Females squawk when they are mounted, which is thought to be evolved behavior intended to attract the attention of the biggest, strongest resident males. To put a human take on it, it is thought that a resident male hears her and runs to her rescue. A female who only mates with one partner could end up with offspring carrying harmful genes. Koalas are disappearing slowly in Queensland, particularly in the southeast part of the state, according to Environment Australia. Some parts of Australia, however, including Kangaroo Island off the south Australian coast have experienced overpopulation of koalas.
Females begin to breed in their third year, and have one baby every year.
Joeys, the koala babies, are born very tiny just 30 days after conception. Born pink, blind, and bald, they are about 2 centimeters long and weight just one gram. Amazingly, they manage to climb unassisted into the pouch where they latch on to one of the mother koala's two teats. They remain in the pouch for up to seven months before moving to the mother's back and begin to wean. DNA testing has become much more popular in conservation biology as a means to identify species, determine genetic diversity of populations, and study mating strategies.