Orangutans have been described as “semi-solitary” animals for a long time now, ever since scientists started following them around in the forests of Borneo and Sumatra some 40 years ago. It was evident then and now that most wild orangutans choose to be alone for much of their time, with the exception of mothers and infants, who have the lengthiest bond in the primate world. However, the longer we study the red apes, we discover that they have the potential and the ability to be very social – when and where they want to, strictly on their own terms. The biggest reason for sociality is food. If a fruiting tree is discovered, it will be set upon by more than one orangutan, and possibly up to six or seven at a time. They will eat peacefully together – until the fruit runs out. And, we have also seen youngsters playing in the forest, when old enough to get off mom and do so. The mothers will pass each other like ships in the night, but the kids will get off and play with each other. And, in zoos and in nature, babies will stay with their mothers for up to 7- 9 years before venturing off on their own.
Here in the zoo, we honor our orangutans semi-solitary nature by not forcing them into big groups. Rather, we manage them by using flexible social housing: that is, by keeping them in more natural social pairings of mother and infant, while allowing them some choice in whom they can visit. We can periodically test the social waters by putting up an introduction door between two rooms – a door with 2”x 2” mesh whereby two animals on either side of the door can see, smell and even touch one another. If they show no interest in visiting, we simply close the solid door between them. If they act aggressive, we close it more quickly! But, if they play or groom or share food, it tells us that a full introduction might be a good thing to attempt.
We have done introductions of various configurations throughout the years, but the ones that can be the most interesting and engaging are those between young orangutans. We are working on introducing two young females currently: Indah and Aurora. Indah is a 9 year old Sumatran orangutan who was surrogate-reared by Cheyenne, our 40 year old hybrid female. When Aurora was born and then sadly rejected by Kelly, we immediately began introducing Aurora to Cheyenne so that she would have the maternal guidance that she needed. During that time, Indah was also involved in the process and was very interested in Aurora. We hoped that they would become a happy trio, at least for a while, but once Aurora was actually given to Cheyenne, it wasn’t long before she decided that Indah needed to leave. This happens with regularity in the wild: mothers will push their older kids out once they give birth to their newest baby. At the age of 7, 8 or 9, it is time to leave the nest, both figuratively and literally. So, we were not too surprised when Indah found herself pushed out.
In an effort to allow Indah the experience with infants that she needs to become a good mother herself, we have begun re-introductions between her and Aurora, without Cheyenne fully in the mix. This is easily accomplished by using what we call a “creep” door. That is a door that we open only widely enough for the infant to pass through it. Cheyenne’s face will barely fit through, so she can watch what goes on, and she can also stick her arms through the open space, but she cannot pass all the way through. This has been highly enriching for both kids but a bit of a conundrum for Cheyenne, who is naturally protective of her newest charge. She frequently decides that Aurora should not pass all the way through the creep door, and holds her firmly but gently by an ankle so that Aurora is tethered to her as she plays with Indah. Enjoy the video clip here to see a bout of play in which Cheyenne controls the situation!
Come to the zoo to see Cheyenne and Aurora together, or see Indah and Solaris together outside some days. You also might see Solaris and his mother Kelly outdoors together, and on these days, we are introducing Indah to Aurora inside the nighthouse. Got all that?
Orangutans are complex creatures and so are their social interactions, as you can see!