How Wolves Change Rivers


One of the most exciting scientific findings of the past half century has been the discovery of widespread trophic cascades. A trophic cascade is an ecological process
which starts at the top of the food chain and tumbles all the way down to the bottom. And the classic example is what happened in
the Yellowstone National Park in the United States when wolves were reintroduced
in 1995. Now, we all know that wolves kill various
species of animals, but perhaps we’re slightly less aware that they give life to many others. Before the wolves turned up – they’d been
absent for 70 years – the numbers of deer (because there had been
nothing to hunt them) had built up and built up in the Yellowstone Park and despite efforts by humans to control them they’d managed to reduce much the vegitation
there to almost nothing. They had just grazed it away. But as soon as the wolves arrived, even though
they were few in number they started to have the most remarkable effects. First, of course, they killed some of the
deer but that wasn’t the major thing. Much more significantly, they radically changed
the behavior of the deer. The deer started avoiding certain parts of
the park – the places where they could be trapped most easily – particularly the valleys and the gorges and immediately those places started to regenerate. In some areas, the height of the trees quintupled
in just six years. Bare valley sides quickly became forests of
aspen and willow and cottonwood. And as soon as that happened, the birds started
moving in. The number of songbirds and migratory birds
started to increase greatly. The number of beavers started to increase
because beavers like to eat the trees. And beavers, like wolves, are ecosystem engineers. They create niches for other species. And the dams they built in the rivers provided
habitats for otters and muscrats and ducks and fish and reptiles and amphibians. The wolves killed coyotes and as a result
of that, the number rabbits and mice began to rise which meant more hawks more weasels more foxes more badgers Ravens and bald eagles came down to feed on
the carrion that the wolves had left. Bears fed on it, too. And their population
began to rise as well partly also because there were more berries
growing on the regenerating shrubs. And the bears reinforced the impact of the
wolves by killing some of the calves of the deer. But here’s where it gets really interesting. The wolves changed the behavior of the rivers. They began to meander less. There was less
erosion. The channels narrowed. More pools formed.
More riffle sections. All of which were great for wildlife habitats. The rivers changed in response to the wolves. And the reason was that the regenerating forests
stabilized the banks so that they collapsed less often. So the rivers became more fixed in their course. Similarly, by driving the deer out of some
places, and the vegetation recovering on the valley
side, there was less soil erosion because the vegitation
stabilized that as well. So the wolves, small in number, transformed
not just the ecosystem of the Yellowstone National Park -This huge area of land… but also, its physical
geography. Subtitles by the Amara.org community

100 thoughts on “How Wolves Change Rivers”

  1. I hate bursting this bubble as a student of ecology, lover of wolves, and huge fan of these sorts of initiatives, but this is largely an exaggeration of what actually happened. For further info:

    https://www.accuweather.com/en/weather-news/scientists-debunk-myth-that-yellowstone-wolves-changed-entire-ecosystem-flow-of-rivers/70004699

  2. I raised a pack of wolves up high in the mountains of South lake Tahoe. We ran the mountains. They were friendly with dogs and humans but hated coyotees. During this time an atricle came out talking about the coyotee problem on the North Shore and down at the lake…lol…My wolves ran them off the South side of the mountain. During this time my wolves rescued atleast a dozen dogs up in the mointains lost. The owners thought the coyotees had got them. I would tell them nope the wolves did. Shoulda have seen the looks on their faces when they came to pick them up and they were in the yard playing with 8 wolves. They also protected the neighborts cats. True story. Today I have 2 left from that pack. They were all very sweet and well behaived as they all slept inside except one, my wild Luna.

  3. Here because of Tim Ferriss, this story is false and misleading. Not sure if we need wolves reintroduced in Colorado https://www.accuweather.com/en/weather-news/scientists-debunk-myth-that-yellowstone-wolves-changed-entire-ecosystem-flow-of-rivers/70004699

  4. This is astonishing. And so beautifully. Truly there is a way for humans and animals to live peacefully side by side.

  5. That's total bs! It's not because people couldn't control elk numbers…it's because the Wyoming Game and Fish makes it extremely hard for residents to get into the field!!!

  6. I've been lucky enough to have a wolf in my life. They are magical. Thank you so much for this information , it helps me to understand why they are so driven to do their job here on this planet♡♡♡♡♡

  7. Wolves were Reintroduced
    Who removed them in the first place
    Why do we always have to interfere with nature if the wolves weren't removed in the first place that catastrophe wouldn't have happened

  8. Oh bullshit. I live in Alaska. Reality here. Wolves wiped out everything in their path until we were able to control wolves after a 5 year period of wolf dominance, and decimation protected by fake news in the late 90s. See "THE VIEW From Our Side of the Mountains" on Amazon.

  9. Hello, my British friend!
    Tell me, please… What will happen for better, if we will reintroduce some German Nazis and some Russian communists in our Polish landscape?

    🤔😺🇵🇱⛪

  10. There’s a lot of misinformation here. Everyone in Idaho will tell you reintroduction of wolves has been a disaster. In fact there’s even a hunting season on them now due to the incredible proliferation we are seeing. I knew it was a mistake the minute it happened and I’m not a rancher or a big game hunter.

  11. This sounds exactly like the work of Alan Savory. He has studied desertification in Africa and worldwide and come up with a system where he uses domestic animals and moves them in tight herds in a fashion that mimics the effect that predators would have had. It is so interesting to see this in action from a different standpoint. ⚘

  12. What people don't realise is that they are blaming "climate change" for things that the climate has little or no effect on. The increased CO2 in atmosphere is not the cause of the problem, it is a symptom. The desertification of America, Austrailia, Africa, and Asia, is happening not because of CO2, not because the climate changes with the Sun's changing output, or the changes in Earth's orbit relative to the Sun that effects oceanic currents, and it's not because of changes in oceanic currents effecting the temperature either, but because the soil is dying. This is due to the use of pesticides and it's due to the lack of grazing & trampling & dunging by animals or by too much grazing by animals preventing the vegetation from growing sufficient enough to help rainwater infiltrate the soil. When there are herds of wild animals there are predators and herbavores. The herabvors group together for safety but the herd has to keep moving because they graze, and trample the plants & leave droppings everywhere, which is great for the soil. Once they've grazed one area they must move to another, and the predators force them to keep moving as a herd. What mankind has done is remove the animals & put them in concentration camps called "farms".

  13. Take anything outta God's creation order and it has effects. Father's from marriages, both male and female from children's lives, wolves from nature, and even common sense from society, 🤪

  14. Scientists debunk myth that Yellowstone wolves changed entire ecosystem, flow of rivers https://www.accuweather.com/en/weather-news/scientists-debunk-myth-that-yellowstone-wolves-changed-entire-ecosystem-flow-of-rivers/70004699

  15. i dont get it so how did the wolfs affect the rivers? by vegetation stabilization? what does vegetation have to do with river size

  16. lol … I'm thinking this guy has a fetish for wolves and discount everything else that contribute to the revitalization process such as natures forest burn cycles and variable weather conditions over a period of time.

  17. I realized that the main role of predators in ecosystems is to control local vegetation by preying upon herbivores.🌱🌱🌳🌳

    We must carefully observe the population dynamics of each species to preserve the entire ecosystem.🐺

  18. Very simplistic view on how eco-systems work. In the recent years a number of scientists have rejected this romantic view put forward in this clip, e.g. Prof. Bill Ripple of Oregon State Univ., Tom Hobbs of Colorado State Univ.

  19. More of this! Share the Impact of good decisions, good initiatives.
    So much doom n gloom. When ur damned if u do or damned if u don’t. U don’t . Every time!

  20. so what does this video show us?
    in us lives another craisy group of doglovers
    😖😖😖😖😖😖😖😖😖😖😖😖😖😖

  21. All from the wolves killing the deer species? Man can do that too. Hunters have never been allowed to kill the deer species of yellow stone so really we could have done the same thing by allowing man to hunt there???

  22. So humans couldn't hunt in Yellowstone, manage the deer population?
    How much of taxpayers dollars goes to the ranchers every time a wolf eats a head of beef?how long before the wolf leave the deer alone to take an easy meal of beef? How long before humans have to come in and take out an overpopulated wolf?

  23. Kind of makes me think humans are sort of like the deer, with nothing to hunt us we've gradually started destroy our own ecosystem…

  24. Dont tell the narrator but a quick google search showed that the beavers havent returned. It's nicer to eat rainbows and fart butterflies though.

  25. I really wanted to watch the video and I swear I care about the wolves but I just can't get over the fact that they used the font from Avatar: The Last Airbender in the introduction.

  26. This is from a Ted Talk called "For more wonder, rewild the world" and he gives more examples of other animals crucial to their ecosystems when reintroduced

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