We love animals, but it’s no secret  that they don’t always love us back.

From eating our crops and  livestock to spreading diseases, there are plenty of times where humans want to keep the rest of the  natural world at arm’s length. But a lot of the time, these efforts  don’t exactly work according to plan.

So from declaring a literal war to shooting at them from helicopters, here are just a few ways we’ve tried and failed to  keep wild animals in check. [♪INTRO] Our first example of animal control gone awry is a historical tale called the emu war. Yes, really. And by all accounts, this war reached Wile.

E. Coyote vs Roadrunner levels of hijinks. The Emu War began in 1932, when  Australians became frustrated by a massive flock of roughly 20,000  migratory emus eating their crops, which was far too many for the  farmers to control on their own.

So they had to call in reinforcements, specifically, the Australian military. And these soldiers came armed with machine guns. First blood was drawn in western  Australia, at the end of 1932.

A group of men were sent to flush  the emus towards the gunners, but the birds all fled into  a patch of timber instead. The gunners opened fire, but  the first rounds fell short. All in all, they only managed  to cull a handful of the emus.

So 5 down, 19,995 to go I guess? The men quickly realised that  they weren’t dealing with dense hordes of birds, and the thousands  of emus were way more scattered, making them much harder to kill en masse. By now, the emus were apparently getting wise, and some people claimed that the  birds would designate sentries to alert the rest of the flock  when those pesky humans showed up.

The humans, however, were not getting wise. In one skirmish, soldiers pursuing the birds with a mounted gun didn’t fire a single shot, as their gunner was almost flung from the vehicle due to the bumpy terrain. In another attempt, the  unfortunate driver ran over an emu that then jammed itself in the steering mechanism, causing the car to spiral  out of control and crash.

Eventually the military got their act  together and found better strategies to cull the flocks, but it turned out  that this wasn’t actually all that great. See, the panicking emus wound up trampling through the farmland and more  crops than they’d been eating, meaning that farmers lost  even more of their yields. The war ended later that year at harvest time, since there was no more wheat to tempt the emus.

All in all, this disastrous emu-culling  effort turned out to be a bit… bird-brained. Emus aren’t the only wild animals  that pose a danger to our crops. And in this case, these creatures are big enough to pose a threat to humans, too.

As majestic and regal as they are, elephants are difficult neighbors to have. They can destroy our crops, and  they’re responsible for more human fatalities than most carnivores  in rural areas of Africa and India. Which is why, in populations  that are not under threat, some people have tried to cull elephant herds.

And it hasn’t gone well. In Kruger National Park in South Africa, thousands of elephants were  culled between 1967 and 1996, due to a belief that elephants  were damaging the vegetation and reducing biodiversity, although  that idea has since been criticized. These culls focused on the  mature adults in the herds, which seemed to have some unintended consequences.

A lot of those younger or orphaned elephants were transported to Pilanesberg National Park. And when compared to unculled groups of elephants, the cull survivors seemed  to lack vital social cues, and even struggled to interpret  social cues among their herds. This doesn’t just make them  awkward at dinner parties.

Lacking social skills may make  them more dangerous to humans too, and at least 5 nature preserves  that were given cull-survivors recorded that their rescue  elephants ended up killing people. Not only that, the Pilanesberg  elephants also killed dozens of rhinos in the 10  years after their arrival. So why does killing some elephants turn the rest into juvenile delinquents?

Well, we think that when  the older animals are shot and family groups were left incomplete, the surviving youngsters were  essentially kids without a babysitter. See, normally the younger bulls  are prevented from breeding by the older males, since female  elephants like more mature mates. But without the calmer bulls  around, younger males had access to females, and would start  reproducing earlier than usual.

That would send them into  a sort of breeding-season testosterone spike called musth at younger ages, while they’re still all immature and brash. So it’s possible that a fair  amount of this aggression came from all that excess testosterone. When the park rangers reintroduced several mature bull elephants into the  population, the killing stopped and the misbehaving teens calmed down.

We now know that older bulls  have a calming influence on younger males that gets  them to behave a lot better, so at least we learned a little something. After all, we don’t need any more bull-ies. Unless you’re a regular elephant hunter or 100-year-old emu war veteran, you may not have had any personal experience with those first two nuisance animals.

But there’s a much bigger chance  that at some point in your life, you’ve had a run-in with a rat. They eat our food, chew our wires and have been known to spread the occasional plague. If you’ve ever had to deal with a rat infestation, you may have put down traps or  even poison to keep them in check.

Although, maybe you should  reconsider that last one. One of the most common  commercial rat poisons is a drug called warfarin, which works as an anticoagulant. In other words, it prevents blood clotting.

It also does that for humans,  so warfarin is also a common medication for people who are at  risk of dangerous blood clots. But in rodents, we ramp up the dose so high that it causes fatal internal  bleeding, because, say it with me now… The dose makes the poison! Warfarin-based rat poisons  first hit the market in 1948, and they’re still a common product.

That’s a whole lot of years of warfarin exposure, and if you breed as fast as a rodent, hat’s a lot of generations for  natural selection to kick in. Just 10 years after the first  warfarin-based poisons were sold, some people recorded the first cases  of warfarin resistance in rats. And since then, warfarin-resistance has become a common adaptation in rats all over the world.

See, warfarin works by inhibiting the way that vitamin K interacts with the coagulation process. But rats who develop  resistance to warfarin are able to use a different enzyme in  the vitamin K clotting process that isn’t as vulnerable to  warfarin’s disruptive effects. Those initial warfarin-resistant rats  did end up with some side effects, like vitamin K deficiencies and lower  growth rates, at least at first.

But a paper in 1993 found that  they’d overcome that hurdle, too. Not only did warfarin resistant  rats not have these deficiencies, they were actually larger  than non-resistant rats even in environments without  frequent warfarin exposure. We essentially made super rats.

As you’d expect, that started  a pharmacological arms race, where researchers developed even more lethal substances creatively called superwarfarins. And these did work… until they didn’t. They’d speculated that  rodents could become resistant to superwarfarin eventually, and sure enough, rats started showing resistance to  the new drugs back in the 2000’s.

Which means that our go-to rodent killer is really just helping make super-rats even super-er. So maybe a trap with some cheese  really is the better idea. I can’t imagine how rats  would become immune to cheese.

But also, all science needs funding, including us, so here’s a quick ad! Thanks to our Presidents of Science: McLaren Stanley and Charlie Stanley for supporting this SciShow video! Some presidents move money away from science, but the Presidents of Science use their budget to keep it accessible to everyone.

For over a year, McLaren  Stanley and Charlie Stanley have financially supported SciShow  so that you can watch for free if it’s not within your budget to contribute. And if it is, you can join in the effort to keep science a part of our  lives at patreon.com/SciShow. Next, let’s move up the food chain and talk about what happens when carnivores become nuisances, and how we’ve also failed to solve those problems.

Specifically, we’re talking  about jackals and coyotes. Humanity usually ends up at war with small dogs basically wherever we overlap. Big dogs too, but we’ll get to them.

Fox hunting in the UK, shooting  jackals in South Africa, and all the nasty ways that we try to keep coyote populations down in the US, are usually done in the name of  lowering livestock predation. Problem is, it doesn’t work. The issue comes from who exactly you’re killing.

For instance, one study from 2015 looked at the effects of culling black-backed  jackals in South Africa. They found that in stable,  non-hunted areas, the breeding adults controlled a sizable territory, with  some subadults off at the fringes, who didn’t have enough territory to breed. But when farmers shot those breeding adults, that territory would become  vacant, and nature abhors a vacuum.

All the younger jackals rushed into the open territory and started breeding all at once. For some reason, these young  jackals end up reproducing earlier in their life than the  older breeding pairs would. So where you once had a single breeding pair, you now have a lot more  jackals than you bargained for.

And it’s not only jackals. One study from South Carolina  looked at changes in coyote populations in response to culling, and found that similarly,  as more coyotes are trapped, the overall population in  an area increases over time. But this increase isn’t the  result of more breeding.

Instead, the nearby younger coyotes realize that there’s territory up for grabs and move in. Unless coyote cull programs are enacted over massive stretches of  land, their research shows that coyote populations in areas with trapping programs will rebound in just a few months. And this pattern applies to bigger  carnivores too.

Like cougars. One study from British Columbia  found that from 1979 to 2008, increased cougar hunting led to even more dangerous encounters between cougars and people. When a mature male cougar gets shot, younger males will move into that territory, like we saw with the jackals and coyotes.

And those young cougars happen  to be the ones most likely to pick a fight with any  hairless apes wandering around. They use human-dominated areas more, move around more while doing so, and are more likely to hunt livestock too. So it’s probably best to let these  sleeping dogs, and cougars, lie.

Now while a lot of these other animals have at least seemed kinda dangerous, these next guys are so stinkin’  adorable that it’s hard to picture why they’d be a problem for anybody. But there has been a long-time beef between badgers and cattle farmers, at least in the UK. And it’s not because they eat the cows, because, how the heck would they even do that?

Instead, the problem is that they infect them. In the UK, badgers are a carrier of a disease called bovine tuberculosis, or bTB. Badger culling has been a part of bTB control efforts in the UK since 1973, but it took a while for anybody to actually do a study  to see if it was working or not.

So in 1998, the government launched  a randomised cull to see if killing badgers would help reduce bTB  prevalence in the United Kingdom, which found that badger culling did basically nothing to stop the spread. Despite this, the government started  another culling campaign in 2013, mainly in the south and southwest of England, with at least 140,000 badgers  killed by the end of 2020. One study found that while there  was a 23% drop in rates of bTB in the culled areas, rates of bTB in  neighboring non-cull areas went up.

By about 25%. Another found that after 5 years of culling there was an almost 30% drop in bTB rates, but these effects disappeared  after just four years, or even less in some places. Overall, they found that TB rates would  fluctuate with or without culling, and a later study in 2022 also  found that badger culling made no meaningful contribution  to disease spread in the UK.

And the reason why culling doesn’t  work to solve our badger problems is basically the polar opposite of  what happens after carnivore-culling. Instead of moving in to culled areas, the problem is that these badgers move out. Badgers in the cull areas  increased their home ranges by 61%, and wandered nearly 40% farther  from their sett, or den, each night.

Plus, badgers from culled  populations typically visited around 45% more fields per month in their nightly voyages than those from non-culled groups. So they were more likely to infect both cattle and other badgers during and  after the cull had finished. One of the studies found the cost  of the cull costs 2 to 3 times more than the amount you’d save  by reducing TB spread in cattle.

Which means we should all  stop badgering them now, okay? Okay, this last one may be the most metal attempt at population control I’ve ever heard. Which is a shame, since it  also backfired hilariously.

Due to severe habitat decline stemming  from logging and oil pipelines, Canadian boreal caribou have  been in trouble for a while. So to fix it, people should probably stop logging and drilling in their habitats. And that’s what the Canadian government did!

Oh, sorry? They didn’t do that?  So what did they do instead? Oh, they shot grey wolves from helicopters.

Since grey wolves are known to  snack on the occasional caribou, the thought process was that by reducing the population of their predators, you’d bolster the caribou’s numbers. And apparently this was  the most humane method that they’d considered for reducing  grey wolf populations, which really makes you wonder  what the other options were. Between 2017 and 2020, helicopter snipers shot 92 wolves in northern Alberta, Canada.

And this kinda worked, until the wolves developed their own counter-maneuvers. Turns out those wolves didn’t like being shot at, and they began changing their behavior to essentially make themselves  impossible to target. The survivors preferred  thick areas of dense forest where they couldn’t be followed, and avoided the logging roads where they were sitting ducks.

All in all, they got a lot harder to kill. Their new homes are pretty great, too. There’s plentiful prey in the  thick areas the wolves now hide in, so it’s likely that their population  will recover relatively quickly.

And if they teach their young  their chopper dodging ways, then they’re going to be  very hard to handle indeed. Oddly enough, this may be good  for those caribou after all. See, the changes that came from  all that logging and drilling may have made things worse for caribou, but they also made things better for  moose, the wolves preferred prey.

The researchers proposed that by reducing moose populations in caribou habitats to historical levels, they can encourage the wolves  to pick less caribou-y homes. Who knows, maybe this year  we’ll make an update video with the wild way the moose are fighting back. All of these stories go to show  that when we get fancy and try to outsmart mother Nature, she usually  has a clapback at the ready.

Here’s hoping that we learned  something from the super-rats so we don’t end up with, like,   super-duper-rats, or anything. [♪OUTRO]