Watch: Colombian drug lord Pablo Escobar left behind an unusual problem for Colombia – hippos

Before Colombian druglord Pablo Escobar became notorious, he was just really rich. In the early 1980s the “Don” created for himself a private zoo at his ranch in Hacienda Napoles, about halfway between Medellin and Bogota. These were still his early days of success, and his campaign against the government, bombings and assassinations hadn’t yet begun.

The zoo was open to the public for free, consolidating the drug lord’s position as a Robin Hood like figure.

For the zoo, Escobar had all sorts of exotic animals flown in – giraffes, elephants, zebras and also four hippos, three females and one male.

After Escobar’s death in 1993, the government took over the ranch, and the animals were sent to various zoos in the country, but not the hippos. The video above by National Geographic details how the animals have multiplied and made their home in an environment that's not natural to them.

A report on the website says, "With mild weather and no competition, the hippos thrived. Over time, some of the animals began to venture away from the pond, into nearby rivers and the surrounding areas."

Surprisingly fast for their size, hippos can be dangerous and have terrorised locals in the region. There are also fears of their increasing presence damaging the ecosystem and displacing native wildlife, such as otters and manatees.

Cornare, a government environmental agency that is overseeing the management of the animals, has resorted to castrating the males to inhibit reproduction.

There are estimated to be about 40 hippos in Colombia, David Echeverri, a researcher with Cornare told National Geographic. "Pablo's hippos" are part of the drug lord's continuing legacy and are routinely covered in the news. In 2010 a feature-length documentary was also made on the creatures.

Below is a National Geographic feature from 2008 on the hippos.