What do you call a wolf that pays attention? An….aware wolf…..
Okay that might not have been a very good wolf joke,
but wolves themselves are definitely good. To celebrate all that wolves do,
let’s take a look back at one of their biggest accomplishments, saving Yellowstone National Park.
The 1800’s were a tough time to be a wolf. US settlers were busy spreading their way across
the continent, building railroads, bridges, and plenty of farmland. But sheep and cow
look awfully tasty to a hungry wolf, and so the settlers began wiping out native wolf species.
In only a few decades populations were cut in half, and some species like the
Northern Rocky Mountain wolves native to yellowstone had been hunted to extinction.
In 1872, Yellowstone was established as the nation's first national park to
preserve the natural landscape and wildlife for generations to come.
Unfortunately wolves were seen as more of a pest than as part of that vital wildlife,
and so were one of the few animals left off the protected species list.
But without the wolves to keep the ecosystem in check, it quickly fell out of balance.
Without their main predator, in the course of only 20 years, elk populations increased by 500%
and not only did their populations increase, but their behaviors changed.
Without the predators, deer and elk began grazing along the river banks,
areas without much coverage where they would’ve been easily spotted by wolves in the past.
As time went on, and they ate more and more of the vegetation around the river banks,
the rivers began to meander more, becoming shallower as they did.
Finally, in 1974, the gray wolf was officially recognized as endangered. The very next year
the long process to restore wolves to Yellowstone began. 41 gray wolves were drugged and abducted,
or relocated as conservationists like to call it, from Canada to Yellowstone.
It’s important to realize that after wolves were reintroduced to the park,
it wasn’t like they instantly ate the overabundance of elk and saved the ecosystem.
To really appreciate the effect the wolves had, you have to think about the numbers.
A single wolf eats around 15-20 elk a year, so collectively the 41 could only eat about 700
a year. That’s only about 2% of total elk populations,
and easily within the number that they could naturally repopulate through breeding.
Much more significantly, the presence of the wolves radically changed the behavior of the elk.
They started avoiding certain parts of the park, the places where they could be
trapped most easily, particularly the valleys and the gorges alongside the river banks.
Immediately those places started to regenerate. In only six years,
the average height of trees along the river banks quintupled. And by 2006,
aspen trees had grown tall enough to where they were too big to be eaten by the elk.
Bare valleys quickly became forests of trees. And as soon as that happened,
the birds started moving in. The number of song and migratory birds increased rapidly.
And with the increase in wooded area, beavers were able to return,
going from just one colony in 1996 to 12 in 2009, allowing for an explosive growth in fish wildlife.
It might sound a little strange that beaver dams help fish populations, but by raising
the water level and calming the stream, they make it easier for fish to hang around and reproduce.
As a result, streams with beaver ponds have about 75 times more abundant fishlife than
those without them, along with providing habitats for all sorts of ducks, reptiles, and amphibians.
The wolves killed coyotes, and as a result of that, the number of
rabbits and mice began to rise, which meant more hawks, weasels, foxes, and 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, partially also
because there were more berries growing on the shrubs the elk would have destroyed.
But here's where it gets really interesting; not just the behaviors of animals,
the wolves change the flow of rivers. The regenerated forests stabilized the river
banks so they collapsed less often, so that the rivers became more fixed in their course. This
meant the rivers began to meander less, causing the channels to narrow and more pools to form,
all of which were great for wildlife habitats. So the wolves, although small in number, transformed
not just the ecosystem of the Yellowstone National Park, but also its physical geography.
And the wolves were also a huge money maker. Their restoration in Yellowstone cost about
$30 million in total, but bring in around $35 million every year in increased tourism.
It’s important to note it wasn’t 100% the wolves that single handedly saved the park,
they did have a little help. At the same time that the wolves were reintroduced,
the elk population was hit by drought and increased human hunting,
but still, it’s amazing to think of the effect these wolves had.
But wolves aren’t the only species who’s
reintroduction brouck back a struggling environment.
Bald eagles once nested on each of the five islands that make up the Channel
Islands off the southern coast of California. But by the 1950s, the birds had disappeared,
largely due to exposure to DDT—a synthetic pesticide
that was used extensively in the 60’s before it was banned in 1972.
After WWII, the Montrose Chemical Corporation
dumped massive amounts of the chemical into the sewer system,
ultimately going into the ocean to contaminate the fish that the Bald Eagles relied on.
The chemical weakened the shells the eagles layed, so much so that they never hatched. As a result,
within just a few years of the chemical dump, bald eagles disappeared from the Channel Islands.
Finally in 2002, biologists brought in eaglets from Alaska and breeding programs
throughout the country. In total, they released 61 eagles between 2002 and 2006.
Today, more than 40 eagles call the park their home, including about a dozen breeding pairs.
But their reintroduction didn't only save the eagles.
With the disappearance of the bald eagle for several decades,
golden eagles gradually moved in and fed on the channel island foxes.
The golden eagles were also enticed to the area because of another readily-available food source:
feral pigs. When settlers moved into the channel Islands, they brought pigs with them.
Many of these pigs escaped, and through successive generations a wild population of feral pigs
inhabited the islands. The piglets, weighing only a few pounds, were a favorite snack for the golden
eagles. So between the pigs and the foxes, the golden eagles thrived, while the channel
island foxes were reduced from thousands to just fifteen, no not fifteen hundred, literally 15!
To preserve the fox species, the golden eagles had to be captured and relocated, and the feral pigs
were successfully eliminated. In a similar fashion, a quarter million goats had to be
exterminated off the Galapagos in order to save tortoise populations. Check out that video here.
At the same time golden eagles and pigs were removed from the islands, the Bald
Eagles were reintroduced, helping to restore balance to the ecosystem. Introducing the bald
eagle back into the ecosystem proved to be a natural deterrent to the colonization of
the golden eagle as the bald eagles would chase the golden eagles off the islands.
In an environment where fish is the primary source of food for bald eagles, the Island
Foxes are not as vulnerable from attacks from the sky, and get to live much more peaceful lives.
It is estimated that 1800 Channel Island Foxes are now living on the islands,
enjoying their favorite foods of plants, insects, and mice.
The recovery of the Channel Island Fox has been one of the most successful
and quickest restoration projects in the history of endangered species.
If you love learning about the complex world of animals, or you’re a teacher assigning this
video to your students, check out our videos on the great goat war in the galapagos and
the coolest symbiotic relationships, and remember, there is always more to learn.