To avoid multiple threats, leopards have to be crafty cats
Where there are people, expect to find few leopards. That’s because the apex predator suffers from hunting for their pelts, from habitat loss and fragmentation, and from retaliatory killings due to real or imagined losses of human or livestock lives. Similarly, where there are tigers, expect to find few leopards. In this case, it’s because the two big cats compete for the same prey, and in most cases the tigers are socially dominant to the leopards.
Despite the odds stacked against them, leopards are actually quite widespread, ranging from Africa up through the Middle East and into southern and Southeast Asia. So how do leopards manage to eke out their existence when they’re forced to contend with competition from other cats and a mix of aggression and habitat loss from humans? New research from National Socio-Environmental Synthesis Center researcher Neil Carter and colleagues suggests that leopards employ different strategies to deal with the different sorts of threats posted by humans and by tigers.
The study took place in Nepal’s Chitwan National Park, which contains leopards and tigers as well as a veritable buffet of prey species on which the cats regularly dine: spotted deer, muntjac, hog deer, sambar deer, gaur (also known as Indian bison), and wild boar.
Carter collected his data primarily by using camera traps in the dry seasons of 2010 and 2011, deployed both within the park and within a forested area just outside the park in the “buffer zone” between the park and human settlements.
Over the two-year study period, Carter’s camera picked up 107 leopards. In 2010, that comprised a total of thirteen individuals, and in 2011 he detected seventeen individuals. Many of those photographed in 2011 were not photographed the year before; only three inside the park and one outside the park were detected both years. Within the park, tigers were detected far more frequently; outside the park, they were only slightly more common. But the most common animals on his camera were people. In fact, people were between 3 and 4.4 times more common than prey animals across the two-year study period.
What Carter wanted to see was where and when the leopards were detected, relative to tigers and people. What they found was that the leopards were avoiding the tigers in space. That is, they were spending their time in places unlikely to be frequented by tigers. By contrast, people – both on foot and in vehicles – did not displace leopards in space, bur rather in time. The leopards were more likely to be active during the parts of the day when people were least likely to be active – at night. Faced with two different threats, the leopards have come up with a unique solution to each problem.
Previous research had suggested that tigers and leopards coexist by dividing up the day rather than dividing up space. It could be, Carter argues, that the presence of people forces the cats to segregate spatially rather than what could be a more natural temporal segregation. Previous research had also suggested that leopards try to spatially segregate themselves from humans, rather than doing so in time. Here too, Carter found the opposite pattern.
It could be that spatial segregation is a response to a high poaching pressure; in Chitwan, the likelihood of poaching is quite low. In fact, Carter never saw a human carrying a firearm on his camera trap images, outside of military personnel who were there as a deterrent to wildlife crime. Indeed, studies of other carnivores in landscapes frequented by humans – brown bears, coyotes, bobcats, and African lions – suggest that the presence of humans pushes those predators towards a more nocturnal lifestyle as well.
Together, the study underscores two important aspects of predator conservation. The first is that leopards appear highly adaptive. That they can respond to two different threats in two different ways suggests they are quite flexible in ensuring their own survival.
Second, it demonstrates that groups of predators in different locations have different needs. It is becoming increasingly clear that very little can be said about the conservation of a given species that applies equally to all populations. The leopards of Chitwan live with a unique constellation of variables: coexistence with tigers, lots of tourists and locals, low poaching pressure, and plenty of prey. Each of those variables combines to produce the temporal and spatial patterns observed by Carter and his colleagues.
The strategies necessary to protect leopards in a setting like Chitwan would be very different from those needed in places with reduced competition from other predators, or with less prey available, or with increased prejudice from humans. Just as the leopards require multiple strategies to deal with multiple problems on an extremely localized scale, so too does conservation. – Jason G. Goldman | 12 December 2014
Source: Neil Carter, Micah Jasney, Bhim Gurung, & Jianguo Liu (2015). Impacts of people and tigers on leopard spatiotemporal activity patterns in a global biodiversity hotspot, Global Ecology and Conservation, 3 149-162. DOI: http://dx.doi.org/10.1016/j.gecco.2014.11.013
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