Colombia's "cocaine hippos" are the offspring of three females and one male illegally imported by drug cartel leader Pablo Escobar. After his death in 1993, Hippopotamus amphibius escaped from his estate and settled in the Magdalena River. With no natural predators or drought native to Africa to control them, these giant herbivores multiplied rapidly, forming an animal population.
Colombian officials have struggled to manage hippos. After they ordered the killing of an aggressive male hippopotamus in 2009, a photo of a soldier posing with a body sparked outrage and halted government efforts to control the hippopotamus.
Using a variety of methods, including hands-on observation, using drones and tracking technology, the research team conducted multiple field trips to count hippos. In places where direct access to animals is not possible, they use drones to count, or estimate numbers from the footprints of hippos.
The results showed that about 37 percent of hippos were juvenile individuals, suggesting that they were breeding rapidly. One hypothesis is that the abundant environmental conditions in Colombia may have contributed to the sexual maturity of hippos earlier than African hippos. Another hypothesis is that hippos have a higher reproductive success rate due to reduced competition for territory and resources among them.
A few years ago, researchers estimated the rate at which these animals reproduce, and it is expected that by 2020 the Magdalena River and its tributaries in the country will have about 98 hippos alive. But the new study estimates that 181-215 animals live in Colombia.
The situation has raised concerns between the Colombian government and scientists. They realized that action must be taken to address the hippo problem to protect local ecosystems and human safety.
Currently, some strategies are being tried against the hippopotamus problem. One strategy is to administer contraceptives to hippos through darts. This method can stop the reproduction of hippos and ultimately reduce their numbers. However, this approach is slower to implement, more expensive, and has not been tested in such a large hippopotamus population. According to a modeling study released in April, this approach could cost at least $850,000 to eradicate hippos within 45 years.
Another strategy is to capture, anesthetize and transfer hippos by helicopter and then castrate them at the facility. This method costs at least $530,000 and can take up to 52 years to eradicate hippos. It is important to note that these calculations are based on lower hippopotamus population estimates prior to census results, so the actual situation may be more serious.
However, the regional agency responsible for dealing with the hippo problem is short of funds and still relies on contraceptive donations from the United States. The agency is in talks with countries, including India and Mexico, to transfer some hippos to protected areas abroad. However, the cost of this strategy can be as high as $3.5 million.
There is no single best solution to the hippopotamus problem. Hippopotamus populations are distributed in different areas, some of which may be easier to migrate, while hippos in other areas are established and reproducing rapidly.
Many researchers advocate the killing of hippos. They believe that this is the quickest and most humane solution and can be solved before the problem becomes irreparable. At the same time, they point out that in Colombia, a country with the second richest biodiversity in the world, the spread of hippos can lead to the loss of native flora and fauna, a cost that must be weighed against the cost of killing hippos.