Wallaby. (Photo by Jessie Cohen)
When one thinks of Australia, the word kangaroo and its smaller relative, the wallaby, comes almost immediately into mind. I doubt that there is another animal that symbolizes the free spirit and bouncy optimism of its homeland quite as well as the kangaroo.
This wallaby, Onychogalea fraenata, is an extremely rare marsupial native to the plains of southeastern Australia. There are two other closely related species: one, now believed to be extinct, once inhabited the central and southwestern part of the continent; the other lives in tropical parts of northern Australia and its population seems to be surviving quite well. All three of the species included in the genus Onychogalea are distinguished by a finger-nail like tip at the end of the powerful tail. So far, no one has yet determined how the animal uses this nail or what purpose it serves.
There is no denying that this is a whimsical and appealing animal, although it is not as well known as many of the popular, charismatic mammals often seen in zoos. In fact, nail-tailed wallabies have rarely, if ever, been exhibited in zoos.
This shy, solitary wallaby has a silky, gray coat, marked with a white pattern on its shoulder and head that suggests a bridle. It weighs between eight to ten pounds. Its head and body are just under two feet long, but its tail, which helps balance the animal as it hops, extends its length by another foot and a half. Females give birth to a single offspring called a joey, usually in May. The helpless, almost embryonic-looking newborn immediately finds its way to its mother's pouch. It lives there for about four or five months before it begins to become more independent and make forays beyond the protection of the pouch. The joey will continue to suckle for three to four months after emerging from the pouch.
The bridled nail-tailed wallaby is active primarily at night, when it feeds on grasses, small plants, and bulbs. During the day, it rests in a shallow nest scratched out under a tuft of grass or a bush. When startled, it escapes by running into thick brush or a tree hollow, holding its forepaws outward, almost at a right angle, and rotating them in a circular motion. (This mode of movement has earned it the nickname, organ grinder .)
With the advent of European settlement and the spread of agriculture, the bridled nail-tailed wallably has become increasingly rare in its native range of savannahs, woodlands, and steppes. The thick vegetation that once characterized the animal's habitat provided not only its food, but protection as well. As the cover of grasses has fallen to the plow and cattle have grazed much of the land, the nail-tailed wallaby's habitat has disappeared at great cost to the animal's chances of survival.
The fate of this animal is not unfamilar to anyone who has followed the story of some of our North American mammals such as the black footed ferret: The pressure exerted by human expansion has changed the ecology of the land to the detriment of many of the animals whose survival is dependent on a delicately-balanced ecosystem. In fact, for 36 years, between 1937 and 1973 the bridled nail-tailed wallaby was believed to be extinct. Then, in 1973 a small population was discovered in central Queensland and a chunk of land was purchased by the state government to provide a refuge. Now, with its habitat secured, biologists hope that this animal, too, will be able to survive and keep its population viable into the next century.
The National Zoo has had a long history of exhibiting kangaroos and wallabies. In 1893, four years after we were established by an act of Congress, the public could see a kangaroo on exhibit here. At the present there are four species in our collection: the western gray kangaroo, red kangaroo, King Island wallaby, and Tammar wallaby. In addition, at our Conservation Research Center near Front Royal, Virginia, we have an active and successful breeding program for the brilliantly-colored Matschie's tree kangaroo from New Guinea. Equally important, the Zoo's researchers and mammal staff also work closely with the Marsupial TAG, or Taxon Advisory Group, which manages the breeding and genetic diversity of these animals living in zoos throughout North America.