A female joey of the endangered Goodfellow's tree species will soon join its mates at the outdoor exhibit of the Singapore Zoo's Australasia zone. These tree kangaroos are among the rarest animals kept under human care, with only about 50 in zoos under a joint preservation programme. The Singapore Zoo is home to five of them, including the nearly year-old joey that was born jelly bean-sized and first popped its head out of mum Blue's pouch in January. It is being conditioned to the exhibit and will be there throughout the day once comfortable.