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Pteropus alectoblack flying fox

By Diane Ten Pas

Geographic Range

Pteropus alecto is found in the Australian and Oriental regions of the world. It is found from tropical/subtropical Australia to Sulawesi (from 0 to 29° south latitude). (Palmer and Woinarski, 1999; Vardon and Tidemann, 1998)

Habitat

In Australia, black flying foxes are found in the subtropical and tropical latitudes, primarily in the coastal areas of the northern territory and as far as 250 km inland. Their habitat consists of rainforest, eucalyptus open forest, and savanna woodland. They roost primarily in bamboo, rainforests, and mangroves. However, there have been a few known roosting sites in caves and overhangs. Palmer and Woinarski (1999) found that, during the cooler dry season months, 74% of black flying foxes roosted in bamboo, 20% in mangroves, and 6% in rainforest habitats. During the build-up season (characterized by warming temperatures and early rains), 68% roosted in rainforest, 17% roosted in mangroves, and 15% roosted in bamboo. During the wet season, 52% roosted in rainforest, 28% in bamboo, and 20% roosted in mangroves. (Palmer and Woinarski, 1999)

Black flying foxes roosting in bamboo thickets roost 12 to 16 m off the ground, space themselves less than 1 m apart, and forage predominantly in woodland habitat. Those roosting in rainforests roost more than 18 m off the ground, space themselves approximately 1 m apart, and forage predominantly in forest and rainforest habitat dominated by Melaleuca species. Females use camps more than males, and smaller camps tend to be primarily made up of males and sub-adults. (Palmer and Woinarski, 1999; Palmer, et al., 2000; Vardon and Tidemann, 2000)

Physical Description

Pteropus alecto has a black body with some lighter hairs, and a black head. These animals may have a brown eye-ring, and often have a reddish collar on the back of the neck. The legs are furred to the knee, but are hairless below. The forearm length measures 153 to 191 mm and average weight is 667g. (Thatcher, 1998; Webb and Tidemann, 1995)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    667 g
    23.51 oz

Reproduction

Little information exists on mating systems in black flying foxes.

Peak birth times are correlated with periods of maximal plant productivity, hence, the timing of births varies with location. In Brisbane, Australia, most births are in October to November. In the northern territory of Australia, peak birth times are from January to March, and births in November are unusual but not rare. (Vardon and Tidemann, 1998; Vardon and Tidemann, 2000)

It takes females 14.8 to 17 months and males 16.3 to 18 months to reach adult size. Females tend to grow faster than males. On average, females gain 2.56 g/day and their forearms grow 0.25 mm/day. On average, males gain 2.28 g/day and their forearms grow 0.15 mm/day. (Vardon and Tidemann, 1998; Vardon and Tidemann, 2000)

  • Breeding interval
    These bats appear to breed annually.
  • Breeding season
    The breeding and therefore birthing seasons vary with geography, and are timed so that births occur during the time of maximum fruit productivity.
  • Average number of offspring
    1.2
    AnAge

Little information exists on parental care in black flying foxes. As mammals, it is likely that females play the largest role in parental care. They provide offspring with protection and nourishment until they are independent and weaned. However, beyond that basic speculation, information is not available.

  • Parental Investment
  • no parental involvement
  • pre-fertilization
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • protecting

Lifespan/Longevity

It is unknown how long black flying foxes live, however, it has been estimated that the females which survive to maturity would need to live about 7 years to maintain a stable population. Approximately 30 % of females born survive to maturity, compared to 37% in males. Survival rates vary between camps and between years. In years in which food is more abundant, lower levels of mortality are expected. (Vardon and Tidemann, 2000)

  • Range lifespan
    Status: wild
    4.5 (high) years
  • Average lifespan
    Status: captivity
    19.7 years
    AnAge

Behavior

Pteropus alecto is a nocturnal species. During the day, P. alecto roosts in colonies called camps. Typically males will travel between roosts more than females throughout the year. However, females travel further distances from roosting sites to food than males do. During the build-up season, females will travel between roosts more than at any other times of the year. Both males and females travel further between roosting sites and food during the dry season than any other season. (Palmer and Woinarski, 1999)

Home Range

Palmer and Woinarski found that males travel an average of 6.8 km, and females travel an average of 5.8 km between roosts. On average, when foraging at night, males will travel 6.2 km and females will travel 10.9 km from their roosts. (Palmer and Woinarski, 1999)

Communication and Perception

Little information exists on communication in black flying foxes. However, as mammals, they are likely to use visual signals, tactile communication, scent information, and vocalizations.

Food Habits

Black flying foxes are dietary generalists known to feed on fruits, pollen, and nectar of 23 rainforest species. These species include Carpentaria acuminata, Terminalia microcarpa, Diospyros littorea, Elaeocarpus arnhemicus, Ficus opposita, Ficus racemosa, Ficus scobina, Ficus virens, Eucalyptus miniata, Eucalyptus papuana, Eucalyptus polycarpa, Eucalyptus tetrodonta, Lophostemon grandiflorus, Lophostemon lactifluus, Melaleuca dealbata, Melaleuca viridiflora, Syzygium nervosum, Passiflora foetida, Grevillea pteridifolia, Nauclea orientalis, Timonius timon, Cupaniopsis anacardioides, and Gmelina schlechteri. (Palmer and Woinarski, 1999; Palmer, et al., 2000)

Black flying foxes forage on different resources depending upon the time of year. During the dry season, they forage primarily in Eucalyptus open forest. During the build-up season, they forage primarily in the Melaleuca open forest, and during the wet season, they forage primarily in rainforest. It has been suggested that P. alecto selects sites that are richer in resources than floristically similar sites, which suggests that apparently similar habitats are actually different in resource abundance. (Palmer and Woinarski, 1999; Palmer, et al., 2000)

  • Plant Foods
  • fruit
  • nectar
  • pollen

Predation

Little information exists on predation in black flying foxes.

Ecosystem Roles

Because of its ability to access patchily distributed resources, P. alecto probably plays an important role in connecting isolated fragments of rainforest by transporting seeds and pollen between feeding sites. It is probably an important pollinator of 2 Eucalyptus species in northern Australia, and it is also probably an important pollinator and seed disperser in Syzygium species. (Palmer and Woinarski, 1999; Palmer, et al., 2000)

  • Ecosystem Impact
  • disperses seeds
  • pollinates

Economic Importance for Humans: Positive

Throughout much of its range, P. alecto is hunted for food. (Vardon and Tidemann, 2000)

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

It is estimated that the Australian commercial fruit industry loses approximately $20 million per year to flying foxes (not just P. alecto). Because of this, P. alecto is shot as an orchard pest in many areas. It also is known to carry/contract bat Lyssavirus, which is similar to the rabies virus and can be contracted by humans. However, it is not known how easily Lyssavirus is transmitted to humans or other mammals. (Tidemann , et al., 1997; Tidemann, et al., 1997; Vardon and Tidemann, 2000)

Conservation Status

Pteropus alecto is currently listed under CITES appendix II and is not mentioned on the IUCN Red List or the U.S. Endangered Species Act. ("IUCN Red List of Threatened Species", 2002; "CITES Official Documents. Appendices I and II", 2000; "Endangered and Threatened Wildlife and Plants", 1999)

Other Comments

There have been some individuals that appear to be hybrids between black flying foxes and grey-headed flying foxes (Pteropus poliocephalus). These individuals had characteristics of both parent species, however, genetic testing of these hybrids failed to confirm that they were hybrids. The authors note that further testing needs to be done to conclude whether or not these individuals are actually hybrids. (Webb and Tidemann, 1995)

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Diane Ten Pas (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

acoustic

uses sound to communicate

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

causes or carries domestic animal disease

either directly causes, or indirectly transmits, a disease to a domestic animal

chemical

uses smells or other chemicals to communicate

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nectarivore

an animal that mainly eats nectar from flowers

nocturnal

active during the night

oceanic islands

islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

CITES. 2000. "CITES Official Documents. Appendices I and II" (On-line ). Accessed 12/03/02 at http://www.cites.org/eng/append/I_II.shtml.

U.S. Fish and Wildlife Service. 1999. "Endangered and Threatened Wildlife and Plants" (On-line ). Accessed 12/03/2002 at http://endangered.fws.gov/wildlife.html#Species.

IUCN. 2002. "IUCN Red List of Threatened Species" (On-line ). Accessed 12/03/2002 at http://www.redlist.org/.

Palmer, C., O. Price, C. Bach. 2000. Foraging ecology of the black flying fox (Pteropus alecto) in the seasonal tropics of the Northern Territory, Australia. Wildlife Research, 27: 169-178.

Palmer, C., J. Woinarski. 1999. Seasonal roosts and foraging movements of the black flying fox (Pteropus alecto) in the Northern Territory: resource tracking in a landscape mosiac. Wildlife Research, 26: 823-838.

Thatcher, O. 1998. "Pteropus alecto" (On-line ). Accessed 12/03/02 at http://www.biology.leeds.ac.uk/staff/dawa/bats/Fruitbats/ALECTO.HTML.

Tidemann , C., M. Vardon, J. Nelson, R. Speare, L. Gleeson. 1997. Health and conservation implications of Australian bat Lyssavirus. Australian Zoologist, 30: 369-376.

Tidemann, C., S. Kelson, G. Jamieson. 1997. Flying-fox damage to orchard fruit in Australia - incidence, extent and economic impact. Australian Biologist, 10: 177-184.

Vardon, M., C. Tidemann. 1998. Reproduction, growth and maturity in the black flying-fox, Pteropus alecto (Megachiroptera: Pteropodidae). Australian Journal of Zoology, 46: 329-344.

Vardon, M., C. Tidemann. 2000. The black flying-fox (Pteropus alecto) in north Australia: juvenile mortality and longevity. Australian Journal of Zoology, 48: 91-97.

Webb, N., C. Tidemann. 1995. Hybridization between black (Pteropus alecto) and grey-headed (P. poliocephalus) flying-foxes (Megachiroptera: Pteropodidae). Australian Mammology, 18: 19-26.

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