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As development of wind energy facilities continues, questions of why fatalities of migrating insectivorous bats occur at turbines still remain. Numerous hypotheses have been proposed, including a feeding-attraction hypothesis that suggests bats may be attracted to insects congregating near turbine nacelles. To test this hypothesis, we analyzed echolocation calls of hoary (Lasiurus cinereus) and silver-haired (Lasionycteris noctivagans) bats recorded over 72 nights at a wind energy facility in Southern Alberta, Canada. We recorded calls at 3 heights: 67 m at turbine nacelles, 30 m at meteorological towers, and ground level at turbines and meteorological towers. We used feeding buzzes as indicators of foraging behavior. We compared the occurrence of feeding buzzes across heights, and between turbines and meteorological towers to test the prediction that if bats are attracted to turbines for foraging, there will be a greater proportion of feeding buzzes at turbines, and in particular, at nacelle height. We found no significant evidence that foraging rates were higher at nacelle height compared to 30 m or ground level, or between turbines and meteorological towers for either species. For silver-haired bats, foraging activity was greater at meteorological towers, and in particular, at 30 m height. These results do not support the feeding-attraction hypothesis for silver-haired or hoary bats, and suggest that while some bats forage in the vicinity of wind turbines, they are not specifically attracted to turbines to feed. [ABSTRACT FROM AUTHOR]

Trophic guilds are useful concepts for advancing our knowledge of trophic structure of communities, dynamics of species interactions, redundancy in ecosystem services, resilience to disturbances, response to climate change, conservation strategies, etc. For insectivorous bats, current literature suggests 8 trophic-related guilds. These include 3 guilds based on the openness of foraging areas, 3 based on the style of feeding, and 2 recently proposed subguilds among gleaners. Some gleaners are "passive," using densely cluttered vegetation in which echolocation is ineffective, and others are "actively" gleaning, using echolocation to procure prey. None of these guilds is based on the actual diets of bats. We analyzed 33 reports of diet composition representing 51 species of arthropod-feeding bats inhabiting North and Central America. We wanted to determine if the classical guild structure was concordant with the actual diets of bats and to compare guild structure in the Nearctic with that in the Neotropics. Discriminant function and principle component analyses generated 5 groups of genera based on the proportion of various arthropod taxa (mainly orders) in their diets. These groups were very different from classical guilds and showed almost no overlap among bat genera between the 2 continental regions. A similar analysis based on prey flying ability and hardness of their exoskeletons suggested 4 guilds that were more consistent with classical guild concepts, had higher rates of unambiguous guild assignment, and also showed major continental differences. Our results suggest a new arrangement of 4 guilds for arthropod-feeding bats in North and Central America that are based primarily on 2 features of their prey. New molecular techniques should allow us to build on this arrangement by significantly improving the taxonomic level of prey identification. [ABSTRACT FROM AUTHOR]

Intraspecific variability in echolocation calls could be an important factor hampering the accurate acoustic identification of species in the field. We studied variations in the echolocation behavior of Lasiurus varius in relation to habitat structure. Echolocation calls of L. varius reflected the degree of clutter present in its foraging areas. Bats foraging in an uncluttered habitat emitted longer and lower-bandwidth calls, with the lowest frequency values, whereas bats foraging in a cluttered habitat broadcast shorter and broadband signals, showing an increase in frequency content of their calls. Discriminant function analysis gave an overall classification of 76% of the calls emitted in the different flight situations. Our results highlight the need for independent recordings at each study area or habitat type to circumvent potential echolocation call variations, particularly in fragmented landscapes. [ABSTRACT FROM AUTHOR]

In this study we combine analyses of wing morphology, echolocation calls, and temporal and spatial activity patterns to explore mechanisms of ecological partitioning among 4 syntopic Antillean mormoopids (Pteronotus macleayii, P. parnellii, P. quadridens, and Mormoops blainvillei). We captured bats with mist nets and harp traps, and monitored bat activity using automated Anabat systems for 31 nights at Sierra del Rosario Biosphere Reserve in Cuba. The wing morphologies (very low wing-loading and average-aspect ratio) and echolocation calls (broadband steep frequency-modulated calls at high frequencies) of all 4 species suggest that Cuban mormoopids are adapted to slow maneuverable flight, adequate for hunting insects by slow aerial hawking in background-cluttered habitat. However, our data show that each species has a combination of wing and echolocation call characters, presumably reflecting differences in their foraging behavior and microhabitat use. All 4 species were present at the 3 sampling sites and a majority showed similar activity rates at each site. Thus, we did not find strong evidence of spatial segregation during foraging. However, overall activity levels were higher in the primary forest when compared with 2 secondary-growth forests. Most pair-wise comparisons of temporal activity patterns between species were significant, suggesting high levels of temporal segregation. Our data suggest that wing morphology, echolocation call structure, and temporal activity patterns are morphological and behavioral factors that could facilitate resource partitioning among the Cuban mormoopid bats. [ABSTRACT FROM AUTHOR]

Brazilian free-tailed bats (Tadarida brasiliensis) emerge from cave roosts in dense columns in which adjacent bats are separated by only small distances. We describe and quantify variation in the structure of echolocation calls produced by these emerging bats and determine if call structure changes in relation to the rate of emergence measured using thermal infrared imaging. We recorded emergence calls at 2 roosts, 1 housing approximately 200,000 bats and the other approximately 17,000 bats. We found that Brazilian free-tailed bats emit distinct frequency-modulated (FMstart) and constant frequency (CFstart) calls during emergence that are significantly different from echolocation calls they emit while foraging. We propose that these calls provide different information for orientation within the emergence column. CFstart calls are very similar to social calls used by Brazilian free-tailed bats, suggesting 2 potential functions for this call type. The structure of both the FMstart and CFstart calls were not related to the number of bats emerging from a roost, although significant structural differences existed between sites. The differences between sites could be associated with the spacing of bats during emergence, because bats appeared to form tighter columns at the larger roost colony compared to the smaller colony. [ABSTRACT FROM AUTHOR]

Occupancy analysis and its ability to account for differential detection probabilities is important for studies in which detecting echolocation calls is used as a measure of bat occurrence and activity. We examined the feasibility of remotely acquiring bat encounter histories to estimate detection probability and occupancy. We used echolocation detectors coupled to digital recorders operating at a series of proximate sites on consecutive nights in 2 trial surveys for the Hawaiian hoary bat (Lasiurus cinereus semotus). Our results confirmed that the technique is readily amenable for use in occupancy analysis. We also conducted a simulation exercise to assess the effects of sampling effort on parameter estimation. The results indicated that the precision and bias of parameter estimation were often more influenced by the number of sites sampled than number of visits. Acceptable accuracy often was not attained until at least 15 sites or 15 visits were used to estimate detection probability and occupancy. The method has significant potential for use in monitoring trends in bat activity and in comparative studies of habitat use. [ABSTRACT FROM AUTHOR]

Most previous studies considering intraspecific differences in bat echolocation call frequency among geographic groups have related this to morphological features not directly involved in producing the characteristics of the emitted signal. We related a pattern of intraspecific call differences to the size of nasal chambers (estimated from radiographs of museum specimens), expecting chamber dimensions to be functionally coupled with the sound source. Such a relationship is potentially informative in the context of competing hypotheses that account tot call frequency differences. Allopatry has been a precursor to differences in echolocation call frequency between isolated populations of the Australian endemic orange leaf-nosed bat (Rhinonicteris aurantia (Gray, 1845); Pilbara isolate: 120.9 ± 1.91 kHz; compared with Kimberley region: 114.65 ± 1.98 kHz and Northern Territory: 114.62 ± 2.10 kHz). Correlations with morphological features not directly involved in signal production or modification were either moderate (nose-leaf width) or absent (forearm length). Overall nasal volume was shown to be relatively smaller in the Pilbara population, which had higher average call frequency. This relationship was expected given the suggested function of nasal chambers in impedance matching. The finding is significant because nasal chamber size was the only character observed to vary in a species that was otherwise conserved morphologically, suggesting adaptation and not a simple scaling relationship with body size that might be more indicative of drift. We consider that the combination of patterns from echolocation call frequency and associated morphological features, as well as neutral DNA markers, provide adequate support for recognition of the separate populations of R. aurantia for conservation, according to more recent concepts that consider ecological as well as genetic characters when allocating groups to evolutionarily significant units. [ABSTRACT FROM AUTHOR]

Echolocation calls emitted by the 4 species of Cuban mormoopid bats were compared to determine vocal signatures that enable identification of each species in the field during their evening exodus. Echolocation calls produced by Mormoops blainvilli are downward frequency-modulated (FM) signals in the range of 68.4-52.5 kHz. Echolocation calls emitted by Pteronotus macleayii and P. quadridens have a similar design consisting of a short constant-frequency (CF) segment followed by a downward FM segment. The CF segment was at 70.0 kHz in calls from P. macleayii, and at 83.3 kHz in calls from P. quadridens. Echolocation calls from P. parnellii consist of a long CF segment, which is preceded by a short initial upward sweep and followed by a downward FM terminal sweep. The CF value of the 2nd harmonic was a good parameter for species identification. The features of the echolocation calls of each of the species were used to identify them during the evening exodus from 2 Cuban caves. [ABSTRACT FROM AUTHOR]

In recent years many cryptic bat species have been unmasked by differences in their echolocation calls. The yellow house bat (Scotophilus dinganii) is 1 of 3 species of Scotophilus currently described in southern Africa and is distinguished from the other 2 species by its size and yellow venter. Here we use genetic, morphological, and echolocation call data to show the existence of a cryptic species. We found that S. dinganii consists of 2 forms, one that uses a peak echolocation frequency of 44 kHz and the other a peak frequency of 33 kHz. Both forms have yellow venters. The 44-kHz phonic type is up to 15% smaller than the 33-kHz phonic type and differed genetically by an average cytochrome-b (Cytb) sequence divergence of 3.3%. Furthermore, combined phylogenetic analyses of Cytb and control region sequences indicate that the 2 phonic types are reciprocally monophyletic, suggesting that they are sibling species. [ABSTRACT FROM AUTHOR]

The structure of echolocation calls, and the distance over which bats perceive their environment, varies with the amount of structural clutter through which they are flying. Clutter and species had significant effects on the frequency-time characteristics of search-phase echolocation calls of northern long-eared (Myotis septentrionalis) and little brown bats (M. launchings). We tested an a priori derived model that predicted the pattern of differences in echolocation call variable values among clutter categories would provide insight into the relative maximum distances that bat species could perceive using echolocation. Specifically, the model predicted that species adapted to flying and foraging in cluttered habitats would have a shorter maximum perceptual distance than species adapted to flying and foraging in uncluttered habitats. The results supported this model and suggest the clutter-adapted M. septentrionalis had a shorter maximum perceptual distance than M. lucifugus, a species known to forage in a variety of habitats but mainly in uncluttered areas (i.e., over water). Using calls as the sampling unit, a neural network correctly classified >94% of the echolocation calls to species in high clutter. In medium and low clutter, >82% of the calls were correctly classified to species; however >90% correct classification was achieved by leaving >30% of calls unclassified. Researchers should develop clutter-specific call libraries to improve species classification accuracy for echolocation calls. [ABSTRACT FROM AUTHOR]

We have studied the effect of habitat and presence of conspecifics on echolocation characteristics of the emballonurid bat Balantiopteryx plicata. Calls during the search phase only showed differences between habitats in bandwidth, as has been found for other open-space bats. Characteristics of calls during the approach phase did change when bats entered open areas. Calls in the terminal phase showed no differences in the characters examined between habitats. Bats flying in groups shifted their peak frequency significantly, which maximized differences between individuals. These results are interpreted as an active mechanism of jamming avoidance. Bats flying in groups also tended to increase the mean of peak frequencies. [ABSTRACT FROM AUTHOR]

Echolocation calls were recorded from Pteronotus quadridens flying in the field and in an enclosed space. In the field, search calls contained 1 or 2 harmonics. Patterns of call design show a segment of quasi--constant frequency (QCF2nd-hamonic at 81-84 kHz), followed by a downward frequency-modulated (FM) component. The 2nd harmonic was always more intense than the 1st. Search, approach, and terminal phases of calls were described during hunting sequences of P. quadridens. The transition between call phases was characterized by monotonic variations in some acoustic parameters, including a decrease in call duration and an increase in repetition rate, bandwidth, and slope of the FM component. We also analyzed calls emitted by bats flying in confined spaces that consistently contained 3 harmonics, of which the 2nd harmonic contained the greatest energy. The values of call duration were shorter and bandwidth was higher than values characterizing calls emitted during the search phase in the field. [ABSTRACT FROM AUTHOR]

Presents a study which described designs of echolocation signals in aerial-hawking insectivorous bats from Malaysia. Materials and methods; Results; Discussion.

Describes field recordings of echolocation calls of the neotropical emballonurid sac winged bats Balantiopteryx (B.) plicata, B. io and B. infusca. Effects of body size on echolocation parameters; Interspecific variation in aspects of echolocation; Reason for the skewness in distribution of pulse interval.

Deals with a study that investigated the postnatal development of vocalizations and hearing in the phyllostomid bat. Information on the two types of isolation calls for young bats; Auditory range during postnatal development; Characterization of the echolocation calls of bats.

Presents a study which compared the measurable features of the echolocation calls of bats as recorded by two bat-detecting systems. Background information on the mammals; Materials and methods used; Findings and discussion.

Presents a study which examined levels of intraspecific variation in search-phase echolocation calls of bats. Materials and methods used; Findings and discussion.

Features a study which explored the ability to discriminate between echolocation calls of adult and juvenile big brown bats (Eptesicus fuscus). Differences in the variation in the echolocation calls of bats; Materials and methods; Results.

Presents a study which examined the advantages and disadvantages of techniques that transform and analyze echolocation calls of bats. Materials and methods; Results and discussion; Conclusions.

Presents a study on echolocation signals broadcast by free-flying naked-backed bats (Pteronotus davyi) from Panama. Materials and methods; Results; Discussion.

Presents a study on the echolocation behavior in the Cuban subspecies of Molossus molossus to investigate how search calls might be adapted to match the bat's hearing capabilities and optimize chance of detecting an insect. Materials and methods; Results; Discussion.

Contends the reliability of acoustic identification of species of bats using the qualitative approach. Points raised on the paper of Barclay (1999); Need for recognition of limitation in equipment and methods used; Suggestions forwarded.

Criticizes the qualitative approach of monitoring and acoustic identification of echolocation calls for identification of species of bats in the field. Intraspecific variation in bat echolocation calls; Limitations of equipment and methods; Guidelines for use of the method in field studies.

Focuses on a study on the identification of species of free-flying bats using the Titley Electronics Anabat II ultrasonic detector. Qualitative procedure and structural characteristics; Analysis of the echolocation calls of bats; Features of Anabat II.

Studies echolocation calls of bats over two streams in the Oregon Coast Range using Anabat II detectors. Correlation of the activity of bats with biomass of insects and minimum nightly temperature; Negative correlation of activity of bats with length of night; Implications of temporal variation in activity of bats on sampling.

Uses monitoring of echolocation calls to assess levels of activity of bats at altitudes less than or equal to 600 meters at a field site in Zimbabwe. Activity of echolocating bats at different altitudes shown as numbers of species encountered with the most energy in different bandwidths.

Presents the conservation implications of some recent findings about the ecology and behavior of bats, notably patterns of habitat use, foraging, and roosting. Utilization of echolocation method to capture the sounds that bats produce; Description of the patterns of bats' habitat use; Bats' food and feeding habits; Activities by humans and bats; Impact of perceptions of bats by humans.