Sounds of the rainforest

Hi everyone! My name is Jen, and I started as a Seasonal Keeper about two months ago in the Primate Department with the orangutans! I’ve always had a love and passion for great apes – I started my career working with macaques, and then chimpanzees, and now orangutans. One of the aspects of taking care of great apes that interests me the most is their behavior.

The scientific study of animal behavior is known as ethology. But rather than bore you all with a science lesson and a bunch of jargon, I’m here to talk to you all about orangutan vocalizations! Vocalizations that animals make are a crucial aspect of identifying and understanding an animal’s behavioral state. Just like people, orangutans express their emotions via body language, facial expressions, and vocalizations. Coming from a background of working with chimpanzees, I was used to hearing the sounds they make and understanding when one of them was angry, upset, excited, or calm. But not all great apes are the same! They share many of the same behavioral traits, but also have several differences as well.

One of the first calls I heard one of our adult females, Miri, make is a gorkum, when a loud truck was nearby while she was on habitat. This vocalization sounds like a low rumble. I learned she expressed her disturbance/annoyance at the vehicle by making this sound while hiding under one of the climbers. Along with vocalizations, you can also observe body language to get a clearer picture of how an animal is feeling or responding to a situation.

Another orangutan vocalization is the kiss squeak, which sounds like a kiss when you purse your lips together. This is usually made in reaction to a threatening stimulus or something that causes anxiety such as a predator or something unfamiliar coming too close. I was cleaning in an area next to one of our groups that consists of Benny, Blaze, and Pongo. I heard a loud kiss squeak coming from Pongo and knew something was upsetting him, so I went over to look and saw a bird had flown into the building! Pelari also was kiss squeaking when a chipmunk was running around in the moat. Vocalizations like these can come in handy for keepers to notify us that something is wrong or out of the ordinary!

My favorite call to listen to is the long call, which is most commonly emitted by flanged males, otherwise known as mature males with large cheek pads. This call starts with a “wooing” noise, gradually getting louder and ends with a bubbling noise. Since orangutans are solitary in the wild, they use this call to attract females for mating or communicate their territory to other males. Their large cheek pads and air sac are used to amplify the sound to carry it far away where a female may be. I can often hear our males Benny and Satu long calling back and forth to one another, as males would in the wild to defend their territory.

Next time you’re passing by the orangutan habitats, be sure to listen in to hear some of the sounds of the redheads of the rainforest!

Jen H.
Seasonal Keeper, Primates