Surprise Wallaby Joey Shows Up a Year After Mating

Mica is a brush-tailed rock wallaby at the Taronga Zoo in Sydney. She’s been doing her job for the endangered species by giving birth. However, the only male wallaby in the zoo was moved away in March of 2015. Mica’s joey emerged from the pouch about six months later. But zookeepers were surprised to find that there’s another baby in there! The new joey recently peeked out from Mica’s pouch, and appears to be about six months old. How did that happen? Wallaby keeper Tony-Britt Lewis explained. 

The birth is the result of a phenomenon known as embryonic diapause, which enables certain mammals to extend their gestation period and time the birth of their young.

The reproductive strategy, which is used by a number of marsupial species including kangaroos, wallabies and wombats, usually occurs when adverse environmental conditions threaten the survival of the mother and her newborn.

“It’s an interesting survival mechanism that allows the mother to delay the development of the embryo in drought conditions or if she already has a joey in the pouch,” said Tony.

Read more about embryonic diapause at Wikipedia. -via Arbroath

(Image credit: Paul Fahy/Taronga Zoo)