Koalas are polygynous and breed seasonally, but males don’t usually mate until they reach 4 years old because competition for females requires a larger size.
Koalas are polygynous and breed seasonally. During the breeding season in October-February, adult males are very active at night and move constantly through their range, both ejecting male rivals and mating with any receptive females.
Female koalas are sexually mature at two years of age. Males are fertile at two years but usually don’t mate until they reach four simply because competition for females requires a larger size.