In the 1980s, after drug baron, Pablo Escobar had become rich and famous, he built a luxurious estate about halfway between the city of Medellin and Bogota, the Colombian capital, according to the BBC He called it Hacienda Napoles. The estate was huge, covering 20 square kilometers (7.7 square miles).
Escobar then proceeded to smuggle in all sorts of wild animals, including elephants, and giraffe, and last but not least, three females and one male hippo. And in a grand gesture to the people of Colombia, he allowed the public to wander freely around the zoo. The public also got to gaze in wonder at the full-sized concrete sculptures of dinosaurs he had built for his son.
When Escobar was shot and killed in 1993, his property was confiscated by the Colombian government. And while all the wild animals were sent to zoos in Colombia and around the world, the hippos were content to stay in their soupy lake for the next twenty years, watching nature reclaim the surrounding environment.
The property was then transformed into a zoo and theme park, complete with water slides. And the hippos? They continued to thrive and multiply. Estimates indicate there may be a total population between 80 and 100, says Jonathan Shurin, an ecologist with the University of California San Diego who studies the animals.
But at least a dozen, and maybe more, have paddled past the flimsy fence and into the nearby Magdalena River, an idyllic home for the large creatures, with slow-moving water and plenty of shallows. And the region never experiences drought, which tends to act as a natural brake on the size of herds in Africa.
You can tell how much the hippos love living in Colombia based on their sexual activity. In Africa, hippos usually become sexually active between the ages of seven and nine for males, and nine and 11 for females. Escobar’s hippos are reported to become sexually active as young as three. All the fertile females are reported to be giving birth to a calf every year.
An accidental “rewilding” experiment
With the hippos left behind, an accidental rewilding experiment was kicked off and it has continued for close to thirty years. And in the meantime, the population appears to be growing exponentially. Shurin says, “Within a couple of decades, there could be thousands of them.”
The hippos present quite a problem for the government. Not only is there the fear of a hippo killing someone, although that has never happened, but there is also concern over the environment. After all, the hippos are an invasive species. For scientists and conservationists, the ultimate question is how these hippos impact the environment.
And that question leads us to a study published in Proceedings of the National Academy of Sciences last month. The study found that some introduced herbivore species are an almost perfect ecological match for extinct species from the Late Pleistocene, such as modern-day wild horses known as mustangs and the extinct pre-domestic horses in North America, while others bring back a mixture of traits.
“The feral hippos in South America are similar in diet and body size to extinct giant llamas, while a bizarre type of extinct mammal – a notoungulata – shares with hippos large size and semiaquatic habitats,” explained study co-author John Rowan, Darwin fellow in organismic and evolutionary biology at the University of Massachusetts Amherst, reports The Guardian.
“So, while hippos don’t perfectly replace any one extinct species, they restore parts of important ecologies across several species.”
In general, the study found that by introducing large herbivore species across the world, humans had restored lost ecological traits to many ecosystems, thereby counteracting a legacy of extinctions and making the world more like the pre-extinction late Pleistocene.
