Conservation relies upon a primary understanding of changes in a species’ population size, distribution, and habitat use. Bats represent about one in five mammal species in the world, but understanding for most species is poor. For flying-foxes, specifically the 66 Pteropus species globally, 31 are classified as threatened (Vulnerable, Endangered, Critically Endangered) on the IUCN Red List. Flying-foxes typically aggregate in colonies of thousands to hundreds of thousands of individuals at their roost sites, dispersing at sunset to forage on floral resources (pollen, nectar, and fruit) in nearby environments. However, understanding of flying-fox roosting habitat preferences is poor, hindering conservation efforts in many countries. In this study, we used a database of 654 known roost sites of the four flying-fox species that occur across mainland Australia to determine the land-use categories and vegetation types in which roost sites were found. In addition, we determined the land-use categories and vegetation types found within the surrounding 25 km radius of each roost, representing primary foraging habitat. Surprisingly, for the four species most roosts occurred in urban areas (42–59%, n = 4 species) followed by agricultural areas (21–31%). Critically, for the two nationally listed species, only 5.2% of grey-headed and 13.9% of spectacled flying-fox roosts occurred in habitat within protected areas. Roosts have previously been reported to predominantly occur in rainforest, mangrove, wetland, and dry sclerophyll vegetation types. However, we found that only 20–35% of roosts for each of the four species occurred in these habitats. This study shows that flying-fox roosts overwhelmingly occurred within human-modified landscapes across eastern Australia, and that conservation reserves inadequately protect essential habitat of roosting and foraging flying-foxes.

Urban flying-fox camps are a major source of human–wildlife conflict, producing noise, odour, vegetation damage, property damage, and concerns about disease. Although there is a significant demand in many communities for bat camps to be dispersed, there is limited information on how such dispersal can be conducted effectively. Determining the habitat characteristics flying-foxes use when selecting a camp site is key to understanding why they establish camps where they do and to where they might move if dispersed. We characterised little red flying-fox (LRFF) camp habitat at two spatial scales: floristics and vegetation structure at the local scale, and climatic and landscape characteristics at the broad scale. We found weak associations with local-scale tree and shrub height and cover, and stronger associations with increased Normalised Difference Vegetation Index (a measure of ‘greenness’) and decreased distance to nearest watercourse. These relationships were not strong enough to explain all variation in the model, suggesting that there are other factors, such as social cues, that could also influence camp site selection. Our results suggest that minor modifications to existing or proposed camp sites will be unlikely to repel or attract LRFFs, as other factors are likely to play key roles in the formation of camp sites for this species.

The permanent exclusion of flying-foxes from camps (camp dispersal) near human settlements is a management tool commonly used to mitigate human–wildlife conflict. We summarised information on the costs and outcomes of 48 camp dispersals in Australia. Our aim was to improve the information base on which camp management decisions are made. Camp dispersals were largely triggered by impacts on neighbouring residents (75%). A disproportionately high number occurred in 2013–14, associated with changes in Queensland flying-fox management policy following an increase in the number of urban camps. Repeat actions over months or years were typically required to exclude flying-foxes from camps (58%). In 88% of cases, replacement camps formed within 1 km and became sites of transferred conflict. Only 23% of dispersal attempts were successful in resolving conflict for communities, generally after extensive destruction of roost habitat. Costs were poorly documented, although no dispersal attempt costing less than AU$250 000 proved successful. We conclude that camp dispersal is a high-risk, high-cost tool for mitigating human–wildlife conflict, in situ management strategies and tools should be developed, evidence-based information on management options should be made available to stakeholders via a nationally curated resource library, and research is required on impacts of camp management practices on flying-foxes.

Determining the diet of flying-foxes can increase understanding of how they function as pollinators and seed dispersers, as well as managing any negative impacts of large roosts. Traditional methods for diet analysis are time consuming, and not feasible to conduct for hundreds of animals. In this study, we optimised a method for diet analysis, based on DNA metabarcoding of environmental DNA (eDNA) from pollen and other plant parts in the faeces. We found that existing eDNA metabarcoding protocols are suitable, with the most useful results being obtained using a commercial food DNA extraction kit, and sequencing 350–450 base pairs of a DNA barcode from the internally transcribed spacer region (ITS2), with ∼550 base pairs of the chloroplast rubisco large subunit (rbcL) as a secondary DNA barcode. A list of forage plants was generated for the little red flying-fox (Pteropus scapulatus), the black flying-fox (Pteropus alecto) and the spectacled flying-fox (Pteropus conspicillatus) from our collection sites across Queensland. The diets were determined to comprise predominantly Myrtaceae species, particularly those in the genera Eucalyptus, Melaleuca and Corymbia. With more plant genomes becoming publicly available in the future, there are likely to be further applications of eDNA methods in understanding the role of flying-foxes as pollinators and seed dispersers.

Fur properties play a critical role in the thermoregulation of mammals and are becoming of particular interest as the frequency, intensity, and duration of extreme heat events are increasing under climate change. Australian flying-foxes are known to experience mass die-offs during extreme heat events, yet little is known about how different fur properties affect their thermoregulatory needs. In this study, we examined the differences and patterns in fur properties among and within the four mainland Australian flying-fox species: Pteropus poliocephalus, P. alecto, P. conspicillatus, and P. scapulatus. Using museum specimens, we collected data on fur solar reflectance, fur length and fur depth from the four species across their distribution. We found that P. poliocephalus had significantly longer and deeper fur, and P. alecto had significantly lower fur solar reflectivity, compared with the other species. Across all species, juveniles had deeper fur than adults, and females of P. alecto and P. conspicillatus had deeper fur than males. The biophysical effects of these fur properties are complex and contingent on the degree of exposure to solar radiation, but they may help to explain the relatively higher mortality of P. alecto and of juveniles and females that is commonly observed during extreme heat events.

Access to suitable roosts is critical for the conservation of tree-hollow roosting bats worldwide. Availability of roost sites is influenced by human land-use, but also by the roosting requirements and behaviour of species. We investigated roosting behaviour of the lesser long-eared bat (Nyctophilus geoffroyi) and Gould’s wattled bat (Chalinolobus gouldii) in a rural landscape in south-eastern Australia. Forty-five N. geoffroyi and 27 C. gouldii were fitted with radio-transmitters, resulting in the location of 139 and 89 roosts, respectively. Most (88%) roosts occupied by male N. geoffroyi contained only a single individual. During the breeding season female colonies were larger, with maternity roosts containing 18.3 ± 5.7 (s.e.) individuals. Mean colony sizes for C. gouldii were 8.7 ± 1.4 individuals. Both species shifted roosts frequently: on average, individual N. geoffroyi moved every 2.2 ± 0.23 days and C. gouldii every 2.2 ± 0.14 days. Notably, lactating female N. geoffroyi shifted roosts more frequently than non-breeding females. Individuals of both species roosted within a discrete area, with roosts typically <300 m apart; and consistently returned there from foraging up to 12 km distant. This roosting behaviour highlights three important requirements: (1) a relatively large overall number of hollows to support a population; (2) discrete roost areas with a high density of suitable hollows in close proximity; and (3) a range of hollow types to provide the specialised roosts required, particularly for breeding.

Mature forest is a key resource for hollow-using bats, but its importance in shaping where bats roost during breeding is not well understood. This lack of understanding limits the ability of forest managers to make informed decisions on the type, amount and spatial arrangement of mature forest to retain for bats in areas used for timber production. Using radio-telemetry, day roosts of three sympatric hollow-using bat species – the chocolate wattled bat (Chalinolobus morio), the Tasmanian long-eared bat (Nyctophilus sherrini) and the lesser long-eared bat (Nyctophilus geoffroyi) – were located in two forested landscapes in south-eastern Tasmania, Australia. By radio-tracking 24 bats in the maternity season, 76 roosts were located, with interspecific variation in roosting preferences evident at the roost, patch and landscape scale. Maternal colonies showed a clear selection for roosting in areas of the landscape containing the highest availability of mature forest, with smaller patches, strips and individual trees used to a greater extent for roosting in the landscape where mature forest was scarce. These findings showcase the importance of retaining mature forest at multiple spatial scales for hollow-using bats.

In Australia, there are at least 50 000 derelict mines, many of which provide habitat for cave-roosting bats. Grating of derelict mines, be it horizontal (adits) or vertical (shafts) drives, is commonly undertaken to prevent human access, though longer-term responses of bats are largely unknown. We assessed the long-term (2–20 years) effects of grating on bats by documenting trends in emergence activity and bat abundance at grated and ungrated derelict mines and quantified behavioural responses of bats in autumn and winter. Emergence activity was dominated by the eastern horseshoe bat (Rhinolophus megaphyllus) with limited activity of other less manoeuvrable species. Both emergence activity and minimum colony size at horizontal adits were 8–9 times greater than at vertical shafts, with bats observed emerging from only 2 of 13 shafts. Emergence activity and minimum colony size were 7–10 times greater at adits with ‘bat friendly’ grating (horizontal bars with spacing >125 mm) than at other treatments (ungrated adits and adits with standard grating). In winter, there were 4–11 times more aborted exit attempts per bat at adits with ‘bat friendly’ grating compared with other treatments, which corresponded to greater emergence activity. Emergence activity and minimum colony size were not related to spacing between bars or time since grating, indicating rapid habituation by R. megaphyllus. However, circling at grates continued for many years and bentwing bats (Miniopterus spp.) made little use of these sites. Bat-friendly grates appear to be an effective management option for R. megaphyllus, but alternatives need to be trialled for other species.

The eastern bent-wing bat (Miniopterus orianae oceanensis) is a small (11–20 g, mean 14 g) insectivorous bat with a distribution that extends along the eastern seaboard of mainland Australia. It is primarily a cave-dwelling species, particularly for breeding females who form large maternity colonies at just a few locations throughout its range. Seasonal population changes at one of the three large New South Wales maternity colonies (Church Cave) were studied from December to March every year for 12 years when adult females were resident at a maternity site. Five key periods were identified: (1) adult arrival, (2) adult peak, (3) juvenile independence, (4) adult–juvenile peak, and (5) autumn migration. The average duration of the adult peak period was 38 days and usually commenced around late December or early January. This is the critical period in which to estimate the female adult population. All other periods lasted ∼14 days. Understanding the timing of these different periods is important in estimating various population parameters. The timing of migration is also important with respect to windfarm construction and impact assessments of turbine strike to migrating bats. Four separate variables were investigated to describe the timing of autumn migration from Church Cave; moon illumination, minimum nightly temperatures, barometric pressure, and timing of adult arrival. The timing of adult arrival was the only model that was significant in explaining the onset of migration. This generally occurs 83–87 nights after the commencement of arrival of female adult bent-wing bats at Church Cave in early to mid December.

Assessing the risk to threatened species of population decline from anthropogenic disturbances is challenging when there are issues with species identification, and little is known of their biology, distribution, population size, and habitat preference. The bare-rumped sheath-tailed bat (Saccolaimus saccolaimus) is one such species that has a poorly defined distribution over two broad areas of northern Australia. Environmental impact assessments are expected to consider the possibility of its presence in intervening areas outside the known distributions. Our study presents new empirical data that can assist with detection of S. saccolaimus across the entire expanse of northern Australia, provides a critical analysis of acoustics-based identification of the species, and assessed presence within the potentially high value habitat of tall Eucalyptus tetrodonta-dominated forest on the western side of Cape York Peninsula using a combination of trapping and acoustic recordings. Capture of other Saccolaimus species was the greatest of any survey conducted to date in Australia, demonstrating that the capture of these high-flying bat species in tall forest habitats can be relatively effective with mist net arrays hoisted into the tree canopy. In addition, reference echolocation call collections from the focal trapping area plus other locations across northern Australia allowed characterisation and comparison of the calls of most low-frequency-emitting (LFE) echolocating bat species of northern Australia. In addition to separation of species-specific search phase call types using multivariate statistics, a compilation of features from search phase, approach phase and feeding buzz echolocation calls will help distinguish S. saccolaimus from most other LFE species. However, the similarity of the echolocation calls of S. mixtus and S. saccolaimus prevented them from being distinguished from one another. A multi-method approach that emulates the present study and incorporates our recommendations and cautions will lead to robustness in ecological studies and greater clarity in environmental impact assessments.

Effective land management and biodiversity conservation policy relies on good records of native species occurrence and habitat association, but for many animal groups these data are inadequate. In the Murray–Darling Basin (MDB), the most environmentally and economically important catchment in Australia, knowledge gaps exist on the occurrence and habitat associations of insectivorous bat species. We relied on the interest and effort of citizen scientists to assist with the most intensive insectivorous bat survey ever undertaken in the MDB region of South Australia. We used an existing network of Natural Resource Management groups to connect interested citizens and build on historical observations of bat species using a fleet of 30 Anabat Swift bat detectors. The survey effort more than doubled the number of bat occurrence records for the area in two years (3000 records; cf. 2693 records between 1890 and 2018; freely available through the Atlas of Living Australia). We used multinomial logistic regression to look at the relationship between three types of environmental covariates: flight space, nearest open water source and vegetation type. There were no differences in species richness among the environmental covariates. The records have been, and will continue to be, used to inform government land management policy, more accurately predict the impact of development proposals on bat populations, and update conservation assessments for microbat species. A social survey tool also showed that participation in the project led to positive behaviours, and planned positive behaviours, for improving bat habitat on private land.

Horseshoe (Rhinolphidae) and Old World leaf-nosed (Hipposideridae) bats are high duty cycle (HDC) echolocators sharing a suite of adaptations including long duration signals relative to their signal periods, peak energy concentrated in a narrow spectral band dominated by a constant frequency (CF) component, ‘auditory fovea’ (over-representation and sharp tuning of neurons responsible for frequencies at or around the CF) and ability to compensate for Doppler shifts in echoes. HDC bats separate signals from returning echoes in the frequency domain. Rhinolophids are more specialised neurobiologically than hipposiderids, producing longer duration signals at higher duty cycles, and have narrowly tuned auditory fovea and almost full Doppler shift compensation. Here, I examine whether these differences have produced ecological divergence between the families by testing predictions of differences in prey perception, prey capture behaviour, foraging habitat and diet. I found no discernible differences in these variables between the two families. Rhinolophids and hipposiderids both forage close to vegetation, capture prey by aerial hawking and gleaning from surfaces, and consume mostly flying insects with spiders and terrestrial, flightless arthropods taken occasionally. The data presented here show that the two families are similar in foraging ecology despite differences in echolocation and audition.