Ecological role and conservation status of the endangered, native Fijian free-tailed bat (Mops bregullae, Felten 1964) in fragmented forest habitats

Bats of Fiji are of significant conservation value because they represent Fiji’s only native mammals and contain the most secure global populations of several threatened taxa. Bats are ecologically important as they provide critical ecosystem services of pollination and insect control in both agricultural and forest ecosystems. The ecology of the endangered Fijian freetailed bat (Mops bregullae), like other endangered bats in the Pacific, is virtually unknown and research is considered to be a priority requirement to inform current management planning and conservation efforts (Waldien et al., 2019, Frick et al., 2020). This study used a multi-disciplinary approach combining temporo-spatial surveys and genetic analyses to address critical ecological knowledge gaps for M. bregullae across fragmented landscapes and islands of Fiji and Vanuatu. Using this approach and guided by conservation intentions, it assessed the question: Could Mops bregullae be a self-sustaining species? The strategy began by reviewing and presenting a reassessment of the priority conservation sites for threatened cave-dwelling bats in Fiji, as well as the key threats and research needs, using the most recent survey findings. High throughput DNA sequencing was also used to determine how many populations exist for this species across its known range (Fiji and Vanuatu), understand its connectivity across islands, and investigate genetic diversity to assess the likelihood of the species surviving in the long term. In addition, DNA metabarcoding of arthropods from their scats and guano was used to provide an additional perspective on survival, taking into account how dependent the species was on specialised foraging habitats. This was achieved by determining i.) what M. bregullae ate throughout a 12-month period, ii) the foraging habitats used by the species, iii.) understanding patterns of foraging activity over seasons, and iv) determining what ecosystem services they provide and how well they could be providing these despite their low numbers. From the review of roost available habitat, this study has confirmed a new cave for Notopteris macdonaldi and eighteen new caves and colonies for the globally endangered Emballonura semicaudata semicaudata. More than 70% of these findings are on smaller islands (<110 km2). For E. s. semicaudata, the abandonment of two caves previously identified as key sites for the conservation of this species were noted, and an ongoing decline in other caves. Population sizes for the other species appear to have remained relatively stable. Critical information about species range, population status, threats, research needs, and priority conservation actions for each species was updated. The conservation of the target species, M. bregullae requires a clear delineation of the number of conservation management units required for its survival. Clear evidence of two distinct genetic units was detected. As suspected, the geographic isolation of bats in Fiji and Vanuatu was reflected in their genetic isolation. However, no population genetic structure was detected within Fiji, supporting the notion of a single connected population in the archipelago. Each of the two separate genetic populations in the Fijian and Vanuatu archipelagos should therefore be considered as separate management units for conservation. Signs of relatively low interbreeding were detected within the Fijian population over thousands of generations despite experiencing two bottleneck events in the past. These findings along with the relatively low but apparently stable effective population size calculated for Fiji, suggest the species' potential to be self-sustaining, however, conservation interventions are required, to ensure that this does not change in the long term, given how prone the species is to stochastic events including the increased severity and frequency of tropical cyclones as well as forest conversion for agriculture and development. The dietary preferences of M. bregullae offer insights into the ecosystem role of insect and pest control in agricultural and forest landscapes as well as their contributions as suppressors of disease vectors. Among all the samples collected, moths (order Lepidoptera) were the most prevalent prey representing up to 99% of the amplicons obtained from scat samples. Several of the most dominant moth taxa identified were closely associated with agricultural landscapes. The diverse range of moths consumed by M. bregullae indicates that it has a generalised diet, which allows it to exploit resources across multiple habitat types, which gives the species some resilience to changes in the landscape and seasonal availability of prey. The methodological approach presented here could serve as a framework in the future to explore how alterations in land use contribute to declines in bat populations and how insectivorous bats can provide critical ecosystem services by controlling pest insect species in transformed environments. The study has addressed key knowledge gaps about M. bregullae’s biology and ecology. A better understanding of the biogeographical history of the species over the separated archipelagos of Fiji and Vanuatu, and the conditions that support the viability of this species in Fiji is still needed. This study serves as an important foundation for future ecological studies of bats in the Pacific and the development of effective conservation strategies for island bats.

Author dc:creator

• Tikoca, Adi Siteri Alisi W

Advisors dc:contributor.advisor

• Armstrong, Kyle
• Keppel, Gunnar (University of South Australia)
• Delean, Steven

• bat conservation
• Pacific conservation
• population structure
• island population
• bat diet
• bat roost

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/2440/144556

OAI identifier oai:identifier

oai:digital.library.adelaide.edu.au:2440/144556