The Proboscis Monkey or long nosed monkey is a reddish brown arboreal Old World monkey that is endemic to the southeast Asian island of Borneo. They also go by the Malay name monyet belanda (Dutch monkey) as Indonesians remarked that the Dutch colonisers often had similarly large bellies and noses. Males have a maximum known weight of 30 kg while Females weigh 7 to 12 kg, with a maximum known mass of 15 kg. The large nose of the male can exceed 10.2 cm in length and hangs lower than the mouth. They live most commonly in coastal areas and along rivers. They favour dipterocarp, mangrove and riverine forests. It is perhaps the most aquatic of the primates and is a fairly good swimmer, capable of swimming up to 20 m underwater and have been known to swim across rivers. They have a long coat; the fur on the back is bright orange, reddish brown, yellowish brown or brick-red. Their face is orange-pink and the male has a red penis with a black scrotum. Both sexes have bulging stomachs that give the monkeys what resembles a pot belly and many of the monkeys' toes are webbed. Females become sexually mature at five years old and copulations tend to last for half a minute with both sexes participating although now always successfully. Perhaps this is because the male will grab the female by the ankles or torso and mount her from behind. It likely doesn't help that when soliciting sexual attention, both sexes will pouted, the males will sometimes vocalize, the females will present their backsides, and mating pairs are sometimes harassed by subadults. Proboscis monkeys eat primarily fruit and leaves, but will also eat flowers, seeds and insects to a lesser extent. Their daily activities consist of resting, traveling, feeding and keeping vigilant. As night approaches, the monkeys move back near the river and forage again. The proboscis monkey is assessed as Endangered and its total population has decreased by more than 50% in the past 36-40 years to 2008 due to ongoing habitat loss and hunting in some areas. The largest remaining populations are found in Kalimantan; there are far fewer in Sarawak, Brunei and Sabah.