The primary mode of reproduction for kangaroos is viviparity, meaning they give birth to live young rather than laying eggs. Female kangaroos have a unique reproductive system that includes a pouch for nurturing their young, called joeys, after they are born. The gestation period for a kangaroo is relatively short, lasting about 30 to 36 days, after which the tiny, underdeveloped joey climbs into the mother's pouch to continue developing. The joey remains in the pouch for several months, feeding on its mother's milk until it grows enough to venture out.