Wattled Bat Research Articles

Bat boxes in urban bushland are associated with inflated activity of an urban generalist bat, but not an altered community

AbstractBat boxes are often installed as substitute habitats to offset the loss of large, hollow‐bearing trees. However, emerging evidence suggests that they are failing to achieve intended conservation outcomes as they only support generalist species. Despite these concerns, the effect of bat boxes on the dynamics of bat communities remains understudied. We assessed the bat community in reserves where bat boxes had been installed in comparison with reserves where they had not using ultrasonic surveys in 16 small bushland reserves throughout Sydney, Australia. Reserves containing bat boxes and those without had comparable species diversity and composition; however, the activity of the dominant species, Gould's wattled bat (Chalinolobus gouldii), was significantly higher at sites with bat boxes. Species that commonly forage in open vegetation, including C. gouldii, were significantly positively associated with sites that had bat boxes. Occupation of boxes by bats was not recorded in the study due to limited information on their locations, so further research is required to understand the direct effects of boxes and the bats that occupy them on the bat community. If bat boxes continue to be recommended as a biodiversity offset, a greater understanding of the potential impact they have on altered competitive relationships and community dynamics is essential.

A light-exploiting insectivorous bat shows no melatonin disruption under lights with different spectra.

Natural light-dark cycles synchronize an animal's internal clock with environmental conditions. The introduction of artificial light into the night-time environment masks natural light cues and has the potential to disrupt this well-established biological rhythm. Nocturnal animal species, such as bats, are adapted to low light conditions and are therefore among the most vulnerable to the impacts of artificial light at night (ALAN). The behaviour and activity of insectivorous bats is disrupted by short-wavelength artificial light at night, while long-wavelength light is less disruptive. However, the physiological consequences of this lighting have not been investigated. Here, we examine the effect of LEDs with different spectra on urinary melatonin in an insectivorous bat. We collected voluntarily voided urine samples from Gould's wattled bats (Chalinolobus gouldii) and measured melatonin-sulfate under ambient night-time conditions (baseline) and under red (λP 630 nm), amber (λP 601 nm), filtered warm white (λP 586 nm) and cool white (λP 457 nm) LEDs. We found no effect of light treatment on melatonin-sulfate irrespective of spectra. Our findings suggest that short-term exposure to LEDs at night do not disrupt circadian physiology in the light-exploiting Gould's wattled bat.

Low Rates of PIT‐Tag Loss in an Insectivorous Bat Species

ABSTRACTThe rate of loss of tags used to mark individuals is an important consideration in wildlife research and monitoring. Passive integrated transponder (PIT) tags (or microchips) generally have high retention rates; however, tag loss rates for small mammals such as insectivorous bats are poorly understood. We double‐marked a population of Gould's wattled bats (Chalinolobus gouldii) with forearm bands and PIT tags (with the injection site sealed with surgical adhesive) in January and February 2020 to determine rates of subsequent tag loss over the short‐ (1–2 months) and medium‐ (13–14 months) term. Loss of PIT tags occurred in 4 (2.7%) of 146 recaptured individuals, all within 2 months of microchipping. We also recorded 1 occurrence of band loss 11 months after banding. Our study supports assertions that PIT‐tag retention rates in small mammals are high, and suggests that rates of tag loss in small bat species are low when surgical adhesive is applied. Quantifying the rate of tag loss enables this variable to be incorporated into mark‐recapture models. © 2021 The Wildlife Society.

A review of the taxonomic status of the New Caledonia Wattled Bat Chalinolobus neocaledonicus Revilliod, 1914 (Chiroptera: Vespertilionidae) and Chalinolobus gouldii venatoris Thomas, 1908 from northern Australia.

The taxonomic status of the New Caledonia Wattled Bat Chalinolobus neocaledonicus Revilliod, 1914 has remained uncertain since its synonymy with mainland Australian Gould's Wattled Bat C. gouldii (Gray, 1841) in 1971. Although Chalinolobus neocaledonicus is now widely accepted as a valid species, this was based on a tentative taxonomic opinion published in 1995. We examined most of the original material used to justify synonymy with C. gouldii, which included the type series of C. gouldii venatoris, a small northern Australian form that superficially resembles C. neocaledonicus but is currently not generally recognised as a valid subspecies. We found consistent differences in key diagnostic external and cranial criteria that support species status for C. neocaledonicus. We also review the taxonomic status of venatoris. Contrary to previous assessments, our re-interpretation of the taxonomic literature supports subspecific recognition of venatoris. Nevertheless, we are unable to conclusively resolve the status of venatoris because a more complex pattern of variation than a simple latitudinal size cline is apparent in C. gouldii. We argue that recognition of venatoris as the northern subspecies of C. gouldii has merit, pending a comprehensive analysis of variation in mainland C. gouldii to test for the presence of cryptic taxa.

Bat roosts in Tasmania’s production forest landscapes: importance of mature forest for maternity roosts

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.

Flexible roost selection by Gould’s wattled bats (Chalinolobus gouldii) using bat boxes in an urban landscape

Bat boxes are often used as a conservation tool in human-disturbed landscapes across Australia; however, to assess their effectiveness we need to understand the factors influencing their occupancy by insectivorous bats. We investigated roost selection by Gould’s wattled bat (Chalinolobus gouldii) using 76 bat boxes, comprising six designs, across three sites in suburban Melbourne, Australia. We conducted monthly surveys for a year and recorded the physical characteristics of each box. Five species of bats were recorded but Gould’s wattled bats dominated box occupancy year-round at all three sites. Group sizes ranged from 1 to 58 individuals, with maternity colonies forming over summer. There was little consistency in the use of selection criteria by Gould’s wattled bats when choosing a bat box as a day roost, with considerable variability across sites and seasons, highlighting the flexibility in roost site selection by this widespread, adaptable species. Our findings show that bat boxes can be an effective tool for providing supplementary roosts for Gould’s wattled bats in urbanised landscapes. However, little is known about the impact on the whole bat community, especially disturbance-sensitive taxa, of artificially increasing roosting resources for common species.

Social interactions, roost usage and notes on the breeding system of the chocolate wattled bat (Chalinolobus morio) in south-east Queensland, Australia

Little is known about the social behaviour of roosting insectivorous bats in Australia. Interactions between individuals and movements between multiple roosts at a building maternity site of the chocolate wattled bat (Chalinolobus morio) were examined using video observation and Passive Integrated Transponder (PIT) tagging, respectively. Bats of both sexes were seen to allogroom, which involved pairs of individuals simultaneously grooming each other around the face. This is the first occurrence of allogrooming reported between male vespertilionids, globally. In total, 366 bats were PIT tagged and analysis of movements revealed that bats exhibited a fission–fusion pattern of roost usage with sufficient switching among nearby roosts, such that all individuals were potentially able to associate and interact over a period of 150–200 days. Rates of roost fidelity varied markedly from 1 to 7.2 days of continuous occupancy of roosts, with females exhibiting slightly higher overall levels of fidelity over the nine-month monitoring period. The information gained from this study, when combined with results from other research, provides a sufficient basis for the description of the apparent breeding system for this species, where both males and females at the summer maternity roost are natally philopatric and mating takes place over winter in an expanded gene pool, comprising individuals that have dispersed from multiple summer maternity roosts.

Wind turbines impact bat activity, leading to high losses of habitat use in a biodiversity hotspot

Previous studies have mainly focused on bat mortality through collision by wind turbines, and very few studies have assessed the indirect impacts on bat activity and on foraging habitat availability. Also, there is a global lack of knowledge on the vulnerability of tropical bat fauna due to wind energy production, even though it is well known that windpower can affect bat communities and biodiversity hotspots are widespread in the tropics. We present one of the first studies to quantify the indirect impact of wind farms on insectivorous bats in tropical hotspots of biodiversity. Bat activity was compared between wind farm sites and control sites, via ultrasound recordings at stationary points. The activity of bent winged bats (Miniopterus sp.) and wattled bats (Chalinolobus sp.) were both significantly lower at wind turbine sites. The result of the study demonstrates a large effect on bat habitat use at wind turbines sites compared to control sites. Bat activity was 20 times higher at control sites compared to wind turbine sites, which suggests that habitat loss is an important impact to consider in wind farm planning We strongly recommend that the loss of the foraging habitat loss is considered in mitigation hierarchy (avoiding, reducing, offsetting) when compensating for negative impacts of wind farms.

Bat boxes are not a silver bullet conservation tool

AbstractNest boxes are often promoted as substitute structures for hollow‐dependent fauna, but are they generally effective? In a long‐term bat‐box monitoring project in south‐eastern Australia, box occupancy was dominated by one common and widespread urban‐adapted species, Gould's wattled bat Chalinolobus gouldii. In contrast, the 13 other bat species in the area made little or no use of the boxes. Policymakers, land managers and conservation professionals working in the field of biodiversity offsets should be aware that bat boxes are unlikely to compensate adequately for the broad‐scale loss of tree hollows caused by various forms of human disturbance.

Effect of roost choice on winter torpor patterns of a free-ranging insectivorous bat

Gould’s wattled bat (Chalinolobus gouldii) is one of only three native Australian mammals with an Australia-wide distribution. However, currently no data are available on the thermal physiology of free-ranging C. gouldii. Therefore, we aimed to quantify the effect of roost choice on daily skin temperature fluctuations during winter in C. gouldii living in an agricultural landscape in a temperate region. Ambient conditions consisted of long periods below 0°C and snow. Some individuals roosted high in dead branches whereas one individual roosted in a large cavity located low in a live tree. Torpor was employed on every day of the study period by all bats, with bouts lasting for over five days. The skin temperature of individuals in the dead branches tracked ambient temperature, with skin temperatures below 3°C on 67% of bat-days (lowest recorded –0.2°C). In contrast, the individual in the tree cavity maintained a larger skin-ambient temperature differential, likely influenced by the internal cavity temperature. Our study presents the lowest skin temperature recorded for a free-ranging Australian microbat and reveals that roost choice affects the thermal physiology of C. gouldii, ensuring survival during periods of cold weather and limited food supply.

Network analysis reveals cryptic seasonal patterns of association in Gould’s wattled bats (Chalinolobus gouldii) roosting in bat-boxes

Tree-roosting bats are highly social mammals, which often form fission–fusion societies. However, extensive, fine scale data is required to detect and interpret these patterns. We investigated the social structure of Gould’s wattled bats,Chalinolobus gouldii, roosting in artificial roosts (bat-boxes) over a continuous 18-month period. Network analyses revealed non-random associations among individuals in the roosting population consistent with a temperate zone fission–fusion social structure. Females generally showed stronger associations with roost-mates than did males. Two distinct sub-groups within the larger roosting population were detected. There was also evidence of smaller subunits within these larger roosting groups in spring and summer, with broader mixing at other times of the year. The extensive roost occupancy data collected across all seasons was critical in defining this fine scale, and otherwise cryptic, social structure, and in particular indicating that associations observed during peak activity periods may not be maintained across the year.

The Effect of Ectoparasites on the Grooming Behaviour of Gould's Wattled Bat (Chalinolobus Gouldii): An Experimental Study

Grooming is an important behaviour for the control of ectoparasites in mammals but it is also energetically costly. Therefore, the time an animal allocates to grooming may be used to evaluate the potential cost of an ectoparasite to its host. Most mammals are host to more than one ectoparasite species, which may impose different costs. We experimentally evaluated the relative cost of three ectoparasite species by observing the grooming response of their host, Gould's wattled bat (Chalinolobus gouldii), to the manipulation of parasite load. The parasite that spent its entire lifecycle on the host, the mite Spinturnix novaehollandiae, triggered the greatest increase in grooming. A grooming response was not as evident for the other parasites (a smaller mite, Trichonyssus womersleyi, and a bat fly, Basilia troughtoni), possibly because part of their lifecycle occurred in the roost, which the host may avoid by discriminative roost selection. Grooming behaviour, although not significantly altered by parasites other than S. novaehollandiae, was performed by most bats, which maintained a baseline grooming rate even when relatively parasite free. This study suggests heterogeneity in the costs imparted on a host by members of its ectoparasite community and the potential importance of considering parasite life-history when evaluating the influence of parasites on the host.

Bat fatalities at two wind farms in Tasmania, Australia: bat characteristics, and spatial and temporal patterns

Bat carcasses from two wind farms in Tasmania (2002–2010) were assessed to determine the species, sex, age, reproductive state, morphometrics, presence of food in the gastrointestinal tract, and evidence of spatial and seasonal patterns. Thirty-eight of the 54 carcasses were Gould's wattled bats, with another 14 likely to be, and two Vespadelus sp. All but two were adults, with an equal ratio of females and males. None were actively breeding when found, and five of the six bats tested, had not been recently feeding. Mortalities predominantly occurred in autumn, with a small difference between sites. There was no pattern in the location of carcasses. There appear to be particular ecological, morphological and behavioural characteristics associated with bat collision risk—tree roosting bats with high wing aspect ratios that forage in the open air at high altitude appear to be susceptible. Seasonal patterns may be associated with specific behaviours.

Bassian bats in the Eyrean sub-region? Preliminary acoustic data from the Bogan and Macquarie Rivers in semi-arid NSW

We conducted acoustic surveys of insectivorous bat fauna in riparian areas along the Macquarie and Bogan River systems in the wheatbelt of semi-arid central-western New South Wales, Australia. In surveys of 10 sites we detected 11 species and two species groups of bats in eight genera. Four species, Chocolate Wattled Bat Chalinolobus morio, Large-footed Myotis Myotis macropus, Large Forest Bat Vespadelus darlingtoni and Southern Forest Bat V. regulus, are predominantly Bassian (chiefly coastal) in their recorded distributions but were detected in the semi-arid Eyrean sub-region on two rivers in vegetation dominated by River Red Gum Eucalyptus camaldulensis. The findings of this study highlight the need for further research to assess the importance of riparian corridors as habitat for insectivorous bats in semi-arid New South Wales.

Observations of a large colony of bats roosting in a church

The nightly and seasonal activity patterns of a large colony of bats roosting in a country church are described. In summer 400–700 bats from two species – southern freetail bat (Mormopterus sp. 4) and chocolate wattled bat (Chalinolobus morio) – left the roost beginning around civil twilight. Bats emerged at a rate of up to 40–50 min–1, and took 30 min or longer to clear the roost.

THERMOREGULATORY BEHAVIOR OF TREE-ROOSTING CHOCOLATE WATTLED BATS (CHALINOLOBUS MORIO) DURING SUMMER AND WINTER

The thermal physiology of tree-roosting bats has been rarely studied in the wild. I used temperature telemetry to locate and record the skin temperature (Tskin) of chocolate wattled bats (Chalinolobus morio, Vespertilionidae) roosting in tree cavities. In summer, male C. morio (n ¼ 4) used torpor on 88% (15 of 17) of days. Bats entered torpor before or near sunrise, remained torpid for 7.3 h 6 3.8 SD (range: 0.8–13.2 h), and aroused midmorning. Torpor bout duration was negatively related to minimum torpid Tskin (R 2 ¼ 0.94, P , 0.001). In winter, a female bat employed prolonged torpor lasting 13.5 and 15 days, during which Tskin fluctuated passively by 5.78C 6 2.58C, following the daily temperature cycle. At the same time of year, a male bat used torpor repeatedly but aroused on most evenings, possibly to find and copulate with females and also forage on warmer nights. These data shows that male C. morio frequently enter torpor in summer and provides the 1st direct evidence of winter hibernation by tree-roosting bats.

Selection of roost sites by the lesser long‐eared bat (Nyctophilus geoffroyi) and Gould's wattled bat (Chalinolobus gouldii) in south‐eastern Australia

AbstractPhysical characteristics of roost sites used by the lesser long‐eared bat Nyctophilus geoffroyi and Gould's wattled bat Chalinolobus gouldii were investigated in a farmland–remnant vegetation mosaic and adjacent forested floodplain in south‐eastern Australia. A total of 45 individuals of N. geoffroyi and 27 C. gouldii were fitted with radio‐transmitters, resulting in the location of 139 and 89 roosts, respectively. Male N. geoffroyi roosted in trees, fallen and decayed timber and artificial structures. These roosts were low to the ground, mainly under bark and in cracks in timber. Roosts of female N. geoffroyi were located higher above ground, and all within trees. Maternity roosts were predominantly located in large dead trees, approximately twice the diameter of roost trees used by females outside the breeding season. No maternity roosts were found under bark, despite half the roosts used by non‐breeding females being located in these situations. Both sexes roosted primarily in dead timber and used cavities where the narrowest dimension of the entrance was 2.5 cm. Most roosts of C. gouldii were in dead spouts on large, live river red gum Eucalyptus camaldulensis trees. Intraspecific differences in roost characteristics were less pronounced for this species. Despite access to the same roosting opportunities, there were marked differences in roost selection between N. geoffroyi and C. gouldii. Both species favoured large diameter trees, but differed significantly for all other measured variables: type of roost structure, condition of roost tree (live or dead), height of roost tree, height of roost, and entrance dimensions. Although these species are among the most widespread bats in Australia and are often considered to be habitat ‘generalists’, both displayed a high level of discrimination in the roosts used. Clearly, roosting requirements are a complex and important issue in the conservation of even the most common species of bats.

Location of roosts of the lesser long-eared bat Nyctophilus geoffroyi and Gould's wattled bat Chalinolobus gouldii in a fragmented landscape in south-eastern Australia

The location of roosts of two species of vespertilionid bats, the lesser long-eared bat ( Nyctophilus geoffroyi) and Gould’s wattled bat ( Chalinolobus gouldii), was investigated in a remnant vegetation-farmland mosaic and adjacent floodplain forest in south-eastern Australia. A total of 45 individuals of N. geoffroyi and 27 C. gouldii were fitted with radio transmitters, which resulted in the location of 139 and 89 roosts respectively. Selection of roosting habitat showed both inter- and intra-specific differences. At the landscape level, locations of roosts used by male and female N. geoffroyi differed markedly. Most males roosted in the farmland mosaic within 3 km (mean 1.9±2.9 km) of where they were captured while foraging in remnant vegetation. In contrast, roost sites of females were predominantly in the floodplain forest, 6–12 km from their capture site in farmland (mean for all females, 6.7±2.9 km). All maternity roosts were in the extensive floodplain forest, 4–10 km from foraging areas. Distances moved by this species were greater than previously recorded and further than predicted by flight morphology. Most C. gouldii roosted in the floodplain forest, 4–10 km from their capture site (6.9±1.6 km). Within the floodplain forest, both species roosted in areas that had higher densities of hollow-bearing trees than generally available; dead hollow-bearing trees for N. geoffroyi and large, live trees for C. gouldii. The scale of movements undertaken by these species means that they can obtain resources from multiple landscape elements. Both species used different habitats for roosting and foraging despite the energetic costs of commuting relatively large distances. Conservation of bat populations in rural environments needs to be considered at the landscape scale, with particular attention to identifying landscape elements that provide key resources.

Geographic variation in the echolocation calls of Gould's Wattled BatChalinolobus gouldii

To investigate potential geographic variation in the echolocation calls of Gould's Wattled Bat Chalinolobus gouldii, descriptive call parameters were examined from five regions throughout Australia. Analysis of these parameters revealed a number of significant differences between the regions, especially in variables related to frequency. However, discriminant function analysis revealed extensive overlap in call parameters for the different regions. It can be concluded that, although there are differences in some parameters between regions, calls are similar overall in the five geographic regions investigated, and that the slight geographic variation which does occur does not confound the identification of C. gouldii.

Bats in bird nests in Australia: a review

AbstractBats (Microchiroptera) utilize few types of bird nests as roosts. Ten species of bats (Molossidae and Vespertilionidae) were recorded roosting in the enclosed bottle‐shaped mud nests of the Fairy Martin Hirundo ariel; two species (Vespertilionidae) were located in the hanging nests of scrubwrens Sericornis spp. and the Brown Gerygone Gerygone mouki; two species (Vespertilionidae) in the enclosed plant material nests of the Grey‐crowned Babbler Pomatostomus temporalis and Fernwren Oreoscopus gutturalis; and one species (Emballonuridae) was recorded in the open cup‐shaped nest of the White‐rumped Swiftlet Collocalia spodiopygius. No information was available on the importance of bird nests as breeding sites and only one species, the Chocolate Wattled Bat Chalinolobus morio, has been recorded hibernating in a nest. Bird nests in Australia provide roosting habitat for four threatened bats and may be important to the conservation of these species.