Bilby droppings used to measure stress levels
Bilby droppings are being used by scientists who have pioneered a new technique to measure stress levels of the endangered marsupial. A study published in the European Journal of Wildlife Research found levels of the stress hormone cortisol in bilbies in captive …
Greater Bilby (Macrotis lagotis)
Click here to download our Bilby Fact Sheet for Schools
The Greater Bilby is a nocturnal marsupial which has a silky light grey and white coat and a long black and white crested tail with a naked spur-like tip. Bilbies have a long snout and well-developed sense of smell to aid in finding food. Their large, hairless ears are extremely useful for listening for predators as well as prey.
Until recently, Australia had two species of Bilbies – the Greater Bilby and the Lesser Bilby. The Lesser Bilby is already believed to be extinct. The Greater Bilby is the largest member of the bandicoot family, measuring up to 55cm in body length with a tail of up to 29cm long. Adult males weigh 1-2.5kg and the females weigh between 800g- 1.1kg. They range from 30 to 60cm in length with a 20cm tail. The females are smaller than the male and they only associate to mate.
Image courtesy Lyle Radford.
The Bilby is omnivorous and its diet includes bulbs, fruit, seeds, fungi, insects, worms, termites, small lizards and spiders. One of its favourite plant foods is the bush onion or yalka which grows in desert sand plains after fires. Bilbies don’t need to drink water regularly because, like the koala, they get most of their moisture from their food.
This makes the Bilby well adapted for survival in the semi- arid and arid areas of Australia.
Image: Bilby Feed Scrape
The Bilby is a fast breeder, with a 12 to 14-day pregnancy. When the baby joey is born, it looks like a baked bean with legs. It stays in its mother’s pouch for between 75 and 80 days and is independent about two weeks later. Female Bilbies have a backward-opening pouch with eight nipples. At six months of age, the female Bilby can breed and usually has 1 or 2 young at a time. Although it is rare, she can have triplets. In a good season in the wild, bilbies can have up to four litters a year.
Bilbies live in grasslands and mulga scrublands in the hot, dry, arid and semi-arid areas of Australia. The preferred habitats are mulga scrublands and Spinifex grassland.
Bilbies live in spiralling burrows which they dig up to 2 metres deep. This depth helps to keep them safe from predators and also to keep them at a constant temperature of 23 degrees, as bilbies can become heat stressed. Bilbies may have up to a dozen burrows, one for sleeping in and the others for escaping from predators.
Image: Astrebla Downs National Park
Of the six bandicoot species that once lived in the arid and semi-arid areas of Australia, the bilby is the sole survivor. It is listed as ‘‘endangered’’ in Queensland and "vulnerable" nationally. The Bilby is a bandicoot and the only surviving representative of the sub-family Thylacomyinae. It is one of the few medium-sized native mammals remaining in arid Australia. Bilbies were once common and inhabited 70% of Australia but they have now disappeared from more than 80% of their former range.
Recent research work in the Tanami Desert has shown bilby fur in about 3 per cent of cat scats examined. There is data also clearly demonstrating that grazing by rabbits and introduced livestock reduces bilby food supplies.
Image: Burrow Entry
Reasons for the Decline in Bilby Numbers
It is believed that the Bilby population has been reduced dramatically by a number of contributing factors including:
- Predation by introduced species such as feral cats and foxes is believed to be the biggest threat to the bilby population
- Farming animals such as sheep and cattle, which destroy the habitat of the Bilby and compact the soil.
- The introduced European rabbit competes with Bilbies for burrows and food.
- Bilbies are also known as Rabbit-eared Bandicoots.
- Their life span is 6-7 years in the wild and 11 years in captivity.
- Bilbies have approximately 28 teeth.
- Bilbies have long ears so that when they are digging, a portion of them remains above ground level so they can hear any predators approaching.
- Bilbies have a long snout which is pink and hairless on the tip. They have an excellent sense of smell. They have a long, sticky tongue which they use to collect seeds and worms from the ground. Bilbies have very poor eyesight and are also sensitive to light.
- They have strong forearms and hind legs which helps Bilbies to dig their homes and also to manipulate their food.
- The Bilby is truly nocturnal. Bilbies don’t emerge from their burrows until an hour after dusk and retreat at least an hour before dawn. A full moon, strong wind, and heavy rain can keep a Bilby in its burrow all night.
- Bilbies once inhabited 70% of Australia and now they are only found in small areas in the Northern Territory, Western Australia and South- West Queensland.
- Bilbies are marsupials, meaning that they have a pouch. The bilbies pouch opens backward so as not to be filled with earth while digging.
Two hundred years ago, the bilby (Macrotis lagotis), occupied more than 70% of mainland Australia. Now, it has disappeared from 80 per cent of its former range. Small populations remain in isolated arid and semi-arid areas in Western Australia, the Northern Territory and Queensland. The total Queensland wild population, estimated to be between 600 and 700 animals, is scattered over 100,000 square kilometres west of Birdsville and Boulia. The lesser bilby is now extinct.