On Friday, however, the regional environmental agency Cornare announced its efforts to control the hippo population had led to 24 more hippos being treated with a new method: darts laden with the contraceptive drug GonaCon.
Scientists must now track the efficacy of the drug by measuring hormone levels in hippo feces.
“It is the first time that we are implementing this procedure. We are going to follow up and monitor it to find out how successful it can be,” said David Echeverri López, coordinator of the Cornare Forest and Biodiversity Group.
Escobar’s hippopotamus collection began with only one male and three females. Upon his death, other species of exotic animals were relocated, but the hippos were left because they were too difficult to capture and transport, according to the Biological Conservation study. They soon began to multiply, spreading around the Magdalena river basin from their original home some 100 miles east of the city of Medellin.
Research has shown negative effects of hippo waste on oxygen levels in bodies of water, which can affect fish and ultimately humans. Hippos also pose a threat to agriculture and to the security of people in affected areas, according to the Biological Conservation study. In May 2020, a hippo attack left a 45-year-old man seriously injured.
CNN’s Stefano Pozzebon reported from Bogota, and Jack Guy contributed previous reporting from London.