Tourists visit South Africa’s wildlife reserves to see lions and
leopards, not civets and servals.
Managers of these parks, responding to this commercial pressure,
tend to favor those bigger, charismatic predatory cats. Although South Africa’s
30-plus species of smaller carnivores play important roles in their ecosystems
by keeping populations of prey species in check, which in turn affects plant
communities, managers give little, if any, thought to their protection.
اضافة اعلان
The assumption has long been that adding lions to the top of the
food chain would lead to healthier populations of these other carnivore species,
and that any efforts to protect large predators, such as lions, automatically
benefit smaller ones, too.
However, scientists lack evidence about whether
these predictions play out in the real world, especially in small reserves of
the sort 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. While the presence of lions slightly increases the number of small
carnivore species living in an area, it decreases their overall range.
“We can’t just assume that when we manage for lions, there will
be umbrella benefits for all of biodiversity,” said Gonçalo Curveira-Santos, a
doctoral candidate in conservation biology at the University of Lisbon, and a
lead author of the findings. “Apex predators are very interactive in an
ecosystem, and we need to take better into account their ecological effect.”
Many wildlife reserves in South Africa are former livestock
farms that have been converted for ecotourism. If lions are present, they have
usually been reintroduced.
“We’re not talking about pristine landscapes where lions roam
free,” Curveira-Santos said. “We’re talking about small, fenced reserves where
lions are put after landscapes have been highly disturbed.”
After reintroduction, managers tend to invest significant money
and effort into maintaining lion populations, including anti-poaching patrols
and regularly removing wildlife snares placed in reserves by people in the
local communities.
Curveira-Santos and his colleagues wanted to see what effect, if
any, those activities had on carnivore species that weigh less than 20kg. They focused on 17 reserves in South Africa’s Limpopo and KwaZulu-Natal
provinces, about half of which had reintroduced lions to their properties. They
used camera-trap data collected by the conservation group Panthera to estimate
the number of small carnivore species in each reserve and calculate the extent
of their presence.
Across reserves, the researchers recorded 22 small carnivore
species, from side-striped jackals and banded mongooses to bat-eared foxes.
They found that overall species counts were slightly higher in reserves with
lions, but that, on average, lions reduced the amount of land that small
carnivores are found on by roughly 30 percent.
Curveira-Santos says it is clear that the lions influence the
distributions 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’re doing this in a very
artificial way?” he said.
It could be that there are fewer individual small carnivores,
because lions are killing or otherwise 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 small carnivores’
ecological roles. More study will be required, but if smaller predators are
being killed by lions or confined to certain locations where the big cats do
not tread, that could lead to population declines of these species and create
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 that reintroducing lions at these South African reserves had been
valuable, with the predators now considered to be of “least concern” for
conservation purposes.
“However, we need to take heed of the findings of this paper and
direct research to ensure we have sufficient information to adapt management to
a more holistic approach for the benefit of the whole ecosystem” she said.
With further research, Curveira-Santos and his colleagues hope
to determine how much overlap exists between the ecotourism industry’s
commercial interests and the conservation community’s ecological ones.
“We are just starting to unravel the complexity of carnivore
community diversity and dynamics,” he said. “There’s more research needed
before we can say how much management and conservation priorities are aligned.”
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