Tourists visit South Africa’s game reserves to see lions and leopards, not civets and servals.
In response to this commercial pressure, managers of these parks tend to favor these larger, charismatic big cats. Although South Africa’s 30+ species of smaller carnivores play an important role in their ecosystems by keeping prey populations in check, which in turn impacts plant communities, managers think little, if at all, about protecting them.
It has long been believed that adding lions to the top of the food chain would result in healthier populations of these other carnivore species, and that any effort to protect large predators like lions automatically benefits smaller ones as well. However, scientists lack evidence as to whether these predictions work in the real world, especially in small reserves such as those found in South Africa.
A study published Wednesday in the journal Proceedings of the Royal Society B shows that the dynamics are more complicated than previously thought. While the presence of lions slightly increases the number of small carnivore species that live in an area, it decreases their overall range.
“We cannot just assume that there will be benefits for all biodiversity in managing lions,” said Gonçalo Curveira-Santos, PhD student in conservation biology at the University of Lisbon and lead author of the results. “Apex predators are very interactive in an ecosystem and we need to better consider their environmental impact.”
Many game reserves in South Africa are former animal farms that have been converted for ecotourism. When lions are present they have usually been reintroduced.
“We’re not talking about pristine landscapes where lions roam free,” said Curveira-Santos. “We’re talking about small, fenced-in reserves where lions are housed after the landscapes have been severely disturbed.”
After reintroduction, managers typically invest a lot of money and effort in conserving lion populations, including fighting poaching and regularly removing wild snares that are kept in reserves by people in local communities.
Mr Curveira-Santos and his colleagues wanted to know what impact these activities are having on small species of carnivore weighing less than 44 pounds. They were focused on 17 reserves in the South African provinces of Limpopo and KwaZulu-Natal, about half of which had reintroduced lions into their properties. They used camera trap data collected by the Panthera Conservation Group to estimate the number of small carnivore species in each reserve and to calculate the extent of their presence.
In all reserves, the researchers registered 22 small carnivore species, from side-striped jackals and banded mongooses to bat-eared foxes. They found that the total number of species on reserves with lions was slightly higher, but that, on average, lions reduced the amount of land on which small carnivores lived by about 30 percent.
Mr Curveira-Santos says it is clear that when the lions are present, they affect the distribution of these smaller carnivores.
“The question is, is this the natural role 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 could be that there are fewer individual small carnivores because lions kill or otherwise suppress them, he said, or that lions make small carnivores avoid certain areas out of fear – or both. The team also cannot say whether these dynamics affect the ecological roles of small carnivores. More studies are needed, but if smaller predators are killed by lions or restricted to specific locations where the big cats will not step, it can lead to a population decline in these species and imbalances for other animals and plants.
Kelly Anne Marnewick, a carnivore biologist at Tshwane University of Technology in South Africa who was not involved in the research, said the reintroduction of lions to these South African reserves had been valuable, with the predators now considered “least of concern” would be considered for protection purposes.
‘However, we need to take into account the findings of this paper and direct 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 the extent to which the commercial interests of the ecotourism industry overlap with the ecological interests of the conservation community.
“We are only just beginning to unravel the complexities of the diversity and dynamics of the carnivore community,” he said. “More research is needed before we can say how well management and conservation priorities are aligned.”