Wombat Life Cycle
Wombats usually give birth to a single young, but twins do occur.
The gestation period for a wombat is 20 to 22 days. At birth, the baby wombat, called a joey, is extremely small and undeveloped. It will weigh approximately 2 grams, less than one-tenth of an ounce, and be about the size of a jelly bean, 2 cm (0.75 inches) long. The joey is hairless with very thin skin and is unable to keep itself warm. They're blind and their ears do not function, but they have a large mouth and tongue, and a well-developed sense of smell.
As soon as it is born, the baby wombat will crawl into its mother's pouch and attach itself to one of the mother's teats. The teat will swell up in the joey's mouth which keeps the joey attached to the teat and helps to prevent the joey from falling out of the backwards-opening pouch.
Orphaned Southern hairy-nosed wombat joey (picture courtesy Wendy Morphett, used with permission)
The joey will remain in the pouch nursing and developing for 4 to 10 months, usually averaging about 8 months. At first the young wombat will leave the pouch for only short periods. When disturbed or frightened, it will return to the mother's pouch for safety. After one to three months, the wombat will no longer use the pouch but may still hide under or behind its mother for protection.
Once out of the pouch, the young wombat will begin to eat solid foods and will be fully weaned anywhere from 11 to 15 months, with 12 months being about average. It will remain alone in the burrow at night when the mother forages for food. Later it may follow its mother around. The mother will rip up tender grass roots and drop them on the ground for her young. The young wombat will grow rapidly during this period and will double its body weight in 3 to 8 months after being weaned.
Wombats stay with their mothers about 2 years. Some will leave their mother shortly after they're weaned, while others stay until they're full grown. Sometimes the mother will force them out. Females will usually stay with their mothers longer than males. With Northern Hairy-nosed wombats, it appears that the adult females are the ones who leave the area to establish new burrows elsewhere.
In captivity, wombats rarely give birth. Only a few zoo births have been recorded, the first one at Regent's Park Zoo in London in 1856. Other zoo births were recorded in 1914 and in 1931. A few others have been born in breeding research programs or in captivity.
A few sources say the Bare-nosed or Common wombat can give birth at any time of the year, while others say that the young are born in late autumn, April to June in Australia. Another source says their breeding periods vary with latitude and altitude. One source says breeding peaks from September to November. In a study of the Bare-nosed wombat of Tasmania, half the births occurred from October to January, while the other half were born during the other months.
Adult Southern hairy-nosed wombat (picture courtesy Wendy Morphett)
Some reports say Bare-nosed wombats don't reach breeding age until they're 3 or even 4 years old. Others say they reach breeding age at about 2 years when they weigh 22 kg (48 pounds). Most sources agree they can have young only once every two years. If the joey dies prematurely, however, the mother may have another baby sooner than this.
One source states that wombats in general can reach full size and be ready to breed in a little over 2 years under ideal conditions, but in the wild this usually takes 3 years.
The Southern Hairy-nosed wombat usually gives birth in the spring from September or October to January. In seasons of drought, no young will be born. Those that are born will often not survive the dry season.
One report says the Southern hairy-nosed females reach breeding age at 3 years, and the males at 2-3 years. Another source says they reach breeding age at 18 months when they are 60-80 cm in length (24 to 31 inches) and weigh 15-20 kg (33 to 44 pounds), and they will reach full size in 2 years.
Details of the Northern Hairy-nosed wombat's life-cycle are not well known. Young are usually born in the summer wet season, November to March or April. They can have about 2 young every 3 years under ideal conditions with adequate rainfall. This is probably rare since the area in which they live experiences frequent droughts. No young will be born during major droughts.
Southern hairy nosed wombats need at least 2 to 3 years of sufficient rainfall in order to successfully rear their young. One study of rainfall patterns over their range suggests that in only 10 to 20% of the years was there adequate rainfall for them to have a good chance of raising young.by Peter Marinacci