study in their native Africa. Alternatively, the introduced hippos could be a form of Pleistocene rewilding project, replacing species like Toxodon that became extinct in prehistoric times, but Pleistocene rewilding itself is highly controversial. Others have argued that the Colombian hippos should be regarded as a safe population, isolated from the threats faced by African hippos, and that they could be beneficial to the local ecotourism industry. Incidents Hippopotamuses can represent a serious threat to fishers and other locals. There have been attacks on humans, but as of 2017 nobody has been killed by the Colombian hippos. In 2020, a hippo chased down and severely injured a farmer, which prompted research into the hippos’ population growth. Control efforts In 2009, one adult hippopotamus (called "Pepe") was killed by hunters under authorization of the local authorities. When a photo of the dead hippo became public, it caused considerable controversy among animal rights groups both within the country and abroad, and further plans of culling ceased. Alternative methods have been considered, but they are unproven, or difficult and expensive. In 2017 a wild male hippo was caught, castrated and released again, but it cost about US$50,000. As of 2020, there were no plans by the local government to manage the population, but further studies on their effect on the habitat have been initiated. Because of the fast-growing population, conservationists recommended that a management plan needed to be rapidly developed. By October 2021, the Colombian government had started a program to sterilize the hippos using a chemical to make them infertile. Media In 2013, the National Geographic Channel produced a documentary about the species in Colombia titled Cocaine Hippos. In series 3 of The Grand Tour, the presenters went to Colombia to photograph wildlife, including hippos. See also List of invasive species in Colombia References Hippos Exotic pets Hippopotamuses Invasive mammal species Feral animals