I wrote a post about the rescue of Joanne the baby kangaroo and a follow-up indicating that she was doing well.
A fellow blogger has commented that a baby kangaroo (or koala, for that matter) seems to be called a “joey” one minute and a “pinky” (or "pinkie") the next. I thought I should explain why this is in more detail here.
Briefly, "joey" is the generic name for the babies of most marsupials, eg: kangaroos, wallabies, koalas, wombats, possums, etc. So, the young marsupial is always a “joey”, but in the earliest phase of a joey’s development it is called a "pinky".
The reason for the different names is that marsupials are not like other mammals; they are not born, and that’s that.
When a koala is born it is about 2cm long, weighs 0.5g and has no fur. This tiny creature crawls up on the outside of its mother, through her fur and up into the pouch which runs vertically down her body (unlike the kangaroo’s which is horizontal). There is an excellent photo of a tiny, pinky koala on the Warrnambool Wildlife Rescue page, showing it drinking from its mother's teat.
The baby spends several months in the pouch where it drinks her milk and grows in size. As I said above, the new-born baby is furless. Without its fur, the baby is just pink skin so until the baby grows its full coat of fur, it is called pinky. You rarely see much a pinky joey outside the pouch unless it is an orphaned pinky being cared for by humans. In the wild, the pinky remains in the mother’s pouch for warmth. Even if it were furred, it would be too small and feeble to get about on its own.
In human terms, a pinky is like a premature baby. They need a lot of care and may not survive. Like premature human babies, very young pinkies are kept in knitted pouches in a humidcrib to simulate the warmth and feeling of a real pouch (or womb).
With lots of special care, they can survive, but it is touch and go. The younger they are, the smaller they are, and the more frequent feeds they require. Such a small animal is not designed to be outside the pouch, so they usually need the care of a pinky expert – someone who has had a lot of experience caring for pinkies.
Just to complicate matters, there is a special class of marsupials called monotremes. There are only two animals in this sub-class: the echidnas and the platypus. They are warm-blooded like other mammals but lay eggs. Their young are not called joeys. Baby echidnas are called “puggles”, whereas, curiously, baby platypi don’t have a name!
As I don't work with monotremes, I don't know if their very young babies are called pinkies as well. Here is a photo of a young puggle...it certainly does look rather pink!