Squirrel monkeys are highly sociable primates that thrive in large groups called troops. These troops can range from 40 to as many as 300 individuals, depending on space and food availability. However, they don’t always stay together as one unit. Instead, they split into smaller subgroups based on age and sex. They are incredibly agile, using their long tails for balance as they navigate the trees with remarkable speed and precision. Although their tails are not prehensile, they help them maintain stability as they leap across branches – sometimes covering distances of up to 2 metres! Communication is essential within these large groups, and squirrel monkeys use a mix of vocalisations, facial expressions, body postures, and even scent marking. One of their unique behaviours includes urinating on their hands and feet to mark territory and to regulate body temperature, track group members, and groom themselves.