CINCINNATI — The Cincinnati Zoo is welcoming another bouncing bundle of joey to its growing family of wallabies.
A baby Bennett's Wallaby, also known as a joey, is expected to emerge from his mother Ava's pouch in the coming months. Wallabies are marsupials, or pouched mammals, similar to kangaroos but much smaller.
What makes Ava's pregnancy interesting is that she just had a joey in May, and she hasn't bred with any of the wallabies in Cincinnati. Is it an immaculate conception? Zoo experts say there’s an explanation.
Ava came to the Cincinnati Zoo in spring 2020, and keepers discovered she was pregnant in May before she gave birth to little Pocket weeks later.
But, keepers and volunteers said none of the Cincinnati Zoo’s male wallabies can mate. So what happened?
“It's actually something really cool called embryonic diapause,” said Myra Bhatnagar, a wallaby volunteer.
Wallaby babies are born underdeveloped after one month and then crawl into their mother’s pouch to nurse and develop for several months. Because of embryonic diapause, it’s possible the fertilized embryo for the new joey was waiting its turn behind Pocket.
“She had that embryo in her uterus, but it was just hanging out waiting for Pocket to be born so that she could have that next embryo develop,” Bhatnagar said.
For this reason, experts say some wallabies can be perpetually pregnant.
Ava's joey has just opened its eyes and will probably grow hair soon. Volunteers like Bhatnagar and other zoo staff are waiting patiently for it to emerge from her pouch, which they first noticed was moving on Dec. 23.
“It was our own little Christmas miracle here at the Zoo, but it was actually the miracle of science,” she said of the early, surprise Zoo Baby for 2021.