Pablo Escobar has been dead for more than three decades, but one part of his private zoo apparently never got the memo. Four hippos were brought to Hacienda Nápoles in the 1980s, one male and three females.
From Nature.com:
The introduction of hippos into the wild in Colombia has been marked by their rapid population growth and widespread dispersal on the landscape, high financial costs of management, and conflicting social perspectives on their management and fate. Here we use population projection models to investigate the effectiveness and cost of management options under consideration for controlling introduced hippos.
We estimate there are 91 hippos in the middle Magdalena River basin, Colombia, and the hippo population is growing at an estimated rate of 9.6% per year. At this rate, there will be 230 hippos by 2032 and over 1,000 by 2050.
Applying the population control methods currently under consideration will cost at least 1–2 million USD to sufficiently decrease hippo population growth to achieve long-term removal, and depending on the management strategy selected, there may still be hippos on the landscape for 50–100 years.
Delaying management actions for a single decade will increase minimum costs by a factor of 2.5, and some methods may become infeasible. Our approach illustrates the trade-offs inherent between cost and effort in managing introduced species, as well as the importance of acting quickly, especially when dealing with species with rapid population growth rates and potential for significant ecological and social impacts.
Escobar died in 1993, but the hippos stayed, and then they got busy.
Colombia now estimates the population has passed 200. Without strong control measures, officials project roughly 500 hippos by 2030 and close to 1,000 by 2035.
Escobar left behind many problems, and a few of them continued having babies.
The strangest part is how comfortable the animals are. Researchers say Colombia's Magdalena River basin gives them abundant grazing land, plenty of water, little dry-season pressure, and no natural predators.
A 2023 study estimated the population was growing about 9.6% a year. Apparently, nobody told the hippos they were invasive.
Colombia did. The government formally declared them an invasive species in 2022, citing risks to water quality, native wildlife, agriculture, fishing, livestock, and people.
From the National Library of Medicine:
The keystone roles of mega-fauna in many terrestrial ecosystems have been lost to defaunation. Large predators and herbivores often play keystone roles in their native ranges, and some have established invasive populations in new biogeographic regions.
However, few empirical examples are available to guide expectations about how mega-fauna affect ecosystems in novel environmental and evolutionary contexts. We examined the impacts on aquatic ecosystems of an emerging population of hippopotamus (Hippopotamus amphibus) that has been growing in Colombia over the last 25 yr.
Hippos in Africa fertilize lakes and rivers by grazing on land and excreting wastes in the water. Stable isotopes indicate that terrestrial sources contribute more carbon in Colombian lakes containing hippo populations, and daily dissolved oxygen cycles suggest that their presence stimulates ecosystem metabolism.
Phytoplankton communities were more dominated by cyanobacteria in lakes with hippos, and bacteria, zooplankton, and benthic invertebrate communities were similar regardless of hippo presence. Our results suggest that hippos recapitulate their role as ecosystem engineers in Colombia, importing terrestrial organic matter and nutrients with detectable impacts on ecosystem metabolism and community structure in the early stages of invasion.
Ongoing range expansion may pose a threat to water resources.
The hippos didn't seem particularly moved by the paperwork.
Their environmental impact begins with a basic hippo routine. They spend much of the day in water, head onto land to graze, then return to the water carrying the results of dinner with them.
Scientists studying Colombian lakes found more land-derived carbon where hippos lived, along with changes in ecosystem metabolism and phytoplankton. Cyanobacteria were more dominant in hippo lakes.
There is a scientific term involved: eutrophication. There's also plain English. Hundreds of enormous animals are eating on land and using the waterways as a toilet, which turns out to be less charming when you're trying to maintain an ecosystem.
Native animals get pulled into the mess. Colombia's environment ministry specifically cites risks to species such as manatees and river turtles, while communities can face crop damage, disrupted fishing, blocked access to water, livestock problems, and damage to infrastructure.
A hippopotamus also weighs several thousand pounds, which gives "blocked access" a little extra meaning.
Colombia has finally moved toward aggressive population control. In April, the government committed 7.2 billion Colombian pesos to the effort and approved a technical euthanasia protocol when relocation isn't practical. Sterilization, relocation, and confinement remain part of the broader plan.
My PJ Media teammate, Sarah Anderson, looked into the government's actions.
The hippos were fine, however, and they made themselves right at home in Colombia's Magdalena River basin. The climate, vegetation, and lack of natural predators worked out for them and they began to multiply. By 2007, there were at least 16 hippos roaming the country, and by 2014, there were at least 40. Today, it's estimated that there are about 170, and that number could reach 500 by 2030 and 1,000 by 2035.
That number is about to decline. Colombia's Environment Minister Irene Vélez says that the country has approved a plan to euthanize at least 80 of the animals. The Colombian government says they're an invasive species, a threat to humans, and damaging local ecosystems.
"If we don’t do this, we will not be able to control the population," she said of the creatures known as the "cocaine hippos" or "narco-hippos." She also noted that they have apparently resorted to inbreeding and have "visible genetic damage" due to it.
While there are no reports of the animals killing or seriously injuring people, they have threatened people in local towns. They've caused traffic and boating accidents, and they've killed crops and livestock.
Please read Sarah's complete piece: Colombia to Euthanize Wild 'Cocaine Hippos'
Officials have also explored transferring some animals to India.
None of the options are simple. Sterilizing a wild hippo is expensive and difficult. Relocation requires enormous logistics, and killing animals that tourists and some locals have grown fond of brings fierce opposition.
Researchers have warned that waiting only makes the population larger, the bill higher, and control harder.
All of it started with four animals in a drug lord's private zoo. No native predator was waiting for them; food was plentiful, water was everywhere, and the descendants kept spreading through the Magdalena basin.
Escobar built an empire that disappeared with him. His hippos appear to have taken a different approach to succession planning.
The drug lord died.
The hippos multiplied.
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