Importance of Natural Resources

Weird Ways We’ve Fought Invasive Species

[♪ INTRO] In a world that’s as connected as ours, it’s no wonder that species sometimes end
up in habitats that aren’t their own. But these invasive species can cause serious
trouble. They often compete with native species for
food, steal their homes, nom on them for lunch, or otherwise wreak
havoc in their new habitats. The survival of entire ecosystems can depend
on getting rid of them. But that’s not so easy. Without predators to keep them in check, invasive
species tend to stick around and multiply, despite our best efforts to fend them off. That means that we have to get pretty creative
to have any hope of eradicating them. And in some cases, humans have risen to the
challenge. Here are five of the strangest ways that people
have fought back against invasive species. The brown tree snake invaded the tiny island
of Guam in the 1940s, after stowing away on a U.S. military plane
coming from another Pacific island. Since then, the snake population, which is
now about two million strong, has eaten its way through the island, devastating
the local ecosystem. The snakes have hunted ten of Guam’s twelve
native birds to extinction. Without birds, the spider population has gone
unchecked. Forests have also thinned because there aren’t
enough birds to spread seeds. To make matters worse, since these tree snakes
live in trees, it’s tough to weed them out with traditional
methods like traps or snake-sniffing dogs. So to try to eradicate these predators, the U.S. government has been experimenting
with a more creative solution: air-dropping dead mice filled with acetaminophen, the active ingredient in Tylenol, over the
jungles of Guam. The mice come sailing down in little parachutes,
which is kind of tragically adorable. Then the parachutes get stuck in trees and dangle the mice in places where snakes
can find and eat them. And the method is pretty deadly. A year-2000 study by the National Wildlife
Research Center found that 100% of brown tree snakes die after ingesting
acetaminophen. Unlike in humans, this medicine prevents the
snakes’ blood cells from carrying oxygen. Just 80 milligrams of the stuff, about a child’s
dose of Tylenol, makes the snake go into a coma and die within
60 hours. Dead mice seem to work really well as a vessel
for the poison, because they attract the brown tree snake
but not Guam’s native species, according to a preliminary study. And so far, research suggests that this approach
is pretty effective. One study looked at a site where two rounds
of poison-mice had been dropped at different times. The researchers found a 40% decrease in the
number of baits eaten after the first round, suggesting that there were fewer snakes to
eat them by round two. So this method could go a long way in clearing
these invasive predators out of the island. While the brown tree snake snuck its way into
its co-opted home, many invasive species waltz into foreign environments
as pets. That’s probably how the spiky, colorful
lionfish got from its native Indo-Pacific seas to the
Atlantic Ocean. Lionfish have been terrorizing the Atlantic
since the late 1980s, taking over reefs, shipwrecks, and other places. It seems likely that these invaders started
out as pets whose owners dumped them in the ocean when
they didn’t want them anymore. Which sounds nice and humane! Except, these fun, zany-looking fish are actually
fierce predators. They eat mostly fish and are super-venomous, so they don’t really have predators in their
foreign territory, which makes them pretty much unstoppable. Lionfish have drastically reduced the populations
of fish where they live. And it doesn’t stop there. Lionfish devour other fish that typically
eat algae, and unchecked algae growth crowds out coral
reefs. So lionfish are indirectly killing our reefs. That’s a pretty serious problem. But it’s not like we can just fish them
out of the ocean. Lionfish have been moving into deeper and
deeper waters, making them hard to catch with a hook and
bait. That depth poses another problem, too: it gets too risky for divers to catch a fish
with, say, nets because the water pressure gets dangerously
high. So, to stave off the lionfish invasion, the
the CEO of iRobot, which made the Roomba, yeah, that little robot
vacuum, has developed human-controlled, pressure-resistant
robots that can go where humans can’t. Deep underwater, the goal is for these weird
tube robots to track down lionfish, give them a good zap to stun them, and then
suck them up with a vacuum. The good news is lionfish are a pretty easy
catch. Since they aren’t used to having predators
around, they don’t really run away from things that
approach them, even weird robots with little clappers attached. Which is pretty convenient for the robot. Along with clearing the water of invasive
species, this underwater robot collects lionfish that
could ultimately be served at restaurants. Lionfish actually makes a pretty tasty dish
that some people compare to snapper. As of 2019, the robot is still being refined,
so it’s not on the market yet. But its makers are perfecting the design and preparing the machine to suck the invasive
lionfish out of the seas. The lionfish isn’t the only invasive fish
that’s been hard to root out. In the Upper Missouri River Basin, brook trout
from the Eastern U.S. have been crowding out the area’s native
trout species since the 19th century, when people introduced them as a way of replenishing
fish populations around the country. In the past, people have gotten rid of invasive
fish by dumping toxic chemicals in the river to
poison them, but it probably doesn’t surprise you that
that solution leaves something to be desired. The toxins kill invasive fish and native fish
alike, including ones we rely on for food. So researchers in Montana have developed a much safer way of removing the trout without
killing everything else. The technique is called backpack electrofishing,
and it’s pretty much what it sounds like. Essentially, researchers wade into the water
wearing backpacks with electric generators. The generators are connected to wands with
positive charge flowing through them, and researchers stick them in the water. Fish are naturally programmed to swim toward
positive charge, so they approach. That’s when the scientists unleash an electric
burst that can temporarily stun hundreds of fish
in one go. The stunned fish float to the surface and
get scooped up in nets. From there, the researchers separate out the
invasives, which can become meals, and return the native fish to the water. Researchers have taken out tens of thousands
of trout from the basin with this method, and the best part is, it doesn’t hurt the
environment they’re trying to protect. It’s nice to be able to tackle invasive
species in bulk, but sometimes you just have to go one by one. That’s the case in Washington state, where invasive mountain goats are wreaking
havoc in Olympic National Park. After hunters in Alaska introduced them in
the 1920s, these goats quickly spread into their new
habitat. As of 2018, around 700 goats were roaming
the peninsula, grazing on the rare plants and eroding the
landscape as they trampled across it. Oh, and there’s another detail. The Olympic goats are addicted to human pee. Turns out pee, and human sweat,is a rare source
of salt in the park; and the goats just love it. As the goats have gotten used to humans, they’ve
also gotten aggressive. Unfortunately, getting rid of the goats is
not a walk in the park. According to the National Park Service, typical approaches to invasive species won’t
cut it for all sorts of reasons. We can’t just introduce goat predators,
like wolves, because they’d happily gobble up the park’s
native animals too, like elk and deer. And we can’t just give the goats salt so
they lay off the pee, since they’d keep eating up native plants
and eroding the landscape. So the U.S. government has come up with a
solution: airlift the goats to their natural habitat
in the Cascade Mountains. To do that, they first paralyze the goats
with a dart, then blindfold them to keep them from panicking. After that, they hoist the goats up in a harness
attached to a helicopter and take them to a staging area, where a truck
picks them up and delivers them to the Cascades. And that may sound like overkill, but there
is some logic to the idea. Because of overhunting, the number of mountain
goats in the Cascades has been dwindling. Some experts believe that bringing the goats
back to their natural habitat could help the population bounce back. Not only would this forced migration add hundreds
more goats to the ecosystem, it would also increase the genetic diversity
of the goats in the region, which could ultimately help the population
thrive. When it comes to removing invasive species, it’s often the last few stragglers that
are the hardest to weed out. But if you don’t get the stragglers, the
population will likely bounce back. That was the problem on Isabela Island in
the Galapagos. Across the archipelago, goats had reduced
or completely wiped out almost 80% of plant species, which seriously
messed up the ecosystem. In 2004, helicopter crews managed to wipe
out about 90% of the goats on Isabela Island by
shooting them, but then they had to deal with the last 10
percent. Unfortunately, it can get pretty expensive
looking around for goats in a helicopter. So researchers turned to undercover goats. They captured around 800 female goats, neutered
them, and laced them with hormones that make them
seem like they’re always in heat. These chemically altered goats are called
Judas goats. Researchers then fit them with a collar so
they could track them, then released them into the wild. Since they were chemically aroused all of
the time, they sought out other goats, especially males, and scientists were able
to follow their trackers to the stragglers. They did that every few weeks, and then shot
all of the goats who weren’t Judas goats. After all the stragglers were gone, the Judas
goats, which couldn’t reproduce, were left to carry out the rest of their lives
alone. Of course, it takes a lot of resources to be able to pull off any of these creative
ways of fighting off invasive species. But even without a helicopter or an underwater
fish vacuum, you can still do things to help control invasive
species where you live, like cleaning off your shoes after hiking
or planting native plants in your garden. Even small steps like these can help keep
our ecosystems in balance. Thanks for watching this episode of SciShow! And thank you to our patrons for your support
and curiosity about the universe. You’re the reason we can keep making videos
like this one. If you’re not a patron but are interested
in supporting, head over to [♪ OUTRO]

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