Interspecific Relationships between the Amur Tiger (Panthera tigris altaica) and Brown (Ursus arctos) and Asiatic Black (Ursus thibetanus) Bears

Abstract

During the years 1992–2013, we studied the relationship between Amur tigers and brown and Asiatic black bears in the Sikhote-Alin Nature Reserve and surrounding areas in the southern part of the Russian Far East. To determine the importance of bears in the diet of tigers, 763 kills were located and identified, and 430 tiger scat samples were collected and analyzed. To detect kills and scat samples, we used radio telemetry and satellite tracking, as well as snow-tracking. Relying on evidence revealed by tracks, as well as radio telemetry, we determined whether bears exploited tiger kills as a food resource and how the two may have interacted at kill sites. Thirty-two Asiatic black bear and 12 brown bear den sites were measured to define properties that might assist in protection from the threat of a tiger attack. We identified 641 instances of marking on trees by both tigers and bears, an indication of the complexity of their relationship. Bears are an important part of the tigers’ diet, representing 2.2% of all kills found. Bear remains were found in 8.4% of examined tiger scat. Bears exploited tiger kills after a tiger had left, by usurping a kill, or by “sharing” a kill at alternate times. The occurrence of den properties that provided some protection from tigers was dependent on the den type and location. Evidence of both tiger and bear marking was detected at 50.1% of marked trees. A review of the literature on the relationship of tigers and bears is provided.