Aug. 07, 2012

The Numbat: A Most Unusual Marsupial

by Kara Rogers

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From the crack at the base of a wide eucalyptus tree in Western Australia's Dryandra Woodlands, a pointed little snout appears. A moment later, the rest of the wedge-shaped reddish-gray head, a black stripe masking the eye, emerges. The eyes are dark but brilliant in the sunlight, and oblong ears stand to attention. Cautiously, the creature steps out, revealing its coarsely furred, almost prairie dog-like body. In the next instant, it leaps away, the white stripes across its back and its bottle-brush tail disappearing in a blur.
The creature, known as a numbat (Myrmecobius fasciatus), is a marsupial native to Australia. It is the sole member of the family Myrmecobiidae, which is one of three families of so-called dasyuromorphs, carnivorous marsupials that also happen to have hairy tails. The numbat's diurnal lifestyle and its almost four-inch-long tongue, which it uses to snatch termites from their underground nests (and which is, in part, responsible for the species' alternative common name, the banded anteater), are adaptations not seen in any other dasyuromorph. Among the small mammals in its woodland habitat, it is further distinguished by its coat, which is gray and reddish-brown on the foreparts and white-striped and gray-black on the back.
Numbats are solitary animals that live in burrows and hollow logs, which provide protection from predators such as the red fox (Vulpes vulpes) and the little eagle (Hieraaetus morphnoides) and shelter from the midday heat in summer. Females use their burrows for nesting as well. Young typically are born in January or February, after a brief 14-day gestation period. The young cling to the hair on the mother's belly and suckle milk from the teats in her open pouch until they are about six months old, at which point they detach and are raised in the safety of the mother's burrow. At about 10 months of age, the young leave to establish burrows of their own.
Each numbat has its own territory, which typically is about 0.1 to 0.2 square miles in area. Some juvenile numbats may travel more than six miles from the burrows in which they were raised before they find a suitable territory of their own -- a great distance for an animal that, when full grown, weighs only about 500 to 700 grams and is about a foot-and-a-half long from the tip of the nose to the tip of the tail.
But the numbat is a tough little animal. Chased into its burrow, it will turn its thick-skinned back to the opening to defend itself and its young. Against introduced predators, including the red fox and domestic cats, however, the numbat as a species has been relatively defenseless. Invasive predators, combined with habitat loss and fire suppression, have trimmed wild numbat populations to fewer than 1,000 individuals. These remaining animals are divided into several populations, including one at Dryandra that consists of just 50 individuals and is in decline and another at Perup, which consists of several hundred animals and appears to be stable or increasing. Both of these sanctuaries are located in the southwestern region of Western Australia. Colonies that exist elsewhere in Australia have been established through reintroduction.
Fortunately, the numbat is a high-profile species in Western Australia, where it has been the region's mammal emblem since 1973. Much of the effort to save it has centered on captive breeding and reintroduction, which has proven successful in several areas. Other efforts underway to aid the numbat's recovery include baiting programs (using the poison sodium fluoroacetate) to control red fox populations and radio tracking to monitor numbat activity and to better understand their interactions with predators. While the numbat remains at high risk of extinction, these efforts have led to much-needed awareness of its endangered status.
About Kara Rogers

Kara is a freelance science writer and senior editor of biomedical sciences at Encyclopaedia Britannica, Inc. She is the author of Out of Nature: Why Drugs From Plants Matter to the Future of Humanity (University of Arizona Press, 2012).

The views expressed are those of the author and are not necessarily those of Science Friday.

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