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African Zoology
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/tafz20
A review of some aspects of the ecology,
population trends, threats and conservation
strategies for the common hippopotamus,
Hippopotamus amphibius L, in Zimbabwe
Beaven Utete
To cite this article: Beaven Utete (2020): A review of some aspects of the ecology, population
trends, threats and conservation strategies for the common hippopotamus, Hippopotamus
amphibius L, in Zimbabwe, African Zoology, DOI: 10.1080/15627020.2020.1779613
To link to this article: https://doi.org/10.1080/15627020.2020.1779613
Published online: 26 Aug 2020.
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African Zoology 2020: 1–14
Printed in South Africa — All rights reserved
Copyright © Zoological Society
of Southern Africa
AFRICAN ZOOLOGY
ISSN 1562-7020 EISSN 2224-073X
https://doi.org/10.1080/15627020.2020.1779613
African Zoology is co-published by NISC (Pty) Ltd and Informa UK Limited (trading as Taylor & Francis Group)
This is the nal version of the article that is
published ahead of the print and online issue
Systematic review
A review of some aspects of the ecology, population trends, threats and
conservation strategies for the common hippopotamus,
Hippopotamus amphibius L, in Zimbabwe
Beaven Utete*
Department of Wildlife Ecology and Conservation, Chinhoyi University of Technology, Chinhoyi, Zimbabwe
*Correspondence: beavenu@gmail.com
This review explores some ecological aspects of the common hippopotamus (hippo), Hippopotamus amphibius L,
threats to its population and contextual peculiarities affecting its conservation in selected water systems
in Zimbabwe. Scoping surveys of literature and thematisation of common issues related to hippo ecology,
human-hippo conflict and conservation were used for data collection. Hippos play integral ecological roles, such
as habitat engineering through track creation in water systems, nutrient recycling by swirl spread of highly organic
faeces, harbouring commensal water birds, parasites and leeches. Regardless, the hippo population is not well
documented for the country with indications of sharp declines in freshwater systems during the period 1982 to
1992 and gradual recovery thereafter. Habitat degradation, water pollution, climate change, drought-induced
extreme water level fluctuation, poaching and deliberate culling, as part of problem-hippo control (PHC), are key
drivers of hippo population declines. However, it appears much of the attention is on human-hippo conflict and
its consequences, resulting in negative perceptions among human communities. Commercial breeding of hippos
for non-consumptive tourism, and export-orientated meat, and ethnomedical mimics of hippo sweat and milk
products are new, potentially viable, but unexplored options for conserving and increasing the population of the
species in Zimbabwe. Currently, it appears more anti-hippo poaching patrols and awareness campaigns especially
in water systems outside protected areas may be key to sustaining the current hippo population. For the future, it is
essential to increase the scope for hippo census data to include water systems inside and outside protected areas
for sustainable conservation of the species in the country.
Keywords: ethnomedicine, freshwater conservation, human-hippo conflict, sustainability
Global conservation concerns on hippo population
The common hippopotamus, Hippopotamus amphibius L,
(hereafter referred to as hippo) is found throughout
sub-Saharan Africa (Kingdon 2015). Hippos are widely
denoted as an ecosystem engineer, bioengineer and iconic
species in many freshwater systems because their activities
profoundly affect and modify the landscape (Lock 1972;
Subalusky et al. 2015). Rangewide, hippo populations
have been declining in developing sub-Saharan African
countries, such as Zimbabwe, South Africa, Zambia,
Democratic Republic of Congo and Namibia (Eksteen et al.
2016; Linchant et al. 2018). A number of factors (e.g. habitat
fragmentation, climate change, droughts and poaching)
have been cited as key drivers of hippo population declines
worldwide (Eksteen et al. 2016; IUCN 2016). In relatively
more developed African nations (e.g. South Africa), long-term
and consistent hippo censuses, that have produced
accurate hippo population estimates, have contributed to
the conservation of the species (IUCN 2016). For resource
challenged African and South American countries (e. g.
Colombia, which has an entirely non-native population), there
are no accurate and reliable hippo population estimates, a
situation that has resulted in confusion over the conservation
status of hippos in the respective countries (IUCN 2016).
The missing key is a comprehensive review, re-examination
and analysis of the few available and fragmented hippo
population data in each country and then consolidation of the
data on a global scale, as indicated by Eksteen et al. (2016)
and IUCN (2016) to develop accurate hippo population
estimates. Accurate hippo population estimation allows the
formulation of pragmatic conservation initiatives best suited
for the unique contextual reality on the ground for each
country (Eltringham 1999; Linchant et al. 2018).
Eksteen et al. (2016) indicated that despite being an iconic
African species, relatively little is published on aspects of the
social behaviour and ecology of hippos in general, even on
a global scale. This reflects that a metapopulation approach
may be required to understand the threats and opportunities
for hippo conservation in developing countries, such as
South Africa, Mozambique, Zambia and Zimbabwe (Eksteen
et al. 2016; IUCN 2016). Accordingly this review paper
seeks to explore some ecological aspects of the common
Introduction
Published online 26 Aug 2020
Utete
2
hippo, Hippopotamus amphibius L, threats to its population
and contextual peculiarities affecting its conservation with
recommendations for future sustainability of the species
in water systems of Zimbabwe. Firstly, the paper explores
some pertinent ecological aspects of hippos that tend to
affect their population dynamics, such as feeding ecology,
its role as a terrestrial/aquatic ecosystem engineer species,
social behaviour, and then briefly reviews issues around the
conservation status of hippo globally, before contextualising
the situation for Zimbabwe and then concludes with a
segmented discussion of the threats, conservation strategies
and opportunities for sustainable commercial utilisation of
hippos for the benefit of humans. The basic idea is that for
effective hippo conservation and reduction in human-hippo
conflict there is a requirement to first accurately estimate
the entire hippo metapopulation and its distribution.
Secondly, it is imperative to identify and examine threats
to hippo populations in wetlands located inside and outside
protected areas. Afterwards, formulation of practical hippo
conservation strategies for sustainable utilisation and
implementation in Zimbabwe and sub-Saharan African
countries will be possible (Eksteen et al. 2016).
Hippos as aquatic ecosystem engineers
Hippos spend the nights grazing in the savanna and during
daytime wallowing in shallow pools to keep cool and escape
the sun (Lewison 2011). Hippos defaecate in water and their
excreted waste enriches the nutrients in water resulting in
favourable conditions for diatoms, macroinvertebrates and
large fish populations (Olivier and Laurie 1974; Onyeanusi
1999; McCauley et al. 2015). Some fish populations, including
Labeo spp. were observed to feed on microorganisms
and algae that grow on hippo skin especially around
the hooves (Onyeanusi 1999). The African mud catfish,
Clarias gariepinus, thrive on the mineral rich detritus,
macroinvertebrates and macrophytes that grow in hippo
tracks (Onyeanusi 1999; Dawson et al. 2016). As hippos
wallow, they excrete waste, which in some cases deplete
oxygen from the water as it decomposes (Olivier and Laurie
1974). Microbial activity in hippo dung and tracks also produce
chemicals like ammonium and sulphide, known to be toxic to
fish (Bengis et al. 2016; Dutton et al. 2018; Stears et al. 2018).
This has resulted in several fish kills in hippo-infested water
systems (Mosepele et al. 2009; Wolanski and Gereta 1999;
Dawson et al. 2016; Dutton et al. 2018).
In hippo pools, hippo wallowing activity tends to positively
correlate with the depth and area of the pool, and partially
determines the changes in the distribution of oxygen levels
in such pools (Dutton et al. 2018). Hippo dung, which tends
to be dropped at the littoral shoreline edges, has been
shown to increase fish predation by terrestrial consumers
and birds, because the fish will be exposed when they are
feeding on the nutritious dung (Stears and McCauley 2018).
Moreover, hippo dung influences the distribution of oxygen
in the water column, with highest oxygen levels being
found at the water surface. Fish alter their behaviour and
move to the water surface to access the oxygen. In doing
so, this exposes them to terrestrial predators. As a result,
hippos directly move nutrients from terrestrial to aquatic
systems, but also indirectly move nutrients back to terrestrial
consumers (Stears and McCauley 2018).
Hippos as terrestrial ecosystem engineers
Hippos play pivotal roles in the terrestrial ecosystem,
primarily, as megaherbivores preferring short palatable
grasses normally in the drawdown zones adjacent to
rivers and reservoirs (Utete et al. 2017). Kingdon (1979),
Cerling et al. (2008) and Timbuka (2012) indicate that
despite their biological requirements for an aquatic habitat,
hippos hardly graze on macrophytes and hydrophytes,
rather they feed mostly on terrestrial vegetation. Hippos
feed on short sweet grasses (Eltringham 1999) although
contemporary stable isotope studies indicate that they
may also feed on dicotyledonous shrubs, forbs and small
trees (Cerling et al. 2008). In the process, hippos play a
critical role in determining vegetation composition, and
by also defaecating on land they aid nutrient cycling for
instance by adding silicon, phosphorus, and nitrogen
(Schoelynck et al. 2019), especially in the drawdown zone
and peripheral areas (Utete et al. 2017). Terrestrial hippo
tracks also act as small ephemeral pans in the wet season
with a succession of plant communities and associated
microflora and microfauna, such as invertebrates (Eksteen
et al. 2016). O’Connor and Campbell (1986) indicate that
hippos and competing herbivores, such as impala, exert
grazing pressure on drawdown zone vegetation, resulting
in the degradation of the river banks through the formation
of gulleys and channels. Some of the gulleys formed by
hippos serve as habitats for small mammals, such as
squirrels and hedgehogs (O’Connor and Campbell 1986).
Hippo feeding ecology
In terms of feeding ecology, a hippo is categorised as
an obligate herbivore favouring short grass and plants
(Owen-Smith 1988; Eltringham 1999; Grey and Harper
2002; Kanga et al. 2013). Other research on water systems
in east, western and southern Africa indicates that in
times of drought and dire herbage shortages (Mugangu
and Hunter 1992), hippos can also eat flesh and are
cannibalistic (Dudley 1996, 1998; Dorward 2015; Dudley
et al. 2016). Some studies have indicated that hippos are
facultative carnivores that can feed on intestinal tissues
from the carcasses of other animals (Lewison 1998; Dutton
and Subalusky 2011; Dudley et al. 2016). Regardless,
there is extensive research showing that hippos are grazers
that supplement with shrubs and other vegetation, and on
odd occasions have been observed ‘feeding’ on carcasses
(Field 1970; Lock 1972; Scotcher 1974; Scotcher et al.
1978; Lewison and Carter 2004; Zoeller and Bond 2013;
Subalusky et al. 2014). This is a crucial element in that it
defines the way hippos use ecosystems, which tend to also
determine their population dynamics in terms of recruitment
and dispersal (Lock 1972; Lewison and Carter 2004;
Clauss et al. 2013).
Social and reproductive behaviour of hippos
The social and reproductive behavioural systems of hippos
are complex comprising solitary individuals, typically bulls,
who forage alone especially at night (Laws 1968; Lock
1972; Klingel 1991). During the day and in aquatic habitats,
hippos are highly gregarious and territorial moving in
pods (Owen-Smith 1988; Klingel 1991; Eltringham 1999;
Linchant et al. 2018). A typical hippo pod comprises calves,
African Zoology 2020: 1–14 3
juveniles, subadults and adults of both sexes (Linchant
et al. 2018). The number of hippos in a pod normally
depends on the size of the wetland (Kingdon 2015). Both
female and male hippos are highly aggressive, a trait
linked to abnormal testosterone levels (Kingdon 1979;
2015). Fights for mates and territory are common among
hippos, resulting in severe injuries and fatalities and
disaggregation of the pod in some instances (Lewison
1998). The social behaviour of hippos largely determines
the population growth of the species, because it allows
for mating, reproduction, dispersal and reconfiguration of
hippo pods in response to forage availability and habitat
suitability in the wetlands (Owen-Smith 1988; Eksteen et al.
2016). More so, hippos are K-selected in their reproduction
strategy, which implies that there must be suitable and
conducive environmental and social conditions for courtship
and mating (Owen-Smith 1992). The fact that hippos are
K-selected is important in aiding understanding of how
quickly their populations can bounce back from droughts
and or serious declines (see Pienaar 1966; Smuts and
Whyte 1981; Owen-Smith 1992, Clauss et al. 2004, 2013).
Conservation status of hippos
Worldwide, hippos are valued for tourism (game viewing
and sport hunting), or cropping (bush meat), and also
for ecosystem services provision, such as fertilizing the
aquatic habitat (IUCN 2016). However, the global hippo
population, which is estimated to be between 125 000 and
150 000, is declining at a rate of 6–8% per annum resulting
in current efforts to reclassify the species as threatened
from vulnerable on the IUCN red list (IUCN 2016). With the
lack of adequate population data, because of the absence
of long-term hippo censuses in Zimbabwe, and most
African countries, the wildlife authorities have a tendency
of following the IUCN classification system on hippos with
little regard to the actual situation in aquatic systems (Erb
et al. 2001; Linchant et al. 2018). Accordingly, there is a
requirement for a review of hippo conservation status in
most African countries.
Habitat degradation (Lewison and Oliver 2008b), drought
(Cole 1992), water pollution (IUCN 2016), water level
fluctuation (Viljoen 1995; Viljoen and Biggs 1998; Stommel
et al. 2016), climate change, poaching and retributive
killings by humans (Linchant et al. 2018) comprise some
key factors affecting the global hippo population. Changing
land-use patterns in developing countries highlighted by
water system modification and destruction, deforestation
and settlement encroachment towards lakes and rivers,
account for loss of hippo habitats and grazing lands
(Nchanji and Fotso 2006; Eltringham 2010; Chansa
et al. 2011; Kanga et al. 2011, 2013). Regardless, the
conservation status of hippos is largely unknown for most
developing countries, such as Zimbabwe, because of
logistical challenges and poor management, resulting
in misinformed classification of the species as least
threatened or vulnerable on the red list of threatened
species (IUCN 2004, 2016; Lewison and Pluháček 2017).
The contextual situation for Zimbabwe
Zimbabwe, is a developing country and has a human
population close to 14 million, with agriculture-, mining- and
wildlife-based tourism as the mainstay of the economy
(ZIMSTAT 2012). The Gross Domestic Product (GDP) of the
country has been constantly changing from 13% in 2009 to
4.5% in 2018, because of the constant change in national
currency, which normally consists of simultaneous circulation
of bond notes and a basket of international currencies.
Majority of the population (approximately 86% of the people)
are unemployed and live on less than one American dollar
per day (ZIMSTATS 2012). The country waged a protracted
liberation struggle, which intensified from 1972 to 1979. In
addition, there were intermittent severe drought periods
in 1984 and 1992 to 1994. The combined effects have
threatened hippo habitats, reduced hippo recruitment,
exacerbated human-hippo conflict, and increased human
fatalities (Marshall 2011). However, the threats tend to
differ in magnitude and intensity, consequently there is a
requirement for a comprehensive review of the risks facing
the hippos in a Zimbabwean context.
This review paper explores the ecology, population
trends, threats, human-hippo conflict and the opportunities
for conservation of hippos in Zimbabwean dams and
rivers. The aim was to highlight some aspects of hippo
ecology and establish factors affecting its population and
conservation with recommendations for future sustainability
of the species.
Materials and methods
A dataset of research articles on hippos was compiled
from all available databases in the commonly used ISI
Web of Knowledge (ISI WoK), with no historical cut off
dates. This study explicitly searched for studies focusing
on hippos in all subgroups of limnology, water resource
conservation and fisheries research, including fishers and
the fishing sector with reports on human-wildlife conflicts
in Zimbabwe. The terminal search terms used were as
follows: (hippopotamuses AND (“human-wildlife conflicts
in Zimbabwe*”)). The articles were ordered by relevance
under ISI Wok search criteria. From an initial list of 213
articles, the abstracts were screened for relevant items
that could be classified into four thematic areas; population
status of hippos, threats to hippos, human-hippo conflict
and conservation options for hippos in Zimbabwe. The
rationale was to screen the dataset to manageable and
relevant sizes. After thorough screening, a total of 106
items were used to reflect the breadth of the context. An
article was included if it met the following criteria: (a) It was
published in a reputable journal with a known impact factor
and a globally recognised International Standard Serial
Number (ISSN number), international organisation technical
report or a book; (b) Relevant conference proceedings
on Zimbabwean water systems; and, (c) Credible
human-wildlife conflict report in the national newspapers or
from the National Parks author sanctioned surveys. Finally,
recommendations were made from a local to global context.
Results and discussion
Population and country status of hippos
According to the IUCN Red List (2016), there are an
estimated 7 000 hippos in Zimbabwean water systems. For
Utete
4
Zimbabwe, hippo population status is categorised as having
a restricted distribution and considered as locally abundant
(RD-LA) using the IUCN (2016) country data facts. In effect,
the trend in hippo population for the country is regarded as
stable (IUCN 2012, 2016). However, there is concern about
the hippo conservation status in Zimbabwe (Zisadza et al.
2010; IUCN 2016; Utete et al. 2017). This concern arises
from the partial protection offered to hippos, because of their
highly migratory nature, which implies that they are also
found in suitable habitats outside protected reserves (Mackie
1976; Sharp 1984; Marshall 2011). There is partial legal
protection of hippos in the country, though the level of legal
enforcement is regarded as excellent (IUCN 2016).
On close analysis, such assertions (above) by the
IUCN (2016) may be far off the mark, because there has
been accelerated human encroachment into riparian
ecosystems with loss of palatable grasses and suitable
pools (Zisadza et al. 2010). In reality, in the major rivers
(e.g. Runde and Save) siltation and altered flow regimes,
because of damming and increased water abstraction
through irrigation, have resulted in the migration of hippos
into the only available reservoirs that are located in national
protected areas. National protected areas are mainly
premised on reservoirs, and offer some respite for hippos.
However, from the onset of the chaotic land reform in 2000,
there was human encroachment into protected areas and
misuse of reservoirs through pollution and poorly regulated
abstraction (Marshall 2011). Combined with climatic factors,
such as drought (Cole 1992), this resulted in the loss of
water and suitable hippo habitats even in the supposedly
protected national parks and dams in Zimbabwe.
Another topical issue relates to the lack of detailed
information on hippo conservation status and population
trends in water systems outside the reserves or protected
areas. Outside the reserves or protected areas, hippos
are prone to persecution and poaching and are a key
species in human-wildlife conflict in riparian systems in
Zimbabwe (Muboko et al. 2016). It is relatively simple to
institute traceable conservation and protection measures
for hippos in protected areas, but it is a different issue to
create and implement effective conservation measures
for hippos outside protected areas. The key question then
should interrogate the kind of conservation strategies to
be crafted and implemented for conserving hippos outside
protected reserves. Moreover, to what extent should closely
located communities be involved in the conservation of
hippos? How hippo conservation awareness programmes
may be packaged and transmitted to the communities
outside the protected reserves in an effective manner, is
a new paradigm that requires a different perspective from
traditional hippo conservation strategies that are mainly
implemented in protected reserves.
Analysis of available hippo population studies in Zimbabwe
The hippo population in Zimbabwe is stable, whereas the
conservation status is categorised as vulnerable (IUCN
2016). However, this IUCN (2016) categorisation of hippo
population for Zimbabwe appears to be primarily based
on at least twenty seven recorded and available, but
fragmented studies on hippo abundance, distribution and
population structure that have been undertaken mainly
in national protected areas or parks (e. g. Gonarezhou,
Hwange, Victoria Falls, Mana Pools, Matusadonha,
Victoria Falls and Zambezi Valley in Zimbabwe)
(Dunham 2004; IUCN 2016). What this means is that the
conservation status of hippos in Zimbabwe is based on
a few incoherent records from fragmented populations in
a few protected parks and therefore may be limited in its
scope. As such, it exposes a requirement for the country
and interested wildlife conservation agencies to conduct
a coordinated, countrywide, and thorough population
estimation of hippos in all water systems in Zimbabwe.
The following discussion examines hippo population trends
where available in Zimbabwe.
Hippo populations in the Gonarezhou National Park
The distribution of hippo studies in Zimbabwe is shown in
Figure 1. It must be pointed out that hippos are present
in large water bodies (i. e. rivers and lakes in Zimbabwe)
in and outside protected areas though their habitats are
dwindling, as a result of a number of factors (Zisadza et al.
2010). In-depth analysis of literature indicated that at least
twenty-two hippo population surveys have been conducted
for the protected areas, such as Gonarezhou National
Park (GNP), focussing on the main rivers, Runde (formerly
Lundi), Save and Mwenezi (see Mackie 1973, 1976; Sharp
1984; Zisadza et al. 2010; Chinho et al. 2015). Studies by
Mackie (1976) recorded an estimated total of >750 hippos
in the Lundi River in the Lowveld region of Zimbabwe.
Mackie’s (1976) data from the Lundi River (now Runde
River) indicated a density of 4.5 hippos km−2 in GNP.
Considering that the Runde River has a total length of 418
km and only approximately 171 km of the river passes
through GNP, an estimated 769 hippos live in the stretch
of river covering the protected national park. However,
intermediate disturbances, such as siltation and human
induced destruction of suitable hippo habitats is rife in the
sections of the river inside and outside the protected GNP
(see Mackie 1973; Zisadza et al. 2010; Chinho et al. 2015).
A simple insight that suggests that protecting suitable
habitats is a plausible conservation strategy to maintain a
stable hippo population
O’Connor and Campbell (1986) indicated that the hippo
population on the Lundi River in GNP increased by 330%
between 1958 and 1980 to reach an estimate of >810
hippos. Follow-up studies within GNP by Zisadza et al.
(2010) showed a total of 187 hippos mainly confined to the
Runde River. Analysis by Zisadza et al. (2010) indicated
that the highest and lowest hippo population for the period
between 1965 and 2008 in GNP were recorded in 1982 and
1992, with counts of 822 and 27, respectively, although
numbers have fluctuated through the period (Figure 2).
Close analysis of the trends starting from the study by
Mackie (1973), which recorded >750 hippos, to the study
by Sharp (1984), which recorded between 810 and 850
hippos in 1980 within GNP, indicate an 8% increase in the
hippo population with approximately 60–70 hippos recruited
during the period 1973 to 1980.
The period 1973–1979 represents an intense phase in
the armed struggle for independence with heavy casualties
in human and wildlife in the Lowveld area in Zimbabwe.
Accordingly, it is plausible that hippos migrated into the
African Zoology 2020: 1–14 5
more protected GNP to avoid persecution hence the
increase in the estimated numbers during this period
1973–1980 (Sharp 1984). However, the fact that only nine
(9) hippos were added to the population may be explained
by the reproductive ecology of the species. Hippos, as
K-selected species, have a gestation period of close to
246 days, and normally start reproducing on average at
6–14 years of age (Erb et al. 2001); factors that may be
responsible for the 8% increase in the population over a
period of nearly ten years (Laws and Clough 1966; Dudley
1998). For GNP, however, there are no accurate estimates
of the real extent of suitable hippo habitats for reproduction
and, hence, no accurate carrying capacity estimates
that indicate constant survival rates of the adults could
be established for the park (Gaillard et al. 1998, 2000).
Smuts and Whyte (1981) indicated that there is a positive
correlation between the availability of suitable grazing
matter, wading habitats, adequate mating space for hippos
and recruitment rate in any given wetland disregarding
human disturbance. It reflects that there is a necessity to
accurately estimate suitable hippo habitats for mating and
reproduction in order to accurately estimate the carrying
capacity of any given wetland (Linchant et al. 2018).
From 1980 to 1982, the estimated hippo population in
GNP slightly decreased from 850 to 822, a decline of 3.4%
(Figure 2). In effect, it just shows that the hippo population
remained stable from 1980 to 1982 in GNP; with the
change in 28 hippos attributable to weather or hippos being
out of water at the time of sampling or a number of other
factors. Sharp (1984) indicated that human encroachment
into GNP by demobilised freedom fighters resulted in a
slight reduction in the hippo population mainly attributed to
poaching by humans. More pertinently, the two studies by
Mackie (1973) and O’Connor and Campbell (1986), used
different methods of estimating hippo populations that
might explain the subtle differences in the estimates.
AFRICA
Zimbabwe
16° S
17° S
18° S
19° S
20° S
21° S
22° S
26° E 28° E 30° E 32° E
0 100 200 km
Major Rivers
Protected areas
Zimbabwe
1
11
4
3
2
Figure 1: Map showing the numbers and distribution of documented hippo studies in Zimbabwe up to date
Utete
6
In the period 1982 to 1992, there was a drastic decrease/
crash in the hippo population in GNP from 822 to 27 in
the Runde-Save confluence, as indicated in Figure 2. The
95% decline in the hippo population within GNP may be
explained by the severe drought that occurred in 1984 and
1992, in Zimbabwe (Zisadza et al. 2010). Major rivers, such
as the Runde River dried up, and there were no suitable
habitats, resulting in massive mortalities of hippos. The
data for the period 1982–1992 is based on estimates from
anecdotal aerial and land-based, foot-patrol hippo surveys
carried out by the Parks Authority in the area (Sharp 1984,
1986; Zisadza et al. 2010). As such the accuracy may be
limited though it generally depicts a pattern highlighting
severe losses in water volume and permanence of flow in
major rivers in these drought years that resulted in massive
migration and deaths of hippos. Moreso, the most feasible
conservation strategies, such as artificial riverbed drilling
and translocation of hippos were constrained by lack of
resources, which were mainly channelled towards saving
human lives and livestock (Sharp 1984; Mazvimavi 2010).
Hippo estimates from the period 1992 (n = 27) to 2008
(n = 187) in GNP indicated that the hippo population
recovered and is steadily growing (Zisadza et al. 2010;
Chinho et al. 2015). This is expected, because the
successive years from 1992 had reasonable to above
normal rainfall levels, which enabled suitable hippo
habitats and palatable riparian grass to reestablish and
consequently hippo recruitment has been on the increase
(Zisadza et al. 2010). From the estimates in 2008 (n = 187)
to 2012 (n = 337), the hippo population in GNP has been
increasing (see Figure 2). Using the hippo population in
1992 as the base for reestablishment, there has been a
1296% increase in hippo numbers in GNP for the period
1992–2012. The increase in the hippo population within
GNP also indicates that the species is resilient enough
to adapt to the prevailing conditions such that if the
environment is conducive the population quickly bounces
back from crashes or declines similar to those induced
by droughts (Smuts and Whyte 1981; Owen-Smith 1992,
Clauss et al. 2004, 2013).
The key drivers to the increase in the hippo population
in the period 2008–2012 comprise intensification of
anti-poaching patrols in the rivers in GNP, and normal to
above normal rainfall levels in the period 2008–2012, which
ensured establishment of permanent suitable hippo habitats
and availability of palatable grass (Mazvimavi 2010; Zisadza
et al. 2010; Gandiwa et al. 2013; 2014; Chinho et al. 2015;
Mhuriro-Mashapa et al. 2018; Matseketsa et al. 2018). Of
note is that the annual variation in hippo numbers for the
different protected areas in Zimbabwe are as a result of the
different sampling techniques, but the overall trend can still be
useful. This suggests a strong case for implementing suitable
sampling techniques that are reproducible in hippo censuses.
Hippo population estimates in Manjirenji Dam in
Zimbabwe
Some fragmented hippo population surveys have been
done in Manjirenji Dam along the Chiredzi River (Utete et
al. 2017). This survey indicated at most 177 hippos over
an eight months study period in the manufactured reservoir
(Utete et al. 2017). The study was a once off survey and
does not provide long-term temporal trends in the hippo
population of the Manjirenji Dam although the estimation
could be useful in calculating the national hippo population.
The boat survey also indicated the suitability of protected
national dams, such as Manjirenji to provide habitats and
support a sizeable hippo population (Utete et al. 2017).
More pertinently, the study established that hippos tend to
move to the deepest parts of the reservoir during daylight
and track into adjacent communities to graze, potentially
clashing with humans and livestock at night (Utete et al.
2017). Additionally, hippo pods migrate into the entrance
point of the tributary Chiredzi River during periods of
intense drawdowns especially droughts. This implies that
HIPPO POPULATION
200
100
300
400
500
1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 2012
YEAR
95% Decline
Estimated Hippo population = 3.76 (yr) − 7049.9
R2 = 0.1363
Estimated Hippo population = 12.32 (yr) − 24513
R2 = 0.8366
Figure 2: Estimated hippo populations in Runde and other fringe wetlands in the Gonarezhou National Park in Zimbabwe (adapted from
Zisadza et al. 2010)
African Zoology 2020: 1–14 7
hippos also move out of the protected reservoir to look for
suitable grass and pools, and become prone to human
persecution and poaching (Matseketsa et al. 2018). It is
imperative then to estimate the population and explore
plausible conservation strategies for hippos when they are
outside protected reservoirs.
Hippo population counts in the Zambezi Valley region
in Zimbabwe
An aerial survey initiated by the African Wildlife Foundation
(AWF) led by Dunham (2004) recorded a total of 825
hippos out of the estimated national figure of 4 751 hippos
in the Zambezi Valley region of Zimbabwe. Dunham (2004)
indicated that the Mana Pools National Park, a UNESCO
Biosphere Reserve, has the largest concentration of
hippos in the country with actual observed figures of 458
hippos. The same study (Dunham 2004) in the Zambezi
Heartland of Zimbabwe found substantial hippo populations
in Hurungwe Safari Area (234), Sapi Safari Area (95),
Chewore Safari Area (4), Charara Safari Area (30) and
Dande Safari Area and Guruve Communal lands (4). Trend
analysis from the long-term annual surveys of hippos
in Hwange National Park (HNP) indicated a sustained
increase from 1972 to 2019 (Figure 3). The highest
numbers of hippos (i. e. 154 and 163) were recorded in
2016 and 2019, respectively, whereas the fewest (i. e. 6)
were recorded in 1986 (Figure 3). The low hippo numbers
observed is expected as the area is very arid such that
artificial water pumps had to be installed to provide
adequate water in the pans for the animals to survive
(Msiteli-Shumba et al. 2017). Naturally, this limits the
availability of suitable hippo habitats (Chinho et al. 2015).
Overall, the significant increase in hippo numbers over
the years in the highly arid, largest, national park (HNP)
in Zimbabwe is attributable to the increased installation
of artificial water pumps in the pans and pools (Msiteli-
Shumba et al. 2017; WEZ 2018).
The most complex issue in estimating hippo numbers
and subsequent calculation of the national population
in Zimbabwe has been the uncoordinated use of
different methods and techniques comprising aerial-,
boat- and foot-based surveying methods. In the aerial
(and even boat) hippo surveys, there is an element of
underestimation, because of the nature of surveying by
aerocraft, which tends to disturb hippos (Linchant et al.
2018). After disturbance, hippos react by submerging and
migrating underwater for longer distances before emerging
at another site, resulting in either underestimation or double
counting of the animals (Tembo 1987; Zisadza et al. 2010;
Linchant et al. 2018). Moreso, aerial surveys do not readily
provide the social structure of hippos, but merely estimates
numbers (Linchant et al. 2018). Use of land patrols has
limitations, which include low spatial coverage, and they are
tedious, costly and expose enumerators to danger from the
species especially during the calving stages (Linchant et al.
2018). This then suggests that more comprehensive hippo
surveys must combine methods, such as aerial survey,
foot- (land-) and boat-based surveys to get adequate
information on hippo pods. Currently, unmanned aerial
vehicles (UAV) or drones are used to monitor hippo pods
temporally and over a large geographical range, although
the expense and expertise required for this method may
limit its applicability in developing countries, such as
Zimbabwe (Linchant et al. 2018).
The exact figures on hippo populations for Mana Pools
and other large water systems, including Lakes Kariba,
Mutirikwi, the newly constructed Tokwe-Murkosi, Sebakwe,
Osborne, Mazvikadei, Manyame and Manjirenji among
others are not readily available from the Parks authorities
(ZIMPARKS 2012). The little available data mainly from
surveys in the GNP, HNP and Mana Pools National
Parks and Manjirenji Dam point to a severe decline in
hippo populations, with current reestablishment of hippo
numbers underway in some of the parks (Zisadza et al.
2010; Utete et al. 2017).
Threats to hippos in Zimbabwe
Analysis of literature within freshwater systems of
Zimbabwe indicated that hippos face ongoing multiple
threats to their habitats and existence. The threats and
severity have been summarised in Table 1. Before political
independence in 1980, human intrusion and disturbance
characterised by war of liberation, civil unrest and military
exercises threatened the existence of hippos especially
in remote areas like Mana Pools, GNP and HNP (Mackie
1976). At independence, the proliferation of residential and
commercial development mainly in urban and peri-urban
areas, resulted in massive encroachment into wetlands,
lakes, rivers, ponds and national protected areas degrading,
silting and polluting many freshwater systems (Wekwete
1992; Cumming 2011; Marshall 2011). In between, there
were massive drought periods like 1984 and 1992 to 1994
(ZIMSTATS 2012), which reduced available hippo habitats.
The land reform program of 2000–2002 also resulted in
encroachment into wildlife areas (Cumming 2011).
Rapid expansion of settlements, especially urban and
peri-urban encroachment, threatens the existence, quality,
integrity and ecosystem services of lakes and rivers
(Wekwete 1992; Munzwa and Jonga 2010; Nyandoro
and Muzorewa 2017). Climate change, expressed mainly
through erratic rainfall, high atmospheric temperatures
and surface evapotranspiration influences water storage
capacity of the freshwater systems in Zimbabwe (Jury
Population = 2.5136 (year) − 4965.7
R² = 0.7134
20
40
60
80
100
120
140
160
1977 1982 1987 1992 1997 2002 2007 2012 2017
POPULATION
YEAR
Hippo population
Trendline
Figure 3: Estimated hippo populations in Hwange National Park in
Zimbabwe (source WEZ 2018)
Utete
8
2012; Masimba 2016; Nyarumbu and Magadza 2016;
Marshall 2017; Utete et al. 2018). Wildlife rich areas
are threatened by poaching of trophy species, such as
elephants, rhinos, pangolins and lately hippos, giraffes,
fish and bird eggs (Groom et al. 2013; Gandiwa et al.
2014; Muboko et al. 2014; 2016). The interactive effects
of socio-economic activities, poaching and climate change
threatens biodiversity in water systems of Zimbabwe
(Kupika et al. 2017; Utete et al. 2018).
This has resulted in migration of hippos to suitable
habitats and reduced recruitment, slowing hippo population
increases (Sharp 1984; Zisadza et al. 2010). Increased
dam construction in response to increased irrigation water
demands caused modification of river systems reducing
suitable hippo pools (Marshall 2011). In as much as
the dams and lakes provide a viable habitat for hippos,
competing water interests, such as abstraction for irrigation,
domestic, industrial use, and recreation in lakes and
dams pose a threat to hippos through erratic water level
fluctuations (Utete et al. 2017, 2018). Natural modification
of the freshwater and peripheral systems through climate
change and severe weather patterns like drought, high
evapotranspiration, wind speed and low humidity results
in reduction in water levels, water quality and herbage for
hippos (Mugangu and Hunter 1992; Timbuka 2012; Utete
et al. 2017). High temperatures pose a threat to hippo
skin, which has a very thin epidermis and lacks sweat
glands and sebaceous glands, therefore allowing quick
evaporation of water, which can cause severe dehydration
to the animal, resulting in death (Estes 1992).
Currently, the biological resource uses, such as legal
and illegal hunting, and poaching and illegal trade for hippo
meat, skin and teeth, as well as deliberate culling, as part
of problem hippo control (PHC) affect hippo populations
in Zimbabwe (Gandiwa et al. 2012, 2013; Matseketsa
et al. 2018). Agricultural activities tend to reduce forests,
degrade wetlands and leach pollutants into water bodies
and result in abstraction of water resources (Utete et al.
2018). These result in aquatic habitat degradation and
displacement of hippos (Mackie 1976; Sharp 1984; Zisadza
et al. 2010). Aquaculture involving cages, dredging, netting,
and use of poison may affect the habitat integrity for hippo
proliferation in some water bodies (e. g. Lakes Kariba,
Chivero, Manyame and Mutirikwi) in Zimbabwe (Marshall
2011). Although it must be pointed out that no studies
have shown the cause-effect relation between aquaculture
and hippo habitat integrity in water bodies of Zimbabwe.
Moreso, in Zimbabwe, to date, data on hippo poaching and
subsequent illegal trade of hippo products to local, regional
and international cartels are scarce, and in most cases
tend to be too fragmented to provide insight into the threats
facing the species. This hampers conservation efforts
towards sustainable exploitation of hippos (Gandiwa et al.
2013; Gandiwa 2014).
Human-hippo conflicts in Zimbabwe
Hippos are facing multiple pressures in Zimbabwe,
however, the species receives a lot of attention in relation
to human-hippo conflicts (Zisadza et al. 2010; Gandiwa et
al. 2013; Zisadza-Gandiwa et al. 2013; Chinho et al. 2015;
Utete et al. 2017). In most cases, human fatalities are
recorded and reported in national media outlets, whereas
hippo fatalities caused by humans rarely receive attention
(Gandiwa and Gandiwa 2012; Gandiwa et al. 2013). This
results in a one-dimensional perspective portraying hippos
as a destructive species, because it feeds on crops and
harms humans (Gandiwa 2012). Accordingly, there is a
requirement for a comprehensive review of the ecological
significance of hippos, offset by their destructive activi-
ties in peripheral communities around lakes and rivers in
Zimbabwe (Chinho et al. 2015).
Hippos differ from other grazing megaherbivores,
because they have a diurnal feeding ecology and space
requirement characterised by day wallowing and littoral
Rank Threat Literature evidence Data quality Demonstrated impact
1 Habitat degradation Mackie (1976), O’Connor and Campbell
(1986), Zisadza et al. (2010)
Qualitative Suitable hippo habitats
destroyed
2 Poaching Sharp (1984), Gandiwa et al. (2012),
Muboko et al. (2014). Matseketsa et
al. (2018).
Quantitative Hippo numbers decrease
3 Damming Marshall (2011) Quantitative Suitable riverine hippo pools
destroyed and converted
4 Agriculture Mazvimavi (2010), Marshall (2011) Quantitative Water abstraction reduce
water volume and flow
regimes
5 Settlement/
encroachment
Zisadza et al. (2010), Cummins (2007),
Cumming (2011), Chinho et al. (2015)
Quantitative Habitat degradation and
poaching
6 Drought Sharp (1984), Zisadza et al. (2010) Quantitative and qualitative Hippo habitats reduced.
Hippo mortality increased
7 Poisoning Muboko et al. (2014) Quantitative Hippo mortality increased
8 Culling Gandiwa et al. (2012). Matseketsa et
al. (2018)
Quantitative Hippos numbers decreased
9 War (Armed conflict) Mackie (1976), Sharp (1984) Quantitative Hippo mortality increased
10 Aquaculture Marshall (2011) Qualitative Hippos displaced by cages
Table 1: Threats facing hippos ranked in order of severity with corresponding evidence in Zimbabwe
African Zoology 2020: 1–14 9
shoreline grazing, and nocturnal far open range grazing
(Eltringham 1999; Timbuka 2012). The nocturnal, far open
range grazing nature of the species entails encroachment
into agricultural lands, forestry, open wooded lands and
grasslands (Nyirenda et al. 2011). This inevitably results
in utilisation of resources in human dominated areas or
settlements, and two-way confrontations or hostilities
between humans and hippos, termed human-hippo
conflicts, frequently occur (Kanga et al. 2011, 2012; Spinage
2012). For this reason, many researchers indicated that
hippos are a conflict species, occasionally attacking people
and damaging crops near aquatic habitats (Mkanda 1994;
Dunham et al. 2010; Kendall 2011; Gandiwa et al. 2013). In
Zimbabwe, several human–wildlife conflict reports frequently
indicate crocodiles, lions, buffaloes, elephants and hippos
as the main mammal protagonists of conflict (Dunham et al.
2010; Gandiwa et al. 2013; Muboko et al. 2016; Matseketsa
et al. 2018).
As a result, hippos, have received negative attention
(Timbuka 2012). However, like most other hippo range states
in Africa (Mkanda 1994; Kanga et al. 2012), Zimbabwe has
done little to evaluate the type, extent and consequences
of human–hippo conflicts, even though local communities
report numerous complaints on hippo damage (Gandiwa et
al. 2013; Muboko et al. 2016; Matseketsa et al. 2018). The
detailed reports, which are mostly highlighted in national
newspapers tend to be lopsided, because they only show the
extent of the damage to crop and human fatalities caused
by hippos. In most cases, the same reports mostly do not
indicate the fate of hippos even in peculiar circumstances
where humans are attacked, while fishing, bathing or doing
laundry in hippo territory or when trying to poach hippos.
However, an online article on News24 (2017) reported on the
deaths of hippos in Mlibizi District in Binga along the Zambezi
River, a transboundary river between Zambia and Zimbabwe.
It highlighted the suspected causes of hippo deaths, which
included, among others, suspected mercury poisoning by
poachers or nearby villagers starved of meat. The report
also suspected some epizootic disease/s. Hungry villagers
in the area were feeding on the carcasses. This sensational
reporting provides an example of the imbalanced nature and
skewedness of reports on human-hippo interaction in some
popular literature in Zimbabwe.
Wildlife interactions are termed conflicts, because of the
negativity associated with the wildlife-human encounters
(Cumming 2011). In Zimbabwe, most human-hippo conflicts
are reported in newspapers with a negative tone, and the
official data are not readily available from parks authorities.
This has resulted in persecution of hippos, which poses a
threat to the population status of the species (Dunham et
al. 2010; Zisadza et al. 2010; Gandiwa 2013; Chinho et
al. 2015). Examination of human–hippo conflict literature
indicates that there is no explicit definition of human-hippo
interaction, the impact of the interaction and the different
interests of the humans and hippos (Cumming 2011). What
this suggests is that the antagonists in human-hippo conflict
have to be specifically identified and their interests and roles
defined in order to deliver long-term solutions for the benefit
of hippo populations and human communities (Matseketsa
et al. 2018). This additionally implies that conservation of
aquatic resources, such as hippos and suitable habitats,
should not only seek technical solutions to deal with the
impacts, but consider hippo ecology, habitat dynamics in the
water and adjacent terrestrial ecosystems for both protected
and unprotected areas, as well as establish the perceptions
and attitudes of surrounding communities towards hippos
(Cumming 2011; Gandiwa et al. 2012; Matseketsa et al.
2018). Consequently, the different livelihood strategies,
such as fishing, irrigation, tourism and water-based
recreation, which interact and interfere with hippos, have
to be integrated as part of long-term conservation efforts
(Zisadza et al. 2010; Chinho et al. 2015).
Conservation and sustainable options for hippos in
Zimbabwe
Conservation of hippos, a charismatic member of the
continent’s megafauna, is a major goal of local and
international conservation groups (IUCN 2016). In that
respect, several conservation organisations have initiated
numerous hippo surveys especially in areas where the
populations are under severe threat (Lewison 1998, 2007,
2011). The key idea for hippo conservation as an ecosystem
engineer, is based on the concept of holistic conservation,
which not only involves hippo ecology, but its environment,
as well as its interaction with humans (Lewison 2011, Kanga
et al. 2012; Timbuka 2012). Figure 4 represents a schematic
framework summarising the interlinked conservation
measures that have been and can also be applied in
future to sustain hippo populations in Zimbabwe. So far a
combined approach has been implemented to understand
the ecological and socio-economic factors, as well as
cultural factors affecting the distribution, population and
hippo ecology in freshwater systems of Zimbabwe (Mackie
1976; Gandiwa et al. 2013). In as much as concerted
efforts to protect hippos have included ring fencing national
parks, and increasing law enforcement patrols in protected
dams and lakes, the highly migratory nature of the species
renders it vulnerable to poaching, hunting and persecution
in Zimbabwe (Mackie 1973; Dunham 2004; Zisadza et al.
2010; Utete et al. 2017).
Poaching is rife in Zimbabwean water systems especially
outside protected reserves (Matseketsa et al. 2018). In
a majority of cases, the poachers use poison, such as
cyanide to kill hippos and target the tusks for sale (Gandiwa
et al. 2012; Muboko et al. 2016). This has the net effect of
reducing hippo populations and degrading hippo habitats
and killing other hydrobionts in the affected area, as a
result of the residual toxicity of the cyanide (Muboko et
al. 2016). Conversely, trophy hunting of hippos, which is
the shooting of carefully selected hippos under official
government licence, for pleasure, results in regulated
or carefully monitored hippo population decreases in
water systems of Zimbabwe (Matseketsa et al. 2018).
Subsistence hunting where humans hunt strictly to provide
food for themselves and their families has been limited for
hippos in Zimbabwe, because of the strict restrictions and
regulations on wildlife hunting (Gandiwa et al. 2012). Legal
hunting, which is the regularised or authorised hunting
of hippos is done as part of culling, as a problem-hippo
control measure or for the provision of meat rations for the
well-being of the Parks officials (Matseketsa et al. 2018).
These conservation measures, particularly trophy, legal
Utete
10
and regulated hunting, have the net effect of reducing hippo
populations in water systems of Zimbabwe, in as much
as the intention is to control hippo populations in aquatic
systems. The gradual increases in hippo numbers observed
in certain protected areas, such as HNP and GNP, from
1992 onwards in this study suggest limiting hunting, until
suitable population estimates have been obtained for areas
where hunting occurs and no population data exist, as a
viable management option in Zimbabwe.
Additional efforts the authorities could adopt to enhance
hippo conservation in Zimbabwe include integration
of indigenous knowledge traditions of the freshwater
systems and hippo and human coexistence with modern
technologies, such as real time GIS and remote sensing of
habitat suitability and monitoring of the hippo populations
in the water systems (Utete et al. 2017). A viable option
would be to undertake a simultaneous hippo and hippo
habitat conservation and education awareness of adjacent
communities (Cumming 2011; Matseketsa et al. 2018).
Moreso, as advocated by Zisadza et al. (2010) and Chinho
et al. (2015) there is a requirement for regular, cyclic
and well-coordinated national hippo surveys for updating
the database and establishing the true population and
conservation status of the species. This must be supported
by astute recording and archiving of balanced and detailed
reports on human-hippo conflicts in the nation. Globally
and locally, there is a genuine requirement for formal
compensation and benefit-sharing schemes from hippo
related products especially for peripheral communities who
are the most vulnerable to hippo attacks (Timbuka 2012;
Muboko et al. 2014).
Affordable wildlife insurance schemes and provision
of land rents for residents and farmers living close to
wildlife rich areas may be initiated to fund retrospective
and prospective compensation in the event of hippo and
other wildlife attacks in Zimbabwe (Cumming 2011).
Translocation of problem hippo is another viable option
to minimise conflicts with adjacent communities although
it is expensive (Kanga et al. 2012; Muboko et al. 2014).
Community conservancy schemes are an initiative that
have been tried in Zimbabwe, but have yielded no tangible
benefits to adjacent communities and appear to work
more favourably for large terrestrial mammals, such as
elephants, but not hippos (Gandiwa et al. 2013).
Innovative utilisation of hippo products, such as meat for
biltong, and milk mimics for medicinal purposes (Saikawa
et al. 2004; Hashimoto et al. 2007) can be beneficial to the
country. Large-scale commercial breeding using artificial
insemination in protected areas can be a functional solution
to increase hippo population and enhance non-consumptive
tourism, which generates foreign currency (Saikawa et al.
2004). It is noteworthy that breeding can only work if the
Commercial
meat sales &
export
Sustainable hippo harvesting
Law enforcement
and patrol
Controlled
hippo culling
Hippo
conservation
measures
Artificial
insemination
Translocation of
problem hippos
Community conservancies
Land
rent
Retrospective compensation
Wildlife insurance
schemes
Commercial
ethno-medical
products
Non-consumptive tourism
Funded whistle
blowing schemes
Figure 4: Conservation measures applicable for hippos in Zimbabwe, Africa and the global entirety
African Zoology 2020: 1–14 11
threats or activities, such as water abstraction, pollution,
poisoning, and poaching that degrade, and destroy suitable
hippo habitats and reduce hippo populations, are addressed.
Breeding programs can be viable only if there are concerted
efforts to track the population trends of hippos, a task that
demands resources, is limited to mostly protected areas,
and would not be effective outside protected water systems.
In areas where hippo population declines have been seen,
it might not be necessary to encourage hippo breeding,
because this exercise is costly and risky. However, for dams
located in private conservancies, breeding programs may
be an alternative method to increase hippo populations,
as long as the capital input is offset by consumptive and
non-consumptive benefits.
Research priorities for hippos in Zimbabwe
This review identified some pertinent, but not exhaustive,
research priorities for hippo conservation. Firstly, it is a
prerequisite to establish, qualitatively and quantitatively, the
impact of illegal hunting or poaching on hippo population
stability and trends in rivers and lakes in Zimbabwe.
Secondly, research has to be intensified into the accurate
estimation of the rates of land-use and land cover pattern
changes near hippo subpopulations in and outside protected
reserves in the country, in order to formulate effective and
long-term hippo conservation strategies. Currently, there
is an urgent requirement for understanding the effect of
climate change on hippo populations, distribution and
loss of suitable hippo areas of occupancy. With a shift
in human demography and settlement encroachment, a
research priority entails exploring the effects of siltation and
sedimentation of hippo pools and declining water quality on
the dynamics and distribution of this bioengineering species.
In summary this literature review prioritises the main areas
for additional research, which include the necessity to:
1. Gain an understanding and development of a functional
model for the prediction of hippo population dynamics.
2. Understand the social structure and interactions
between hippos and other hydrobionts.
3. Describe the impacts of hippos on the environment in
their role as bioengineers.
4. Determine the carrying capacity for the population, and
what the consequences will be if this is exceeded in
protected (and even for unprotected) water systems.
5. Gain an understanding of human-hippo interactions, both
from the aspect of crop-damage, human injuries and
fatality, hippo mortality and injuries, and for ecotourism.
The hippo population in Zimbabwe is no doubt under
severe threat from a plethora of interactive factors, and
accordingly concerted and astute conservation measures
are required to guarantee the sustainability of the species
(Zisadza-Gandiwa et al. 2013; Utete et al. 2017). Broadly,
human-hippo conflicts in Zimbabwe cannot be entirely
eliminated, but can be mitigated by prohibiting agricultural
and industrial, as well as mining activities in protected
areas, wildlife migration corridors, riparian and littoral
shoreline zones of freshwater systems (Cumming 2011).
Urban and peri-urban encroachment on lands bordering
riparian habitats must be avoided at all costs, because the
areas serve as grazing pastures for hippos and spawning
habitats for other aquatic species like fish and wetland birds
(Marshall 2011). It is essential to promote sustainable use
of water systems, including through wildlife conservation,
and maximising the ecosystem and economic value
obtained from hippos with the overall goal of enhancing
human wellbeing. Besides the deleterious human-hippo
conflicts, creative and innovative utilisation of the hippo and
its products in the freshwater ecosystem has the potential
to make it a keystone, charismatic and iconic species.
Acknowledgments — The author is grateful to Patience Zisadza-
Gandiwa for the assistance with the hippo data in the Gonarezhou
National Park, Tatenda Manyuchi for the help with maps, Rob Whiley
and Pam Birch of Wildlife and Environment Zimbabwe for the help with
hippo data for Hwange National Park and all the anonymous incisive
reviewers who helped to make the manuscript readable.
ORCID
B Utete: https://orcid.org/0000-0001-5493-4421
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Manuscript received: 3 July 2019, revised: 4 May 2020, accepted: 12 May 2020
Associate Editor: D Parker
