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12-20-2019
Potential ecological and socio-economic effects of a novel megaherbivore introduction: the hippopotamus in Colombia
Amanda L. Subalusky
Elizabeth P. Anderson
German Jimenez
David Post
David Echeverri Lopez
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This work is brought to you for free and open access by the College of Arts, Sciences & Education at FIU Digital Commons. It has been accepted for inclusion in Department of Earth and Environment by an authorized administrator of FIU Digital Commons. For more information, please contact [email protected]. Authors Amanda L. Subalusky, Elizabeth P. Anderson, German Jimenez, David Post, David Echeverri Lopez, Sebastian Garcia-R., Laura J. Nova Leon, Juan R. Reatiga Parrish, Ana Rojas, Sergio Solari, and Luz F. Jimenez-Segura Review Potential ecological and socio-economic effects of a novel megaherbivore introduction: the hippopotamus in Colombia
A MANDA L. SUBALUSKY,ELIZABETH P. ANDERSON,GERMÁN J IMÉNEZ D AVID M. POST,DAVID E CHEVERRI L OPEZ,SEBASTIÁN G ARCÍA-R. L AURA J. NOVA L EÓN,JUAN F. REÁTIGA P ARRISH,ANA R OJAS S ERGIO S OLARI and L UZ F. JIMÉNEZ-SEGURA
Abstract Introduced species can have strong ecological, and may pose a threat to the many inhabitants of the region social and economic effects on their non-native environ- who rely upon the Magdalena River for their livelihoods, al- ment. Introductions of megafaunal species are rare and though the species could provide economic benefits through may contribute to rewilding efforts, but they may also have tourism. Further research is needed to quantify the current pronounced socio-ecological effects because of their scale and future size and distribution of this hippopotamus popu- of influence. A recent introduction of the hippopotamus lation and to predict the likely ecological, social and economic Hippopotamus amphibius into Colombia is a novel intro- effects. This knowledge must be balanced with consideration duction of a megaherbivore onto a new continent, and raises of social and cultural concerns to develop appropriate man- questions about the future dynamics of the socio-ecological agement strategies for this novel introduction. system into which it has been introduced. Here we synthe- Keywords Colombia, ecosystem engineer, Hippopotamus size current knowledge about the Colombian hippopotamus amphibius, introduced species, novel ecosystem, population population, review the literature on the species to predict growth, rewilding, socio-ecological system potential ecological and socio-economic effects of this in- troduction, and make recommendations for future study. Hippopotamuses can have high population growth rates (–%) and, on the current trajectory, we predict there Introduction could be – individuals in Colombia by . The hippopotamus is an ecosystem engineer that can have pecies introductions are a major conservation concern, profound effects on terrestrial and aquatic environments Spresenting complex social and ecological challenges and could therefore affect the native biodiversity of the (Ehrenfeld, ; Gallardo et al., ; Courchamp et al., Magdalena River basin. Hippopotamuses are also aggressive ). Concerns may be particularly pronounced when the species in question is known to have strong effects in its native range. Much literature is focused on the detrimental effects of introduced species, but there has been recent AMANDA L. SUBALUSKY* (Corresponding author, orcid.org/0000-0001-8893- 6871) and DAVID M. POST Department of Ecology and Evolutionary Biology, discussion of the potential role of introduced species to Yale University, 165 Prospect Street, New Haven, Connecticut, 06511, USA replace species lost through extinction (Dembitzer, ; E-mail [email protected] Lundgren et al., ) and/or contribute to conservation ELIZABETH P. ANDERSON and ANA ROJAS Department of Earth and Environment, through provision of ecosystem services (Schlaepfer et al., Institute of Water and Environment, Florida International University, Miami, USA ). This discussion reveals the complexity inherent in de- termining appropriate approaches to manage introduced GERMÁN JIMÉNEZ,LAURA J. NOVA LEÓN and JUAN F. REÁTIGA PARRISH Departamento de Biología, Pontificia Universidad Javeriana, Bogotá, Colombia species (Werner et al., ; Kodric-Brown & Brown, DAVID ECHEVERRI LOPEZ Corporación Autónoma Regional de las Cuencas de los ; García-Llorente et al., ; Mascaro et al., ; Ríos Negro y Nare, Antioquia, Colombia Svenning et al., ; Svenning & Faurby, ). ‡ SEBASTIÁN GARCÍA-R. Grupo Mastozoología, Universidad de Antioquia, A recent introduction of the hippopotamus Hippo- Medellín, Colombia potamus amphibius into Colombia brings together many SERGIO SOLARI and LUZ F. JIMÉNEZ-SEGURA Instituto de Biología, Universidad de of the major research themes on species introductions. Antioquia, Medellín, Colombia The hippopotamus played an important role in ancient *Also at: Cary Institute of Ecosystem Studies, Millbrook, New York, USA ‡ Egyptian symbology, with females representing fertility Also at: Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia and males representing chaos (Pinch, ). These are Received July . Revision requested September . apt characterizations, as the species can have powerful Accepted December . and multifarious effects on its environment. In its native
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PLATE 1 (a) A hippopotamus Hippopotamus amphibius approaching tourists for food at Hacienda Nápoles, and (b) a hippopotamus in a pond outside Hacienda Nápoles.
range the hippopotamus has high rates of reproduction and population growth (Martin, ), is an ecosystem engineer that can have strong and complex effects on FIG. 1 Timeline of the introduction of the hippopotamus its environment, and can be dangerous and destructive Hippopotamus amphibius to Colombia and dispersal into the (Eltringham, ). These characteristics have been relative- Magdalena River basin. Distances in parentheses are straight line distances from Hacienda Nápoles, the point of introduction. ly well-studied in the species’ native range, in which popu- lation declines as a result of poaching and habitat loss are the primary concerns (Lewison & Pluhacek, ). The was killed in , and most of the animals were distributed recent introduction of hippopotamuses into the wild in the to Colombian zoos. The hippopotamuses, being difficult to Magdalena River basin of Colombia, the most populated transport, were left on the property, where they inhabited basin in the country, raises questions about how the species one primary pond. Hacienda Nápoles fell into disrepair, will affect this ecosystem and its inhabitants (Dembitzer, but in it was developed for tourism. By this time, ; Lundgren et al., ). there were an estimated hippopotamuses living on the Here we synthesize the history of this introduction and in- property. The population continued to grow, spreading terventions to date. We provide initial population estimates, into nearby aquatic environments (Fig. ). predicted growth rates and a range map. We review published Hacienda Nápoles is located in rolling pastureland near literature on the hippopotamus in its native range and in the town of Doradal, . km west of the Magdalena River the Magdalena River basin, to discuss the potential ecological at an altitude of m(Fig. ). There are many floodplain and socio-economic consequences of the introduction, and lakes (known as ciénagas), man-made cattle ponds, and provide recommendations for further study. small streams throughout the landscape, which seem to be facilitating the species’ dispersal. In c. hippopota- Status of the hippopotamus in Colombia muses were observed in ponds near Hacienda Nápoles. In three hippopotamuses were observed in a ciénaga In the drug trafficker Pablo Escobar imported four near the town of Puerto Berrío (c. km north of hippopotamuses (three females and one male), amongst Hacienda Nápoles). In an individual was seen in the other animals, from a zoo in the USA, for his private collec- main channel of the Magdalena River near the town of tion of exotic animals. The hippopotamuses lived in a pond Puerto Perales ( km north). In three individuals on Escobar’s ranch at Hacienda Nápoles (Plate ). Escobar were observed in the Cocorná River, a tributary of the
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FIG. 2 The currently known range of the hippopotamus in the Magdalena River, with known localities, dates and initial numbers of hippopotamuses observed.
Magdalena River, near the town of Estación Cocorná ( km growth rates, particularly at low densities (Martin, ; north). Hippopotamuses were also seen around that time in Kanga et al., ). Females can become reproductive at Ciénaga Barbacoas ( km north). In a hippopotamus years of age and can give birth to a calf every – years was again observed near Puerto Berrío. In two in- (Laws & Clough, ; Pienaar et al., ; Smuts & dividuals were seen again near Estación Cocorná over at Whyte, ). The species is long-lived (up to – years least months. Although the majority of the hippopotamus of age), reproductive for decades, and has low mortality, population in Colombia is in the main pond near as adults have few predators other than people. Life Hacienda Nápoles, these reports raise questions about the history tables developed to model hippopotamus popula- potential for this introduced species to spread across a tion growth upon reintroduction into Namibia showed wide swath of the Magdalena River basin. that populations can grow at an annual rate of –% Across its native range, which extends throughout sub- (Martin, ). In Namibia the population grew at %, simi- Saharan Africa, the hippopotamus is categorized as Vulner- lar to the rate observed in the Mara River region of Kenya able on the IUCN Red List (Lewison & Pluhacek, ). following increased protection of the population since the Populations declined by –% from the mid s to the s (Kanga et al., ). Population growth rates can be early s, and disappeared from some regions, although particularly high at low densities, as recruitment tends to they may now have stabilized (Lewison & Pluhacek, ). decline because of competition as populations approach In regions where hippopotamuses have been protected, carrying capacity (Chomba, ). their populations have rebounded, in large part a result of There are currently no census data available for the life history characteristics that promote high population Colombian population, but there are observations from
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There have been discussions about which strategies should be used to remove the hippopotamuses from the wild, but management interventions have not been straight- forward. In three hippopotamuses living near Puerto Berrío were reportedly damaging crops and scaring fishers and cattle owners. The government brought in specialists to hunt and kill the hippopotamuses, helped by the Colombian military. A large male hippopotamus, known locally as Pepe, was killed, and a photograph of the team posing with the dead hippopotamus was published, prompting an outcry within Colombia. Animal rights activists took the govern- FIG. 3 Range of estimated population growth rates for the ment to court, and the subsequent ruling banned the killing hippopotamus population in Colombia, based on an initial of hippopotamuses to manage their population. In a population of four individuals and population growth rates group of Colombian researchers wrote to the government documented in low-density hippopotamus populations in Africa, and anecdotal population estimates (DEL, pers. obs.). to publicly denounce the ruling, arguing that the hippopota- muses were a large and potentially dangerous non-native people working at Hacienda Nápoles regarding both life species and should be killed before they could spread history characteristics and population estimates over time. more widely. Nevertheless, the ruling remained, and surgi- Female hippopotamuses at Hacienda Nápoles become re- cal sterilization was adopted as the official management productive at – years of age and can have a calf every strategy. Since four hippopotamuses have been steri- months, and there has been little to no mortality among lized (Betancur et al., ), but surgical sterilization is juveniles or adults. Using these traits, the life history expensive and logistically challenging. Hippopotamuses models developed for the hippopotamus in Africa suggest are particularly difficult to tranquilize for capture because the population could be growing at an annual rate of –%, they have thick skin, are frequently found in or near water in line with population growth rates observed in other low- (in which a tranquilized individual could drown), and can be density hippopotamus populations. Comparing the predic- dangerous to people in close proximity (Dembitzer, ). The tions from this estimated growth rate to population estimates ability of dominant males to mate with multiple females also for Colombia at various times over the last years, the data suggests sterilization will not be effective unless a high pro- align well, suggesting these are reasonable initial estimates of portion of males are castrated. Several individuals have been population growth for this population (Fig. ). Using the translocated to zoos but there are a limited number of facilities most recent population estimate (– individuals; DEL, with sufficient habitat and resources to support them. pers. obs.) and a constant rate of growth at –% per year, – we estimate there could be hippopotamuses in the Potential ecological effects on the Magdalena River Magdalena River Basin by . However, a growth rate of Basin nearly % per year is not unrealistic, in which case there could be . , hippopotamuses by . The Magdalena River is the largest river system in There are ongoing discussions about who is responsible Colombia, flowing , km and draining , km for the management of the Colombian hippopotamus (% of Colombia’s area). The river begins at , min population. After Escobar’s death, the Colombian Dirección the Andes Mountains and flows north-west through an Nacional de Estupefacientes (the national drug enforcement extensive valley between the eastern and central Cordilleras agency) took responsibility for his property, but because of a (Restrepo et al., ). Downstream of the convergence lack of technical expertise with large animals, responsibility of the Magdalena and Cauca Rivers, the main channel for the hippopotamuses was transferred to the environmen- flows through an extensive floodplain (, km ), the tal authority CORNARE (Corporación Autónoma Regional Momposina depression, and into the Caribbean Sea at de las Cuencas de los Ríos Negro y Nare), the provincial au- Barranquilla. The Magdalena–Cauca has one of the highest thority for management of environment and wildlife in the sediment yields of the large South American rivers, transport- region encompassing Hacienda Nápoles. The management ing Mt of sediment to the ocean annually (Restrepo & goal is to halt the growth of the hippopotamus popula- Escobar, ). The Magdalena–Cauca River basin contains tion and relocate them from the wild. Regions in which % of Colombia’s human population, and there are a num- hippopotamuses have been observed (including Puerto ber of anthropogenic activities influencing its conservation, Berrío) also include areas under the jurisdiction of including hydropower development, deforestation, urban- CORANTIOQUIA (Corporación Autónoma Regional del ization, mining, and livestock and agricultural development Centro de Antioquia), another regional environmental (Galvis & Mojica, ; Jiménez-Segura et al., ). authority in the Magdalena River Basin. There are currently dams in the Magdalena–Cauca
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River basin, and plans for additional dams, although environments (Dawson et al., ; Stears et al., ). further hydropower development is likely to have substan- These inputs may not be a significant factor at the whole- tial environmental costs (Jimenez-Segura et al., ; river scale in a river the size of the Magdalena, but the effects Angarita et al., ). of such resource loading on aquatic ecosystems can be high- The middle Magdalena River has a highly variable flow ly localized because of the tendency of hippopotamuses to regime, with peak flows in April–June and October– aggregate in pools, leading to zones of anoxia and down- November corresponding to the rainy seasons, and low stream effects (Wolanski & Gereta, ; Dutton et al., flows in January–February and July–August corresponding ). For example, aggregations in ciénagas along the to the dry seasons (Restrepo et al., ). The hydrological Magdalena River could lead to eutrophic conditions and dynamism of this river helps maintain a complex riparian/ ultimately anoxic pools, which could be harmful to aquatic floodplain habitat of inter-connected marshes, swamps and life, particularly during low water flow. As ciénagas are nur- channels that connect to the main river channel and exert a sery grounds for a wide range of aquatic species, even loca- regulatory effect on river discharge (Cormagdalena, ; lized zones of poor water quality could have negative effects Guhl, ). Seasonal changes in the river level result in on aquatic biodiversity and fisheries, particularly when high dramatic changes in the connectivity of aquatic habitats and flows reconnect these anoxic pools to other components of migration of freshwater fishes. Seasonally inundated flood- the river system (Dutton et al., ). plain lakes, known as ciénagas, provide nursery grounds Hippopotamus movements could have significant effects for native fish species, many of which are threatened on the geomorphology and hydrology of the middle (Jiménez-Segura et al., , ). As river levels and con- Magdalena River by wallowing, scouring and compressing nectivity decline, fish migrate into the main river channel in the bottom of pools, increasing the duration for which they search of spawning grounds. This regular migration sustains hold water (Naiman & Rogers, ). When hippopota- the most important fishery in the country (Jiménez-Segura muses move through densely vegetated aquatic habitats et al., ). they create paths that may form or connect ponds, or that The middle Magdalena River basin, where the hippopota- may fill with sediment in subsequent floods, altering hy- muses have been observed, has a warm and humid climate, drological connectivity and geomorphological heterogeneity with a mean annual temperature of °C and a mean annual (McCarthy et al., ). These behaviours create habitats rainfall of , mm. The natural landscape was historic- that have been shown to benefit fish in African ecosystems, ally tropical moist forest, c. % of which has been replaced such as the Okavango Delta, by creating deep pools that by anthropogenic land use, including human settlements hold water for long time periods and by increasing hy- and agro-ecosystems such as palm plantations and livestock drological connectivity into backswamp habitats (Mosepele pasture (Cormagdalena, , ). Nevertheless, the region et al., ). Such behaviours could influence ciénagas remains important for floristic (Balcázar-Vargas et al., ) along the middle Magdalena River in a similar way, increas- and avian biodiversity (Hurd & Bohórquez, ; Laverde-R. ing the duration of inundation and hydrological connec- et al., ), and is home to the Critically Endangered brown tivity with the Magdalena River, which may help maintain spider monkey Ateles hybridus, one of the most threatened open channels and pools that would otherwise be filled Neotropical primates (Aldana et al., ;Linketal., with sediment from land-use change. However, the life his- a), and the Vulnerable Antillean manatee Trichechus tories of aquatic plants and animals in this ecosystem are manatus (Deutsch et al., ). tightly linked to the ecosystem’s hydroperiods, and any Hippopotamuses could have potentially significant eco- changes are likely to alter the composition of aquatic plant logical effects on the ecosystems of the middle Magdalena and animal communities in unpredictable ways. For ex- River, as they are capable of modifying their physical envi- ample, the ecological importance of ciénagas and their ronment in a way that alters habitat and resource availability macrophyte communities as nursery habitat for larval and for a range of other species (Eltringham, ; Moore, ; juvenile fish partly depends upon their separation from Bakker et al., ). Hippopotamuses wallow in aquatic the mainstem channel at low flows and associated protec- environments, which can include rivers, lakes and wetlands, tion from other, larger predators; this could be compro- during the day and at night graze on the adjacent land. mised by increased hydrological connectivity with the An individual can transport kg dry mass per year of car- main river. These habitats also provide important feeding, bon and nutrients from terrestrial to aquatic ecosystems via resting and breeding sites for Antillean manatees (Mojica- defecation and excretion (Subalusky et al., ). These re- Figueroa et al., ), raising the possibility of intra- source subsidies can influence aquatic productivity in com- specific interactions between these two aquatic species. plex ways (Subalusky et al., ). Low to moderate levels of Hippopotamuses coexist with the African manatee Tri- resource input may stimulate productivity and provide food chechus senegalensis in West Africa, but we are not aware resources for aquatic insects and fish (Masese et al., ). of any research that has examined interactions between High levels of input can decrease productivity in benthic them.
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The movement of hippopotamuses between aquatic and depends directly upon the river and its waterways (Galvis terrestrial habitats creates paths on riverbanks and increas- & Mojica, ), and the further expansion of the hippopota- es connectivity between riparian and aquatic ecosystems mus into this ecosystem is likely to affect these livelihoods. (Naiman & Rogers, ), which may become a conduit Hippopotamuses are territorial and aggressive, and could for terrestrial nutrients and sediment into the aquatic eco- pose threats to fishermen and cascajeros (people who extract system from overland flows (Jacobs et al., ), and may sand and rocks from the riverbed), who frequently use the also allow expansion of wetlands into the surrounding ter- side channels and shallow waterways likely to be favoured by restrial ecosystem (McCarthy et al., ). Such movements hippopotamuses. Some local people have already changed could expand ciénagas in the middle Magdalena into sur- their behaviour to avoid encounters with hippopotamuses rounding habitats utilized by people and livestock, and (LJS, pers. obs.). could influence riparian vegetation by destabilizing river- The species’ nocturnal terrestrial foraging, which is banks and altering the hydrological regime. typically over – km but can be up to – km inland In terrestrial systems, hippopotamuses alter biodiversity (Eltringham, ), could also have socio-economic effects. through grazing patterns. Their mouth morphology enables In Africa conflict with the species arises from their de- them to graze close to the ground, cropping grass and forbs struction of agricultural crops, particularly during droughts at their base (Eltringham, ). This creates grazing lawns, (Post, ; Kanga et al., ). Crops cultivated within which influence the species composition of the vegetation – km of the middle Magdalena River and its ciénagas and that of ungulates that graze there (Lock, ;Kanga could be at risk, and this would be challenging for et al., ). There has been a large degree of conversion small-scale farmers. Hippopotamuses also pose risks to from native landcover to agroecosystems in the Magdalena human safety, particularly when they are on land. Across River basin, so it is unlikely hippopotamuses will have a sig- sub-Saharan Africa numerous deaths are attributed annual- nificant effect on the native terrestrial vegetation. However, ly to the species (Kanga et al., ). Any communities living their focal zones of activity along riparian corridors are im- within km of the current range of the species in Colombia portant for faunal diversity (Link et al., b; Sandoval-H (Fig. ) need to be educated about the risks and how to et al., ), which could lead to effects in areas that have avoid them. escaped conversion. Hippopotamuses also supplement their At its current density, the hippopotamus may be per- grazing with aquatic macrophytes when available (Grey & ceived positively by some people living in the region. Harper, ), which could negatively impact macrophyte Hippopotamuses around Hacienda Nápoles have become communities in the ciénagas that provide fish nursery habitat. a tourist attraction, advertized by the water and theme park and celebrated with statues and signs by local businesses in Doradal, seemingly to appeal to tourists. Potential socio-economic effects in the Magdalena Residents have become accustomed to seeing hippopota- River basin muses walking within the city limits in the evenings. Further research is needed to adequately characterize The Magdalena River is vital for transport and commerce people’s perceptions of the species in Colombia and their for a large swath of Colombia. It produces % of the total assessment of the costs and benefits associated with the thermal energy and % of the hydroelectric power gener- introduction. ated in the country (Cormagdalena, ; Jimenez-Segura et al., ). The middle Magdalena was historically impor- tant for commercial navigation, but sediment accumulation Discussion has reduced the main channel’s depth and prevented the navigation of large ships (Cormagdalena, ). The ma- The middle Magdalena River basin is in the nascent stages jority of artisanal fishing in Colombia is located in the of the introduction of a non-native megaherbivore, but little Magdalena basin, with , artisanal fishers in the middle is as yet known beyond anecdotal information about the Magdalena (Cormagdalena, ), but the river’s fishery has current status of the population and its potential ecological declined since because of unsustainable fishing prac- and social effects (Dembitzer, ). Research is required to tices, construction of reservoirs, and changes in land use document this novel occurrence, to contextualize it within resulting in anthropogenic contamination (Cormagdalena, the current scientific understanding of introduced species ; Galvis & Mojica, ; Jiménez-Segura et al., ). and human–wildlife interactions, and to inform resource Increasing extraction of sand and rocks from the river bed managers and local stakeholders confronting the realities for infrastructure construction is a new challenge for river of this introduction. We offer three recommendations for conservation. further study. A large proportion of socio-economic development and Firstly, we need a better understanding of the current human livelihoods in the middle Magdalena River basin and predicted future population size. The estimates we have
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provided, which span an order of magnitude, are based of accidental rewilding, functionally replacing historical- upon anecdotal accounts of the current population size. A ly native megafaunal species that went extinct . , comprehensive survey is required, to refine this estimate. years ago at the end of the Pleistocene (Dembitzer, ; We also need more information on life history characteris- Lundgren et al., ). It has been suggested there is poten- tics of this population (age at maturity, fecundity and mor- tial for rewilding in South America because of the absence tality), to improve population growth estimates, and on the of megafauna, and megaherbivores in particular, compared potential fitness costs of inbreeding depression, given the to both prehistorical and historical baselines (Svenning & small founding population of four individuals, with only Faurby, ), suggesting the hippopotamus could provide one male (Huisman et al., ). These data would facilitate ecological functions that were lost with the extinction of predictions of population growth under different manage- taxonomically different but functionally similar species. ment scenarios and help resource managers determine the In addition, the establishment of a robust hippopotamus best response to this introduction. population in South America could have conservation Secondly, coincident with the population survey, the cur- benefits, as hippopotamus populations in their native range rent range of the species needs to be confirmed. The char- of sub-Saharan Africa have, until recently, been declining acteristics of potential habitat for hippopotamuses could be (Lewison & Oliver, ; Lewison & Pluhacek, ). The po- used to develop a habitat suitability map for prediction of tential costs and benefits of this introduction must be careful- the geographical spread of the species. Together, these tools ly weighed to determine the most appropriate response. could allow researchers and environmental authorities to The eradication of an introduced species after it has be- determine the likelihood of the potential expansion of the come established can be difficult and expensive, and it is im- hippopotamus into other regions and countries. perative to decide early in the introduction how the species Thirdly, a study is needed of the ecological and socio- will be handled, and then to properly fund the desired ap- economic effects that the species is already having and proach (Puth & Post, ). The current policy is to halt the may have in the future. This introduction provides a unique growth of the population, and ultimately relocate them from opportunity to examine how hippopotamuses may influ- the wild, but not by culling. It is important to predict the ence ecological functions through provision of resource future distribution of hippopotamuses in Colombia in re- subsidies to aquatic ecosystems, alteration of terrestrial sponse to current management approaches and the likely and aquatic vegetation communities through grazing and social and ecological effects across this range to inform disturbance, and influence on riparian and hydrological the decision-making process sufficiently (Ricciardi et al., connectivity. We also need to identify any native flora and ; Jeschke et al., ). Consideration also must be fauna that could be sensitive to the effects of the species’ taken of local perceptions of hippopotamuses and proposed presence, to understand potential effects on humans and methods of controlling their spread, to avoid conflict over their livelihoods, and to predict and mitigate negative inter- proposed management actions (García-Llorente et al., ; actions between humans and hippopotamuses. The latter Crowley et al., ). A complex confluence of history, culture will require an understanding of people’s perceptions of and environment in Colombia have set the stage for this risk and engagement in participatory planning for any inter- novel, and unintended, ecological introduction of hippopot- ventions (Treves et al., ). amuses into the Magdalena River basin. Research and infor- The introduction of novel species can have major rami- mation sharing will be critical for management authorities fications for native ecosystems and the human populations as they navigate an array of potential social, ecological and that depend upon these ecosystems. There are already a financial concerns in their response to the introduction. number of non-native mammal species in Colombia, several of which are considered invasive (Ramírez-Chaves et al., Acknowledgements Funding was provided by a grant from the National Geographic Society to EPA (W447-16) and by grants from the ). These species can impact native biodiversity directly US National Science Foundation to DMP (DEB 1354053, 1753727). This and managing them draws limited funding away from is contribution no. 929 from the Southeast Environmental Research conservation of native species. In South America the intro- Center in the Institute of Water & Environment at Florida International duced beaver Castor canadensis, for example, has altered University. We thank colleagues in Colombia for sharing valuable infor- large areas of native forest and led to changes in species mation about introduced hippopotamuses, especially historical accounts, and A. Farah and G. Herrera for creating the map. composition and ecosystem function (Anderson et al., ; Anderson & Rosemond, ); the introduction of Author contributions Compilation of historical information and the hippopotamus could have similar effects on native literature review: all authors; development of population estimate: habitats in Colombia. AS, DP; writing: all authors. Alternatively, in a time of global defaunation, the estab- Conflicts of interest None. lishment of a new megaherbivore population could have benefits (Dirzo et al., ; Lundgren et al., ). The intro- Ethical standards This research abided by the Oryx guidelines on duction of the hippopotamus in Colombia may be a form ethical standards.
Oryx, Page 7 of 9 © 2019 Fauna & Flora International doi:10.1017/S0030605318001588 Downloaded from https://www.cambridge.org/core. IP address: 107.221.181.201, on 08 Jan 2020 at 16:53:17, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605318001588 8 A. L. Subalusky et al.
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