The pygmy hippopotamus spends the day in water, and emerges at night to feed on fruits, leaves, roots and grasses (2), which it bites with the thick lips rather than with the teeth (2). Hippopotami have extraordinarily high rates of water loss (three to five times the rate in man) due to their unique skin structure; this explains why they must spend the day in water (2). Pygmy hippopotami usually live alone unless they are mating or with a calf, and they are not thought to hold territories (2). The home ranges of various individuals often overlap, but individuals seem to actively avoid encounters with others, possibly through dung marking (5). In the breeding season, males seek out females and form consortships for a time prior to mating, which tends to occur in the water but may also occur on land (2). Gestation lasts about 6.5 months, calves are suckled for six to eight months and stay with their mother until around eight years of age, when they are fully grown (2). The pygmy hippopotamus is not a particularly vocal species, but has been recorded grunting, hissing, squeaking and snorting (5).