In this file photo from Feb. 4, 2021, hippos float in the lake at Hacienda Napoles Park, once the private estate of drug kingpin Pablo Escobar who imported three female hippos and one male decades ago in Puerto Triunfo, Colombia. Image Credit: AP

Bogota: Colombia's hippos, an oversized legacy of deceased drug lord Pablo Escobar, are being darted with adapted contraceptives normally used for controlling deer populations to stop over-breeding.

Around 90 hippopotamus, descendents of those Escobar imported more than 30 years ago for his private zoo, are thought to roam Colombia, said David Echeverri, coordinator for forests and biodiversity at regional environmental authority Cornare, in an interview.

Cornare and USDA APHIS experts prepare a dart with the drug GonaCon, used for immunocastration of animals, before using it on hippos to control the expansion of their population, in Puerto Triunfo, Colombia. Image Credit: Reuters

Hippo waste threatens water environments, and the beasts may attack people and destroy crops, according to a study published in the journal Biological Conservation. Neutering the animals, native to Africa, through surgical sterilization is risky and costly.

The US Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) donated 70 doses of the adapted GonaCon contraceptive to dart the invasive animals.

The darting campaign will hopefully help "stop (population growth) now, before it gets to the thousands, before people get killed and more of the environment gets negatively affected," said Jason Bruemmer, project leader for fertility control at APHIS.