Colombian Rivers Host Hippopotamus Invasion from Drug Lord’s Legacy

In Colombia’s Magdalena Basin, Pablo Escobar’s legacy lives on through a growing hippo population, posing unique challenges to the local ecosystem and community.

A recent Smithsonian report described how, in the afternoon’s heat, Yamit Diaz Romero steered a motorized longboat around overhanging bamboo branches and islets in the Claro Cocorná Sur River in western Colombia. Red howler monkeys swung from the cables of a footbridge and screeched in the jungle. Herons, snowy egrets, brown pelicans, and parakeets darted across the coffee-colored water and soared overhead. The river is known as a destination for white-water rafting. But these days, it’s also become the scene of a more unsettling natural phenomenon.

Near the opposite bank, 300 yards away, three pairs of gray ears flicked, and beady eyes darted above the water line. The boatman circled cautiously and winced when Joshua Wilson, an American jujitsu champion, suddenly launched an aerial drone and banged on the boat’s gunwale to get the animals’ attention. One animal raised a gigantic, bulbous head and opened its mouth, exposing a sharp set of canines. “Tourists think that this is cute,” Romero said in Spanish. “But it’s a sign of aggression.”

Unexpected Inhabitants

Wild hippopotamuses, the vast, semiaquatic mammal native to sub-Saharan Africa, in the rivers—and ponds, swamps, lakes, forests, and roads—of rural Colombia are an unlikely legacy of Pablo Escobar, the infamous drug baron from Medellín. Decades ago, Escobar spent part of his vast fortune assembling a menagerie of exotic animals, including elephants, giraffes, zebras, ostriches, and kangaroos, at his hacienda outside Doradal, a town about ten miles west of the Magdalena. After he was shot dead in Medellín by Colombian police in 1993, local people poured onto the property. They tore apart Escobar’s villa in search of rumored caches of money and weapons. Afterward, the hacienda sank into ruin. In 1998, the government seized possession of the property and eventually transferred most of the animals to domestic zoos. However, several hippos—most sources say three females and one male—were considered too dangerous to move. And that’s how Colombia’s current trouble began.

The hippos multiplied. (Once they reach maturity, female hippos can produce a calf every 18 months, and they can give birth 25 times during a lifespan of 40 to 50 years.) Males cast out of the herd by the dominant male migrated elsewhere, started their herds, and took over new territory. Today, people are still determining how many hippos inhabit the rivers and lakes of the Magdalena Basin, which covers roughly 100,000 square miles and is home to two-thirds of Colombia’s human population. As of late 2023, the official government count was 169. David Echeverri López, chief of the Biodiversity Management Office of Cornare, a regional environmental agency, says the number could be 200. Colombian biologists recently predicted that by 2040, if nothing is done to control their breeding, the population will grow to as many as 1,400. The hippos will use the Magdalena River as their primary expansion route, says Francisco Sánchez, an environmental official in the riverside municipality of Puerto Triunfo, which includes Doradal. “They’ll get to the sea because they will just follow the river.” He calls the situation “completely out of control.”

The presence of these beasts in the heart of South America, waddling at night down rural paths and staring into the headlights of jeeps and motorcycles, might be comical if it weren’t so deadly serious. In Africa, hippos are thought to kill some 500 people a year, making them among the most dangerous animals to humans, according to The Smithsonian. And while, for now, violent encounters in Colombia have been limited, unsettling incidents are increasing. The beasts have attacked farmers and destroyed crops. Last year, a car struck and killed a hippo crossing a highway. (Hippos tend to spend daytime hours in the water and move around land at night, adding to a menacing sense of danger striking in the dark.) This wasn’t long after a hippo lumbered into the yard of a school, sending frightened teachers and kids running for cover. The animal munched on fruit that had fallen from trees before shuffling off to nearby fields. Although nobody was hurt, the incident was widely covered in the Colombian media, increasing pressure on authorities to do something before the problem spins out of control.

Environmental Impact

The danger is hardly limited to people. Colombian scientists are sounding alarms about the impact on the region’s ecosystem. For example, a single hippo produces up to 20 pounds of feces daily. In Africa, the dung long provided nutrients for fish populations in rivers and lakes. Still, in recent years, perhaps due to warming temperatures, water-intensive agriculture, and increasing drought, the dung has accumulated toxic levels in stagnating pools, killing off the same aquatic life that once benefited from it. Experts fear the same thing could happen in Colombia. And competition for food and space could displace otters, West Indian manatees, capybaras, and turtles. “If I lived in Colombia, I would be worried,” Rebecca Lewison, an ecologist at San Diego State University’s Coastal and Marine Institute, said in an interview with The Smithsonian. “Colombia has great biodiversity, and this is not a system that has evolved to support a mega-herbivore.”

This bizarre problem is compelling Colombian conservationists to search for unusual solutions. Alejandro Mira is a member of a newly formed, first-of-its-kind animal control program that seeks not to capture or “cull” hippos but to sterilize them in the wild. But the procedure, an invasive surgical castration, is medically complicated, expensive, and sometimes dangerous for hippos as well as for the people performing it. After successfully piloting the program last year, the team sterilized seven hippos in three months—a considerable achievement but short of the estimated 40 castrations a year they believe will be necessary to control the population. “There have been sterilizations in zoos, but no information was available about doing this in the wild,” Mira said in an interview with The Smithsonian. “We had to learn it as we went along.”

A History of Flamboyant Wealth—and Violence

When Pablo Escobar appeared in Puerto Triunfo in 1978, the government had just constructed a two-lane asphalt highway between Medellín and the Magdalena River, making the jungled region far more accessible. The 28-year-old Escobar identified himself as a “businessman” and wanted to buy property. “There was perfect tree cover and good water resources,” Sánchez, the local environmental official, said in an interview with The Smithsonian as they sat in Puerto Triunfo’s riverfront town hall, where he has worked for over three decades. “It was the perfect place to build a retreat.” After a search, Escobar bought a 5,000-acre property near Doradal.

The drug baron installed an airplane runway, a villa, heliports, aircraft hangars, horse stables, 27 artificial lakes, a dinosaur theme park, and a bull ring. He also hired a staff of more than 1,000 people to run the hacienda. In the early 1980s, inspired by other Latin American drug traffickers and drawn to the symbolic power of wild beasts, he reportedly paid exotic animal breeders in Dallas $2 million in cash for the first animals in his menagerie. Many more, including the hippos, were procured from other dealers and possibly zoos. Sánchez said that he examined the records of Escobar’s transactions in the archives at town hall, but the documentation was destroyed when the Magdalena River flooded the town in the 1990s.

Escobar was picky about his animals. “He would not buy lions, tigers, or other big cats,” Sánchez said. “Taking care of carnivores is very complicated. Just keeping them fed is a tremendous amount of work.” Escobar had also decided to open his menagerie to the public, and he didn’t want predators roaming freely around the grounds. Giving ordinary Colombians access “was a way of making himself popular,” Sánchez said. In the early 1980s, crowds stood in line for hours in the heat at the hacienda gates, waiting to board electric vehicles and bounce over the property past elephants, ostriches, and other wild beasts. Sánchez did the tour himself in 1982. “There was a female elephant that would put her trunk inside the cars, and people loved her,” he recalled in an interview with The Smithsonian.

Escobar’s days at Hacienda Nápoles didn’t last long. After he was publicly identified as a leader of the Medellín Cartel, he fled into hiding. In 1984, he dispatched a hit team to assassinate Colombia’s minister of justice. Five years after that, an unwitting courier carried a bomb onto a Colombian airliner, which blew up midflight, killing all 107 people on board. Escobar’s intended victim, presidential candidate César Gaviria Trujillo, had missed the flight; he was later elected president and made the capture or killing of drug traffickers a priority. As Colombia’s security forces hunted the narcotraficante, violence spread across the region. Right-wing death squads known as autodefensas allied with drug cartels—offering the cartel members protection in return for a cut of their profits—and declared war on the Revolutionary Armed Forces of Colombia (FARC), a Marxist guerrilla group, and its sympathizers. Puerto Triunfo became a center of violence, with many people kidnapped and murdered during the late 1980s and 1990s.

After Escobar was shot dead and his property abandoned, the hippos survived on their own, eating the grass, fruits, and other plants that proliferated on the land. Over the years, the population established new pods beyond the hacienda. Reports trickled in that the animals were trampling farmland, attacking cattle, and menacing fishing boats.

By 2008, the population had reached about two dozen, and Colombia’s Ministry of the Environment decided it was time to act. Echeverri López, who had recently graduated from the University of Antioquia in Medellín with a botany degree, was hired to help search for solutions. One of his first initiatives was to seek advice from wildlife experts in South Africa, who visited Doradal to investigate. “They told me, ‘You have a problem,'” Echeverri López, a bearded, 40-year-old biologist, said in an interview with The Smithsonian. “They said, ‘The only solution is to kill them.'”

The following year, the government hired a hunter to cull the hippos. Still, when a photograph circulated in the media showing the corpse of a male called Pepe, who had wandered 60 miles from Escobar’s hacienda, pro-hippo protests erupted across Colombia. Echeverri López found himself puzzled by the response. “I was saying to myself, ‘Think about how many people are murdered in Colombia every day.'” This was a time when the ongoing civil war was still claiming the lives of more than a thousand civilians per year. “And then there’s this outpouring of sentiment to protect the hippo. I couldn’t explain it.” In the face of public outrage, the minister of the environment resigned, and hippo killings were put on hold.

Echeverri López was obliged to search for other methods. “I had nothing in my background to suggest I could handle this,” he admitted in an interview with The Smithsonian. Conservation teams prowled the region near Escobar’s hacienda at night, looking for hippos to shoot with tranquilizer darts while they grazed. But it took an hour for the tranquilizer to have an effect, by which time the animal had returned to the water. In 2011, veterinarians managed to anesthetize and castrate one hippo named Napolitano 50 miles from Escobar’s former ranch. A military helicopter then transported the unconscious beast in a cage back to the hacienda to regather the wandering hippos at their point of origin. But the helicopter’s engine overheated, and the pilot barely made it down safely.

To contain the hippos, Cornare tried cordoning off the hacienda with bushes, barbed wire, and electric fences, but the animals kept finding escape routes. The agency approached zoos in India, the Philippines, Ecuador, and other countries about adopting the animals. Still, the Hippo Specialist Group of the International Union for Conservation of Nature (IUCN), a Switzerland-based committee of biologists and animal conservationists, criticized the plan. A zoo relocation program, IUCN declared in 2023, “would be extremely costly, have no conservation benefit, and represent a poor use of conservation resources that are critically needed to protect common hippos” in Africa. Cornare’s initiative has yet to result in a single transfer.

Out in the Field

“Most captive facilities can’t accommodate them,” said Lewison, the San Diego State University ecologist, who also serves as the co-chair of the IUCN Hippo Specialist Group, in an interview with The Smithsonian. “Hippos are difficult to keep, they’re huge, and water filtration”—necessary to account for all the poop—”is expensive. Most zoos that want a hippo already have one; if they don’t, they don’t have the capacity for it.”

Staffers also tried chemically castrating the animals with darts, a procedure used successfully in zoos around the world. However, hippos require multiple shots, months apart from each other over two years, and it proved impossible to tag and track the free-ranging animals that had received the first dose. Inside the park near Doradal, they surgically castrated a dozen juvenile hippos, which are more docile and more accessible to maneuver than adults. But that still left an adult population scattered across the Magdalena Basin.

Alejandro Mira got the call to assist in his first surgical castration of a hippo last October. “I was nervous,” he told The Smithsonian. In the predawn darkness of the previous year, Mira arrived at the lakeshore to confront an 800-pound male—relatively junior-sized—pacing inside the enclosure. A team member fired three tranquilizer darts into the hippo’s buttocks. Then, the group waited outside. After 45 minutes, the animal sank into a seated position—”like a dog,” Mira said—then rolled onto its side in a mud pool.

Mira had castrated many horses, dogs, and cats, but this differed from the usual neutering. “The surgery is taking place in a wild environment, with a dangerous animal, with the testicles hidden deep inside the body,” he told The Smithsonian. A team member tickled his ears to verify that the hippo was in a deep state of unconsciousness. When they didn’t twitch, he signaled the others. The veterinarians tied a rope around the animal’s feet, then dragged him a few yards to a sterile canvas sheet on which the surgery would take place. The team donned surgical scrubs and raised a canvas tent to shield themselves and the animal from the rising sun. Then, they swabbed the hippo with sterile wipes and inserted intravenous drips—antibiotics, anti-inflammatories, and anesthetics—into his ears and tongue veins. Administering the anesthetic is a dangerous part of the procedure. For unclear reasons, hippos, like other marine mammals, are highly sensitive to sedation and, in zoos, have sometimes had fatal reactions.

The lead veterinarian, Cristina Buitrago, knelt and palpated the hippo’s abdomen to feel for his testicles located in the inguinal canal. They can be challenging to find because they are retractable and can reside as deep as 15 inches inside the body. Buitrago made a two-and-half-inch incision, cutting with difficulty through thick skin and layers of fat. Mira knelt beside her, handing her surgical instruments. Then, slicing delicately around the blood vessels, she pulled out the mango-sized testicles, “about the size of a horse’s balls,” Mira told The Smithsonian. The vet snipped them off, sutured the wound, and sewed the incision shut.

As the animal slept, the team hurriedly removed the equipment. It exited the corral, monitoring the hippo until it returned to consciousness and shuffled through the gate and into the lake. From darting to awakening, the procedure lasted seven hours. The team had tagged the animal’s ears during the surgery, though monitoring hippos in the wild is difficult. Still, they were confident it would recover well. “They have a strong immune system, and there’s no reason to believe they can’t survive,” Mira said. Biologists have discovered a pigment in hippo skin that absorbs ultraviolet light and may prevent bacteria from growing; it’s a natural antibiotic, they theorize, that can help stave off infections from the animals’ frequent tussling and castration.

A Colorful Legacy

Throughout the fall of 2023, the Cornare team refined the procedure to be as close to a science. Then, in December, Mira and his colleagues faced a male hippo weighing 1,500 pounds, among the largest they had encountered. Tying ropes around the feet to pull the animal onto a sheet wouldn’t work with an animal of this size. Instead, Mira and his six colleagues stationed themselves around the hippo’s hind legs, forelegs, backside, and head. After a count of “uno, dos, tres,” they pushed, tugged, yanked, dragged, and inched the sleeping behemoth a few yards toward the makeshift operating theater. With a final heave, they raised the animal just enough to slide the canvas sheet beneath his bulk. (Two animals they operated on in 2023 were female, which became known only after the hippos’ sedation. “It’s 200 percent more complicated with females,” Mira told The Smithsonian. “You have to access the ovaries through the flanks, cutting through thicker skin and several layers of muscle. You have to go much deeper and use your hands.”)

The operation on the 1,500-pounder was a success. But, at the end of 2023, Cornare’s contract with the government expired, and there was some question about when the program would continue. By April, however, the veterinary team was back in the field and had castrated three more hippos. Meanwhile, Colombia’s Ministry of the Environment has decided that more than the catch-and-castrate program is needed to handle the hippo problem. Susana Muhamad, the environment minister, says that of 169 hippos so far confirmed to be roaming the Colombian countryside, “some” will have to be euthanized. However, she also noted that castrations and attempts to move the beasts to overseas zoos will continue.

But the sentiment for a hard-line solution is growing. After years of searching for a viable alternative, Echeverri López acknowledged to The Smithsonian that a cull would probably have to happen. Indeed, more and more hippo experts around the world say that a controlled killing program is inevitable. “Castration can slow population growth down a bit, but it’s not a solution,” Jan Pluháček, a Czech biologist and hippo specialist, told The Smithsonian. Culling, he said, is “the only thing that makes sense.”

The Future of Escobar’s Hippos

Despite a recognition among Colombian officials that the hippos will have to be managed, whether by a culling program, wide-scale sterilization, targeted translocation, or some combination, even in the best of circumstances, Colombians will likely have to live with a vestige hippo population. Of some 3,500 invasive animal species introduced by humans into new, unsuitable biomes worldwide, few have been eradicated. Whether the intruders are Burmese pythons imported by exotic pet collectors and abandoned in the Florida Everglades, or lionfish from the Indo-Pacific, eating up crustaceans, snappers, groupers, and other aquatic animals along the East Coast and Gulf of Mexico, or giant African land snails, devouring native plants across Asia and Latin America, there is no realistic way to turn back the clock. Colombians may have no choice but to make their peace with this reality.

Also read: Colombian Biologist Wins National Geographic Explorer of the Year Award Saving Dolphins

At dusk, as Mira and Flor Daza watched the hippo behind Villa Sara leave the lake and begin a search for food in the adjacent woods, Daza said, “I’ve accepted him, and I’ve come to view having him here as a privilege.” 

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