Colombia is proposing transferring at least 70 hippopotamuses that live near Pablo Escobar’s former ranch – descendants of four imported from Africa illegally by the late drug lord in the 1980s – to India and Mexico as part of a plan to control their population.

The hippos, which are territorial and weigh up to 3 tons, have spread far beyond the Hacienda Napoles ranch, located 200 kilometere (124 miles) from Bogota along the Magdalena River. Environmental authorities estimate there are about 130 hippos in the area in Antioquia province and their population could reach 400 in eight years.

Escobar’s Hacienda Napoles — and the hippos — have become a sort of local tourist attraction in the years since the kingpin was killed by police in 1993. When his ranch was abandoned, the hippos, sometimes reffered to as ‘cocaine hippos’ survived and reproduced in local rivers and favourable climatic conditions. Scientists warn the hippos do not have a natural predator in Colombia and are a potential problem for biodiversity since their feaces change the composition of the rivers and could impact the habitat of manatees and capybaras. Last year, Colombia’s government declared them a toxic invasive species.

The plan to take them to India and Mexico has been forming for more than a year, said Lina Marcela de los Ríos Morales, director of animal protection and welfare at Antioquia’s environment ministry.