Even eating as much as much as they do, koalas don’t have much energy. So they rest about 20 hours a day. That doesn’t leave them much time to search for mates. For the population to multiply, koalas must be part of a colony, or group. Within a colony, the animals’ home ranges fit together like pieces of a puzzle. Koalas generally live alone, but colony members from small groups at mating time. Five or so weeks after mating, koala mothers give birth. Each mother has a single joey, or baby. Blind and hairless joeys are no bigger than jellybeans. Like other marsupials, such as kangaroos, koalas keep their joeys in pouches. After six months, joeys are strong enough to crawl out of their mother’ pouches. But they don’t go off on their own until they’re about a year old. Then it’s time for the young koala to find its own “puzzle piece” to call home. But what happens when the puzzle starts to lose pieces?