What Is a Baby Kangaroo Called? Joeys and Pouch Life

What is a joey?

Joey is the name for the young of kangaroos and wallabies, and the word is also used for other marsupials, such as koalas, wombats and possums. Marsupials are mammals that give birth to very small, undeveloped young, which then finish growing outside the womb, usually in a pouch.

People sometimes use different words for joeys at different stages. A newly born, hairless joey is often called a pinkie by wildlife carers, a joey still living in the pouch is a pouch young, and an older joey that lives outside but still drinks milk is called a young-at-foot.

Other kangaroo names are just as distinctive. Adult males are bucks, boomers or jacks, adult females are does, flyers or jills, and a group of kangaroos is a mob.

How big is a newborn kangaroo?

At birth, a red kangaroo joey is about 2.5 cm (1 in) long and weighs less than 1 g (0.04 oz). It is blind, hairless and pink, with tiny back legs that are little more than stumps. Its front limbs, however, are strong and have claws, and its mouth, tongue and nostrils are well developed. These are the parts it needs for the journey to the pouch and for feeding.

The contrast in size is extreme. A mother red kangaroo weighs around 18–40 kg (40–88 lb), so her newborn is tens of thousands of times lighter than she is. In placental mammals such as deer or horses, newborns are far larger compared with their mothers.

The climb into the pouch

Shortly before birth, the mother cleans her pouch by licking it. She then sits with her tail forward between her hind legs. The newborn emerges and, without any help, pulls itself through the fur on her belly with its front limbs. The climb to the pouch takes only about three to five minutes.

Inside the pouch, the joey finds one of the four teats and takes it into its mouth. The tip of the teat swells, and the joey stays firmly attached for about the next two months, drinking milk and growing. A red kangaroo’s pouch opens upward and forward, toward the mother’s head, which keeps the joey secure while she hops. Wombats are different, as explained in why do wombats have backward pouches?

How long does a joey live in the pouch?

A red kangaroo joey develops in stages:

In the weeks before leaving the pouch for good, the joey hops out to explore and graze, then dives back in head first when frightened or tired, turning around inside. Once it is too big to fit, it stays close to its mother as a young-at-foot, pushing its head into the pouch to drink.

Gray kangaroos develop more slowly, and their joeys stay in the pouch for most of their first year.

Three young at once: embryonic diapause

Kangaroo reproduction has a remarkable trick. A female red kangaroo usually mates again within a day or two of giving birth. The new embryo grows for only a few days, then stops at a tiny ball of cells called a blastocyst. This pause is called embryonic diapause.

The embryo stays paused while the joey in the pouch is suckling. When that joey is ready to leave the pouch, or if it dies, the embryo starts developing again and is born about a month later. In good times, a mother can therefore have three young at once: a young-at-foot, a joey in the pouch and a paused embryo.

She can even make two kinds of milk at the same time. Each teat produces milk suited to the joey drinking from it: more watery, low-fat milk for the tiny pouch young and richer, fattier milk for the older young-at-foot.

Why do kangaroos give birth to such small babies?

Marsupials invest very little in pregnancy and much more in milk. This suits life in Australia’s unpredictable dry country. If a drought strikes, a mother can stop feeding a small pouch joey and lose relatively little, then quickly replace it with the paused embryo when conditions improve. In severe droughts, females may stop breeding altogether until rain returns.

Even so, many joeys do not survive. Most red kangaroos die in their first year, especially when dry weather reduces the green grass mothers need to make milk.

Myths and facts about joeys

Myth: the mother carries the newborn into her pouch. The newborn makes the climb entirely by itself, possibly guided partly by smell. The mother helps only by cleaning her fur and pouch and holding still.

Myth: joeys are born in the pouch. The joey is born the same way as other mammals, from the birth canal, and only afterward reaches the pouch. Young marsupials of other species, such as the koala, make a similar journey.

To learn how big joeys become when fully grown, see how big is a red kangaroo?