It is a large feline in the mammalian class, with nine subspecies and significant differences in body size and morphology between each subspecies. The Siberian tiger is the largest, with a male body length of up to 3.7 meters and a weight of 423 kilograms. The Sumatran tiger is the smallest living subspecies, with a male tiger measuring 2.34 meters in length and weighing 136 kilograms. Tigers are typical mountain forest dwelling animals that can thrive in tropical rainforests and evergreen broad-leaved forests in the south, as well as deciduous broad-leaved forests and mixed coniferous and broad-leaved forests in the north. Due to human hunting and fragmentation of wild habitats, tigers have become rare and endangered species. A 2016 survey showed that there were 3890 wild tigers worldwide.