A new database of African hippo populations has revealed huge gaps in our knowledge of where the megaherbivores live and thrive, with populations fragmented and reliant on protected areas.
Hippos are classified as "vulnerable to extinction" by the International Union for the Conservation of Nature (IUCN) Red List and have been called the "neglected megafauna", with a lack of scientific attention and much less research into their lives and habitats than other large mammals.
University of Leeds School of Biology Postgraduate Researcher Hannah Lacy has developed a spatial database of distribution and population estimates for common hippos across southern Africa. She has uncovered gaps in data on where hippos are present across the region, with some areas lacking population estimates altogether.
On top of this, different survey methods used across countries and regions has made monitoring less reliable, with different levels of funding across African states causing a lack of consistency. In some cases, hippo populations were noted as an incidental finding while researchers were focusing on other species, meaning the data is not comprehensive.
Ms Lacy said: "Without reliable information on where hippos live, and the state of their populations, it is challenging to effectively plan to protect them.
"We need a centralised spatial database and coordinated surveys to improve the conservation of common hippos – who are important ecosystem engineers - across southern Africa."
As semi-aquatic animals, hippos play a significant and unique part in the ecosystems that support other animals in their surroundings.
She added: "Their feeding habits shape vegetation patterns along water courses, and their dung contributes to aquatic food webs, supporting species like fish and invertebrates. In many regions, they are also an important attraction for eco-tourism, which contributes to local economies and livelihoods. However, despite their ecological, social, and economic importance, common hippos face numerous threats, primarily from human activities."
Over the last century hippo populations have been hit hard by habitat loss, poaching and conflict with humans. Overall crude population estimates vary from 60,000 to 87,000 in southern Africa, so accurate data on where the animals live and thrive – including geographic range maps and population estimates – is crucial for effective conservation efforts.
The research found that where hippo populations are known to exist, they often rely on cross-border protected areas known as Transfrontier Conservation Areas (TFCAs), which shows just how important and impactful international collaboration is for successful conservation efforts.
While these protected areas provide an important home for hippos, populations that are cut off from other hippos and only able to breed within a small gene pool are at risk of becoming genetically isolated.
Ms Lacy's research, published in the journal Biological Conservation , was carried out by studying nearly 200 records from across nine countries in southern Africa - Angola, Zimbabwe, Zambia, Malawi, Mozambique, Botswana, Namibia, South Africa and Eswatini – including records from other research literature, reports from government bodies and charities, websites, and aerial surveys, dating from 2003 to 2023.
Now she is calling for coordinated surveys and a centralised database to improve hippo conversation efforts and outcomes across the region. A similar African Elephant Database managed by the IUCN African Elephant Specialist Group has become an important tool for protecting elephant populations across the continent.
PhD supervisor Dr Lochran Traill backed Ms Lacy's research, saying: "The work provides an update on the distribution of common hippo populations across southern Africa, and highlights the extent of population fragmentation and isolation. Hopefully, this information will be useful to conservation decision makers."
