Wild proboscis monkeys live in just one area: the lowland swamps and mangrove forests on the island of Borneo. They are at once hideous and beautiful, having unusually long, pendulous noses and oversized bellies. And this endangered monkey species lives in fascinating social systems called harems.
The average size of a harem is nine individuals, but they can range from four to twenty members. These groups are more flexible than other primate groups, and can be comprised of all males or just one male with numerous females and their young.
A proboscis monkey harem is a lively group – they can be heard honking, groaning, squealing and roaring at one another. Females will often clean and groom their offspring, and a harem male will often climb to the top of a tree and stand guard for the group, like this young proboscis monkey I photographed during an August ecotour in Borneo:
The dominant male in a harem will become aggressive towards the younger males once they mature, so these juveniles eventually leave and roam in bachelor groups until they are in a position to start a harem of their own.
There may be fewer than 8,000 proboscis monkeys left in the wild. This species is threatened by habitat loss, illegal hunting, mining, forest fires, agriculture and settlement expansion.
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