One of the challenges to conserving big cats, and indeed many animals, is human-wildlife conflict. This is a complex phenomenon that can involve many different social, economic, and other drivers. However, in the case of large predators, human-wildlife conflict is often related to attacks on livestock (depredation).
In rare instances, cats like snow leopards (Panthera uncia) and pumas (Puma concolor) will get into livestock enclosures and kill many animals at once. These “surplus killings” can be burdensome on livestock producers, who may lose large percentages of their flocks in a single night. This, in turn, is unlikely to produce positive feelings towards the cats. As a result, conservationists need to better understand the severities and causes of surplus killing events.
Fortunately, Lucherini, Guerisoli, and Vidal (2018) recently published a paper about surplus killings by pumas.
To investigate surplus killings, Lucherini et al. (2018) drew on multiple types of data; they sorted through 73 publications in both English and Spanish, and also incorporated information they had gathered from a previous study in Central Argentina. That study – which I have written about here – involved eight years of work, 213 interviews, and examinations of 17 puma depredation sites.
This variety of data allowed Lucherini et al. (2018) to compare results across different sources of information. This was important, because affected parties sometimes overreport the amounts of livestock they lose to predators.
Results and Discussion
Lucherini et al. (2018) found nine publications that described surplus killings by pumas. Five of these cases were reported by ranchers, two were assessed by the authors themselves, and in the remaining two cases it was unclear how the authors learned of the surplus killings.
Concerning the data from Lucherini et al.’s (2018) previous study, 22 interviews and five depredation site surveys dealt with surplus killings. The researchers thus estimated that 25-30% of the ranches in their earlier study area suffered from surplus killings, and that sheep were targeted in 26 out of 27 of these events. The numbers of livestock killed during surplus killings ranged from two to 70.
Lucherini et al. (2018) also discovered that the amount of livestock lost at the surplus kill sites they examined was about one-fourth of what interviewees said it would be. Thus, interview-based reports may indeed exaggerate the severities of surplus killing events. But why do pumas occasionally kill more livestock than they can eat?
Many ranchers in Lucherini et al.’s (2018) study area seemed to believe that surplus killings took place when mother pumas were teaching their cubs how to hunt. In contrast, Lucherini et al.’s (2018) evidence suggests that such events occur when a puma’s hunting instincts are overloaded by an abundance of easily-captured prey. They point out that the most serious surplus killings took place on stormy nights, when livestock would have been least able to detect and escape from a puma.
Although surplus killings are uncommon, they can place great strain on ranchers and engender hostility towards predators. Lucherini et al.’s (2018) study is a step forward in understanding why these surplus killings take place, and which sources of information about them are the most reliable. Of course, the most critical step is to learn how to prevent these occurrences in the first place.
In that respect, several snow leopard conservation groups have been working to reduce surplus killings in Central Asia. They typically help local people to build “predator proof corrals” that snow leopards cannot break into; partially supplying the materials needed to construct the enclosures.
A similar model might work in puma range countries like Argentina; although, since many people are leaving rural areas in Lucherini et al.’s (2018) study area (Guerisoli et al., 2017), conservationists would likely need to recruit volunteers to help build the corrals.
Regardless of the specifics of what conservationists do about surplus killings, hopefully Lucherini et al.’s (2018) study will spur additional research on this phenomenon. If we can ease the burdens of living with big cats and build strong relationships with local people, then perhaps we will be able to improve the future prospects of these magnificent animals.