To
say that wildlife management can be complicated would be an
understatement. Take African lions. Most of their populations have
declined by 50 percent over the past two decades, and they’re expected
to decline by half again in the coming 20 years. They’re nearly wiped
out entirely from Western Africa and aren’t doing too well in the east
or center of the continent, either. Poaching and hunting
can take a small share of the blame, but the overwhelming causes for
their decline, as for the decline of many species, are habitat loss and
landscape fragmentation. That leads us to the complicated bit: lion
populations appear stronger inside a fenced-in park or reserve – that
is, within a fragment – despite the young males’ inability to disperse
into new communities. They say that fences make good neighbors, and that
turns out to be true for lions as well.
But then again, what lions need are corridors, protected spaces to
move from one landscape into the next, so that their genetic diversity
can be as high as possible to guard against inbreeding. Can lions be
better off both within fences and without?
The truth is of course far more complex, as US Forest Service researcher Samuel A. Cushman points out this month in the journal Landscape Ecology. Together with his colleagues, Cushman assesses the viability of lion populations in the Kavango-Zambezi Trans-frontier Conservation Area (KAZA), a landscape that covers parts of Botswana, Zambia, Zimbabwe, and Namibia, under a variety of imagined future scenarios. Those scenarios include more or fewer protected areas (with various levels of protection), more or fewer fences, and more or fewer humans.
For example, aside from national parks and forest reserves, quite a bit of land in KAZA is comprised of privately owned “wildlife management areas” or WMAs. It’s on these lands that some forms of legalized hunting are permitted. If a hunting ban was enacted, then it might be more profitable for landowners not to manage their properties for the benefit of wildlife, and instead encourage agricultural development or mining.
Or what if all non-national parks, including both forest reserves and WMAs, were converted for human uses thanks to political or economic pressures? Or to push that scenario even further, what if the remaining protected lands were all fenced, keeping poachers out and keeping animals in? (It’s not a crazy notion; South Africa’s Kruger National Park, for example, is mostly fenced.)
What if, on the other hand, protected corridors were implemented – either combined with the judicious application of fencing to keep lions away from human settlements, or not?
In all, Cushman and his colleagues examined the ability for lion populations to remain connected under a mathematical model describing KAZA’s current reality, along with eight possible future models.
Some of their findings were consistent with their expectations. For example, if lands outside of national parks lost their protections, then lions’ population connectivity would substantially suffer. While the conversion of privately owned WMAs alone had a smaller effect than the conversion of all non-parks, the effect was still considerable. Indeed, Cushman writes, “should [Botswana’s] trophy hunting ban result in conversion of wildlife areas to activities that are less beneficial to wildlife (e.g., cattle ranching) there is a danger that the currently secure Okavango-Hwange population could be severely fragmented.” The Okavango-Hwange Lion Conservation Unit is only one of just six lion populations in Africa that exceeds 2,000 individuals, an important stronghold for the species.
And not only would the lions be less able to disperse under these scenarios. They’d be at greater risk of being killed by humans because they’d be more likely to wander too close to settlements or to kill livestock.
In addition, despite the local benefits of fencing, the fencing of protected areas would increase population isolation, even if all non-park protected lands remained protected. Connected habitats, it turns out, aren’t all that useful if the animals can’t move from place to place. The worst future scenario, in terms of the long-term viability of lion populations, involved both fencing of national parks and the conversion of non-parklands for agricultural, pastoral, or mining purposes.
Where fencing becomes useful, however, is where protected lands border human communities in such a way that it becomes impossible to otherwise protect wildlife from poaching or to mitigate human-wildlife conflicts. “While fences are likely the most appropriate intervention for small habitat fragments subject to high anthropogenic edge effects, our results suggest that it is risky to intentionally fragment functioning ecosystems with fences,” they write.
If fences are to be used, they should be used extremely judiciously and only where appropriate. For example, some fences could be useful to maintain corridors between protected areas, to funnel animals towards parks and reserves and away from high-risk areas.
As is so often the case, the best means of protecting wildlife, including lions, is to protect as much land as possible, and to connect those landscapes—all while attempting to keep poachers away from animals, and animals away from humans and livestock. It’s a tall order, to be sure, but modeling efforts like this allow landscape and wildlife managers to establish the optimal methods from a dizzying array of possibilities. – Jason G. Goldman | 06 November 2015
Source: Cushman, S.A., Elliot, N.B., Macdonald, D.W., & Loveridge, A.J. (2015). A multi-scale assessment of population connectivity in African lions (Panthera leo) in response to landscape change. Landscape Ecology. DOI: 10.1007/s10980-015-0292-3.
Header image: African lion at Nambiti Private Game Reserve, copyright Jason G. Goldman.
The truth is of course far more complex, as US Forest Service researcher Samuel A. Cushman points out this month in the journal Landscape Ecology. Together with his colleagues, Cushman assesses the viability of lion populations in the Kavango-Zambezi Trans-frontier Conservation Area (KAZA), a landscape that covers parts of Botswana, Zambia, Zimbabwe, and Namibia, under a variety of imagined future scenarios. Those scenarios include more or fewer protected areas (with various levels of protection), more or fewer fences, and more or fewer humans.
For example, aside from national parks and forest reserves, quite a bit of land in KAZA is comprised of privately owned “wildlife management areas” or WMAs. It’s on these lands that some forms of legalized hunting are permitted. If a hunting ban was enacted, then it might be more profitable for landowners not to manage their properties for the benefit of wildlife, and instead encourage agricultural development or mining.
Or what if all non-national parks, including both forest reserves and WMAs, were converted for human uses thanks to political or economic pressures? Or to push that scenario even further, what if the remaining protected lands were all fenced, keeping poachers out and keeping animals in? (It’s not a crazy notion; South Africa’s Kruger National Park, for example, is mostly fenced.)
What if, on the other hand, protected corridors were implemented – either combined with the judicious application of fencing to keep lions away from human settlements, or not?
In all, Cushman and his colleagues examined the ability for lion populations to remain connected under a mathematical model describing KAZA’s current reality, along with eight possible future models.
Some of their findings were consistent with their expectations. For example, if lands outside of national parks lost their protections, then lions’ population connectivity would substantially suffer. While the conversion of privately owned WMAs alone had a smaller effect than the conversion of all non-parks, the effect was still considerable. Indeed, Cushman writes, “should [Botswana’s] trophy hunting ban result in conversion of wildlife areas to activities that are less beneficial to wildlife (e.g., cattle ranching) there is a danger that the currently secure Okavango-Hwange population could be severely fragmented.” The Okavango-Hwange Lion Conservation Unit is only one of just six lion populations in Africa that exceeds 2,000 individuals, an important stronghold for the species.
And not only would the lions be less able to disperse under these scenarios. They’d be at greater risk of being killed by humans because they’d be more likely to wander too close to settlements or to kill livestock.
In addition, despite the local benefits of fencing, the fencing of protected areas would increase population isolation, even if all non-park protected lands remained protected. Connected habitats, it turns out, aren’t all that useful if the animals can’t move from place to place. The worst future scenario, in terms of the long-term viability of lion populations, involved both fencing of national parks and the conversion of non-parklands for agricultural, pastoral, or mining purposes.
Where fencing becomes useful, however, is where protected lands border human communities in such a way that it becomes impossible to otherwise protect wildlife from poaching or to mitigate human-wildlife conflicts. “While fences are likely the most appropriate intervention for small habitat fragments subject to high anthropogenic edge effects, our results suggest that it is risky to intentionally fragment functioning ecosystems with fences,” they write.
If fences are to be used, they should be used extremely judiciously and only where appropriate. For example, some fences could be useful to maintain corridors between protected areas, to funnel animals towards parks and reserves and away from high-risk areas.
As is so often the case, the best means of protecting wildlife, including lions, is to protect as much land as possible, and to connect those landscapes—all while attempting to keep poachers away from animals, and animals away from humans and livestock. It’s a tall order, to be sure, but modeling efforts like this allow landscape and wildlife managers to establish the optimal methods from a dizzying array of possibilities. – Jason G. Goldman | 06 November 2015
Source: Cushman, S.A., Elliot, N.B., Macdonald, D.W., & Loveridge, A.J. (2015). A multi-scale assessment of population connectivity in African lions (Panthera leo) in response to landscape change. Landscape Ecology. DOI: 10.1007/s10980-015-0292-3.
Header image: African lion at Nambiti Private Game Reserve, copyright Jason G. Goldman.
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