Scientists warn that a rapidly growing population of hippopotamuses that were introduced to Colombia decades ago by drug kingpin Pablo Escobar should be culled to preserve the local ecosystem, according to a study published this month.
Researchers warned in the study, published in the journal Biological Conservation, that hippos, the "largest invasive animal" in the world, are likely to colonize habitats around the country with serious environmental impact.
Hippos, which are not native to Colombia, were illegally imported in the 1980s by Escobar — the narcoterrorist and drug trafficker who was killed in 1994 — to create a private zoo at his Hacienda Nápoles ranch. While many of Escobar's animals were relocated after his death, the hippos remained because of the difficulty of capturing them, the study said.
Last year, the hippos at Hacienda Nápoles were cause for concern because of how their feces affected the water they resided in, according to Smithsonian Magazine. The animals' excrement fertilized the growth of cyanobacteria, also known as blue-green algae, and threatened the water quality.
"Our models predicted that the worst-case scenario would occur if no management strategies are implemented: the population will continue positively growing, with potential ecologic and socio-economic long-lasting negative effects," the study said.
Although authorities have made efforts to sterilize the hippos, the animals' population in Colombia has remained on the rise. Hippos have won approval from locals, who consider them a potential tourist attraction, and they are protected by environmental law.
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The researchers have asked Colombian authorities to reconsider their stance on culling the hippos, which is the most effective way to control the population, the study said. The study also urges the need for public education about the risk of hippos as an invasive species and their potential impact on local livelihood.
"This knowledge is essential for guiding public perception to the social and ecological affectations potentially faced by hundreds of thousands of vulnerable rural citizens, in the most important hydrographic basin in Colombia," the study said.
Hippos, the largest land animal in the world, after elephants, can weigh up to 8,000 pounds, according to the World Wildlife Foundation. The organization lists them under the status "vulnerable."
Normally native to Africa, the hippo has been considered vulnerable to habitat loss because of destruction from human behavior. Hippos are also at risk from hunters because they have been excluded from bans or harvesting ivory, the African Wildlife Foundation says. Ivory poachers have sought hippo teeth, the tusks that are the species' incisors and canine teeth.