Last year, keepers at the Nashville Zoo’s Kangaroo Kickabout learned that our mob of Red kangaroos would begin breeding. They developed an ambitious training plan to observe and record kangaroo babies (joeys) throughout the developmental process from birth to emergence from the pouch.
Kangaroos are considered marsupials which means they give birth to a premature fetus that finishes developing while attached to a teat in the mother’s pouch. The pouch is a fold of skin that covers the mother’s teats and is held closed by muscles located on her stomach.
“Joey development is well documented, but much of the data is collected from wild kangaroos in their native homeland of Australia,” said Emily Easter, one of the keepers at Kangaroo Kickabout. “The data we collect may reveal differences in physical or social development between kangaroos in the wild and those under human care.”
Using positive reinforcement (a process much like giving your dog a treat when they so something good), keepers began training the kangaroos to voluntarily stand in a stationary position and allow keepers to open the pouch and peek inside. Keepers were uncertain if less social kangaroos would participate in these sessions but were pleasantly surprised when all the kangaroos completed the training.
“Kangaroos have the option of ending their training session at any time,” said Easter. “However, we’re finding that they are actually vying to be first in line. Even the shy ones are eager to participate!”
Once the pouch is opened, keepers can check on the joey and take pictures and videos to document the developmental process. Like a digital baby book, the photos and video are stored online so keepers can share them with other keepers both at Nashville Zoo and around the world.
Because it is dark in the pouch, a penlight is used to help keepers see. “As joeys get bigger and their eyes begin to open, we switch to using a green light which is less perceptible to the developing joeys,” explains Lauren Lott, another keeper at Kangaroo Kickabout. “At as young as 27 days, female joeys will actually begin to develop a pouch of their own, so we can tell if a joey will be male or female very early in the process.”
Tracking the development of a joey is beneficial to the overall care of both the mother and the joey. Because the behavior is voluntary and is not stressful for the animal, keepers and the Zoo’s Veterinary Team can safely identify and address any problems or potential health issues. The observation process also acclimates joeys to human interaction at an early stage and lets them begin to view people as part of their natural environment.