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How can
you tell the difference between male and female koalas?
A male koala is easily distinguished by his active sternal (chest) gland, which is used for scent-marking trees. The glandular secretions leave a brown stain on his chest. Males are usually larger in size than females. In Victoria, the average weight of a male is 11.8 kilograms compared with 7.9 kilograms for a female. Males also have flatter, less pointed faces than females (see figure) (Phillip Island Nature Park 1998).
Koalas mate at a time which allows the young to emerge from the pouch when quality food is abundant. In southern Australia, most births are from December to February (Phillip Island Nature Park 1998).
How many babies (joeys) do koalas have?
Koalas usually produce only a single joey, but occasionally twins are born (Phillip Island Nature Park 1998).
What is the gestation period (the period between mating and birth)?
Koalas are born 34 to 36 days after conception. They are about 19 millimetres in length and weigh approximately half a gram (about the size of a jelly bean). They are very underdeveloped. Only the forelimbs (vital for the climb into the pouch) and lips (vital for suckling once in the pouch) are well developed (Phillip Island Nature Park 1998).
How long do joeys remain in the pouch?
A joey remains in the pouch without emerging for the first 22 weeks after birth. Between 22 and 36 weeks of age, the joey will become more independent, spending more and more time out of the pouch. At 36 weeks, it weighs about one kilogram and no longer fits in its mother's pouch. It spends much of its time sitting on its mother's back, but returns to its mother's belly in cold, wet weather and to sleep. Koalas are weaned at approximately 12 months old and are fully independent at 18 months of age (Phillip Island Nature Park 1998).
Do koalas have the same mate each year?
No. Koalas are very solitary animals and the only relationships that form are between mothers and joeys before they become independent (Phillip Island Nature Park 1998).
At what age do koalas begin breeding?
Females usually begin breeding at about two years of age. Males usually begin breeding at four to five years of age, once they are big enough to dominate other males (Phillip Island Nature Park 1998).
References
Phillip Island Nature Park. (1998). Nature Notes: Everything you ever wanted to know about koalas. Phillip Island Nature Park: Cowes, Vic.
Site last updated Autumn 2008. © Friends of the Koalas