Estimating Amur tiger (Panthera tigris altaica) kill rates and potential consumption rates using global positioning system collars

The International Union for Conservation of Nature has classified all subspecies of tigers (Panthera tigris) as endangered and prey depletion is recognized as a primary driver of declines. Prey depletion may be particularly important for Amur tigers (P. t. altaica) in the Russian Far East, living at the northern limits of their range and with the lowest prey densities of any tiger population. Unfortunately, rigorous investigations of annual prey requirements for any tiger population are lacking. We deployed global positioning system (GPS) collars on Amur tigers during 2009-2012 to study annual kill rates in the Russian Far East. We investigated 380 GPS location clusters and detected 111 kill sites. We then used logistic regression to model both the probability of a kill site at location clusters and the size of prey species at kill sites according to several spatial and temporal cluster covariates. Our top model for predicting kill sites included the duration of the cluster in hours and cluster fidelity components as covariates (overall classification success 86.3%; receiver operating characteristic score of 0.894). Application of the model to all tiger GPS data revealed that Amur tigers in this study made a kill once every 6.5 days (95% confidence interval [95% CI] 5.9-7.2 days) and consumed an estimated average of 8.9 kg of prey biomass per day (95% CI 8.8-9.0 kg/day). The success of efforts to reverse tiger declines will be at least partially determined by wildlife managers' ability to conserve large ungulates at adequate densities for recovering tiger populations.