Hippo, Africa’s under-appreciated megaherbivore

I’m sure that heaps of people, when told about an African megaherbivore (herbivores with an adult body mass over 1000 kg) will conjure up images of elephant and rhino. Sure, those animals are charismatic and endangered, but what about the other two African megaherbivores; Hippo and giraffe? Didn’t even think of giraffe? And the common Hippo (Hippopotamus amphibius)? They aren’t even listed as part of the must-see African ‘big five’. I can’t say why.beware.hippo

And if Hippo have failed to capture the public imagination to the same extent that elephant have, well it is true of scientific research too. A quick search through SANParks data repository for Kruger National Park returned 29 data ‘packages’ for elephant but just 3 for Hippo. Equally, a quick Web of Science search for African Hippo returned ~150 research articles (many of which are paleontological); while a similar search for African elephant returned ~1300 published articles. That may be because Hippos are dangerous, difficult to immobilise and are all but impossible to fit GPS transmitters to. Not that science equates to conservation – but Hippo just don’t seem to be getting much attention, despite their ecological importance as catalysts of geomorphological change [1], and their role in wetland/riverine ecosystem function through nutrient deposition [2].

Despite being listed by the IUCN Redlist as Vulnerable, I think Hippo will be Critically Endangered by 2100. They are dangerous to people living alongside them, destroy crops and are a source of bushmeat. And their ivory is valuable within the illicit wildlife trade. A number of social surveys have found that attitudes of local people toward hippo are negative and that Hippos are frequently killed in response to conflict [3].

Further, the last IUCN SSC Hippo Specialist assessment (in 2008) reported a 7–20% decline in Hippo populations, with a projected 30% decline over 30 years (1998-2028). Indeed, since then the Hippo population in Mocambique has been reduced to ~3 000, from ~16 000 ten years ago [4]. A recent survey of Gonarezhou NP found that Hippos are down to fewer than 200 animals, less than the total N in 1965 [5]! And two separate aerial surveys of the Limpopo River reported just ~100 Hippo along a stretch of 645 km in South Africa [6], and ~20 animals along 129 km of the river in Mocambique [4]. A Leslie-matrix population model based on vital rates sourced from the literature – and accounting for illegal harvest and habitat loss – predicted a more than 50% global population decline in the next 30 years [7].

I think that hippo will be lost from a lot of their present-day range in the coming decades. They are just too easy to kill during the daylight hours.

So what can we do? Well apart from baseline data collection on meta-population structure, distribution, dispersal and vital rates, as well as genetic diversity – I think that hippo will be best served through mitigation of human-wildlife conflict. That may require the transfer of funds from affluent countries to communities living alongside hippo, and incurring losses to both livelihoods and life. A recent paper on pygmy Hippo [8] found that local people appreciated the income derived from visiting tourists and scientists, and saw a value in (the less dangerous) pygmy hippo through that. Community based NRM will then have to ensure that funds from tourism, or even regulated trophy hunting go back into the communities.

And conservationists need to bring Hippo (back) into the public’s imagination. They should work with artists!

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