Wombat Burrows
Wombats are efficient diggers, and their burrows can be from 3 to 30 meters (10 to 100 feet) long and up to 3.5 meters (11.5 feet) deep. The burrow's diameter is about the same size as the wombat and can be up to 20 inches wide, large enough for a small person to crawl into. Although wombats just fit in their burrows, they are agile and can turn around in them.
Wombats dig with their front claws. They then push the loose soil backward with their hind feet and their rump as they back out of their burrow. A wombat can excavate several feet of a tunnel in a single night. One report says that a wombat dug through 6 feet of hard soil in an hour.
Bare-nosed wombat and its burrow (All Bare-nosed wombat pictures on this page are courtesy of Womland, used with permission)
Wombats have burrows for different purposes. Bare-nosed wombats may have up to 12 burrows each, with 3 or 4 of these being main burrows. Some of these may be shared with other wombats, with each wombat using the burrow at a different time.
Short burrows, up to 2 meters (6 feet) long, may be quickly dug by a wombat in order to hide or escape. Burrows about double this size may be used for refuge or a short rest. These burrows may be later expanded to full-sized burrows with multiple sleeping chambers, side tunnels, and additional entrances.
In one study it was found that a wombat would dig with a single front paw for about 5 minutes, and then switch to the other paw. A wombat will use its incisors to cut through underground obstructions such as roots.
Bare-nosed wombat digging
Young wombats learn to tunnel by digging while in their mother's burrow. They may, for instance, dig a small side tunnel on their own.
Wombat burrows are well designed and well ventilated. Since temperatures underground are more moderate (less variable), the burrows help keep the wombat cooler in the warm months, and warmer in the cooler months. The burrow's design provides a "stable micro-environment" for the wombat (ref. 16) by controlling the temperature, oxygen, and carbon dioxide levels (ref. 25).
The wombat's sleeping chamber is at or near the end of the burrow, or about 2-3 meters (6-12 feet) from the burrow's entrance, "situated in half-light." The sleeping chamber is about 2 meters (6 feet) underground, and is slightly elevated from the burrow's entrance, presumably to prevent flooding. The nest can be lined with dried grass, leaves, bark, and sticks.
In the summer, a wombat spends the day in the burrow which helps it to avoid the heat of the day. By keeping cooler in its burrow, it can lower its metabolism and conserve energy. And since the air in burrow is more humid than the outside air, this helps the wombat to conserve water.
Bare-nosed wombat lying in the shade
In the winter, the burrow usually stays above 4 C ( 40 F). During this time the wombat will spend time outside in the daytime to graze or sun themselves.
Near the burrow's entrance, the wombat will often dig a shallow depression which is usually beside a tree or log. This area is used for resting or basking in the sun.
A wombat's burrow is sufficiently deep that it's fireproof. After a fire, a wombat can subsist on roots and bark until the grass regrows.
Underground, burrows will often branch and interconnect. They may contain numerous entrances, side tunnels, and resting chambers. It is thought that a single wombat lives in a burrow; however, burrows may shelter pairs of wombats or family groups.
Wombat burrows are also used by rabbits (introduced to Australia and considered a pest), wallabies (small kangaroos), foxes, and lizards.
Bare-nosed wombat burrows on a hill
Bare-nosed wombats usually have their own, separate burrows, though this may not always be the case. These burrows usually have only one entrance/exit, although it has been reported that they may have more than one. In a study of Bare-nosed wombats in Tasmania, a colony with 17 burrow entrances was discovered.
Bare-nosed wombat burrows are most often located on the slopes or banks above streams and ravines in well-drained soil. They can also be located on the sides of hills. The burrow's entrance is usually near a tree or a large rock. The tree roots or rocks will often help support the entrance and prevent it from collapsing.
The Bare-nosed wombat's burrows are often branched, but seem to be less complex than those of the Hairy-nosed wombats.
Wombat hiding in the entrance of its burrow
On the surface, paths or trails will lead from the burrow to the wombat's feeding area. Paths will also often lead to other burrows. These trails may be several kilometers long.
Probably the best investigation of Bare-nosed wombat burrows was done in the early 1960's by a 16 year old schoolboy, Peter Nicholson. He would sneak out at night to explore the burrows, and crawled through many of them. He found that there was usually only one wombat in a burrow, but sometimes there'd be two. The burrows were often a network of tunnels, and one burrow was about 60 feet long. The wombats were often digging, altering or extending their burrows. They were also sociable and would visit each other's burrows.
Bare-nosed wombat emerging from its burrow
Hairy-nosed wombats live in colonies that consist of a large, complex system of interconnected burrows. Many separate burrows often join together to form a central warren or crater. Smaller warrens may surround the main warren.
Earth excavated to form the warren produces mounds of soil 0.5 to 1 meter (20-40 inches) high. These craters are 1 to 1.3 meters (3-4 feet) deep and contain the entrances of 1 to 100 separate burrows. The burrow's entrance is a low arch, the average size being about 75 cm (30 inches) wide and 28 cm (11 inches) high.
Many of these burrows may be quite old, 50 years or more, and are passed on to newer generations.
Above ground, the Hairy-nosed wombats' burrows are linked by a network of well-used trails. Trails also radiate out to feeding grounds and to other warrens. These burrow complexes are so large that they're visible in satellite images.
Northern Hairy-nosed wombat burrows are often close to trees. The trees provide shade, and the roots help to support the burrow in the soft sandy soil.
Southern hairy-nosed wombat burrow (picture courtesy Wendy Morphett)
The burrows occur in groups of up to 20 over an area of a few hectares (about 5 acres). Each burrow will have up to 7 entrances, with most having 2 to 3. The group of burrows is usually occupied by 4 to 5 wombats, with 10 being the maximum. For Northern hairy nosed wombats, it's estimated that an average of 8 animals live in each warren.
Even though they live in these interconnected burrows, they seem to spend most of their time alone.
One study of the Hairy-nosed wombat found that their colonies covered from 3,000 to 12,000 sq ft, and had anywhere from 7 to 59 entrances. In a report from the early 1900's, a single colony was found to be 800 meters by 80 meters (2,500 ft by 250 ft) or 64,000 sq meters (625,000 sq ft).
by Peter Marinacci
