Colombia has begun sterilizing an invasive herd of hippos dominating rivers near Hacienda Nápoles, the former estate of drug lord Pablo Escobar. The roughly 170 hippopotamuses are descended from the four that Escobar illegally imported in the 1980s to live in his private zoo.
Since Escobar’s death, the 3.5-ton animals have been reproducing at a rapid rate—if measures aren’t taken to control them, their population could grow to 1,000 individuals by 2035, per a statement from the Colombian government. This could lead to serious environmental problems as the creatures tromp through fragile ecosystems, outcompete native species and deposit enormous amounts of feces in waterways. Some officials also worry that the aggressive mammals, which are responsible for about 500 deaths annually in Africa, could be a danger to nearby communities.
Pablo Escobar, leader of the Medellín cartel, was one of the world’s most powerful drug traffickers in the 1980s. In his peak, he controlled about 80 percent of the cocaine entering the United States and had an estimated $3 billion fortune, per the New Yorker’s Jon Lee Anderson. Escobar purchased his 7.7-square-mile property in 1978 and converted it into a lavish estate filled with a sculpture garden, a car collection, swimming pools, man-made lakes and his zoo—a menagerie complete with elephants, rhinos, exotic birds, giraffes and a small herd of hippos with three females and one male.
When Escobar was killed by police during a shootout in 1993, his estate was abandoned. Most of the animals either died or were transferred to zoos, except the hippos, which were left to fend for themselves. With no natural predators or droughts—which help control populations in Africa—the hippos thrived.
The country has since declared the animals an invasive species, much to the displeasure of some locals, who have grown accustomed to their gigantic neighbors.
“They make laws from a distance. We live with the hippopotamuses here and we have never thought of killing them,” Isabel Romero Jerez, a local conservationist, told Marko Álvarez and Astrid Suárez of the Associated Press last year. “The hippopotamuses aren’t African now; they are Colombians.”
Earlier this month, the government announced the initiation of its new plan to control the hippos, which involves sterilization, relocation and, in some cases, euthanasia.
“All three strategies have to work together,” Susana Muhamad, Colombia’s environment minister, said in a statement, per CNN’s Hafsa Khalil. “Here we are in a race against time in terms of the permanent environmental and ecosystem impacts that are being generated and that is why we cannot say that only one strategy is effective for our objective, which is to control the population.”
But sterilizing the highly territorial creatures is no easy task. The hippos must first be located and tranquilized with a dart through their two-inch-thick skin. The surgical procedure usually takes place wherever the sedated animals land, writes Michael Levenson of the New York Times, so getting them into an optimal position for the operation can be difficult. Complicating matters further, hippos spend most of their time in the water and usually only emerge at night.
The surgery takes between six and eight hours to complete and requires a team of eight people, including veterinarians, technicians and support staff, per Nature News’ Luke Taylor. Because hippos have internal reproductive organs, the operation is invasive and can be difficult.
“The surgery itself isn’t the most complicated part—the tricky thing is anesthetizing them,” Gina Paola Serna, a biologist and veterinarian in Colombia who has castrated hippos from the herd, told the Guardian’s Joe Parkin Daniels in 2021. “And, as we don’t have those drugs for such enormous creatures available in Colombia, it is very expensive.”
Each sterilization will cost an average of about 40 million pesos (about $10,000), per the statement. The country has a goal of completing 40 procedures per year.
“Obviously, you can’t let these hippos keep reproducing, which is what they’ll keep doing because they are in paradise,” Enrique Zerda Ordóñez, a biologist at the National University of Colombia, told the Guardian. “They’ll always have water, all the plants they could ever want to eat, and they can pop out of the river and eat grass with the cows.”