History of Megachiroptera
are over 4,000 mammal species in the world and almost one
in four of them is a bat. All bats belong to the order Chiroptera.
This order includes two major sub-orders, the Microchiroptera,
or true bats, currently comprising 782 species, and the Megachiroptera,
comprising 175 species (Neuweiler, 2000).
The Microchiroptera, without exception, possess a highly developed
echolocation system (Neuweiler, 2000). Thanks to a combination
of echolocation and flying skills most species have become
skilful nocturnal hunters and the majority are insect feeders,
although other food sources include fish, amphibians, small
mammals (including bats), blood, fruit and flowers (e.g. Altringham,
1996). Microchiropteran bats are found in all areas of the
world apart from the Arctic and Antarctica and some isolated
oceanic islands (Nowak & Walker, 1994).
The Megachiroptera (consisting of a single family, the Pteropodidae
or Old World fruit bats or ‘flying-foxes’) are
found throughout the Old World tropics and range from Africa,
the eastern Mediterranean, Madagascar and the Indian Ocean
islands in the west, across mainland southern Asia, throughout
the islands of the western Pacific from the Ryukyu Archipelago
and Ogasawara-Shato in the north, to coastal eastern Australia,
New Caledonia and the Loyalty Islands in the south, and east
to Fiji, Tonga, Samoa and the Cook Islands (Figure 1) (Mickleburgh
et al., 1992). They are especially diverse in south-eastern
Asia and Indo-Australia (Hall & Richards, 2000; Mickleburgh
et al., 1992).
Figure 1. World distribution of the Megachiroptera.
(from Hill & Smith, 1984)
megachiropterans are nocturnal with the notable exception
of Pteropus samoensis (e.g. Brooke, 2001). Echolocation
is, with a few exceptions (i.e. some Rousettus and
perhaps Epomophorus species) unknown in the Megachiroptera,
and members of the group largely depend on their large eyes
specialized for night vision. Many species are sexually dimorphic.
Differences between the sexes include the larger body size
of males (most species), males having larger canines (many
species), and males with conspicuous skin glands (a few species)
(Hill & Smith, 1984; Nowak & Walker, 1994). Sexual
differences are extreme in one species, H. monstrosus,
in which males have very large pharangeal sacs that extend
into the chest and a huge larynx (used in producing a loud
"honk" that is part of a sexual display) (e.g. Bradbury,
All pteropodids are frugivorous or nectarivorous (Mickleburgh
et al., 1992). Pteropodids are important pollinators and dispersers
of tropical trees, many of which are adapted to attract bats
and make their pollination/dispersal activities more efficient
(Marshall, 1985). In some instances pteropodids may also cause
significant damage to orchards. The larger species are sometimes
hunted for their meat.
of the genus Pteropus are the largest bats in the
world, ranging in adult weight from 250 to 1000 g and have
a wingspan of up to 1.7 metres. The Pteropus genus has currently
57 recognised species (Mickleburgh et al., 1992). Pteropus
is primarily an island taxon, with 55 species having some
or all of their distribution on islands. In this genus levels
of endemism are extremely high, with 35 species confined to
single islands or small island groups. Only nine species are
found in continental areas (five in Asia and four in Australia),
and only two (P. lylei and P. poliocephalus)
are restricted to continents (Mickleburgh et al., 1992).
All Pteropus species are exclusively phytophagus,
feeding on floral resources (primarily nectar and pollen),
fruits, leaves, bark and seeds (Marshall, 1985). Diet trees
for most species comprise canopy and sub-canopy rainforest
species, although Pteropus also feed in mangrove,
swamp and temperate forest vegetation (Marshall, 1983).
The distributional characteristic and dietary limitations
make Pteropus populations vulnerable to agricultural
clearing of forests, harvesting of animals for human consumption,
and programs for culling animals on crops (Wilson & Graham,
1992 and references therein). As a result, the current conservation
status of many Pteropus species is not secure.
The priority grading for species action assigned by the International
Union for the Conservation of Nature and Natural Resources
(IUCN) (Baillie & Groombridge, 1996) assigns species to
categories according to their danger of extinction. In 2004
(IUCN, 2004), five species were classed as extinct (EX), seven
species were classed as critically endangered (CR), three
species were classed as endangered (EN), sixteen species were
classed as vulnerable (VU), three species were classed as
lower risk (LR), and of two species not enough was known to
determine their conservation status (DD). The remaining species
were classed as Not Evaluated (NE) because they have not been
assessed against these criteria.
Pteropus species have a slow life cycle characterized
by low fecundity and a long life-span (e.g. McIlwee &
Martin, 2002). Species that possess slow life cycles are likely
to contain a higher proportion of old, experienced individuals
than short-lived species, providing scope for intricate forms
of social organisation (e.g. Calder, 1983).
species in Australia
Australian mainland is home to 56 species of Chiroptera.
Of these, four species belong to the genus Pteropus:
the Little Red Flying-Fox, Pteropus scapulatus,
the Spectacled Flying-Fox, P. conspicillatus, the
Black Flying-Fox, P. alecto and the grey-headed
flying-fox, P. poliocephalus (Hall, 1987; Hall
& Richards, 2000).
With the exception of the distribution of P. scapulatus
that extends deep into Australia’s hot interior, the
distributions of Australia’s mainland Pteropus
species are predominantly coastal (Figure 2; Churchill,
1998; Hall & Richards, 2000; Markus, 2000). P. conspicillatus
is limited to the wet tropical coast of Far North Queensland,
north of Townsville to the tip of Cape York Peninsula (Hall
& Richards, 2000). P. alecto’s northern distribution
extends into Papua New Guinea and Indonesia (Mickleburgh
et al., 1992). In Australia the range of P. alecto
is approximately 1.6 million km2 (Webb & Tidemann, 1996).
In the west its southern limit is currently near Carnarvon
(Western Australia) (Hall & Richards, 2000); in the
east it extends to Port Macquarie (N.S.W.) (Eby, pers. comm.).
South of Rockhampton (Queensland), P. alecto shares
its range with P. poliocephalus (see Figure 2).
P. poliocephalus is endemic to the south-eastern
forested areas of Australia, principally east of the Great
Dividing Range. It extends as far as Melbourne (Victoria)
(Hall & Richards, 2000; Ratcliffe, 1931) where it occupies
more extreme latitudes than any other megachiropteran (e.g.
Mickleburgh et al., 1992; Reardon, 1999; Tidemann, 1999).
Figure 2. Distribution of Pteropus species
on the Australian mainland. Dotted line – southern
limits of P. scapulatus, dotted area – P.
conspicillatus, vertical lines – P. alecto,
horizontal lines – P. poliocephalus (from
The majority of field-based biological research on Australian
Pteropus species to date has focused on foraging
patterns and its implications for seed dispersal and pollination
of native forests (e.g. Eby, 1991; Palmer & Woinarski,
1999); however, very little is known about Pteropus
behaviour in colonies and at feeding sites, a problem commonly
encountered in this ecologically important group of animals
(Mickleburgh et al., 1992; see also Wilson & Graham,
is perhaps the best studied species in the Pteropus
genus, and base-line information on its general ecology
(see Eby, 1996; McWilliam, 1986; Nelson, 1965b; Parry-Jones
& Augee, 1991; Ratcliffe, 1932) and reproductive biology
(Martin, 1998; Martin et al., 1993; Martin et al., 1995;
Martin et al., 1987; O'Brien et al., 2003) have largely
been established. However, even for this species information
on behaviour in colonies and at feeding sites is largely
anecdotal and the only published study on the social organisation
of P. poliocephalus dates to the 1960’s (Nelson,
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