The World’s Largest, and Most Popular, Invasive Species Presents Equally Large Problems

By Matthew Kramer

In February 2019, Medellín, the second-largest city in Colombia, demolished one of its most infamous buildings.[1] This demolition was part of the “Medellín, Embrace Your History” initiative and marked a significant step in recontextualizing the legacy of one of the country’s most notorious outlaws: Pablo Escobar.[2] The building demolished served as Escobar’s family residence during the 1980s and was consequently highlighted in most of the city's controversial “narco tours.”[3] The current plan is to build a memorial on the site to Escobar’s victims.[4] But while Medellín addresses Escobar’s legacy by replacing the symbols of his wealth with memorials to his victims,[5] another of Escobar’s residences, the infamous Hacienda Napoles (“Napoles”), has left behind an unusual danger to the future of Colombia: Hippopotamuses.[6]

Napoles is in the Magdalena River Basin (“Basin”), the region between Medellín and the Colombian capital of Bogota.[7] The Basin is traversed by the Magdalena River, one of the most important rivers in Colombia.[8] Not only is the Magdalena River an integral part of the local ecosystem, but it is also a vital part of the local economy and heavily relied on by the people who live in the Basin.[9]

During the 1980s, Escobar imported one male and three female hippos to his private zoo in Napoles.[10] After he died in 1993, the government removed most of the animals from the zoo.[11] However, the hippos stayed due to the costs of transporting such large animals.[12] Far from dying, the hippos thrived and multiplied, eventually escaping the confines of Napoles.[13] There are currently an estimated 90 hippos; however, a recent study predicts that the population could reach 1,500 as early as 2035.[14] As their numbers increase, the hippos present a predicament for both the humans and the ecology of the Basin. Currently, there are four options for the government to mitigate the potential damage the hippos are causing and will continue to cause: to ignore, transport, sterilize, or cull the hippos.

First, ignoring the hippos is not a viable option. Hippos are regarded as one of the most dangerous animals in the world, “killing an estimated 500 people per year.”[15] Although no person has yet died from hippo attacks in Colombia, there was one serious attack in May 2020.[16] As the hippo population increases, the number of human-hippo encounters and the chances of fatal interactions necessarily increases.[17] Additionally, hippos in the Basin's many rivers are causing chemical and structural changes to the local environment.[18] Hippo secretions trigger toxic algae blooms that deplete oxygen levels in the water and suffocate local fish.[19] They are also physically destroying vegetation vital to native animals.[20]  

Because hippos cannot be ignored, the cost of any action becomes a factor in how the government proceeds. Both sterilization and transportation are expensive options. For example, the cost to track, catch, sedate, and sterilize one male hippo in 2009 was USD 50,000.[21] Adjusted for inflation, that is more than four times the current median yearly income in Colombia.[22] Consequently, the cost of sterilization has labeled this option as "simply not an option."[23] Locating every single male hippo is not guaranteed, and missing just one means the problem will persist.[24]

Extracting and transporting the hippos would have similar costs. Similar to sterilization, the hippos would have to be tracked, caught, and sedated. After an expensive capture, there would be a costly transport to either a zoo[25] or a more expensive transportation to be part of the wild African population.[26] However, no zoo is willing to take on 90 hippos, and no African nation is willing to risk introducing “dozens of [hippos] with mysterious origins and unknown behaviors.”[27] Introducing Colombian hippos to their native habitat in Africa creates a risk of disease, undesirable genetic mutations, and unpredictable social interactions as the Colombian hippos were not raised in natural African populations.[28]

The last currently available option is to cull the population. The government authorized this option in 2009, which resulted in one dead hippo.[29] In response, the local community protested and demanded the resignation of the officials involved.[30] Unrest continued until a judge issued an order prohibiting further hunts.[31] That order and the community support for hippos remain in effect today, and even the mere suggestion of culling hippos triggers “abuse and death threats.”[32]

However, it must be noted that there are some advocating leaving the hippos alone.[33] These advocates argue that hippos fulfill a vital ecological role in shifting nutrients from the land to the river.[34] Additionally, local people are benefitting from the increase the tourism that the hippos generate.[35] However, the longer the hippos are left alone, the more difficult any potential solution becomes to implement and the greater any currently accruing problems become.[36]

Pablo Escobar's legacy contains many complex issues. One remnant that gets harder to deal with every year is the presence of hippos as an unlikely invasive species. There is currently no consensus on whether the effects of hippos in the Magdalene River Basin are positive or negative; however, there is more research indicating the effects are negative.[37] With economic barriers to two options and a legal ban on a third, there is no “good” solution; however, removing the legal cull ban would grant more time to study the problem and formulate mitigation measures. Despite their popularity, the hippos are an invasive species in Colombia, and every option should remain open in an attempt to mitigate potentially devastating changes.

[1] Dust and Ashes: What Remain of Escobar’s Legacy, Colom., https://www.colombia.co/en/updates/dust-and-ashes-what-remain-of-escobars-legacy (last visited Aug. 12, 2021).

[2] Maureen Orth, “So Much Pain Still Exists”: Why Medellín Blew Up Pablo Escobar’s House, Vanity Fair (Apr. 9, 2019), https://www.vanityfair.com/news/2019/04/why-medellin-blew-up-pablo-escobars-house.).

[3] Id.

[4] Id.

[5] Id.

[6] Assoc. Press, Pablo Escobar’s Hippos Must be Culled to Halt Biodiversity Disaster - Scientists, Guardian (Feb. 9, 2021), https://www.theguardian.com/world/2021/feb/10/pablo-escobars-hippos-must-be-culled-to-halt-biodiversity-disaster-scientists.

[7] D.N. Castelblanco-Martínez et al., A Hippo in the Room: Predicting the Persistence and Dispersion of an Invasive Mega-Vertebrate in Colombia, South America, 253 Biological Conservation Article 108923, 3 (2021).

[8] Id.

[9] Id.

[10] Assoc. Press, supra note 6.

[11] Id.

[12] Id.

[13] Jacob Dembitzer, The Case for Hippos in Colombia, Isr. J. Ecology & Evolution, 2017 at 5, 5.

[14] See Castelblanco-Martínez, supra note 7, at 3.

[15] What are the World’s Deadliest Animals?, BBC (June 15, 2016), https://www.bbc.com/news/world-36320744.

[16] Castelblanco-Martínez, supra note 7, at 9. The hippo broke a local farmer’s leg and multiple ribs. Sarah Kaplan, Invasion of the Hippos: Colombia is Running Out of Time to Tackle Pablo Escobar’s Wildest Legacy, Wash. Post (Jan. 11, 2021, 12:16 PM), https://www.washingtonpost.com/climate-environment/2021/01/11/invasive-hippos-escobar-colombia-castrate.

[17] Castelblanco-Martínez, supra note 7, at 9.

[18] Id.

[19] Id.

[20] Id. Although some scientists argue that the threat is overblown and that the hippos fill a vital ecological role that benefits the Basin. Dembitzer, supra note 13, at 6.

[21] Rahul Nagvekar, Zoo Gone Wild: After Escobar, Colombia Faces His Hippos, Politic (Mar. 8, 2017), https://thepolitic.org/zoo-gone-wild-after-escobar-colombia-faces-his-hippos.

[22] See Average Salary in Colombia 2021, Salary Explorer, http://www.salaryexplorer.com/salary-survey.php?loc=47&loctype=1 (last visited Aug. 12, 2021).

[23] Fernando Duarte, Pablo Escobar: Why Scientists Want to Kill Colombia’s Hippos, BBC News (Feb. 11, 2021), https://www.bbc.com/news/world-latin-america-56011594.

[24] Id.

[25] Christie Wilcox, Could Pablo Escobar’s Escaped Hippos Help the Environment?, Nat’l Geographic (Jan. 31, 2020), https://www.nationalgeographic.com/animals/article/colombia-cocaine-hippos-rewilding-experiment-news (transporting one juvenile in 2018 cost USD 4,500).

[26] See, e.g., Brian Straight, From A to Z: How Animals Get to Aquariums and Zoos, and Everywhere in Between, FreightWaves (Aug. 20, 2019), https://www.freightwaves.com/news/from-a-to-z-how-animals-get-to-aquariums-and-zoos-and-everywhere-in-between (discussing how national transportation of large mammals alone can cost hundreds of thousands of dollars).

[27] Kaplan, supra note 16.

[28] See id.

[29] Nagvekar, supra note 21.

[30] Id.

[31] Id.

[32] Duarte, supra note 23. One researcher reported receiving death threats shortly after releasing her paper in 2021. Id.

[33] See, e.g., Dembitzer, supra note 13, at 5.

[34] Id.; Wilcox, supra note 25.

[35] Wilcox, supra note 25.

[36] See Kaplan, supra note 16.

[37] Compare Dembitzer, supra note 13 (arguing that the hippos fill a vital ecological niche currently missing in the Basin), with Castelblanco-Martínez, supra note 7 (arguing that the hippos are an invasive species detrimental to the Basin).