list including the one you mentioned of research on this topic. Wolves play a very important role in ecosystem management which the research supports. There are other key players such as beavers. For instance wolves cannot bring back willows. Beavers are needed to raise the water tables so that willow recruitment can occur. We need each species. Wolves reenforce the affects of willow recruitment by reducing over grazing from ungulates. When it comes to aspen, cottonwood, berry plants etc wolves have a much bigger impact in their recruitment as evidenced by MOST of the studies on the topic. The Kaufman study is the only one to my knowledge thus far that does not support this. I even saw one researcher that recreated both Kaufman’s study and other one supporting that wolves had a trophic affect on aspen and concluded that wolves to have a positive affect.

    You can’t cherry pick the data you must read all of it, the methods, who funded it, etc.

    Baril, L. M., Hansen, A. J., Renkin, R., & Lawrence, R. (2011). Songbird response to increased
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    Beschta, R. L., & Ripple, W. J. (2008). Wolves, trophic cascades, and rivers in the olympic
    national park, USA. Ecohydrology, 1(2), 118-130.
    Beschta, R. L., & Ripple, W. J. (2009). Large predators and trophic cascades in terrestrial
    ecosystems of the western united states. Biological Conservation, 142(11), 2401-2414.
    Beschta, R. L., & Ripple, W. J. (2010). Mexican wolves, elk, and aspen in arizona: Is there a
    trophic cascade? Forest Ecology and Management, 260(5), 915-922.
    Beschta, R. L., & Ripple, W. J. (2012). The role of large predators in maintaining riparian plant
    communities and river morphology. Geomorphology, 157, 88-98.
    Beschta, R. L., & Ripple, W. J. (2015). Divergent patterns of riparian cottonwood recovery after
    the return of wolves in yellowstone, USA. Ecohydrology, 8(1), 58-66.
    Dobson, A. P. (2014). Yellowstone wolves and the forces that structure natural systems. Plos
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    Iercek, M. T., Stottlemyer, R., & Renkin, R. (2010). Bottom-up factors influencing riparian
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    Kuijper, D. P. J., Verwijmeren, M., Churski, M., Zbyryt, A., Schmidt, K., Jedrzejewska, B., et al.
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    Ordiz, A., Bischof, R., & Swenson, J. E. (2013). Saving large carnivores, but losing the apex
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  • Steve

    What a crock.
    Every time biologists think they can “improve” nature, they create a catastrophe, just as the increasing population of reintroduced Gray Wolves have done all through the PNW.
    …Unfortunately, highly schooled *ologists seem to prefer the destruction of the environment, over admitting it was a stupid idea.

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