Pablo Escobar's 'cocaine hippos' may be helping river ecosystems in Colombia

Hippos are native to sub-Saharan Africa, but a once captive herd of escaped animals is right at home in northwestern Colombia.
Hippos are native to sub-Saharan Africa, but a once captive herd of escaped animals is right at home in northwestern Colombia. (Image credit: Shutterstock)

Hippos that were brought to Colombia decades ago by Pablo Escobar, the notorious cocaine kingpin, are now thriving in the country's river ecosystems. Scientists even suspect that river habitats may benefit from the presence of these non-native hippos, with the large herbivores filling an ecological niche that has been vacant in the region for thousands of years.

Many species of big plant-eaters that once roamed the planet were driven to extinction beginning about 100,000 years ago, with extinctions peaking toward the end of the Pleistocene Epoch (2.6 million to 11,700 years ago). As big herbivorous animals   vanished, their absence starved the soil of nutrients, altered plant growth and even affected water flow and availability, researchers wrote in a new study.

However, newly introduced nonnative herbivores — such as Escobar's "cocaine hippos" — could revitalize and enrich such ecosystems, and could do so in locations around the world, the scientists reported. 

Related: Image gallery: 25 amazing ancient beasts

Escobar imported four hippos from America in 1981, for a private zoo at his hacienda near Medellín, Colombia. After his drug empire collapsed, the hippos escaped and have been breeding in the wild ever since, now numbering 80 individuals or more, Scientific American reported in February.

For the new study, scientists analyzed the ecological impacts of 427 large herbivores weighing at least 22 lbs. (10 kilograms) that lived between 130,000 years ago and the present day, to see if ailing ecosystems that were once populated by herbivores could be restored to health if big herbivores came back.

In Colombia, the renegade hippos "present a chimera of multiple extinct species' trait combinations," the study authors wrote. In other words, the hippos' impact on their adopted habitat — how much and what type of plants they eat; how much they move around within their range; how they digest their meals; and the quantity of nutrients they return to the habitat as poop — was once performed by a variety of sizable native plant eaters.

Before Escobar's hippos invaded Colombia's waterways, the last big herbivore to roam that part of South America was the giant llama Hemiauchenia paradoxa, or large-headed llama, which vanished around 11,000 years ago. The closest extinct equivalent to a modern hippo is the large-headed llama, the scientists wrote in the study. However, the researchers found that hippos were also very similar to an extinct semiaquatic hoofed beast called Trigonodops lopesi, "in all traits but fermentation type," according to the study. 

This means that hippos may graze on riverbanks in a manner that echoes the habits of extinct llamas, but may distribute nutrients — via poop — in a manner that is more similar to another extinct river animal, the researchers reported. 

For now, the ecological impact of Escobar's hippos is still largely unknown. But some experts have suggested that the hippos aren't such a boon for the environment. In fact, they may upset the balance of Colombian ecosystems, because they produce significant quantities of dung that can affect the water's oxygen levels, according to Scientific American.

Indeed, researchers previously noted that in Kenya, river runoff saturated with hippo poo led to 13 mass die-offs in fish, in which fish suffocated in oxygen-poor water, Live Science previously reported

The findings were published online March 23 in the journal Proceedings of the National Academy of Sciences.

Originally published on Live Science.

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  • Casual Observer
    The article`s authors are enthusiastic about the hippos returning the ecosystem to a past state but I imagine that the current residents that are being displaced are not so sanguine about it.
  • Urquiola
    Confounding comment, headings propose Hippos in South America rivers may be good, but last lines in text indicate the suffocation induced in some African rivers from Hipoo poo is terrible. So what?

    A flight of species I'd like watching is of Yak, Sheep and other farm animals from Nepal, Tibet, adapted to extreme height and cold weather, sent to Bolivia altiplane, now hosting Llama as biggest animal.

    If Nepalese and Tibet animals adapt well to the land, an invitation to some people from Tibet and Nepal settling in Bolivian heights could be considered, let's say 199, those who travelled to Egypt were less than 90, Moshes extracted 300 thousand 'apiru' from Pharao's labor force in 4 generations.

    Even if Native Americans have European and Asian roots, some even compare American languages to Greek and its variants, the genetic adaptative mechanisms to height may differ between Bolivia respect to Nepal and Tibet, where Denisovich (Denisova) and other older human species contributed with genes to endure low Oxygen pressure in the air.

    Anything improving physical performance in Bolivia heights will help reducing the Coca leave use, a NYAS Annals was about: 'The effects of cocaine on the developing brain', perhaps three generations without Coca leave use may be needed for Bolivians to be in full command of themselves. My prayer for general Hugo Bánzer. Blessings +
  • Casual Observer
    Don’t you think it is irresponsible to introduce foreign fauna to an ecosystem and displace its current residents? I don’t see what is confounding about that. And what do the fauna of the region have to do with human cocaine use?
  • Sopaconondas
    What is confounding is that head or article is about supposed beneficial effects of Hippo released from Escobar's zoo, to conclude listing the bad effects of Hippo on African rivers.

    Besides taking advantage of an opportunity to attack an outsider to your tribes, you missed it all the content of Urquiola' post.

    Cattle and Sheep were brought to South America by Spaniards, so, Yak and other animals from Tibet and Nepal will pose no bigger nor different challenge to ecosystem from those already there, simply, newcomers could be better adapted, thus yielding better productivity in the output expected from it. A pilot study is always feasible.
    The connection to people is that if animals from these Asian high mountains adapt well to Bolivian heights, so may adapt Asian heights' people; arrival of a new set of genes that improve human performance in extreme heights, if these genes differ in Bolivian to Nepalese and Tibet people, may help Bolivia inhabitants resist the workload in the poor oxygen supply there, thus reducing the pressure to use Coca leaves, you know the reason for the ethnic use of Coca leaves is the very hard working is in such high places.
    Don't you think people coming from a constant battle desert culture, thriving on other's money (Deut 23,..), or prone to the looting side of double Viking activity, sometimes trading, sometimes ravaging, posed a threat to Native American Human cultures and people?
    What nature did not give, Cambridge does not lend.
    Increasingly clumsy? Gesund +