Potential ecological and socio-economic effects of a novel megaherbivore introduction: the hippopotamus in Colombia

Abstract

Introduced species can have strong ecological, social and economic effects on their non-native environment. Introductions of megafaunal species are rare and may contribute to rewilding efforts, but they may also have pronounced socio-ecological effects because of their scale of influence. A recent introduction of the hippopotamus Hippopotamus amphibius into Colombia is a novel introduction of a megaherbivore onto a new continent, and raises questions about the future dynamics of the socio-ecological system into which it has been introduced. Here we synthesize current knowledge about the Colombian hippopotamus population, review the literature on the species to predict potential ecological and socio-economic effects of this introduction, and make recommendations for future study. Hippopotamuses can have high population growth rates (7–11%) and, on the current trajectory, we predict there could be 400–800 individuals in Colombia by 2050. The hippopotamus is an ecosystem engineer that can have profound effects on terrestrial and aquatic environments and could therefore affect the native biodiversity of the Magdalena River basin. Hippopotamuses are also aggressive and may pose a threat to the many inhabitants of the region who rely upon the Magdalena River for their livelihoods, although the species could provide economic benefits through tourism. Further research is needed to quantify the current and future size and distribution of this hippopotamus population and to predict the likely ecological, social and economic effects. This knowledge must be balanced with consideration of social and cultural concerns to develop appropriate management strategies for this novel introduction.

Wild and trapped: a history of Colombian zoos and its revelations of animal fortunes and State entanglements, 1930s-1990s

“…By managing to survive and reproduce without human assistance, these mammals have become an invasive species. Fecundity is a known trait in hippos: females can start having offspring at three years of age, and can bear a calf every two or three years for up to four decades (Subalusky et al, 2021)! Although the original group came from the United States, hippos are African herbivores that are still found, in declining numbers, in various spots across West, Central, and East Africa.…”

“…Three more male hippos have been castrated, but the herd continues to grow, and occasionally scare and injure neighbors (Suárez, 15 Mar. 2011;Subalusky et al, 2021). Like Escobar's, the hippos' fame goes well beyond Colombia; they appear in YouTube videos, have starred in several documentaries, and are the subject of scholarly articles (Pablo's..., 2009(Pablo's..., , 2012Los hipopótamos..., 2011).…”

Science denialism limits management of invasive hippos in Colombia

“…Following Escobar's fall, hippos escaped confinement and invaded floodplains in the Middle Magdalena River basin. Ample suitable habitat and the absence of natural enemies have allowed the hippos to proliferate, which are now having overt impacts on social and ecological systems throughout the region (Subalusky et al 2019;Shurin et al 2020).…”

Gorgeous villains

“…Environmental agencies attempts to control their reproduction have had no impact on population growth, and nowadays an estimate of between 93 and 102 hippos inhabit an area of around 2,000 square kilometers (Castelblanco-Martínez et al 2021). Empirical evidence has demonstrated that hippos are important drivers of habitat modification, being capable to dramatically change the chemical and structural features of aquatic and terrestrial ecosystems (Stears et al 2018;Subalusky et al 2019). In the long term, this may pose an important risk to many native species and environmental services.…”

“…In the last years, several research teams have addressed this case from the ecological point of view (e.g. Castelblanco-Martínez et al 2021;Shurin et al 2020;Subalusky et al 2019), providing necessary input for the debate. However, we need a transdisciplinary approach to solve the dilemma related to the management of this non-native species in Colombia.…”