BANDICOOTS AND BILBIES – [Peramelemorphia]

Bandicoot

PHYSICAL CHARACTERISTICS

Peramelemorphia is an order of small ground-dwelling marsupials known as bandicoots and bilbies. All species in this order live either in Australia, New Guinea, or a few nearby Indonesian islands. Although some of the species in this order have been classified differently in the past, current genetic evidence has led scientists to divide this order into two families, the Peramelidae and the Peroryctidae. The Peramelidae include the true bandicoots of Australia and the bilbies. The Peroryctidae are made up of the spiny bandicoots of the New Guinea rainforest.

Bandicoots and bilbies look like a cross between a rabbit and a rat. They range in size from 6.5 to 23 inches (17 to 60 centimeters), excluding tail length, and weigh from 0.3 to 10.5 pounds (0.1 to 4.8 kilograms). Their tails are usually short in proportion to their bodies.

Bandicoots and bilbies have small pointed snouts and ears that are usually short and rounded. One exception is the greater bilby which has long rabbit-like ears. Most species have thin, rat-like tails, and their fur is usually solid earth tone colors. The fur of the rainforest bandicoots is harsh and spiny.

The front legs of most species in this order are adapted for digging. The front feet have strong claws on toes two, three, and four. Toes one and five are either absent or very small and clawless. The hind limbs are strong and muscular, allowing these animals to leap and hop like a rabbit. However, they are also able to run at a fast gallop. On the hind legs, the bones of the second and third toe are fused, joined into one, but still have separate claws. This pattern of fused toes suggests that these animals may have evolved from the Diprotodonta family.

Bandicoots and bilbies are omnivores, meaning they eat both plants and animals. Members of this order have teeth that are adapted to this diet. Their tooth pattern suggests that they may have evolved from the Dasyuromorphia order (Australasian carnivorous marsupials). Because of the conflicting physical evidence, scientists remain unsure exactly which other marsupial families are their closest relatives.

GEOGRAPHIC RANGE

Species in this order are found only in limited parts of Australia, New Guinea, and the Indonesian island of Seram. In the past, these animals were abundant. They were found in about 70 percent of Australia, throughout New Guinea, and on several other Indonesian islands. Since the beginning of the twentieth century, their range has been drastically reduced by human activities.

HABITAT

The two families in this order live in different habitats. Peramelidae, or true bandicoots and bilbies, live in dry, desert areas, dry grassland, shrubby grassland, open forest, and suburban gardens. Peroryctidae, or spiny bandicoots, live in the tropical rainforests of New Guinea. Several species live in isolated areas at elevations up to 13,000 feet (4,000 meters).

DIET

Bandicoots and bilbies are omnivores, eating both plants and animals, and insects such as ants and termites usually make up most of their diet. They also eat earthworms, insect larvae, insects such as centipedes, and plant parts, such as seeds, bulbs, and fallen fruit. Occasionally larger species eat lizards and mice.

They are opportunistic feeders, tending to eat whatever food is available.

Bandicoots and bilbies find food by smell and hearing. Their eyesight is poor. When they locate food underground, they dig cone-shaped holes up to 5 inches (13 centimeters) deep and remove the food with their long tongues. Because so much of their food is dug out of the ground, they also accidentally eat a lot of dirt. Studies have found that between 20 and 90 percent of their waste is earth that was swallowed with the food, then passed through their digestive system. 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

Most species in this order are nocturnal, active only at night.

The exception is the southern brown bandicoot, which is active mainly during the day. All members of this order live alone, coming together only for a short time to mate. Females will mate with more than one male. Many species mate year round. Both males and females are territorial. Males have larger territories than females. Some species mark their territory with scent from a special gland. Males become aggressive when another male enters their territory. Males kept together in captivity will fight.

Most familiar mammals such as dogs, rabbits, and horses, are called eutherian (yoo-THEER-ee-an) mammals. These mammals have a placenta, an organ that grows into the mother’s uterus (womb) and lets the mother and developing offspring share food and oxygen until the organs of the developing young mature. Marsupial mammals do not have this type of developed placenta.

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 mammals, but does not function as well, because it does not attach as closely to the wall of the mother’s uterus. As a result, members of the order Peramelemorphia have very short pregnancies, and, like other marsupials, the young are physically immature and undeveloped when they are born. At birth they crawl to their mother’s backward-opening pouch where they attach to the mother’s teats, or nipples. They are carried inside the pouch until they are mature enough to survive independently.

BANDICOOTS, BILBIES, AND PEOPLE

Aboriginal (native) people hunted bandicoots and bilbies for meat and fur, however these animals were abundant, and hunting did not cause a major decrease in their populations. The coming of European colonists to Australia and New Guinea began the decline of many species of bandicoots and bilbies.

Europeans changed the ecology of Australia. They introduced non-native species such as the red fox and the domestic cat, both of which prey on bandicoots and bilbies. They also introduced rabbits that compete with them for food. In addition, Europeans introduced cattle and sheep ranching to Australia. This reduced the habitat suitable for many species of bandicoots and bilbies. Finally, native people regularly burned the grassland, and the plants that grew after the burn provide a good habitat for bandicoots and bilbies. This practice changed after large scale livestock ranching began, creating less diverse habitats that did not support these na- tive species well.

The number of bandicoots and bilbies has decreased dramatically since the beginning of the twentieth century. Three species have gone extinct. Conservation organizations are tying to provide safe habitat for these animals by fencing preserves and controlling predators, animals that hunt them for food. However, people living in suburban areas still tend to think of bandicoots and bilbies as pests, because they dig up lawns and gardens when hunting for food.

CONSERVATION STATUS

Since the coming of European colonists in 1770, three species have gone extinct: the pig-footed bandicoot, the desert bandicoot, and the lesser bilby. The number of animals in four other species has dropped to dangerously low levels and they are considered Endangered, facing a very high risk of extinction in the wild, or Vulnerable, facing a high risk of extinction in the wild. So little is known about most of the species in the Peroryctidae family that their conservation status cannot be accurately evaluated.

Since the 1980s captive breeding and conservation programs have succeeded in increasing the number of bilbies. The Australian Bilby Appreciation Society has developed public relations programs to increase awareness of the need to protect these animals. They have also raised money for a fenced preserve, because bilbies cannot thrive in the wild without predator control. Other species have been the focus of less conservation awareness and continue to decline.

bilby

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. To day 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.

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).