Academic literature on the topic 'Nyctophilus'

The sensory abilities of two species of long-eared bats were studied in captivity. Prey location trials demonstrated that Nyctophilus spp. may employ a diverse array of sensory cues, including use of prey sounds, vision and echolocation. Insects were readily captured from substrates, confirming the hypothesis that Nyctophilus can feed by gleaning, but flying insects were taken with equal ease, showing that these bats are flexible not only in their sensory behaviour but also in their mode of prey capture. Echolocation was not used for orientation except when in an unfamiliar environment, and even then was 'switched off' on approaching fluttering prey. Nyctophilus used prey sounds to capture flying insects as well as those on substrates, a feeding technique not previously reported for gleaners. Visual cues were used to capture insects from the air, but not from substrates. This mode of feeding is an effective replacement for echolocation, including the 'feeding buzz', and thereby circumvents the evasive responses of sonar-sensitive insects.

The ultrasound calls of the six species of Nyctophilus bat in Western Australia can be differentiated using power spectral analysis. Their search-mode call sequences show distinctive trends of variation in peak-frequency (Fpeak) values call-to-call. These differences are too subtle to be separated in amplitude-time domain with the processing tools currently available. The call-to-call variations in Fpeak through time can be characterised from the call sequence recordings using Fourier analysis if care is taken to select genuine search-mode sequences. These variations can then be used to correctly identify the species emitting the call.

AbstractTrypanosomes are blood-borne parasites that can infect a variety of different vertebrates, including animals and humans. This study aims to broaden scientific knowledge about the presence and biodiversity of trypanosomes in Australian bats. Molecular and morphological analysis was performed on 86 blood samples collected from seven different species of microbats in Western Australia. Phylogenetic analysis on 18S rDNA and glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) sequences identified Trypanosoma dionisii in five different Australian native species of microbats; Chalinolobus gouldii, Chalinolobus morio, Nyctophilus geoffroyi, Nyctophilus major and Scotorepens balstoni. In addition, two novels, genetically distinct T. dionisii genotypes were detected and named T. dionisii genotype Aus 1 and T. dionisii genotype Aus 2. Genotype Aus 2 was the most prevalent and infected 20.9% (18/86) of bats in the present study, while genotype Aus 1 was less prevalent and was identified in 5.8% (5/86) of Australian bats. Morphological analysis was conducted on trypomastigotes identified in blood films, with morphological parameters consistent with trypanosome species in the subgenus Schizotrypanum. This is the first report of T. dionisii in Australia and in Australian native bats, which further contributes to the global distribution of this cosmopolitan bat trypanosome.

The purpose of this study was to measure microhabitat use by light-tagged foraging Nyctophilus geoffroyi and Nyctophilus gouldi, two at-least-partly sympatric species of Australian microchiropteran long-eared bats. We tested the hypothesis that because of their similar wing morphology (low wing loading and aspect ratio) and echolocation-call design (high-frequency, frequency-modulation calls), the two species’ choice of foraging microhabitat should be similar. Our results showed that, typically, individuals of both species flew relatively slowly in large circles approximately 2–5 m above the ground and below the canopy but amongst the trunks of forest trees, with some individuals occasionally flying amongst smaller branches and the vegetation of the forest canopy. We found no statistical difference in the proportion of time spent in different forest microhabitats by individuals of the two species. Furthermore, on only one occasion did we observe a bat land on the ground to forage, despite the fact that both species are described in the literature as substrate gleaners. We also found no evidence for any change in habitat use with changing lunar condition. Our data support ecomorphological predictions generated from simple measurements of wing form and lend credence to the notion that, at least in some circumstances, measurements of wing morphology alone can be a useful indicator of the ecology of similar bat species.

A new species of Nyctophilus is described on the basis of three specimens from the hinterland of Noum�a, New Caledonia. Comparisons are made with a large series of the most similar species, N. gouldi and N. bifax from eastern Australia, from which it differs on external, cranial, dental and penile morphology. The new species most resembles N. gouldi and its affinities appear to lie within the Australian fauna. An IUCN threat category of ?Vulnerable? is suggested due to a localised distribution in threatened high elevation rainforest.

Context Tree cavities suitable to rear young are a key resource in managed landscapes to support viable populations of tree cavity-roosting bats. Little is known about the selection of cavities for maternity roosts, presumably because of the difficulty in accessing such roosts. Aims Our study investigated physical and microclimate characteristics of maternity roosts of two species, namely, Gould’s long-eared bat (Nyctophilus gouldi) and little forest bat (Vespadelus vulturnus). Methods Maternity-roost cavities were identified in a timber-production landscape in south-eastern Australia. Roost trees (V. vulturnus n=5; N. gouldi n=9) and a subsample of available cavity-bearing trees (n=16) were climbed to obtain cavity characteristics. Key results Vespadelus vulturnus used tree hollows exclusively, whereas N. gouldi used both tree hollows (n=7) and thick loose bark (n=2). No significant difference in roost-cavity characteristics was detected between the species. However, V. vulturnus selected significantly narrower cavity entrances (mean: 16±3mm) than those of the available cavities. Temperature did not differ between maternity roosts and available cavities when investigated after the maternity season. However, a V. vulturnus maternity roost occupied for 33 consecutive days was warmer than mean roost and available cavities, suggesting that long-term roost use may be influenced by the thermal property of a cavity. Conclusions Our study has provided the first detailed tree-cavity description of maternity roosts of N. gouldi and V. vulturnus. The nightly roost switching and the large variation of tree-cavity characteristics used by N. gouldi suggest that this species requires a high density of non-specific tree cavities that are large enough for colony formation, whereas preferred roost cavities for V. vulturnus are likely to be hollows comprising narrow entrances that facilitate long-term use. Implications Our results highlighted the likely importance of narrow roost entrances for V. vulturnus, presumably for predator protection, and the conservation of tree cavities large enough for colonies to congregate. The formation of such hollows is likely to take many decades. Poor silvicultural practices, land clearing and inappropriate management of veteran trees have the potential to have an impact on this hollow resource. Our study also highlighted the need to further assess the importance of cavity microclimate for maternity-roost selection in warm climates.

Habitat fragmentation represents one of the greatest threats to biodiversity, yet for the second largest mammalian order Chiroptera we have only just begun to assess the impacts of this threatening process on population connectivity and genetic diversity. Many aspects of chiropteran ecology remain unknown due to their cryptic lifestyle and difficulties in applying traditional observational and field-based techniques. At the time of this PhD project‘s conception there were no published studies utilising genetic techniques to address the influence of habitat fragmentation on any chiropteran species. Since that time two studies have been published, in 2009 and 2011. I add to this new body of literature by conducting genetic analyses to assess population connectivity and genetic diversity in two congeneric vespertilionids, Nyctophilus gouldi and N. geoffroyi. The study was conducted in western Victoria and south-eastern South Australia across a landscape comprising continuous and fragmented regions of native habitat. Populations within continuous forest provided a benchmark for parameters including gene flow, genetic diversity and social structure, for comparison with forest fragments. This thesis also capitalises on the underutilised potential of molecular techniques for the study of chiropterans. I applied molecular approaches to assess dispersal strategies and social structure in both species offering novel ecological insights. Four data chapters covering these topics are outlined below. Chapter 2 describes the isolation and characterisation of 16 microsatellite markers developed to facilitate this research. I utilised next generation sequencing technology (454) to generate a microsatellite DNA library and employed Multiplex Ready Technology (MRT) as a flexible and cost effective method to test primers and design marker panels for screening. DNA was isolated from N. gouldi resulting in 15 loci, while cross amplification in N. geoffroyi produced 7 reliable loci. Chapter 3 addresses the impact of habitat fragmentation on the forest and woodland specialist N. gouldi, which is listed as endangered in South Australia. Based on roosting requirements, rarity in the agricultural landscape and limited dispersal ability I predicted that N. gouldi populations would display reduced gene flow and signs of isolation as a result of habitat fragmentation. This prediction was confirmed by my analyses which identified reduced population connectivity, decreased genetic diversity, elevated measures of relatedness and inbreeding, and altered demography within fragmented populations isolated by ≥27km of agricultural land. Agricultural distances <2km did not influence population connectivity providing a benchmark for habitat restoration to improve connectivity and mitigate population isolation in this species. Management recommendations include the enhancement of population connectivity between threatened SA populations, and recognition of a unique Management Unit at the Grampians National Park. The forth chapter investigates the influence of habitat fragmentation on N. geoffroyi for comparison with N. gouldi. In contrast to N. gouldi, N. geoffroyi is a habitat generalist that occupies a diverse range of ecosystems and which is commonly recorded within agricultural landscapes. N. geoffroyi‘s presence in modified habitat coupled with plastic ecology and roosting requirements led to the prediction that the species would display limited impacts from habitat fragmentation. My analyses again confirmed this prediction with N. geoffroyi displaying virtually no response to habitat fragmentation and a panmictic population structure across the study region. The comparison between N. geoffroyi and N. gouldi provided an opportunity to test the merit of several proposed predictors of bat vulnerability to habitat fragmentation, in particular wing morphology, matrix tolerance, specialisation and geographic range. The much touted predictor wing morphology failed to predict differing responses from the two species while the following three predictors listed above received further support from this study. I conclude that wing morphology may still be a useful predictor of bat vulnerability to habitat fragmentation when coupled with other indicators such as matrix tolerance and habitat specialisation. The fifth and final data chapter utilises molecular analyses to assess several previously unknown aspects of N. gouldi and N. geoffroyi ecology, dispersal strategies, mating systems and social structure. N. gouldi displayed patterns consistent with female natal philopatry, male biased dispersal and a polygynous mating system, while no such evidence was found for N. geoffroyi. Results for N. geoffroyi may have been influenced by larger population sizes which, coupled with higher dispersal rates, may have masked any evidence of sex-biased dispersal. Both species displayed significant numbers of relatives at the population level, with N. gouldi displaying particularly high levels of related females. N. geoffroyi displayed higher numbers of relatives at the roost level indicating that kin selection may play an important role in social structure and cooperative roosting. Despite significant numbers of related N. geoffroyi at the roost level, the vast majority of pairwise comparisons indicated no relationship between individuals suggesting that the dominant driver of sociality and cooperative behaviour may not be solely based on relatedness. Nevertheless, high incidence of related females at the population level for N. gouldi, and at the roost level for N. geoffroyi, suggests that the bonds between related females are an important aspect of Nyctophilus behavioural ecology and social structure.
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2013