It may seem hard to believe, but male proboscis monkeys use
their fleshy, pendulous noses to attract mates. Scientists think
these outsize organs create an echo chamber that amplifies the
monkey’s call, impressing females and intimidating rival males.
Proboscis monkeys are endemic to the jungles of Borneo, never
straying far from the island’s rivers, coastal mangroves, and
swamps. They are a highly arboreal species and will venture onto
land only occasionally to search for food. They live in
organized harem groups consisting of a dominant male and two to
seven females and their offspring. Various groups often
congregate near water at night to sleep. Proboscis monkeys are
the primate world’s most prolific swimmers, frequently leaping
from tree limbs and hitting the water with a comical belly flop.
They’ve evolved webbed feet and hands to help them outpace the
crocodiles that are some of their main predators. Among the
largest of Asia’s monkeys, male proboscis specimens can reach 50
pounds (23 kilograms), altho