Hippos are native to Africa, but drug lord Pablo Escobar introduced them to Colombia in the 1980s, and today they represent a serious environmental problem that is spreading across the country and displacing native Colombian fauna.

Colombia’s environmental authorities regard ‘Hippopotamus amphibius’ as an invasive exotic species. Although they have implemented birth control strategies, they recognize that these are not comprehensive.

There’s a risk that the population of around 80 individuals will continue to grow and gain ground. In less than two decades, there could be up to 1,500 individuals extending over an area exceeding 13,000 square kilometers.

The CORNARE environmental authorities will consider culling individuals as a last resort, despite opposition from animal rights groups. (Photo: CORNARE)

Silent reproduction

In the 1980s, drug lord Pablo Escobar had a collection of giraffes, elephants, rhinoceroses, hippopotamuses, and other exotic animals at his Hacienda Nápoles estate.

Upon his death, his assets were seized by the Colombian government, and the animals were relocated to zoos and parks, all except the hippos (there were only four individuals at the time.)

Over the following years, the population quietly reproduced without control in the Magdalena River Basin, while the country experienced one of the worst episodes of violence in its history, which is why the issue was left last on the list of priorities.

Today, it is estimated there are 80 individuals in different areas of Colombia. The main group, made up of around 55 individuals, is located in the Magdalena Medio region, where the departments of Antioquia, Boyacá, and Santander converge.

The authority responsible for the invasive exotic species in this area is the Regional Autonomous Corporation of the Negro and Nare River Basins (CORNARE for its initials in Spanish), which explains its different birth control strategies to Tec Review.

Contraceptive darts

Last year, CORNARE began the process of immunocastration in 24 hippos with the drug GonaCon, thanks to a donation from the United States Department of Agriculture’s Animal and Plant Health Inspection Service (USDA APHIS).

David Echeverri López, the agency’s Forest and Biodiversity coordinator, explains in an interview that the drug is a type of contraceptive for both males and females. And in 2022, they’ll be applying a second dose of a total of three in order to achieve a lasting effect.

This method of sterilization is the most efficient, but it’s still a challenge. They have tried marking hippos with paint to identify them, “But as their skin secretes an oily liquid that allows them to stay in water for a long time, the pigmentation doesn’t last very long.”

Another individual had a collar placed on its leg, but it deactivated the device in just one move, and they haven’t received any data from it. They darted others, but the darts bounced off.

This year, together with the USDA APHIS agency, they will try marking them with long-lasting tattoo ink to be able to follow up on them.

Hippopotamuses can weigh up to five tons and can be very aggressive, which is why it is not easy to control them. (Photo: CORNARE)

Other strategies

In previous years, they worked on surgical sterilization of certain individuals, but it’s a very expensive process (for each hippo, the price ranges between 129,000 and 150,000 Mexican pesos) and is complex and dangerous for the personnel in charge of administering it.

Another alternative CORNARE has worked on is the donation of hippos to zoos and legal sanctuaries. In Colombia, they have already been relocated to every possible space, and Echeverri López says they might soon be taken in Ecuador. However, it isn’t enough. We need more places where they can be relocated.

The last option, although not very popular, is deciding to cull the animals because they represent an environmental problem that could affect native biodiversity and harm people (some cases have already been recorded).

“Technical and scientific arguments are what support any decision. If we do decide to cull them, it will be our last resort, to ensure the protection of Colombian biodiversity,” says Echeverri.

The mere mention of it has sparked controversy, and there has been opposition from groups of animal activists, such as the Animal Legal Defense Fund in the United States.

The population could continue to grow

Last year, the journal Biological Conservation published an estimate that without any birth control strategy, 80 individuals could become 1,500 individuals and spread to an area of over 13,000 square kilometers in less than two decades.

CORNARE’s director acknowledges that there hasn’t been any comprehensive management of the species because they are very territorial, unpredictable animals and are very difficult to manage, and there are groups of hippos outside their jurisdiction.

He hopes that the Colombian Ministry of Environment and Sustainable Development, along with institutions, research centers, and a community of experts, will participate in controlling the species in order to prevent them from colonizing other areas.

It’s estimated that the population could grow to 1,500 individuals and extend to an area of over 13,000 square kilometers in less than two decades. (Photo: CORNARE)

Return them to Africa?

If the species is native to sub-Saharan Africa, one solution that comes to everyone’s mind is, “Why not return them to their place of origin?”

CORNARE’s Forest and Biodiversity coordinator says it isn’t feasible because in addition to costly and complex logistics, the hippos have adapted to the pathogens and natural conditions of Colombia.

The only way is for them to be adopted by controlled centers where they can guarantee they will be dewormed and vaccinated.