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Invasive Hippos in Colombia: An Issue Too Big To Ignore

Colombia Hippo Problem

In Columbia, the hippo has no natural predator.   ©Germán Jiménez
In Colombia, the hippo has no natural predator. ©Germán Jiménez

In the 1980s, notorious drug trafficker Pablo Escobar imported four hippopotami to Colombia. These animals were brought to Escobar’s private ranch, Hacienda Nápoles, as additions to his personal zoo that showcased animals from other continents. When Escobar was killed in 1993, his property was expropriated, and custody of his menagerie was assigned to the National Narcotics Directorate, the Colombian equivalent of the US Drug Enforcement Agency. Because the National Narcotics Directorate did not have the capacity to manage these animals, custody was then transferred to CORNARE, the Colombian regional environmental agency responsible for the area where the hippos were located. Most of the confiscated animals were donated to other zoos around the country; however, the four hippos, because they were deemed too difficult to seize and move, were left untended in Nápoles.

Instead of dying out, the hippos, one male and three females, thrived and bred. Being a new non-native species, the hippos were without natural predators, diseases, or competitors in the environmentally favorable territory of the middle Colombian Magdalena river basin. And their population has grown exponentially: it is currently estimated that roughly 100 hippos have now derived from the founder population of four; left unchecked, numbers are projected to increase into the thousands over the next several decades. These numbers present a serious problem because of the negative impacts that a population of this size puts on our ecosystems, biodiversity, and human safety.

By 2007, records documented the spread of hippos outside of Nápoles. Of particular concern were subsequent reports that the invasive animals had moved north of the Magdalena watershed, an area very rich in biodiversity. A consequential incident occurred in 2009 when a hippo named Pepe had repeatedly left Nápoles and actively threatened neighboring people and livestock. After being deemed a threat, the Environment Ministry authorized hunting of the hippo. Once the order was executed, images of the dead animal, exposed as a trophy by the Colombian army, unleashed a wave of public outcry spurred by negative responses from animal welfare groups. Such condemnation and public pressure led to a ban on any further culling, and also provided the hippos legal protection.

A survey we conducted in 2017 distinguished two groups of people in terms of their relationships with hippos in the Magdalena watershed. One group, that lives predominantly in towns near Nápoles, like Doradal, claims that hippos have given them economic welfare; the people in this group view the hippos as gentle and peaceful animals that do not represent a threat to people or to biodiversity. Lately this group has received the support of animal rights organizations. Persons belonging to this group carry out media campaigns that use non-scientific and non-evidence based arguments to advocate against measures designed to control the growth of the hippo population. These campaigns do not recognize threats from hippo populations to people or to biodiversity. Rather, arguments are made that link the welfare of peoples living in the Magdalena watershed to the well-being of the hippos.

In Africa, attacks from hippos kill at least 500 people per year. While their numbers in Colombia may yet be manageable, an exploding hippo population is sure to drastically affect the environment and pose a danger to local residents in the future.

In contrast, the survey identified another group of people who live further away from Nápoles; this second group, composed especially of farmers and fishermen, view the expanding hippo population as a potential threat to their livelihoods, activities, and safety. They consider the evidence provided by their own experiences, as well as by science-like arguments, to give them a reason to be afraid.

Faced with the problem of a rapidly increasing hippo population, CORNARE instituted various population control strategies. Unfortunately, given budgetary constraints and limited technical expertise with species management, the goals set by CORNARE have been difficult to reach. Population control measures implemented by CORNARE have included sterilization, capture, and relocation; yet these activities are expensive and pose serious dangers to field teams.

To provide CORNARE with scientific counsel, a number of researchers, including myself, from different disciplines have published various papers and documents describing how the growth and expansion of hippos could be dangerous to biodiversity. In those publications, we presented evidence showing that sterilization, as well as capture and relocation, are grossly inadequate responses in dealing with Colombia’s hippo problem. This evidence includes models and simulations based on actual field data. These simulations forecast areas of dispersion under different scenarios, and different population sizes under different management scenarios. This data presented strong evidence that if the hippo population is not actively controlled, the risks to both the biodiversity and the personal safety of the resident population will be high.

Distinct Threats and the Hippo Population

On one side are those who are attracted to the charismatic species.   ©Domingo Trejo/Pixabay
On one side are those who are attracted to the charismatic species. ©Domingo Trejo/Pixabay

Distinct threats that could ensue from a burgeoning hippo population include:

  1. Significant damage to native ecosystems or to specific species of flora and fauna;

  2. Deleterious changes to lakes and waterways including shifts in oxygenation levels, biochemical changes, altered nutrient levels, and generation of algal blooms;

  3. Spread of disease;

  4. Adverse impacts on people’s livelihoods such as fishing, farming, and livestock production; and

  5. Human injury and fatalities.

Because of their large size and dramatic impacts on the landscape, hippos are considered “ecosystem engineers.” In Africa, attacks from hippos kill at least 500 people per year. Even with the current, limited numbers of hippos, there is evidence of ecological damage around the pools and wetlands outside of Nápoles, as well as accounts of hippo attacks on people.

A hippo attack in May 2020 that left a farmer seriously injured raised the priority of the surging hippo population from that of a regional concern under the purview of CORNARE, to a national one that is being dealt with by Colombia’s national environmental authority, the Ministry of Environment and Sustainable Development. Following last year’s hippo attack on a farmer, several groups of people residing in the Nápoles watershed demanded action from the Ministry of Environment. The Ministry of Environment acquiesced and called upon the scientific institutions of the Environmental National System (ENS), to devise a national strategy for management of the hippos. With the assistance of allies such as Colombian academic and research institutions, the ENS is crafting such a strategy.

Colombia is one of seventeen designated “megadiverse countries” exhibiting great biodiversity and a high number of unique species.

Colombia is one of seventeen designated “megadiverse countries” exhibiting great biodiversity and a high number of unique species. For a megadiverse country like Colombia, the challenge is trying to maintain its biodiversity as well as the goods and services derived from its unique variety of species. To meet this challenge, a first line of defense should include the eradication of invasive species. This eradication strategy has been supported by thousands of researchers around the world and by the International Union for Nature Conservation (IUCN). This year the IUCN sent a letter to Environment Ministry where they claim population control as a valid measure to deal with hippos in Colombia.

​​​​​​​The problem of Colombia’s increasing hippo population is bipartisan but requires consideration of multiple factors. On one side are those who are attracted to the charismatic species, and value the considerable economic boost the hippos bring in the form of tourism. On the other side are those who recognize the necessity of conserving and protecting Colombia’s priceless biodiversity for present and future generations. The prospect of eliminating a local species, particularly one of such magnificence as the hippopotamus, is distasteful to anyone.

However, this sentiment should be weighed against the need to prevent a single alien invasive species from destroying the enormous and irreplaceable native biodiversity of an entire region. In the author’s opinion, the answer is clear: it is necessary to protect our native species. It is these unique, local species that represent a legacy that supports the ecosystem, species diversity, and the goods and services on which Colombians depend.

Policy decisions regarding management of alien invasive species can in practice be difficult and expensive to implement. Thus, achieving and maintaining a balanced and continuous operation may require sustained effort from concerned parties. Informed management decisions made in the first stages of the invasive species control process are crucial, and should address the urgent time frame, responsibilities, and procurement of funds necessary to successfully carry out the operation. Special attention must be focused on peoples' perceptions about hippos in the Magdalena watershed; the avoidance of conflict, and input from stakeholders, is also a priority. Stakeholders should be assured that public sentiment will be appeased whenever possible; however, stakeholders must also be clearly informed when specific measures enacted within a specific time frame are the only viable means of dealing with an imminent threat. The exponentially increasing hippo population is a growing threat to Colombia; and not just its people, but also its resident wildlife. While their numbers may yet be manageable, an exploding hippo population is sure to drastically affect the environment and pose a danger to local residents in the future. Regardless of which measures are taken, it is necessary to prevent continued expansion of the invasive hippo population if we want to protect Colombia’s national treasure: its precious native biodiversity and the Magdalena river people's livelihood and welfare.


*Germán Leonardo Jiménez Romero is an associate professor in the Biology Department, Pontificia Universidad Javeriana, Bogotá, Colombia. His research areas are in conservation biology, ecology and wildlife management, and human-wildlife conflict.


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