Pablo Escobar’s illegally imported pets have had “extraordinary unintended consequences.”

That's according to Science Foundation Ireland’s Director of Science for Society, Dr Ruth Friedman.

During the 1980s, notorious drug lord Pablo Escobar illegally imported exotic animals to his Hacienda Nápoles estate in Colombia.

Among the exotic animals were one male and three female hippopotamuses.

On Green Scene, Dr Friedman told Pat Kenny that when Escobar’s empire collapsed, Colombian authorities moved a lot of the other big animals out of the country.

“Quite frankly, they didn't know what to do with these hippos – they just left them there,” she said.

“There were four initially, but now there's 150.”

Museum and memorial at the Hacienda Napoles, former estate of drug baron Pablo Escobar, head of the Medellin Cartel // CRB35T

‘The Hippopotamus headache’

Dr Friedman said a modelling study predicts that the number of hippopotamuses could grow to 1500 if nothing happens to them.

“This is causing some problems,” she told the show.

“One hippo eats about 40kg of grass a day, and they're now living in the rivers and lakes in Columbia.

“Unfortunately, the excrement from a hippo causes all sorts of problems; it pollutes the water, kills the fish, creates algal blooms - so that's causing problems for local fishermen.

“They're probably going to be displacing some of the very delicate creatures there like manatees and otters and caiman – an alligator-like creature that lives in South America.”

Herd of Hippopotamuses in Colombia // Image ID: 2ERPJ96

‘Population control’

Dr Friedman said the biggest threat they pose is to the Columbian people.

“They're very dangerous – I mean hippos cause many deaths in Africa,” she said.

“They've no predators in Colombia. In Africa, they're faced with the lions, the hyenas, the crocodiles.”

Dr Friedman said to tackle the growing hippopotamus population, the Colombian government decided to cull the animals.

“They got into an awful lot of trouble – they had very graphic pictures of dead hippos and a huge public outcry,” she said.

“Then they decided to send vets in to sterilise them – you can imagine how difficult that is.

“Plans are in place to send 60 of these hippos to a park in India, a sanctuary in Mexico is going to take 10.

“Sedating and moving a hippo isn't an easy job, and it's going to cost them $3.5 million to do this.”