Monkeys are incredibly intelligent animals with diverse physical traits. They can leap and cling from tree to tree in a way that would make a human acrobat jealous, but they also walk on all fours and use their tails like a brace. Some monkeys have webbed feet that let them swim, and others, such as the night-foraging owl monkey (Chlorocebus sabaeus), are strictly nocturnal. They communicate with a wide variety of sounds, including grunts and other squeaks, that resonate in the forest.
Some monkey species live in harsh environments, such as desert-like savannas or snowy mountains. Others, such as geladas and golden monkeys, are tree dwellers, while Japanese macaques, known as snow monkeys, spend a lot of time sitting in hot springs to keep warm in the winter, as Live Science previously reported.
Almost all monkeys are highly social, living in groups called troops. Troops usually consist of several females and their young, with one or more males. Once males reach maturity, they leave their mother troop and seek out new ones in which to establish their own families.
Although many monkeys are found in the wild, their numbers are declining rapidly. They are often killed for the pet trade or hunted for bushmeat or traditional medicines, and their habitats are being destroyed by agriculture, hunting and development. The IUCN lists dozens of monkey species as endangered, and some are on the verge of extinction. The most vulnerable monkeys are those that are difficult to breed. Some monkeys breed seasonally, such as the pygmy marmoset (Cebuella pygmaea), which mates between September and November and gives birth in February to April after 160 to 170 days of gestation. Others, such as baboons, breed continuously throughout the year.