Winter food habits of sympatric carnivores, Amur tigers and Far Eastern leopards, in the Russian Far East

Amur tigers and Far Eastern leopards are sympatric in the Russian Far East. Different ecological characteristics, such as different resource use, may enable coexistence of these two large predators, as indicated in other tiger–leopard habitats in Asia. We examined the winter food habits of tigers and leopards in the sympatric range in Southwest Primorskii Krai, Russian Far East using feces collected during four winters (2000–01, 2001–02, 2002–03, and 2004–05). Fecal samples were identified as either tiger or leopard by genetic analysis, and we examined 63 and 139 samples of tiger and leopard feces, respectively. We found that leopards preyed on 13 species and tigers on 8 species. Wild boar and sika deer were the most frequently consumed prey for tigers and leopards, respectively. Three ungulates (sika deer, roe deer, and wild boar) appeared to be the essential prey because they provided a large proportion of the relative biomass consumed by tigers (92%) and leopards (87%). Tigers showed a strong preference for wild boar (Jacobs index: +0.55), whereas leopards did not show such a strong preference for any particular ungulate species. Moreover, both species consumed mid-sized carnivores and small mammals, with leopards consuming a more diverse range of prey, including squirrels, rodents, birds, and clams, none of which were identified in the tiger feces. There was a significant difference in the composition of their prey, suggesting resource partitioning between the two predators; however, Pianka's niche overlap index was high (0.77) because both species heavily relied on the three ungulates. Our study suggests that the availability of three different ungulate species, the tigers’ preference for wild boar, and the diverse prey base of leopards contribute to the coexistence of tigers and leopards in this region.