Mammals > Bats

Bats of Fiji

• Background
• Introduction
• Methods
• Description of species and results
• References

Background

During the early 1990s the Mammal section at the Australian Museum undertook a series of surveys of the mammals of the South-west Pacific region. These surveys involved trapping and collecting mammals from a number of Pacific Island countries including the Solomon Islands, Fiji, Vanuatu, New Caledonia and the islands of New Britain and New Ireland in Papua New Guinea. The surveys led to the discovery of new mammal species as well as more detailed information about the ecology, systematics and conservation status of many others. The results of the surveys are presented in the scientific literature and in Tim Flannery's book, Mammals of the South Pacific.

A brief background and summary results from a part of this survey for the island of Fiji, is given here. A scientific paper presenting these results is in the press.

Introduction

Fiji is situated in the South-west Pacific Ocean about 3 000km east of Australia and about midway between Vanuatu to the west and Tonga to the east. It comprises three archipelagos that include several large, mountainous islands (Viti Levu, Vanua Levu, Kadavu and Taveuni), over 300 smaller islands and numerous small sand or coral islets.

The native vegetation of Fiji is predominantly rainforest although most of the lowland forest on the drier sides of the large islands and on small islands has been cleared and replaced with sugar cane, other commercial crops, gardens or grassland. Secondary forest covers large parts of the wetter regions although small areas of undisturbed montane forest still exist in the rugged interior of the large islands such as Viti Levu, Vanua Levu and Taveuni.

Fiji's native land vertebrates have their origins primarily in the Australia-New Guinea region or island south-east Asia, although at least two species of reptiles, the Fijian Crested Iguana, Brachylophus vitiensis and Fijian Banded Iguana, Bracylophus fasciatus, are thought to have originated in the Americas. The number of terrestrial vertebrate species recorded from Fiji is low compared to the Solomon Islands, Vanuatu and New Caledonia.

Fiji's native mammal fauna consists of six bat species and little is known about the ecology, conservation status and evolutionary relationships of these. One species, the Fijian Monkey-faced Bat, Pteralopex acrodonta, and one subspecies, the Samoan Flying fox, Pteropus samoensis nawiensis are endemic to Fiji. The four remaining species (two other megachiropterans and two microchiropterans) are either widespread in the Pacific region, or occur on adjacent island groups such as Vanuatu, New Caledonia or Samoa (Flannery 1995).

The purpose of this study was to examine the evolutionary relationships of Fijian bats using biochemical techniques, as well as gain additional information about their distribution and conservation status.

Methods

Survey work took place in April 1990 and May 1991 and involved visits to the islands of the Yasawas, Viti Levu, Vanua Levu, Ovalau, Taveuni, and Kadavu. Bats were trapped using mist nets set across potential flyways in both low and high altitude forests. Cave dwelling bats were captured using mist nets set across the entrance or inside caves. Information concerning the distribution and abundance of bats was also obtained from local residents.

Specimens collected during the study are lodged in the Australian Museum. Allozyme electrophoresis was used to examine systematic relationships between bats from Fiji and those from other parts of the Pacific

Description of species and results

Fijian Monkey-faced Bat, Pteralopex acrodonta

The Fijian Monkey-faced bat has an extremely restricted distribution and is known from only a few specimens collected from a single locality on Taveuni Island (Hill and Beckon 1978, Flannery 1995). It is one of five species currently described in this genus, the other four being from the Solomon Islands. One of the Solomon Islands species, Pteralopex taki, has only recently been described (Parnaby 2002).

Electrophoretic studies indicated that the P. acrodonta is the most divergent of Fiji's bat species. The level of separation between it and two other Pteralopex species examined P. taki and P. pulchra was comparable to that found between different genera (Ingleby and Colgan in press).

Virtually nothing else is known about the biology of P. acrodonta. It appears that that this species may be restricted to the summit forests of Taveuni. If this is the case, then its highly restricted distribution and apparently narrow habitat requirements would make it particularly vulnerable to extinction. It is currently classed as critically endangered.

Insular Flying Fox, Pteropus tonganus

The Insular Flying Fox is widespread in the Pacific region extending intermittently from Karkar Island off the north-east coast of New Guinea to the Cook Islands in the western Pacific Ocean. Three subspecies of P. tonganus are currently recognised, the isolated P. t. basilicus from Karkar and Koil islands off Papua New Guinea, P. t. geddiei from the Solomon Islands, Vanuatu and New Caledonia and a widespread eastern form P. t. tonganus from Fiji, Tonga, Kiribati, Tuvalu, American Samoa, Western Samoa, Niue and Cook Islands.

This study examined the relationships between two subspecies, P. t. tonganus (Fiji) and P. t. geddiei (Solomon Islands and Vanuatu) as well as those between the morphologically similar but apparently distantly related Spectacled Flying Fox, Pteropus conspicillatus from Australia. The electrophoretic results showed little evidence of genetic divergence between the two subspecies despite clear differences in body size between the two. They also identified a previously unidentified but close relationship between this species and P. conspicillatus.

P. tonganus was found to be widespread and common throughout the Fiji group occurring on small islands, such as those in the Yasawas as well as the larger islands. It was recorded from sea level up to 1 000m and was found to occupy a variety of habitat types including lowland, intermediate and highland forest as well as mangroves. However, people from several parts of Fiji felt that this species had declined in abundance over the last 20 years because of the loss of forest as a result of burning, clearing, logging and cyclones.

Samoan Flying Fox, Pteropus samoensis

The Samoan flying fox has a fairly restricted distribution being found only in Fiji and Samoa with a distinct subspecies in each place. P. samoensis is placed in a different subgroup to the other Pteropus species from Fiji, P. tonganus, and is generally thought to be most closely related to P. anetianus from Vanuatu. This study compared P. samoensis to a range of other morphologically similar Pteropus species from the region and found it to be most similar genetically to P. nitendiensis from the Solomon Islands.

Figure 1: Neighbour joining tree of phenetic relationships of Pteropus based on Nei's unbiased genetic distance.

There have been no detailed studies examining the conservation status of P. samoensis in Fiji although it has been regarded as abundant (Pernetta and Watling 1978). This study found P. samoensis to be moderately common in both low and high altitude forest on the three largest islands of Fiji. Local people from a number of areas felt that this species had declined in abundance over the last 20 years. A more detailed study is needed to assess the conservation status of this species in Fiji, however, we believe its current IUCN status of vulnerable is appropriate. This species has undergone a dramatic decline in Samoa where it is now very rare (Cox 1983) and in Fiji where little is known of its habitat requirements, its numbers also appear to have been reduced.

Long-tailed flying Fox, Notopteris macdonaldii

The Long-tailed Flying Fox is a very distinctive species that occurs in Fiji and Vanuatu. A closely related species, N. neocaledonica is found in New Caledonia and until recently it was considered to be a subspecies of macdonaldii. This study examined the relationships between two populations from Fiji and Vanuatu of N. macdonaldii and found very low levels of differentiation, supporting their current classification as the same subspecies.

Prior to this study N. macdonaldii was known in Fiji from only a single island, Viti Levu. We found N. macdonaldii to be common on the three largest islands of Fiji and its status there seems reasonably secure at present. Large colonies were found in a number of caves and the species was found at all altitudes and in a variety of habitat types. However, because it roosts in large numbers in caves it is easily hunted or disturbed and given there is little detailed information about its habitat requirements, its status should be monitored in future. It is currently classed as vulnerable.

Fijian Mastiff Bat, Chaerephon bregullae

The Mastiff bat, formerly classified as Chaerephon jobensis has recently been split into separate species based on biochemical analysis conducted during this study. It was previously considered to occur intermittently from the central Moluccas in Indonesia, through mainland New Guinea, Solomon Islands, Vanuatu and Fiji as well as a large part of northern Australia. Four subspecies were recognised until recently, C. j. jobensis (Papua New Guinea), C. j. colonicus (Australia), C. j. solomonis (Solomon Islands) and C. j. bregullae (Vanuatu and Fiji).

This study found considerable variation in what had been previously considered a single species. The Australian C. j. colonicus showed levels of divergence from the Fiji/Vanuatu form consistent with that of a distinct species. C. j. solomonis from the Solomon Islands is also divergent, although to a lesser extent. Accordingly, Chaerephon from Fiji and Vanuatu (now C. bregullae) and those from the Solomon Islands (now C. solomonis) are now regarded as distinct species (Flannery 1995).

Figure 2: Neighbour joining tree of phenetic relationships of Chaerephon samples based on Nei's unbiased genetic distance.

Prior to this study there were very few records of C. bregullae from Fiji. We located a number of colonies, one of which was a large maternity colony that is likely to be extremely important to the survival of this species in Fiji. Our survey indicated that the Fijian populations of C. bregullae should be classed as vulnerable for several reasons. It has a limited distribution, roosts in large numbers in caves where it can be easily hunted or disturbed and according to local inhabitants, the large maternity colony has declined in size over the last 20 years. The species is currently classed as low risk/near threatened by IUCN.

Polynesian Sheath-tailed Bat, Emballonura semicaudata

The Polynesian Sheath-tailed Bat, Emballonura semicaudata, has a wide but disjunct distribution that extends from Palau and the Northern Mariana Islands in the western Pacific to Vanuatu, Fiji, Tonga and Samoa in the east. Three subspecies are currently recognised, however, we were unable to examine relationships within this species as we only had samples from Fiji.

E. semicaudata had been recorded from several of the large islands in Fiji and a number of small ones prior to this study. We found E. semicaudata to have declined in distribution and abundance in Fiji during the last 60 years. It appeared to have become rare on Viti Levu and many caves where it was once recorded were found to be empty. This species appears to persist on some smaller islands although in reduced numbers. The cause of the decline of this species in Fiji is not known but is consistent with what has occurred in other parts of its range such as the Northern Marianas, Guam and Samoa where it is now very rare. It seems likely that this species is endangered in Fiji and remaining colonies should be protected.

References

• Flannery, T.F. (1995). Mammals of the South-west Pacific and Moluccan Islands. Reed Books. Chatswood. Sydney.
• Hill, JE and Beckon, W.N (1978). A new species of Pteralopex. Thomas 1888 (Chiroptea pteropodidae from the Fiji Islands. Bulletin of the British Museum of Natural History (Zoology) 34 (2) 65-82.
• Parnaby, H.E. (2002). A taxonomic review of the genus Pteralopex (Chiroptea pteropodidae) the monkey-faced bats of the South-western pacific. Australian Mammalogy. 23 (2) 145-162.
• Hilton-Taylor (2000). IUCN redlist of threatened species.

Photography by and copyright to Pavel German.

Copyright © Australian Museum, 2003