The conservation status of bats in Fiji

Bats provide important ecosystem services throughout the South Pacific but many species are threatened. The Fiji archipelago has a rich bat fauna yet few arrangements exist to promote the conservation of this group. From July 2008 to March 2011 we visited important sites identified in previous surveys for bats on Vanua Levu, Taveuni, Viti Levu and the Yasawa Islands. We netted and recorded five of Fiji's six bat species (Pteropus tonganus, Pteropus samoensis nawaiensis, Notopteris macdonaldi, Chaerephon bregullae and the Critically Endangered Mirimiri acrodonta). This was only the sixth recorded capture of M. acrodonta. P. tonganus is widespread in Fiji and exploits many different environments. P. samoensis nawaiensis mostly uses forested areas, and large tracts of forest are required for its long-term protection. Cave protection is vital for the two insectivorous species (C. bregullae and Emballonura semicaudata) and N. macdonaldi. In particular, the Nakanacagi maternity site remains globally significant for C. bregullae. E. semicaudata was not caught or detected during our surveys. It appears to be extinct from most large islands in Fiji and has abandoned the only large cave roost (Yaqeta) observed 10 years ago. This species has disappeared from or declined dramatically on Vanuatu, Samoa, Tonga and Fiji. We recommend that the category of E. semicaudata semicaudata on the IUCN Red List be changed to Critically Endangered. Management priorities should focus on community engagement and education, and improved cave and forest management and protection.

Insectivory in Fijian flying foxes (Pteropodidae)

We used scat and isotope analyses to assess insectivory in Fijian flying foxes (Pteropodidae), seeking insights into niche partitioning of co-occurring bat species with high plant diet overlap. Moth scales were most common in scats of Notopteris macdonaldi (87%; P. tonganus: 62%; Pteropus samoensis: 36%) and may indicate shared resources. The small and highly manoeuvrable N. macdonaldi exploited nectar-rich flowers also favoured by moths (e.g. Barringtonia spp.). Other invertebrate remains were most frequent in scats of P. tonganus (69%). On the basis of scat results and ecological observations, P. tonganus uses a combination of insectivory and a highly varied plant diet to obtain sufficient nutrients. Scats of P. samoensis contained few invertebrate remains, but abundant protein-rich plant species (including Freycinetia spp.), and juveniles seemed to consume moths frequently. Clustered δ15N and δ13C for N. macdonaldi and P. samoensis indicated a narrower dietary breadth than that of P. tonganus. P. tonganus juveniles appeared at a significantly higher trophic level than did adults, probably the result of milk consumption and/or higher rates of protein synthesis. The methods used detected little evidence that bats partitioned resources vertically. This study generates hypotheses for the further examination of flying-fox diets.

Distribution, status and conservation of the bats of the Fiji Islands

The poorly studied bat fauna of the Fiji Islands is of notable conservation importance because it includes one endemic species, several near endemics, and the best global populations of several threatened species. In addition, some of the species play a keystone role as pollinators and seed dispersers in valuable forest ecosystems. We visited 30 islands of the archipelago to survey bats and assess their conservation status and the potential threats to their continued existence. The Vulnerable Notopteris macdonaldi occurs on the three main islands but may only have nurseries on one of them. The Critically Endangered, endemic Mirimiri acrodonta appears to be restricted to a small montane area on a single island. Pteropus tonganus is consumed throughout rural Fiji but remains common and is not currently threatened by the harvest. The Near Threatened Pteropus samoensis is locally common on the largest islands but threatened on some smaller islands. The Endangered Chaerephon bregullae exists only on two islands and appears to concentrate in a single large colony to nurse young. The Endangered Emballonura semicaudata has declined dramatically in Fiji, as across most of its range, although a few substantial populations remain on some small islands. Factors threatening these species are variable but include small ranges, concentration in a reduced number of colonies, deforestation, over-harvesting, and introduced predators. We propose conservation measures and indicate a number of priority sites.

Electrophoretic studies of the systematic and biogeographic relationships of the Fijian bat genera Pteropus, Pteralopex, Chaerephon and Notopteris.

Allozyme variation at 24 - 29 presumptive loci was used to examine the systematic relationships between Fijian bats and those from neighbouring areas such as Vanuatu, Solomon Islands, New Caledonia, New Guinea and Australia. Genetic data indicate that the Fijian bat fauna contains highly divergent taxa as well as some populations that are virtually indistinguishable electrophoretically from conspecifics in neighbouring islands groups, particularly species shared with Vanuatu. The endemic Fijian monkey-faced bat Pteralopex acrodonta, had a level of distinctiveness from two of its congeners in the Solomon Islands comparable to that between different genera. There was also considerable electrophoretic variation within what is generally considered a single species, the northern freetail-bat Chaerephon jobensis. The Australian form, C. j. colonicus, shows levels of divergence from the Fiji/Vanuatu subspecies, C. j. bregullae, consistent with that of a distinct species. C. j. solomonis from the Solomon Islands appears to represent a third species within this group. Moderate levels of divergence were found within the one subspecies of long-tailed flying-fox Notopteris macdonaldii sampled from Fiji and Vanuatu. In contrast to Pteralopex and Chaerephon, close affinities were found between and within several other southwest Pacific bat species, in particular, the two different subspecies of insular flying-fox Pteropus tonganus from Fiji, Vanuatu and the Solomon Islands. Low levels of genetic divergence were also found between P. tonganus and the morphologially similar spectacled flying-fox P. conspicillatus from Australia and New Guinea. The Samoan flying-fox Pteropus samoensis appeared to be most closely allied to the Temotu flying-fox Pteropus nitendiensis, from the Solomon Islands.