I smell you: While okapis travel for the most part by themselves within their home ranges, they still have ways of communicating with others whose ranges overlap. A scent gland on each foot leaves behind a sticky, tar-like substance wherever they have walked, marking their territory. Okapis have a great sense of smell. By checking the ground, an okapi can tell if another okapi has been there. Males also mark their territory by urine spraying. Normally silent, female okapis vocalize only when they are ready to breed.

Okapi newborns can stand up within 30 minutes of birth and nurse for the first time within an hour of birth. They have the same coloring as an adult but have a short fringe of hair along the spine, which generally disappears by the time they are 12 to 14 months old. In the wild, mothers hide their newborn calves in one spot, returning regularly to allow the calf to nurse.

An okapi calf starts trying solid food at just three weeks old and defecates (poops) for the first time between four and eight weeks of age. This adaptation helps keep predators from sniffing out the hidden newborns until they have had a chance to grow and gain strength. Calves triple their size by the end of their second month but do not reach full adult size until three years of age.

Okapis are very shy animals. Their reddish brown-black coat camouflages them in the deep forest. In the thick trees and underbrush, okapis rely on their hearing to warn them of danger. Their huge ears pick up even the softest sounds coming from any direction. They listen for leopards, which hunt adult okapis, as well as smaller wild cats, which can attack a young calf.

San Diego Zoo researchers discovered that okapis have a secret language. They watched okapis closely and recorded their sounds. The researchers heard coughs, bleats, and whistles quite often, but it wasn’t until they returned to the Sensory Ecology Lab to examine their recordings closely that they realized okapis also use other calls with very low frequencies. These calls are so low, in fact, that we humans cannot hear them at all! It’s only when we look at recordings via specialized computer software that these infrasonic mutterings become visible.

Our researchers then recorded our okapis around the clock to find out why they use these low-pitched calls. One explanation is that these calls have evolved for communication between Mom and her baby while she’s out foraging. In this situation, Mom can “check in” with her offspring without alerting potential predators of the fact that her baby is vulnerable. Predators remain unaware of these chats, as, like us, they cannot hear sounds so low in pitch. It’s the okapi version of students who text message each other in class so that the teacher is unaware that they are “talking.”