Press release: When wild prey reaches a certain bottom level, big cats begin to kill livestock
Nr. 260/2015 - 03.11.2015
German research team examines relationship between livestock predation by big cats and biomass of wild prey
(pug) Human-carnivore conflicts challenge the balance between biodiversity conservation and livelihoods of rural communities. Big cats, such as lions, tigers or leopards, are well known to kill domestic livestock and provoke counteraction from local people. As a result, people incur economic losses and wipe out cats even though these carnivores are threatened and officially protected. Deficiency of wild prey biomass is often described as a driver of such conflicts, but the question “at which level of prey density and biomass do big cats begin to kill livestock?” still remains unanswered. Meanwhile, knowing such a threshold would be an important step forward to predict human-felid conflicts, identify conflict hotspots and set priority conservation actions.
“We analyzed and mapped a global database of human-felid conflict sites and found out that the probability of cattle predation by big cats increases when prey biomass is less that about 812 kilograms per square kilometer. When prey biomass drop further to less than 540 kilograms per square kilometer, big cats also kill sheep and goats”, says leading researcher Dr. Igor Khorozyan. “What is most interesting and intriguing, however, is that this rule appears to be general regardless of species of big cats, their body masses, population densities and sizes of study areas”. This strategy strives to maximize the net energy budget of surviving felids by taking out the best available alternative prey (cattle) when prey biomass begins to dwindle, and by killing all available alternative prey (cattle, sheep and goats) when prey resources are too low. The study shows that the main candidates for cattle killing are large-bodied lion, tiger and jaguar, as well as the light-weighted snow leopard which demands for substantial energy input to survive in snow-capped highlands of Central Asia.
The model developed by the authors allows to reliably predict conflicts from current prey biomasses and demonstrates that only some well-protected areas of India, lowland Nepal and South Africa contain sufficient prey that averts big cats from killing livestock. In most cases, even in protected areas, the status of prey species and especially ungulates, which are always a favorite food for cats, is very alarming. Apparently, big cats cannot survive when prey biomass plummets to 7 kilograms per square kilometer, except for the highly adaptable leopard, which can even attain high densities in some prey-free human-dominated landscapes by killing only domestic animals.
“We also found situations, where the model predicts conflicts, but in practice they are not recorded”, says Dr. Matthias Waltert, senior author of the study and coordinator of the research team. “This can happen when big cat populations are very small and local prey resources suffice and when big cats prefer to kill smaller wild species instead of livestock, trying to avoid retaliatory killing by people.”
Contrary to other studies which offer to eliminate human-carnivore conflicts by reducing livestock numbers and stimulating vegetarian diet, the study did not find a direct effect of livestock numbers or biomass on conflicts with big cats. This is because big cats kill livestock when they are easier to catch, for example in dense vegetation or when shepherds are absent, and not when livestock are more numerous.
Original publication: Igor Khorozyan et al. (2015) Big cats kill more livestock when wild prey reaches a minimum threshold. Biological Conservation 192: 268-275, doi:10.1016/j.biocon.2015.09.031
Contact address:
Igor Khorozyan, PhD
Alexander von Humboldt postdoctoral scientist
Workgroup on Endangered Species
J.F. Blumenbach Institute of Zoology and Anthropology
Georg-August-Universität Göttingen
Bürgerstrasse 50, Göttingen 37073, Germany
phone: +49 551 395633
email: igor.khorozyan(at)biologie.uni-goettingen.de
website: www.uni-goettingen.de/en/483588.html