Satu sits slightly down with a piece of burlap over his head; Indah lies in a hammock completely covered by burlap, and Karen has a burlap bag clutched in her foot as she does somersaults in front of the glass. What’s up with the burlap? Burlap is one of the enrichment items we give the orangutans on exhibit. If you have spent anytime at the San Diego Zoo, you probably have heard of enrichment. Enrichment basically refers to anything given to the animals that will increase their activity both physically and mentally.
When animals are on exhibit, we are limited to items that are natural in appearance, and with orangutans, we are limited further to items that are “orangutan proof.” Orangutans are intelligent, strong, and creative animals. Great care has to be given so that individuals cannot hurt themselves, destroy the items, or, more likely, use the item as a tool for mischief.
In addition to the burlap, pinecones, gourds, bamboo, browse, and palm fronds are enrichment items we commonly use on exhibit. We try to give them items that will encourage natural behaviors. Orangutans are arboreal mammals from the rain forest. They use branches and large fronds to protect themselves from the rain and sun. We give them burlap, browse, and palm fronds to mimic this behavior. We put treats and smears in and on the pinecones, gourds, and bamboo to encourage foraging behaviors and tool use. We have a simulated termite mound in the exhibit, which, of course, does not contain ants or termites but different sauces. It is not so important what is in the termite mound but that they use tools to extract what they want out of it.
Tool use is a learned behavior passed from mother to offspring. We saw Indah actively teaching Cinta to use the termite mound, and it will be great to see her do the same with her newest baby, Aisha. Different groups have different tool use methods, and even individuals have a preference when it comes to extracting the enrichment. When we give bamboo cups with gelatin inside, Satu likes to use his strong jaws and teeth to just break it open, Cinta would pound it on rocks and knock out the gelatin, while Karen uses a small stick to get the good stuff.
You will also notice when you look at the exhibit that there are large, plastic items hung on ropes. While they are not natural looking, they fulfill the other requirement: they are orangutan proof. We use these as permanent enrichment items in the exhibit. In addition to the animals using them to swing and play with, we also put food items inside periodically. As a result, the orangutans check them every day. This increases their activity level, but it also mimics a natural behavior. Orangutans have a mental map of the rain forest: where the fruiting trees are located, and what is edible. They remember where they found food in the past and return to it later.
Tanya Howard is a senior keeper at the San Diego Zoo. Read her previous post, Orangutan Aisha at 5 Months.