At the peak of his cocaine-smuggling career, Colombia’s most notorious drug lord Pablo Escobar built a sweeping estate in the country’s rolling hills for his cartel friends and family, complete with a fully functional zoo filled with illegally transported exotic animals. After his death in 1993, one species was left to its own devices and has since thrived in the wet Amazonian rainforest. Now, the hippopotamus has been dubbed the “world’s largest invasive animal” and researchers at the University of California San Diego (UCSD) are evaluating the environmental impact of these massive semiaquatic mammals.
For the last two years, Jonathan Shurin, a UCSD biology professor, has been working with Colombian scientists, veterinarians, fishermen, and students under a project funded by the National Geographic Society to monitor water chemistry, study microbiome samples, and record the soundscape to paint a holistic picture of how hippos are impacting their environment across all spectrums.
Because they are dangerous, territorial, and weigh several tons, Escobar’s four hippos – three females and one male – were let loose rather than transported to nearby zoos. It’s expected that one female gives birth to a new calf every year, resulting in an annual population growth of about 6 percent that now puts Colombia’s hippo population at up to 60 animals. The massive herbivores are endemic to the rivers and swamps in Africa, where their numbers are limited by seasonal drought. However, Colombia’s hot, humid, and year-round wet climate, paired with no natural predators, has allowed their population to boom.