[music]
MALE: The Northern Range is the hub of wildlife in Yellowstone.
So much of the wildlife in Yellowstone lives here.
It's ten percent of the area of the park yet half the wolves live here.
It's arguably the most carnivore rich area in North America
and it's been studied a lot.
WOMAN: The Northern Range has been referred to as the Serengeti of North America
and that's because of the vast numbers of ungulate species mostly, and so
when people look out they may, in one afternoon in the valley bottom of
a Northern Range valley, they may see bison, elk, pronghorn, mule deer, wolves and bears
and all of these species interacting with each other.
MALE: Well, the Northern Range is the northern area of the park where
the northern Yellowstone elk herd spends the winter.
[elk bugles]
So it's winter range for the biggest elk herd in the park,
it's probably the densest year round wolf population at any location in North America.
We roughly have 35 to 40 wolves year round in the park portion of the Northern Range,
but we've been as dense as a hundred wolves
just in the northern part of Yellowstone, and we have pretty high bear densities
and cougar densities as well. So we have a great mix of carnivore species
and we have high density. You know, 50 years ago that was not the case.
[music]
CASSIDY: We came into the Northern Range as Yellowstone was designated a park
and changed a lot of things. So wolves, coyotes, mountain lions, bears to some degree
were all being removed in vast numbers.
SMITH: Wolves were eliminated by people directly in the early part of the 20th century.
So what happens when you kill off the predators? Well, the prey increases to very high levels
and starts to impact the environment and by doing that the elk herd shot up,
and no one really knows how high they shot up,
20 to 30 thousand was the estimated figure and they were degrading the environment.
Our policy on helping restore nature is fairly clear: if humans did it we'll help
the system get back on the right track.
So what was missing was all these carnivores
and so they were not performing their ecological function.
Cougars came back to Yellowstone on their own through natural dispersal.
We started seeing signs of that in the eighties and we reintroduced wolves in the mid nineties
and now that wolves and cougars have been restored and bears have increased
the new story is about what happened to all the elk,
and what is happening to the willow and aspen now that the elk have declined
and these carnivores are back.
CASSIDY: Willow is relied on by a lot of animals and so it's kind of a positive feedback loop:
the more willows there are, the more moose and beaver,
and the healthier the ecosystem because of those animals being involved too.
And so beavers are, of course, nature's engineers and they'll build lodges and dams
that will help raise the water tables and raising the water table is
one of the things that the willows rely on the most.
They can't deal with cut banks and swiftly moving creeks.
They have to have that slow moving water.
SMITH: So this smaller elk herd is more natural,
we're seeing a response of willow and aspen, which used to be suppressed.
We've got wolves and cougars back, we've got more bears, so Yellowstone's system now
is a National Park Service success story.
[music]
CASSIDY: I think the Northern Range is incredibly unique,
not only for the Greater Yellowstone Ecosystem, but for the world.
Protecting Yellowstone is important to just protect the species that live here,
but also provide people a place to be able to see natural processes and use that throughout their life
for making decisions on what they think is important.
[elk bugles]
SMITH: I think a huge value of the national parks is to instill awe of nature into people.
Going out on landscape filled grizzly bears is not the same as, you know, going to the mall
and seeing wolves bring down an elk or seeing two wolf pack's clash right in front of you
are life-altering events.
There's no question we are changing people's lives by having places like Yellowstone.
And the Northern Range is probably the heart of the park
and the park is the heart of the ecosystem, so it's all built upon each other,
but ground zero is the Northern Range.