Tourists visit South Africa’s wildlife reserves to see lions and leopards, non-civets and servants.
The administrators of these parks, responding to this commercial pressure, tend to favor the larger and charismatic predatory cats. Although South Africa’s more than 30 smaller carnivore species play important roles in their ecosystems, keeping prey species populations under control, which in turn affects plant communities, administrators pay little or no attention to their protection.
It has long been assumed that adding lions to the top of the food chain would result in healthier populations of these other carnivorous species and that any efforts to protect large predators, such as lions, would also automatically benefit minors. However, scientists have no evidence as to whether these predictions happen in the real world, especially in small reserves of the type found in South Africa.
A study published Wednesday in the journal Proceedings of the Royal Society B reveals that the dynamics are more intricate than previously thought. Although the presence of lions slightly increases the number of small species of carnivores that live in an area, it decreases their overall distribution.
“We cannot just assume that when we manage the lions, there will be general benefits for all biodiversity,” said Gonçalo Curveira-Santos, a doctoral student in conservation biology at the University of Lisbon and the main author of the findings. “Apex predators are very interactive in an ecosystem, and we need to take their ecological effect into account.”
Many wildlife reserves in South Africa are former cattle ranches converted to ecotourism. If there are lions, they are usually reintroduced.
“We are not talking about immaculate landscapes, where lions roam freely,” said Curveira-Santos. “We are talking about small enclosed reserves where lions are placed after the landscapes have been highly disturbed.”
After reintroduction, managers tend to invest significant money and efforts in maintaining lion populations, including patrols against poaching and the regular removal of wildlife traps placed in reserves by people in local communities.
Mr. Curveira-Santos and his colleagues wanted to see what effect, if any, these activities had on species of small carnivores that weigh less than 20 kilos. They concentrated on 17 reserves in the provinces of Limpopo and KwaZulu-Natal, in South Africa, of which about half had lions reintroduced into their properties. They used camera trap data collected by the conservation group Panthera to estimate the number of species of small carnivores in each reserve and calculate the extent of their presence.
In all reserves, the researchers recorded 22 species of small carnivores, from striped jackals and mongoose to foxes with bat ears. They found that the overall species count was slightly higher in lion reserves, but that, on average, lions reduced the amount of land on which small carnivores are found by about 30 percent.
Curveira-Santos says that it is clear that lions, when present, are influencing the distribution of these smaller carnivores.
“The question is, is this natural paper and a good thing for conservation or is it a negative thing because we are doing it in a very artificial way?” he said.
It may be that there are fewer small individual carnivores, because lions are killing or repressing them, he said, or that lions are causing small carnivores to avoid certain areas out of fear – or both. The team also cannot say whether these dynamics are impacting the ecological role of small carnivores. Further studies are needed, but if smaller predators are killed by lions or confined to places where big cats do not step, this can lead to a decline in the population of these species and create imbalances for other animals and plants.
Kelly Anne Marnewick, a carnivorous biologist at Tshwane University of Technology in South Africa who was not involved in the research, said the reintroduction of lions into these South African reserves was valuable, with predators now considered “less of a concern” for conservation purposes.
“However, we need to take the conclusions of this article into account and direct the research to ensure that we have enough information to adapt management to a more holistic approach for the benefit of the entire ecosystem,” she said.
With further research, Mr. Curveira-Santos and his colleagues hope to determine how much overlap exists between the commercial interests of the ecotourism industry and the ecological interests of the conservation community.
“We are just beginning to unravel the complexity of the diversity and dynamics of the carnivorous community,” he said. “There is a need for more research before we can say how closely aligned management and conservation priorities are.”