Ecosystems are like very complicated Jenga towers: one wrong move, and suddenly you’ve got starlings in New York, hippos in Colombia, and scientists frantically trying to put the pieces back together.

One of my favourite lessons from high school biology was about ecosystems. I remember being amazed to learn how neatly everything inside a particular habitat fits together, with plants, herbivores, and carnivores all playing their part to keep the whole thing ticking along. Antelope roam the savannah, munching on plants and scattering seeds as they go. Lions, in turn, keep the antelope population from getting too ambitious.

It’s a delicate system. Too few antelope get eaten, and suddenly there are far too many nibbling mouths, stripping the plants faster than they can regrow. Too many lions, and the antelope start disappearing, leaving the plants to run wild until the lions, now short on dinner, start disappearing too. This balancing act repeats itself in every corner of the natural world. It’s an ordinary miracle that we often overlook, even as it happens right under our noses.

Naturally, it didn’t take long for humans to step in and throw a few wrenches into these carefully balanced systems, sometimes by accident, and sometimes with the kind of confidence only humans can muster. One of the more famous examples is the existence of European starlings in North America.

As the name hints, European starlings are not, in fact, from the United States. They owe their American citizenship to a group of Shakespeare enthusiasts in the 1890s who decided that what New York really needed was to be populated by all the birds ever mentioned in Shakespeare’s works. About a hundred starlings were released into Central Park, and after a few false starts, the birds settled in (with gusto).

Today, there are over 200 million starlings spread from Alaska to Mexico. Their success story is mostly thanks to their aggressive feeding and nesting habits, which local birds often can’t match. While hawks and falcons do their best to keep them in check, there simply aren’t enough predators around. In fact, the biggest force managing the starling population now is humans. We introduced them into an ecosystem where they didn’t belong, and we’ve been managing the fallout ever since.

Still, each starling is only about the size of a hand, which is a manageable problem, all things considered. In another part of the world, someone introduced a much larger animal into an ecosystem, and let’s just say the consequences have been considerably harder to wrangle.

Paradiso Escobar

Back in the late 1970s, famed Colombian drug lord Pablo Escobar decided that being wildly rich wasn’t worth it if you didn’t have your own personal kingdom to rule over. So he built Hacienda Nápoles, a 20-square-kilometre playground in Puerto Triunfo, Colombia.

Now, the man they called the King of Cocaine wasn’t exactly a minimalist. His estate featured a sprawling Spanish colonial mansion, a sculpture park, a private airport, a brothel, a fleet of luxury and vintage cars and bikes, and even a Formula 1 racetrack. And because no self-respecting kingpin’s home is complete without a zoo, Escobar built one and filled it with animals from around the world: antelope, elephants, exotic birds, giraffes, ostriches, ponies and, most memorably, hippos.

Of course, no earthly paradise could last forever. When Escobar was killed during a rooftop firefight with Colombian police in 1993, his family got into a messy legal fight with the government over who would inherit the estate. The government eventually took control, only to realise they’d won themselves a massive, crumbling property full of very expensive mouths to feed. As a result, most of the animals were crated up and shipped off to various South American zoos.

The hippos, however, turned out to be a much bigger problem (quite literally). Moving several tonnes of grumpy, semi-aquatic muscle proved too costly and complicated, so officials shrugged and left them where they were. And that’s how a handful of Escobar’s hippos ended up becoming permanent (and very prolific) residents of Colombia.

The problem with the hippopotamus

In case there was any doubt in your mind before, let me clarify that hippos are absolutely not native to South America. How Escobar even managed to get his hands on them in the first place remains a bit of a mystery, but when you’re worth $80 billion and have a Rolodex full of questionable contacts, it turns out very few things are off-limits.

When Escobar died in 1993, there were just four hippos living at Hacienda Nápoles – three females and one male. By 2007, that number had grown to 16. Not long after, they decided they were done with the whole zoo life and made a break for it, settling into the nearby Magdalena River like they’d been there all along.

If you’re wondering why the Colombian government didn’t just send in a few zookeepers to round them up at that point, then you’re seriously underestimating just how much of a handful a wild hippo can be. After elephants and rhinos, hippos are the heaviest land animals on Earth, with adult males tipping the scales at around 1,500 kg, and females not far behind at 1,300 kg. And it’s not just their size that’s the issue: hippos are famously bad-tempered, wildly unpredictable, and considered some of the most dangerous animals in the world. They’ve been known to charge boats for no good reason, and can sprint at speeds of up to 30 km/h on land (which, frankly, is way too fast for something built like a wine barrel on legs).

In 2020, researchers tried to estimate how fast the Colombian hippos were multiplying, and figured there could be about 98 of them roaming along the Magdalena River and its tributaries. But a more recent study involving good old-fashioned head counts, drones, and a few other tracking tricks suggests the real number is actually somewhere between 181 and 215.

Without the usual checks of life in Africa (like predators or droughts), Escobar’s “cocaine hippos” have been thriving, building the largest hippo population outside of their native continent. Read that again: the only place in the world that has more hippos than Colombia right now is Africa. Researchers also found that about a third of the hippos they counted are juveniles, which implies that they’re breeding quickly and enthusiastically. One theory about why this is happening is that the lush Colombian environment is letting them hit sexual maturity earlier than they would back home. Another is that life is just a lot less stressful without so many territorial battles over limited food and space. More grass, less drama, more time for a roll in the proverbial hay.

So what do you do with 200 hippos?

After a few serious hippo attacks on humans in 2020 and 2021, plus a car crash that left a hippo dead on a Colombian highway, scientists are sounding the alarm: something has to be done.

The idea of culling isn’t new. Back in 2009, authorities greenlit the hunting of one adult hippo, nicknamed “Pepe.” But when a photo of Pepe’s body surfaced, it sparked outrage from animal rights groups both locally and internationally. Plans for further culling were quickly shelved, and the hippos were left to their own devices (and reproductive instincts) once more.

Since then, people have been brainstorming alternatives, but none of them are easy, cheap, or particularly foolproof. The current strategy involves firing contraceptive darts at the animals, which sounds promising on paper, but in reality it’s slow, expensive, and has never been attempted at this kind of scale. A modelling study in 2023 estimated that if everything went perfectly, the contraceptive plan could wipe out Colombia’s hippo population in about 45 years, at a minimum cost of $850,000.

Another idea is to sedate them, haul them into helicopters, fly them to facilities, castrate them there, and release them back into the wild. The price tag for this is around $50,000 per hippo, with a generous 52-year timeline. And these numbers are probably optimistic, given that they were calculated before anyone knew just how many hippos were actually out there.

Plenty of researchers are now openly advocating for culling. They argue it’s the fastest, most humane solution, and crucial to protecting Colombia’s native ecosystems. After all, Colombia is the second-most biodiverse country in the world. Losing that to a herd of misplaced hippos (each one of which consumes about 40 kg of vegetation per day) would be a pretty catastrophic twist in the story.

At the time of writing this article, there are still no actionable plans for dealing with Colombia’s cocaine hippos. Deadlines have been announced and committees have been established, but progress is maddeningly slow. And while environmentalists and politicians squabble behind closed doors, the wild hippos of Colombia are doing what they do best: making more hippos.

On the plus side, these hippos don’t seem to have seen Cocaine Bear on Netflix. Let’s hope it stays that way.

About the author: Dominique Olivier

Dominique Olivier is the founder of human.writer, where she uses her love of storytelling and ideation to help brands solve problems.

She is a weekly columnist in Ghost Mail and collaborates with The Finance Ghost on Ghost Mail Weekender, a Sunday publication designed to help you be more interesting. She now also writes a regular column for Daily Maverick.

Dominique can be reached on LinkedIn here.