Bulmer’s fruit bat is the largest bat species known to roost in caves. It is nocturnal, and usually leaves the cave at dusk to forage for food. Based on dental structures and its close relationship to other fruit-eating bats, the species is thought to eat only fruit. It does not have a well-developed echolocation system like the insectivorous bat species, but instead relies on sight to navigate and find food. The bats are extremely cautious. When leaving the cave they first send out a couple of scouts who circle the cave entrance and utter strange bird-like calls for several minutes before departing. If people are present they will delay their exit from the cave until after dark. The bats are thought to fly considerable distances to feed (one individual was found approximately 32 km away from the roost). They return to the roost at about 6am, before light. Although predominantly nocturnal, they will occasionally emerge during the day in sunny weather. Females are thought to become sexually active at around three years of age. They give birth in April and carry the young for the first few weeks of life whilst foraging.

The only known roost of the species is an enormous vertical-sided cave near the edge of a large escarpment at an altitude of 2,400 m. The cave is surrounded by mossy montane forest dominated by conifers.

In April 1993 the population was estimated to be approximately 160 individuals.

Declining.

Classified as Critically Endangered (CR B1+2c) on the 2006 IUCN Red List of Threatened Species.

Believed to have been hunted to extinction at the end of the last Ice Age glaciation, this species was rediscovered roosting in a remote cave in 1975. At that time, local inhabitants described the bat as being abundant, perhaps numbering in the thousands. However, just two years later the colony had been virtually eliminated. The bats had traditionally been protected by the local people, and the fact that the cave was so treacherous that virtually no-one could enter it. However, mining operations that began in the mid 1970s enabled the local men to work for cash for the first time. With the money they were earning they bought ropes with which to enter the cave. Once inside they had used shotguns to kill hundreds of bats at a time for their meat. Several searches over the next decade failed to find any trace of the bats and they were believed once again to have become extinct at the hands of humans.

In May 1992 a small colony of 137 individuals was rediscovered at Luplupwintem. By April 1993, the colony had increased to about 160 individuals. However, this is much less than the potential natural rate of increase, and it is likely that significant hunting may still be taking place. Other threats may include human disturbance and the removal of wood from its feeding grounds.

There do not appear to be any conservation measures in place.

International conservation groups should work with the PNG government and local people to develop and implement a management plan for the species. Since the species is known from a single, small colony, a captive breeding programme or relocation of a few individuals to start a new colony should be considered to guard against extinction of the wild population.

Bonaccorso, F.J. 1998. Bats of Papua New Guinea. Conservation International, Washington, DC.

Chiroptera Specialist Group. 1996. Aproteles bulmerae. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. Downloaded on 09 August 2006.

Flannery, T. 1995. Mammals of New Guinea. Reed books. Australia.

Flannery, T. F. 1994. The Rediscovery of Bulmer's Fruit Bat. BATS 12(1): 3-5.

Nowak, R.M. 1999. Walker's Mammals of the World. Sixth edition. The Johns Hopkins University Press, Baltimore and London.

Distribution map based on data provided by the IUCN Global Mammal Assessment.