Okapis are majestic yet secretive animals. Native to the lush rain forests of Zaire, they remained hidden within the forest’s dense vegetation for centuries before Western scientists became aware of them. By contrast, local forest people have always known of this wary species with their acute sense of hearing and use of well-trodden paths in the forest. Of all the animals in the San Diego Zoo’s collection, they are the most unusual, appearing at first glance to be a hybrid of a zebra, brown cow, and giraffe. Indeed, their striped rump could be mistaken for a zebra from a distance and their head (complete with horns or ossicones) is particularly reminiscent of the giraffe (albeit with a much shorter neck!).
Recent genetic research on this species has revealed that okapis are indeed most closely related to the giraffe. However, it’s not just their unusual appearance that has drawn the attention of the San Diego Zoo’s Behavioral Biology Division; it turns out that this elusive species has a secret language, too. Our Sensory Ecology Lab studies animal communication and has been using novel acoustic techniques to study a range of different species from cheetahs to gibbons. Recently, we’ve been watching okapis closely and recording their sounds. We hear coughs, bleats, and whistles quite often, but it wasn’t until we returned to the lab to examine our recordings closely that we realized that okapis also use other calls, or words, with very low frequencies. These calls are so low, in fact, that we cannot hear them at all! It’s only when we look at recordings via specialized computer software that these infrasonic mutterings become visible.
Amazing though it sounds, these unusual animals have been using a secret language that, until very recently, we’ve been completely unaware of. Now that we know that they also use infrasound to communicate with one another, we are recording them 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. The predators remain unaware of these chats as, like us, they cannot hear sounds that low in pitch. It’s the okapi version of students text messaging each other in class so that the teacher is unaware that they are “talking.”
Watch out for more insights into the fascinating world of the okapi as we begin to unravel this exciting area of research!
Matt Anderson is a scientist with the San Diego Zoo’s Behavioral Biology Division.
Read Matt’s previous blogs, The Sounds of Shoebills, Sounds from Cameroon’s Ebo Forest, and Singing in the Rain.
Read another blog about okapis, Okapi School at the Park