When Colombian drug lord Pablo Escobar was killed in 1993, most of the animals he had imported as pets – zebras, giraffes, kangaroos and rhinos – died or were moved to zoos.
But not his four hippos. They prospered. Maybe a little too well.
Officials estimate that around 170 hippos, descended from Mr Escobar’s original herd, now roam Colombia, and the population could grow to 1,000 by 2035, posing a serious threat to the country’s ecosystem.
This month, after years of debate over what to do with the voracious herbivores, Colombian officials announced a plan to sterilize some, possibly euthanize others and relocate some to sanctuaries in other countries. On Friday, an official said four hippos – two adult females and two juvenile males – had already been surgically sterilized.
“We are in a race against time in terms of permanent impacts on the environment and ecosystems,” Susana Muhamad, Colombia’s environment minister, said in a statement.
Colombian officials describe hippos as an aggressive, invasive species with unnatural predators.
Mr. Escobar brought the first four to his luxury estate, Hacienda Nápoles, in the 1980s as part of a menagerie of wild animals that he used to entertain guests.
Mr. Escobar’s son, Juan Pablo Escobar, wrote in a book: “Pablo Escobar: My father,” that his father went in the early 1980s to a wildlife breeding center in Dallas, where he negotiated a deal to bring the animals to his estate. Hacienda Nápoles also had an airstrip, swimming pools, and a 1,000-seat arena.
After Mr. Escobar was killed in a rooftop shootout with security forces in Medellín in 1993, his hippos defended themselves. They waddled into a man-made pond and bred, attracting affection and leaving as their numbers multiplied.
The animals, for better or worse, have become recognizable mascots in Colombia, commemorated in sculpturesincluding one of a giant pink hippopotamus called Vanesa which welcomes visitors to Mr. Escobar’s former estate, which has been transformed into a theme park.
In the United States, the media less nobly labeled them “cocaine hippos.”
A group of hunters that included Colombian soldiers, hoping to prevent hippos from spreading beyond Mr. Escobar’s estate, shot and killed a man named Pepe in 2009. The hunt sparked a public outcry, fueled by the publication of a photo of the soldiers in poses with dead hippopotamus A judge in Medellín subsequently suspended the hunt for Pepe’s partner and their offspring.
Ms Muhamad blamed 30 years of government inaction for allowing hippos to multiply far from their natural habitat in sub-Saharan Africa. She said 130 to 150 live in the Magdalena River, Colombia’s main river.
The government’s goal is to sterilize 40 hippos a year.
But spaying a hippo is not like spaying a cat.
Hippos can weigh more than three tons and spend most of their days splashing in the water, so they are easier to catch at night. Experts say they are generally tranquilized with a dart and undergo surgery wherever they land. If they jumped into the water after being hit by a dart, they could drown, experts said.
“This procedure is very dangerous since the veterinarian must be very skilled to sterilize him in the shortest time possible, before he wakes up,” said Germán Jiménez, a biologist at the Pontifical Javeriana University in Colombia.
Hippos could also be lured into an enclosure with vegetables, where it might be easier to operate them, said Jonathan Shurin, an ecologist at the University of California, San Diego, who has studied the effects of hippos on water quality in Colombia .
“Sedating them into a position where you can work on them is the hardest part,” Dr. Shurin said, adding that the feat is “not for amateurs.”
Colombian officials say each sterilization will cost about 40 million pesos, or about $10,000, and require a team of eight people, including veterinarians, technicians and support staff.
Ms Muhamad said the government was also developing an “ethical euthanasia protocol”, but did not say how many hippos might be targeted or by what method.
Andrea Padilla, a Colombian senator and animal rights activist, said she supports the plan as long as it does not require killing healthy hippos. Euthanasia should be a last resort, she said, “especially in cases of sick animals whose suffering justifies it.”
“The important thing is to act quickly and effectively” by sterilizing as many hippos as possible, transferring others to sanctuaries and confining the population.
Dr Shurin said it would be “much more effective and humane” to control the population when it is small than when it is large and may require extensive hunting.
“This led to a lot of strong emotions and tempers on both sides,” he said. “I think the plan they’ve come up with is very reasonable and sensitive, and you’ll be able to see if it works if you don’t see little hippos around.”
Researchers have warned that hippos, if left unchecked, could displace other mammals, such as manatees and capybara, and that the large amount of waste they produce could alter aquatic ecosystems, causing harmful algal blooms. As hippos spread, they could also come into more frequent contact with people.
In April, Aníbal Gaviria Correa, governor of the Colombian region of Antioquia, posted a message a photo on social media of a hippo who died in a street after being hit by a car. He implored Ms Muhamad and Colombia’s president, Gustavo Petro, to speed up the relocation of what she called “these majestic animals”.
Ms Muhamad said the government was in talks to relocate some hippos to sanctuaries in Mexico, India and the Philippines.
Dr Jiménez expressed concern about the plans outlined so far, saying they were “not sufficient to control” the exploitation of the hippo population. If hippos are not eliminated completely, he said, Colombia will have to consider the possibility of “coexisting with this species permanently.”