Ghost Bat

## Description

The ghost bat (Macroderma gigas ) is a flying mammal found in northern Australia. The species is the only Australian bat that preys on large vertebrates – birds, reptiles and other mammals – which they detect using acute sight and hearing, combined with echolocation, while waiting in ambush at a perch. The wing membrane and bare skin is pale in colour, their fur is light or dark grey over the back and paler at the front. The species has a prominent and simple nose-leaf, their large ears are elongated and joined at lower half, and the eyes are also large and dark in colour.The first description of the species was published in 1880, its recorded range has significantly contracted since that time.

## Appearance

The Ghost bat is a flying mammal found in northern Australia. It is the only Australian bat that preys on large vertebrates such as birds, reptiles, and other mammals. The wing membrane and bare skin of the Ghost bat are pale in color; its fur is light or dark grey over the back and paler at the front. It has a prominent and simple nose-leaf and its large ears are elongated and joined at the lower half; the eyes are also large and dark in color.

## Distribution

Ghost bats are native to Australia where they occur in the Northern Pilbara and Kimberley in Western Australia, the Top End of the continent, and in Queensland. They typically roost in caves, sheltered rock crevices, boulder piles, or disused mines, and only occasionally in abandoned buildings. Ghost bats prefer sites with a complex of shafts or cavities and several openings to the outside. They favor these caves with multiple entrance ways as they are large enough to accommodate the greater wingspan of the species and allow an alternative exit when sensing a threat. Ghost bats require several suitable sites for rest, feeding and reproduction, and change locations seasonally.

## Behavior

Ghost bats are nocturnal creatures. They are inactive during daylight hours and do not hibernate. They live in colonies which size usually reduces in the austral winter and increases when bats gather to breed or females form maternity groups. Ghost bats leave their roosts several hours after sunset, alone, in pairs, or as small groups. They hunt via a 'sit and wait' technique while suspended from a tree or as low surveys over vegetation. Ghost bats detect their prey using acute sight and hearing, combined with echolocation. Prey may be taken at or to the ground. Once located, an animal is held down via the thumb claws and killed by a single bite to the neck. The prey is killed at the ground or in flight and taken to a perch to be consumed, feeding may be at an overhanging rock or smaller cave for this purpose. Ghost bats are able to communicate with each other vocally. Their voice is audible to humans and transliterated as 'dirrup dirrup'. This twittering call is given when the bat is excited or before leaving the roost to feed. A chirp uttered by the species resembles crickets. Ghost bats are generally quiet, but some vocalization is known in captivity when a squealing sound accompanies a squabble over food. The twittering sound was reported in captivity as hunger, and the young will continually emit a chirp when the mother is absent.

## Diet

Ghost bats are carnivores, feeding on small mice, other bats, small birds, frogs, legless lizards, geckos, snakes, and large insects if the prey is scarce. They also hunt other species of microbats such as sheathtails, bentwings, horseshoe bats, and the little cave eptesicus.

## Reproduction

Ghost bats breed between late October and early November. During this time females congregate in groups and give birth to a single pup. The gestation period lasts about 2.5-3 months. Maternity colonies are founded in large and open caves and occupied until the young are reared. The young are born in the austral spring, are able to fly after 7 weeks, and become fully weaned at 16 weeks. The males play no part in the rearing of the young. The juveniles typically hunt with their mothers until they become completely independent.

## Population

### Population threats

Ghost bats are vulnerable to several anthropogenic hazards, one of which is barbed wire fencing that accounts for many deaths when bats are snagged through the easily torn wing membrane while in flight. The damage caused by the barbed wire strands often left littering their environment, is greatly increased as the bat becomes entangled as it attempts to dislodge itself. Ghost bats are especially sensitive to disturbance by humans in wintering roosts, and a single fleeting visit will see the site deserted for several weeks or altogether if human activity continues. Attempts to view at Ghost bats' roosts are especially discouraged due to the rapid decline in range and population. New or reopened mining operations have an impact on local colonies, although they may provide diurnal roosts when complete; the bats are vulnerable to dilapidation in former mines such as the collapse of ceilings.

### Population number

According to the IUCN Red List, the total population size of the Ghost bats is 4,000-6,000 mature individuals. Currently, this species is classified as Vulnerable (VU) on the IUCN Red List and its numbers today are decreasing.

## Fun Facts for Kids

The name 'ghost bat' derives from the distinct coloring of this species; the predominant color of its fur may be near white or pale grey.

The large ears of Ghost bats allow them to hear prey moving on the ground. They may drop to catch large locusts detected moving through the grass at 10 to 20 meters distance. They are also able to detect the echolocation signals of the microbats on which they prey.

Due to their sharp vision, Ghost bats are able to visually locate birds roosting in trees, and budgerigars are often detected by their silhouettes against the evening light. The budgie is a favored food of Ghost bats, which they detect by the flock's chatter while retiring for the night.