BANDICOOTS AND BILBIES: Peramelidae

PHYSICAL CHARACTERISTICS

Peramelidae are Australian bandicoots and bilbies. This family is sometimes referred to as the true bandicoots to distinguish it from the Peroryctidae, or rainforest bandicoots of New Guinea. True bandicoots are small marsupials with long, pointed snouts. They range in size from 6.5 inches (17 centimeters) and 5 ounces (140 grams), or about the size of a mouse, to 23 inches (60 centimeters) and 10.5 pounds (4.8 kilograms), or about the size of a cat.

Bandicoots live and feed on the ground. They have claws to dig for food, and in the case of bilbies, digging burrows. Their front feet have five toes. The middle three toes have strong claws. Toes one and five are either small or absent. On the hind feet, the bones of the second and third toes are joined, but each toe has a separate claw. Bandicoots look something like a cross between a rat and a rabbit. Their hind legs are longer than their front legs and are strong and well developed for hopping and leaping. They are also able to gallop.

Most bandicoots have short rounded ears and a thin, short tail. However, the extinct pig-footed bandicoot had both long ears and a long tail, and the bilby's ears are very large. All bandicoots have good hearing and a good sense of smell, but poor eyesight. They are nocturnal, or active at night, when their sense of smell and hearing are important in helping them locate food.

True bandicoots live mainly in dry areas. Their fur ranges from dark brown to gray and they are normally darker on their back than on their belly, allowing them to blend into the deserts and dry grasslands where they live. Most bandicoots are solid colored, although a few, such as the eastern barred bandicoot, are striped. The fur of true bandicoots is soft when compared to the harsh, spiky fur of the rainforest bandicoots.

GEOGRAPHIC RANGE

Before the arrival of European colonists in 1770, bandicoots and bilbies were found in about 70 percent of Australia and on several nearby islands. Today they are found in many fewer places in Australia and the island of Tasmania. The bilby, especially, can be found only in isolated pockets mainly on protected park land or in captive breeding areas.

HABITAT

Bandicoots and bilbies prefer dry areas. Before European colonization, up to five species could be found in the Australian inland deserts. Today only one species lives there. Other species live in dry grasslands and open forests. Three species have adapted to human activity and live in suburban neighborhoods and parks.

DIET

True bandicoots are omnivores. They eat both plants and animals. Included in their diet are ants, termites, insect larvae (LAR-vee), earthworms, spiders, centipedes, bulbs, seeds, and bird eggs. Larger species will occasionally eat lizards and mice. Although bandicoots eat a variety of food, each colony seems to prefer one or two particular foods, probably because these are more easily available. Bandicoots dig for food with their strong claws. They make holes up to 5 inches (13 centimeters) deep and scoop out the food with their long tongues. Some species that live in desert areas do not need to drink water. They can get all the moisture they need from their food.

BEHAVIOR AND REPRODUCTION

True bandicoots are nocturnal. The exception is the southern brown bandicoot, which is active mainly during the day. Bandicoots are solitary animals, living alone and coming together only to mate.

Bandicoots are territorial animals. The males defend larger territories than the females. They challenge any other male that comes into this area, and will fight if the intruder does not leave. Although females spend all night feeding, males spend part of the night patrolling their territories and marking them with scent to scare off other males.

Female bandicoots can reproduce at about four months of age. A female may mate with several different males. Pregnancy is one of the shortest of all animals—from twelve days to a few weeks.

Like all marsupials, bandicoots do not have a well-developed placenta. A placenta is an organ that grows in the mother's uterus (YOO-ter-us; womb) that allows the developing offspring share the mother's food and oxygen. Most marsupials have what is called a yolk-sac placenta, where there is no sharing of the mother's food and oxygen. Bandicoots and bilbies are different from other marsupials, because they have a second placenta in addition to the yolk-sac placenta. This placenta resembles the placenta in eutherian (yoo-THEER-ee-an) mammals, such as dogs, rabbits, and humans, but does not function as well, because it does not attach as closely to the wall of the mother's uterus.

Young bandicoots, called joeys, are born hairless, blind, and poorly developed. They are about 0.4 inches (1 centimeter) long. They use their front legs to pull themselves into their mother's pouch. There they attach to her teats, or nipples, where they remain for at least several weeks until they are able to survive on their own. After that they may remain in the nest and be fed by the mother for another week or two before becoming completely independent. Rarely do bandicoots have more than four young in a litter, and one or two offspring are more common. The death rate of newborn bandicoots is high. Those that live to adulthood have a lifespan of two to three years. Predators of the bandicoot include red foxes, dingoes (wild dogs), and feral cats (domestic cats that have been turned loose and become wild). Rabbits are their main competitors for food.

BANDICOOTS, BILBIES, AND PEOPLE

Australian aboriginal (native) people considered the bandicoot one of the creators of life. According to their legends, Karora, a giant bandicoot, awoke from under the earth and gave birth to humans out of his armpit. Aborginal people also hunted bandicoots for food.

European colonists thought bandicoots looked like rats and tended to treat them as pests. Many were killed when colonists tried to rid Australia of rabbits that were introduced and soon overran the country, because they had no natural predators. Legal protection of bandicoots did not occur until the middle of the twentieth century, after several species were already extinct. Today conservation groups are trying to save bandicoots and bilbies, but many suburban residents still consider them pests, because they dig up gardens when hunting for food. They also carry ticks, lice, and fleas.

THE EASTER BILBY

Starting in the 1990s, the Foundation for Rabbit-Free Australia and the Save the Bilby Fund began a public relations campaign to replace the Easter rabbit with the Easter bilby. The fund teamed up with candy makers to make chocolate bilbies for children's Easter baskets. Part of the sales price of each candy bilby went to bilby conservation and restoration programs. By 2004, several hundred thousand dollars had been raised through candy bilby sales.

CONSERVATION STATUS

Three species of bandicoot are extinct: the pig-footed bandicoot, the desert bandicoot, and the lesser bilby. All the extinct species lived in the dry inland area of Australia. The western barred bandicoot is considered Endangered, facing a very high risk of extinction. Four other species are considered Vulnerable, facing a high risk of extinction. Captive breeding projects have been started to save the greater bilby and the western barred bandicoot. These projects have had some success, but it is unlikely that populations of bandicoots in the wild will increase without control of their predators (animals that hunt them for food).

EASTERN BARRED BANDICOOT (Perameles gunnii): SPECIES ACCOUNTS

Physical characteristics: The eastern barred bandicoot, also called the barred bandicoot, the Tasmanian barred bandicoot, the striped bandicoot, or Gunn's bandicoot, measures 10.5 to 14 inches (27 to 35 centimeters) not including the tail and weighs 26.5 to 35 ounces (0.75 to 1 kilogram). It has grayish brown fur with pale bars on its hindquarters. It has large ears, a thin, pointed snout, and its tail is relatively short.

Geographic range: Eastern barred bandicoots are found in the Australian state of Victoria and on the island of Tasmania. At one time it was also found in the state of South Australia, but it is now extinct there.

Habitat: This species lives in grasslands, open grassy woodlands, and suburban yards and parks.

Diet: Eastern barred bandicoots eat mainly insects, insect larvae, earthworms, bulbs, seeds, and fallen fruit.

Behavior and reproduction: Eastern barred bandicoots have the shortest pregnancy of any mammal—around twelve days. The young, usually only two or three, are carried in the mother's pouch another fifty-five days and become completely independent about three weeks later. This species becomes fully mature and capable of reproducing at about four months of age and has a lifespan of two to three years.

Eastern barred bandicoots and people: Aboriginal peoples hunted the eastern barred bandicoot for food. Suburban residents find it a pest because it digs up lawns when hunting for food.

Conservation status: As of 2003, the eastern barred bandicoot was considered Vulnerable to extinction. At one point it was considered Critically Endangered. In 1991, only 109 animals were known to exist on mainland Australia.

Serious conservation efforts are underway in Victoria. These include habitat protection, predator control, community education, captive breeding, and reintroduction of captive-bred bandicoots to the wild. By 1993, the population had grown to over seven hundred animals. The main threats to this species are predators such as the red fox and cats, and being hit and killed by automobiles.

GREATER BILBY (Macrotis lagotis): SPECIES ACCOUNTS

Physical characteristics: The greater bilby, also called the rabbit-eared bandicoot, is a small bilby about the size of a rabbit. It measures 9 to 10 inches (23 to 26 centimeters). Males weigh from 2 to 5.5 pounds (1 to 2.5 kilograms). Females are smaller, weighing from 1.8 to 2.5 pounds (0.8 to 1.1 kilograms). Bilbies have soft, silky blue-gray fur on their back and white bellies. They have a long, thin snout and a long black tail with a white tip. The lesser bilby, a relative of the greater bilby, became extinct in 1931, so the greater bilby is usually referred to simply as the bilby.

Geographic range: Bilbies are found in the Northern Territory, Western Australia, and Queensland, but their populations are isolated from each other.

Habitat: Bilbies prefer hot, dry grassland, and will occasionally live in dry, shrubby, open woodlands.

Diet: Bilbies feed at night. They are omnivores, and like other bandicoots eat insects, insect larvae, earthworms, bulbs, and seeds.

Behavior and reproduction: Bilbies are the only bandicoots that dig burrows. They are excellent diggers, and these burrows can be up to 6 feet (2 meters) deep. They stay in the burrows during the day for protection against the heat.

Like all bandicoots, bilbies live alone, coming together only to mate. They mate throughout the year and give birth only fourteen days after mating. The young are then carried in the mother's pouch for eighty days. After they leave the pouch, they live in the burrow with their mother who feeds them for another two weeks.

Greater bilbies and people: Bilbies were very common until the beginning of the twentieth century and were an important source of food for native peoples. However, their numbers rapidly decreased with the introduction of non-native predators such as the red fox and the cat. Today, the bilby has become a symbol of Australia's efforts to save its native species.

Conservation status: As of 2003, the bilby was considered Vulnerable to extinction. Their numbers decreased because of non-native predators, competition for food by rabbits, and changes in habitat brought about by livestock ranching and farming. The bilby has been the focus of an intensive public awareness and recovery program. The Save the Bilby Appeal was begun in 1999 and has been quite successful. Sales of chocolate Easter bilbies have helped to finance captive breeding programs and reintroduction of bilbies to the wild. Most recently, the Save the Bilby Appeal has started a campaign to fence a large area where bilbies released into the wild will be protected from predators. ∎

FOR MORE INFORMATION

Books:

Menkhorst, Frank. A Field Guide to the Mammals of Australia, 2nd ed. Oxford, U.K.: Oxford University Press, 2001.

Nowak, Ronald M. Walker's Mammals of the World. Baltimore: Johns Hopkins University Press, 1995.

Periodicals:

Clark, Tim W., Richard P. Reading, and Gary Backhouse. "Prototyping for Successful Conservation: The Eastern Barred Bandicoot Program." Endangered Species Update (July–August 2002): 125.

Smyth, Chris. "Bilbies' Call of the Wild." Habitat Australia (October 1998): 13.

Web sites:

Queensland Government Environmental Protection Agency/Queensland Parks and Wildlife Service. Nature Conservation.http://www.epa.qld.gov.au/nature_conservation (accessed on June 22, 2004).

University of Michigan Museum of Zoology. "Family Peramelidae." Animal Diversity Web.http://animaldiversity.ummz.umich.edu (accessed on June 22, 2004).

Other sources:

Australian Bilby Appreciation Society. P.O. Box 2002, Rangview, Victoria 3132 Australia. E-mail: [email protected] Web site: http://members.oze-mail.com.au/bilbies