In the past four years 18 lions — eight females and 10 males — were relocated from the south to either Vlakteplaas, Pafuri and the Makuleke Contractual Park in the north. (File photo by Eric Lafforgue/Art in All of Us/Corbis via Getty Images)
Poisoning and snaring pose a serious threat to lions, especially in the northern parts of Kruger National Park, according to its scientists.
The Endangered Wildlife Trust and South African National Parks (SANParks) joined forces to individually identify lions, obtain mark-recapture estimates — a method to estimate the size of populations — and to determine the number of prides and their demography.
The results of the survey are in SANParks’ 2023/2024 research report, where scientists Erin Crowhurst, Pauli Viljoen, Marnus Roodbol and Sam Ferreira noted how lions are sought-after by many, including “tourists [who] want a lasting memory, healers are in search of treatments or cures and conservationists want to conserve the species”.
The survey consisted of playing hour-long recordings of a distressed buffalo calf at night at 64 sites in Nxanatseni north. At 13 sites, 41 lions arrived, and at an additional eight sites distant lion vocals were noted.
The team drove 9129km over a period of 90 days, recording 229 lion sightings with a possible 91 individual lions identified and both sides of their faces photographed. “Initial analysis revealed that multiple of the 91 individuals captured were recaptures,” the authors said.
Ninety-four camera traps were placed in the field for 90 days with two cameras at each station to photograph both sides of the face. This included seven individuals that had not previously been identified.
“Comparison of estimates from call-up surveys over time suggest that disruption of the lion populations may have been taking place over a long period. Nevertheless, lions have not decreased between 2015 and 2023,” the authors wrote.
This could be because of the introduction of lions that escaped from southern Kruger, which “may have compensated for the impacts of poisoning and poaching in the far north of Kruger”.
In the past four years 18 lions — eight females and 10 males — were relocated from the south to either Vlakteplaas, Pafuri and the Makuleke Contractual Park in the north, the scientists noted.
Another article in the SANParks research report found that the number of hippos at all six rivers in the Kruger National Park plunged by about 2 500 just before the drought in 2015 to the same time in 2016. The numbers fell by a further 8% in 2017, when the one of the most intense regional droughts on record ended.
Megaherbivores such as elephants, rhinos, hippos, giraffes and buffaloes once dominated the planet, scientists Robert McCleery, Sam Ferreira, Pauli Viljoen, Danie Pienaar, Cathy Greaver, Philip Mhlava and Obert Mathebula wrote, but now, “a full complement of these large mammals occurs only in African savannas”.
“These species are crucial for providing ecosystem services and fostering biodiversity but are under threat from land use change, over-harvesting and climate change. As the climate changes, we can expect more frequent and intense droughts, which stress most savanna species but have particularly pronounced impacts on water-dependent mammals like the common hippo.”
Among large mammals, hippos are unique in several aspects of their ecology, the authors said. “Hippos are central-point foragers: at night, they leave the water to graze in the surrounding area before returning to the same place. They spend their days in pools of water in social groups or pods, with water important for hydration and to protect their sun-sensitive skin.”
This makes hippos ecologically important and vulnerable to drought. To understand how hippos respond to drought and how they influence the environment and surrounding species, the researchers initiated a long-term study on the hippo population in the Kruger.
This was to investigate how and why hippos respond to droughts by examining changes in their distribution and group sizes.
The Kruger supports about 7 000 hippos, representing one of the largest hippo populations in a single protected area in the world.
The scientists found that before the drought, areas with abundant green vegetation and large pools of water had more hippos than others.
While elephants, rhinos and other megaherbivores often move to areas with greener vegetation during droughts, hippos have a limited ability to migrate long distances because of their territoriality.
“Nonetheless, hippos moved to new areas on Kruger’s rivers and altered their social behaviour in response to the severe drought. These responses, however, appeared less successful in mitigating drought-induced mortality than the responses of other large herbivores that could migrate to less severely affected areas,” the scientists said.
Hippos appear “acutely vulnerable” to competition from other hippos and are unable to find food during prolonged droughts.
“The strong social bonds of hippos and their tendency to form large groups may force them to compete with each other when food is scarce.”
The combined effects of drought-induced declines in surface water because of increased extraction for agricultural and residential use, dams and more variable rainfall cycles associated with climate change, will probably have negative consequences for hippo populations, the researchers said.
The next phase of their research aims to understand how changes in surface water in dams and rivers alters the movements and densities of hippos and other large megaherbivores.
“We seek to better understand the environmental consequences of these changes, specifically how water-induced changes to megaherbivores alter important nutrients, the type and structure of savanna vegetation and biodiversity.”
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