Owl monkeys have two primary glandular areas that secrete substances with olfactory messages. These two glands are called the sternal gland (found on the chest area) and the subcaudal glands ( found at the base of the tail). We know from studies at the DuMond Conservancy that each family has a distinctive family odor. Though much is learned, they probably use the scents that are deposited onto substrates ( known as scent marking) for individual identification, marking their territory, and in reproductive biology.