and weigh . Females weigh and measure in length between the pegs with a greatest length of skull of . Distribution and habitat The Sumatran tiger persists in small and fragmented populations across Sumatra, from sea level in the coastal lowland forest of Bukit Barisan Selatan National Park on the southeastern tip of Lampung Province to in mountain forests of Gunung Leuser National Park in Aceh Province. It is present in 27 habitat patches larger than , which cover . About a third of these patches are inside protected areas. Sumatran tigers prefer lowland and hill forests, where up to three tigers live in an area of . They use non-forest habitats and human-dominated landscapes at the fringes of protected areas to a lesser degree. In 1978, the Sumatran tiger population was estimated at 1,000 individuals, based on responses to a questionnaire survey. In 1985, a total of 26 protected areas across Sumatra containing about 800 tigers were identified. In 1992, an estimated 400–500 tigers lived in five Sumatran national parks and two protected areas. At that time, the largest population unit comprised 110–180 individuals in Gunung Leuser National Park. As of 2011, the tiger population in Kerinci Seblat National Park in central Sumatra comprised 165–190 individuals, which is more than anywhere else on the island. The park has the highest tiger occupancy rate of Sumatra's protected areas, with 83% of the park showing signs of tigers. Sumatra's total tiger population was estimated at 618 ± 290 individuals in 2017. Ecology and behaviour Sumatran tigers strongly prefer uncultivated forests and make little use of plantations of acacia and oil palm even if these are available. Within natural forest areas, they tend to use areas with higher elevation, lower annual rainfall, farther from the forest edge, and closer to forest centres. They prefer forest with dense understory cover and steep slope, and they strongly avoid forest areas with high human influence in the forms of encroachment and settlement. In acacia plantations, they tend to use areas closer to water and prefer areas with older plants, more leaf litter, and thicker subcanopy cover. Tiger records in oil palm plantations and rubber plantations are scarce. The availability of adequate vegetation cover at the ground level serves as an environmental condition fundamentally needed by tigers regardless of the location. Without adequate understory cover, tigers are even more vulnerable to persecution by humans. Human disturbance-related