establish themselves thereby comprise the highest mortality rate (30–35% per year) amongst adult tigers. To identify his territory, the male marks trees by spraying urine, anal gland secretions, marking trails with feces and marking trees or the ground with their claws. Females also use these "scrapes", urine and fecal markings. Scent markings of this type allow an individual to pick up information on another's identity, sex and reproductive status. Females in oestrus will signal their availability by scent marking more frequently and increasing their vocalisations. Although for the most part avoiding each other, tigers are not always territorial and relationships between individuals can be complex. An adult of either sex will sometimes share its kill with others, even with unrelated tigers. George Schaller observed a male share a kill with two females and four cubs. Unlike male lions, male tigers allow females and cubs to feed on the kill before the male is finished with it; all involved generally seem to behave amicably, in contrast to the competitive behaviour shown by a lion pride. Stephen Mills described a social feeding event in Ranthambore National Park: Male tigers are generally less tolerant of other males within their territories than females are of other females. Territory disputes are usually solved by intimidation rather than outright violence. Several such incidents have been observed in which the subordinate tiger yielded by rolling onto its back and showing its belly in a submissive posture. Once dominance has been established, a male may tolerate a subordinate within his range, as long as they do not live in too close quarters. The most serious disputes tend to occur between two males competing for a female in oestrus, sometimes fighting to the death. Facial expressions include the "defense threat", where an individual bares its teeth, flattens its ears and its pupils enlarge. Both males and females show a flehmen response, a characteristic grimace, when sniffing urine markings, but flehmen is more often associated with males detecting the markings made by tigresses in oestrus. Tigers roar to signal their presence to other individuals over long distances. This vocalization is forced through an open mouth as it closes and can be heard away. They may roar three or four times in a row, and other tigers may respond in kind. When tense, tigers will moan, a sound similar to a roar but softer and made when the mouth is at