In the 1980s, Pablo Escobar brought 4 hippos to Colombia. Today, they have become the world's largest invasive hippo population

Four common hippos imported to Colombia as part of Pablo Escobar's private collection in the late 1980s have multiplied into the world's largest known population of invasive hippos. More than 80 of the animals now roam Colombia's rivers and wetlands, raising concerns about their impact on freshwater ecosystems and native species.

The hippos were brought to Escobar's Hacienda Nápoles estate, located east of Medellín. After Escobar was killed in 1993, the animals were left behind. Moving them proved difficult and expensive because of their size and strength, allowing some of them to leave the estate and settle in nearby waterways.

Colombia's warm climate, abundant water and lack of natural predators provided favorable conditions for the hippos to reproduce. What began with just four animals has since developed into a growing population spread across rivers and wetlands.


The hippos spend much of the day in water before emerging at night to feed on vegetation. Their daily movements have consequences for the environment, as large quantities of dung and urine enter the waterways.

A study published in Nature, titled Organic matter loading by hippopotami causes subsidy overload resulting in downstream hypoxia and fish kills, found that waterways occupied by hippos can experience changes in oxygen levels, nutrient concentrations and water chemistry.

Hippo waste introduces large amounts of organic matter and nutrients into freshwater systems. Excess nitrogen and phosphorus can encourage algae growth, while the decomposition of organic material can consume oxygen in the water. Lower oxygen levels can put fish and other aquatic organisms under stress.

The animals also affect ecosystems on land. Their grazing changes vegetation, while their movements can create paths and disturb riverbanks. As their numbers grow, these effects can extend across a larger area.

The Colombian hippo population has therefore created a difficult conservation problem. Authorities face the challenge of controlling a large and expanding invasive population while also considering animal welfare, costs and the potential long-term effects on native ecosystems.

Unlike many invasive species, these animals are difficult to manage because of their size, strength and ability to reproduce. Catching, transporting and controlling them can be technically challenging and expensive.

Scientists continue to study how the hippos are changing Colombia's freshwater ecosystems. For authorities, the question is no longer simply how four animals escaped from a private collection. It is how to manage a growing population that has become an established part of the Colombian landscape while limiting its impact on native wildlife and waterways.