Annette T. Scanlon

Effects of site, time, weather and light on urban bat activity and richness: considerations for survey effort

To maximise bat retention in urban environments, efficient bat monitoring is needed, but the factors that influence survey results for urban bats are unclear. We used echolocation call detectors (n = 378 detector-nights from November 2005 to October 2006) to assess bat activity among different sites in the Adelaide City parklands, temporal variations in activity (hourly, nightly, monthly), and responses to weather and light (artificial and moon). Bat species did not occur evenly in urban conditions; dark parks were more important for bat diversity and activity (six species groups in the darkest park) than were artificially lit parkland areas (three species groups in the flood-lit park). Gould’s wattled bat (Chalinolobus gouldii) and Mormopterus species 4 (94% of calls) were advantaged in urban parklands, being the only species recorded when lights were on at sports parks, whereas five species groups occurred when the lights were off. Minimal bat activity was recorded in the first 2 h after civil twilight, suggesting that bats may roost outside the city and commute nightly into parklands. Bat activity increased with temperature, with a burst in activity occurring after 7°C. Rainfall (>1 mm/24 h) and moon illumination at midnight did not influence activity. Urban environments should provide diversity to attract a diverse assemblage of bat species. Activity fluctuated among sites, nights, and across the year, indicating that large sample sizes over long periods of time are required to monitor and survey bats reliably with detectors.

Insectivory in Fijian flying foxes (Pteropodidae)

Abstract. 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.

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 Fijis 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.

Capture success of Fijian bats (Pteropodidae) and their evaluation as umbrella species for conservation

Easily captured species provide powerful opportunities to motivate research and conservation action. Conversely, rare and cryptic species with low capture probability can be difficult to study. We examined the capture success of Fiji’s Pteropodidae (Pteropus tonganus, P. samoensis, Notopteris macdonaldi, and Mirimiri acrodonta) and incorporated capture success and associated observations into an assessment of their suitability as umbrella species for conservation. We caught 252 bats from 2493 mist-net-hours in lowland rainforest near Waisali on Vanua Levu, and 38 bats from 1915 mist-net-hours in cloud forest on Taveuni. Of these captures, 67% were N. macdonaldi, 16% P. tonganus, 18% P. samoensis, and <1% M. acrodonta. All species were difficult to net in cloud forest, where we recorded a female sex bias. Capture success was affected by site, season, and net height; peak capture times varied among species and between sites. N. macdonaldi was recaptured most frequently (8.8%), revealing habitual nightly movements. It has strong potential as an umbrella species for rainforest and cave-dwelling organisms of Fiji, and was readily netted. P. tonganus is an unsuitable umbrella species, P. samoensis has potential as an umbrella species, and M. acrodonta has many attributes of a flagship species. Capture efficiency of N. macdonaldi provides opportunities for monitoring and conservation management activities in Fiji. However, variability in capture success among species means that different approaches should be explored for conserving bats effectively with limited resources.

How fecal subsampling methods affect the accuracy of dietary pollen detection

Abstract Subsampling is used to process scat collections in diet and pollination studies involving nectarivores, but what constitutes a sufficient sampling effort is undetermined. We analyzed entire scat samples from 3 bat species (Pteropodidae) and recorded all pollen; we then tested various levels of subsampling to determine the most efficient regimes. Secondary subsampling (5 fields of view) was inappropriate for plants with low pollen loads (rare pollen); however, abundant pollen morphospecies were detected reliably with little effort. Similarly, the rarer the pollen, the higher was the chance of missing pollen in primary subsampling. Low subsampling effectiveness occurred for scats with high incidences of singletons (= rare pollen); they required the greatest effort to identify ≥ 80% of pollen morphospecies. Diet homogeneity varied among bat species, and subsample efforts should relate to diet strategy and ecology of target species. We recommend using a standard volume of material per subsample; avoiding secondary subsampling unless screening for abundant pollen morphospecies; analyzing fully 20% of material if ≤ 80% of pollen morphospecies need to be detected; and increasing subsampling effort for studies targeting plants with low pollen loads. Subsampling effort needs to match study objectives, or flower species will be greatly underrepresented or missed completely.

Differences in abundance and diversity of diurnal invertebrates among three Fijian forests, and a comparison of two trapping methods for rapid assessments

Apart from some high-profile exceptions (e.g. charismatic long-horned beetles), the ecology and conservation of Fijian invertebrates have received little research attention, and their potential as biodiversity surrogates or indicators is poorly understood. We surveyed diurnal terrestrial invertebrates within three Fijian forest types (lowland, upland, and coastal) using Malaise traps and beating trays to compare invertebrate abundance and diversity among forests. We also evaluated the efficiency of the two trapping methods for rapid invertebrate assessments. Overall, we collected 2584 invertebrates representing 321 morphospecies within 22 arthropod orders. We found significant differences in the abundance and diversity of invertebrates among forest sites for beating-tray samples, but not for Malaise-trap samples. Upland forest had the greatest diversity (Simpsons diversity index, D = 0.98); coastal forest recorded the lowest diversity (D = 0.14), but the greatest abundance of invertebrates. Several orders of invertebrates were relatively abundant across sites and traps (i.e. had high sampling reliability; they included Coleoptera, Hemiptera, Hymenoptera, Lepidoptera, and Diptera), so could be targeted as surrogates for broader biodiversity sampling. Given the urgency with which baseline data are needed across the South Pacific, invertebrate sampling provides a rapid biodiversity assessment tool, including for working in remote areas with few resources.