Researchers are racing against time to stop the spread of invasive hippopotamuses in Colombia by castrating the animals. Hippopotamuses (Hippopotamus amphibus) were first brought into the South America by one of the best at the smuggling game: drug cartel leader Pablo Escobar. But after Escobar’s death, some of the animals managed to reproduce and spread through wetlands around the city of Medellin. One study published last year estimated the population to be around 80 animals. According to new research, the number of these animals would grow to nearly 1,500 animals by 2040 — a number nearly impossible to control. Since public outcry resulted in a ban on killing the animals, wildlife managers are working to castrate them to stop their spread.