Written By: Rachel Allen
With Hesty approaching her due date in the next week, Animal Care Specialists in the Great Ape building thought it would be fun to share some of the training that we’ve been working on with Hesty over the last nine months. A big part of what we do here at the Zoo is training animals to voluntarily participate in their own medical care, which helps reduce the need for anesthesia or sedation.
Hesty was born here at Denver Zoo Conservation Alliance almost 16 years ago. When she was born to first-time mom Nias, there were some challenges for Hesty to properly nurse. This was partly due to Nias’s unusual nipple placement, combined with the fact she’d never experienced a baby orangutan before. In those first few days, Hesty couldn’t latch properly, so she had to be temporarily hand-raised for feeding. Hesty was returned to Nias a couple of times, and training helped Nias guide her to successfully latch and nurse. As Hesty grew up, Animal Care Specialists noticed that she had inherited the same anatomical features as her mom. This means she might face similar challenges nursing her own baby.
With this knowledge, Animal Care Specialists started working with Hesty years ago to present her chest to the mesh so she was comfortable in this position and also allow tactile. We also taught her at a young age to urinate when asked so we could collect urine samples for hormone testing. This behavior was asked for regularly and is how Animal Care Specialists are able totrack her menstrual cycles that started around five years old. These two behaviors would be very important later on when Hesty was old enough to have a baby.
DZCA is a part of the Association of Zoos and Aquariums’ Orangutan Species Survival Program which essentially acts as an orangutan dating service, taking into account genetics, compatibility, and other factors. They helped to determine that Hesty would be a good match with our male orangutan Jaya. She was taken off birth control and her menstrual cycle was tracked monthly. As soon as her cycle stopped, we were able to collect a urine sample and use a human pregnancy test (along with some anatomical changes) to confirm that Hesty was expecting!
Once we knew that Hesty was pregnant, we began training her on a long list of maternal behaviors. The first priority was ultrasound training so we could track the infant’s health and development. For this, Hesty needed to press her belly firmly against the mesh, keep her hands up, and hold that position for up to 10 minutes. She then needed care staff to use ultrasound gel to press down her hair and allow for the best contact for the ultrasound probe.
We trained this step by step, first teaching the position, then gradually increasing the duration while rewarding her with small treats. We also used a fake probe to get her used to the feeling. However, when we introduced ultrasound gel, we hit a snag. Hesty didn’t like the gel in her hair and would immediately move away to wipe it off.
After a couple of weeks of trying to desensitize her to the gel, we changed our approach. In consultation with our veterinary team, we switched to using warm water sprayed onto her hair. While it doesn’t provide as much detail, it allows us to see the baby’s movement and positioning—which is what we need most. Hesty was much more comfortable with this, and we’vebeen able to do regular ultrasounds since then. Like any individual, though, she sometimes chooses not to participate, and that’s always her choice. On those days, we try to encourage her with especially high-value treats like sugar-free candy or even a piece of bubble gum.
Hesty is a first-time mom, but she has had a lot of opportunities to see how to care for an infant. She was able to watch Nias care for her little sister Cerah for the first two years of her life and then Berani took over care of Cerah when Nias passed away unexpectedly. More recently, Hesty has been able to observe Eirina as she has cared for Siska over the last two and half years and she has been watching carefully. In the wild, this is how young orangutans would learn to care for their infants, by watching their mothers or other females care for young. Wefeel confident that Hesty will naturally know what to do and how to care for her baby, but we want to make sure that if she needs any help, we are able to provide that so she can ultimately raise her baby on her own.
Working as a team, different Animal Care Specialists focused on different skills. One continued strengthening her nipple presentation behavior. Another introduced bottle presentation at the mesh, teaching Hesty to ignore the bottle since it would be for the baby, not her. A third worked on teaching her to “pick up” objects using a laser pointer and then bring them to the mesh to give to an Animal Care Specialist. We also created small burlap bags filled with hay to act as a “baby.” Animal Care Specialists adapted an existing metal chute (normally used for voluntary blood draws) to safely pass the burlap “baby” to Hesty. She learned to retrieve it, hold onto it, and calmly present it at the mesh. Once she was comfortable with that, we upgraded to a stuffed animal orangutan.
This is where all the trained behaviors came together. Hesty was asked to pick up the “baby,” bring it to the mesh, and position it so its “mouth” touched the bottle when offered. It took some practice and repositioning, but she caught on quickly. She’s rewarded with fruit and other treats for calmly holding the “baby” during these sessions. Animal Care Specialists also taught Hesty to hold the “baby” against her chest with the “mouth” close to her nipples to simulate how she’ll need to position her real infant for nursing. At the end of each session, she’sasked to return the “baby” to the chute so it can be safely removed. This behavior would allow Hesty to safely and voluntarily pass her infant to staff if intervention or assist rearing is needed temporarily.
The hope with all this training is that Hesty will not need to use any of it, and she will naturally understand what she needs to do and be successful. We have a lot of confidence in Hesty, but sometimes new moms just need a little help, and we want to be able to provide that.
This has truly been a team effort from all of our Animal Care Specialists on the Primate Team. Together, we feel confident that Hesty is as prepared as we can help her be for this next great adventure.
