The Sumatran tiger (Panthera tigris sumatrae) is a rare tiger subspecies that inhabits the Indonesian island of Sumatra. It was classified as critically endangered by IUCN in 2008 as the population is projected to be 441 to 679 individuals, with no subpopulation having an effective population size larger than 50 individuals, with a declining trend. The Sumatran tiger is the only surviving member of the Sunda Islands group of tigers that included the now extinct Bali tiger and Javan tiger. Sequences from complete mitochondrial genes of 34 tigers support the hypothesis that Sumatran tigers are diagnostically distinct from mainland populations. The Sumatran tiger has been described as darker in fur colour and as having thicker stripes than the Javan tiger. Stripes tend to disintegrate into spots near their ends, and lines of small dark specks between regular stripes may be found on the back, flanks and hind legs. The frequency of stripes is higher than in other subspecies. The Sumatran tiger is one of the smallest tiger subspecies. Males weigh 100 to 140 kg (220 to 310 lb) and measure 220 to 225 cm (87 to 89 in) in length between the pegs with a greatest length of skull of 295 to 335 mm (11.6 to 13.2 in). Females weigh 75 to 110 kg (170 to 240 lb) and measure 215 to 230 cm (85 to 91 in) in length between the pegs with a greatest length of skull of 263 to 294 mm (10.4 to 11.6 in). Males have a bearded and maned appearance; neck and cheek hair are well developed. In 1994, the largest population of Sumatran tigers was reported from the Gunung Leuser National Park as comprising 110 to 180 individuals. Their habitat ranges from lowland forest to sub-mountain and mountain forest including some peat moss forests. According to the Tiger Information Center and the World Wildlife Fund, there are no more than 500 of these tigers left in the wild with some estimates considerably lower. Sumatra has undergone much agricultural growth, and as a result, tiger habitat has become fragmented with about 400 tigers inhabiting five national parks and two game reserves. The largest populations live in the Kerinci Seblat National Park and Gunung Leuser National Park. Another 100 live in unprotected areas that are in danger of being lost to agriculture as of 2012. The tigers that live in unprotected areas are very vulnerable to poaching as well as the killing of problem animals that come in contact with villagers encroaching upon the animals' habitat. The Sumatran tiger's habitat is being drastically reduced by logging, clearing for agriculture and plantations, and settlement. In Sumatra, tiger habitat is shrinking fast with timber resources being exploited on a large scale. The tiger in Sumatra faces precarious prospects if its present distribution continues to be substantially reduced and populations become small, fragmented and isolated from one another. They have other problems, such as; illegal logging, poaching and illegal hunting. Although the numbers of tigers incidentally killed or as a result of human-tiger conflict are significant, most tigers in Sumatra are apparently killed deliberately for commercial gain. Moreover, there is no evidence that tiger poaching has declined significantly since the early 1990s. This is despite intensified conservation and protection measures in Sumatra, and the apparent success globally in curtailing markets for tiger bone.