@article {58051, title = {Qualitative Identification of Free-flying Bats Using the Anabat Detector}, journal = {Journal of MammalogyJournal of Mammalogy}, volume = {80}, number = {1}, year = {1999}, note = {JRS}, pages = {11-23}, abstract = {

A variety of ultrasonic bat detectors have been used over the past 3 decades to identify freeflying bats. Analyses of recorded echolocation calls were slow and typically restricted to few calls and at a resolution obscuring details of call structure. The Anabat II detector and associated zerocrossings analysis system allows an immediate examination, via a laptop computer, of the timefrequency structure of calls as they are detected. These calls can be stored on the hard drive for later examination, editing, and measurement. Many North American bats can be identified to species by qualitatively using certain structural characteristics of calls, primarily approximate maximum and minimum frequencies and morphological aspects of calls e.g., linearity and changes in slope). To identify calls precisely, it is important to use a continuous sequence of calls from an individual in normal flight rather than from single isolated calls. All calls are not equally useful, and many fragmentary calls must be discarded before making a determination. Each sequence of calls must be examined to ensure that multiple bats have not been simultaneously recorded, which confounds correct identification. We found the percentage of nonusable calls within usable vocal sequences to be highest in vespertilionids 20-40\%), whereas for other families this was frequently \<10\%. Active rather than passive collection of data maximizes quality and quantity of diagnostic calls and provides a contextual base for the investigator.

}, keywords = {Anabat, bats, Chiroptera, echolocation, Eptesicus furinalis, identification, Lasionycteris noctivagans, Lasiurus cinereus, Lasiurus ega, Molossus ater, Molossus molossus, Molossus sinaloae, Myotis californicus, Myotis ciliolabrum, Myotis yumanensis, Noctilio leporinus, Saccopteryx bilineata, Tadarida brasiliensis, technique, vocal signatures}, author = {O{\textquoteright}Farrell, Michael J. and Miller, Bruce W. and Gannon, William L.} } @article {57914, title = {Molossid unlimited: extraordinary extension of range and unusual vocalization patterns of the bat, Promops centralisAbstract}, year = {2019}, abstract = {

The big crested mastiff bat, Promops centralis, occurs in Central and South America, but knowledge of its ecology is limited due to its open space hunting strategy, making captures extremely challenging. Notwithstanding, members of the species produce echolocation calls that are easy to identify. After recording calls of P. centralis 1,500 km away from its known range in Brazil, we hypothesized that the distribution range of this species was probably greatly underestimated. To improve the accuracy of P. centralis\’ real distribution, we employed acoustic surveys throughout parts of Brazil, conducted after a bibliographic review to gather additional records, and used MaxEnt to model the species\’ potential distribution. We have found that P. centralis has a much wider distribution in South America than previously thought, adding more than 3.8 million km2 to its former known area. We also describe an unusual vocalization pattern of P. centralis, with individuals emitting at least three very distinct but highly variable calls. This study shows that bioacoustic surveys and species distribution models can complement traditional methodologies in studying species that are difficult to capture, such as P. centralis, potentially contributing to more effective conservation and management plans.

}, keywords = {big crested mastiff bat, Chiroptera, duty cycle, echolocation calls, frequency, MaxEnt, Molossidae, Social calls, species distribution modeling, vocalizations}, doi = {10.1093/jmammal/gyz167}, url = {https://academic.oup.com/jmammal/advance-article/doi/10.1093/jmammal/gyz167/5637356}, author = {Hintze, Frederico and Arias-Aguilar, Adriana and Dias-Silva, Leonardo and Delgado-Jaramillo, Mariana and Silva, Carina Rodrigues and Juc{\'a}, Thays and Mischiatti, Francyne Lyrio and Almeida, M{\'a}rcio and Bezerra, Bruna and Aguiar, Ludmilla M S and Ramos Pereira, Maria Jo{\~a}o and Bernard, Enrico}, editor = {Loeb, Susan} } @article {53540, title = {Noise as an informational cue for decision-making: the sound of rain delays bat emergence}, journal = {The Journal of Experimental Biology}, year = {2019}, month = {Sep-01-2020}, pages = {jeb.192005}, abstract = {

Background noise can have strong negative consequences on animals, reducing individual fitness by masking communication signals, impeding prey detection and increasing predation risk. While the negative impacts of noise across taxa have been well documented, the use of noise as an informational cue, providing animals with reliable information on environmental conditions has been less well studied. In the tropical rainforest, downpours can be intense and frequent. Strong rainfall may impede efficient orientation and foraging for bats that need echolocation to both navigate and detect prey, and can result in higher flight costs due to increased metabolic rates. Using playback experiments at natural roosts we tested whether two bat species, differing in their hunting strategies and foraging habitats, use rain noise as a cue to delay emergence from their roosts. We found that both species significantly delayed their emergence time during rain noise playbacks compared to silence and ambient noise controls. We conclude that bats can use background noise, here the acoustic component of rainfall, as a reliable informational cue to make informed decisions, here about whether to initiate foraging trips or remain in the shelter of their roosts. Our findings suggest that environmental background noise can sometimes be beneficial to animals, in particular in situations where other sensory cues may be absent.

}, keywords = {bats, decision-making, foraging, information cues, Noise, rain}, issn = {0022-0949}, doi = {10.1242/jeb.192005}, url = {http://jeb.biologists.org/lookup/doi/10.1242/jeb.192005https://syndication.highwire.org/content/doi/10.1242/jeb.192005https://syndication.highwire.org/content/doi/10.1242/jeb.192005}, author = {Geipel, Inga and Smeekes, Marcus J. and Halfwerk, Wouter and Rachel A. Page} } @article {53509, title = {Groups of bats improve sonar efficiency through mutual suppression of pulse emissions}, journal = {Frontiers in Physiology}, volume = {4}, year = {2013}, month = {Jan-01-2013}, abstract = {

How bats adapt their sonar behavior to accommodate the noisiness of a crowded day roost is a mystery. Some bats change their pulse acoustics to enhance the distinction between theirs and another bat\&$\#$39;s echoes, but additional mechanisms are needed to explain the bat sonar system\&$\#$39;s exceptional resilience to jamming by conspecifics. Variable pulse repetition rate strategies offer one potential solution to this dynamic problem, but precisely how changes in pulse rate could improve sonar performance in social settings is unclear. Here we show that bats decrease their emission rates as population density increases, following a pattern that reflects a cumulative mutual suppression of each other\&$\#$39;s pulse emissions. Playback of artificially-generated echolocation pulses similarly slowed emission rates, demonstrating that suppression was mediated by hearing the pulses of other bats. Slower emission rates did not support an antiphonal emission strategy but did reduce the relative proportion of emitted pulses that overlapped with another bat\&$\#$39;s emissions, reducing the relative rate of mutual interference. The prevalence of acoustic interferences occurring amongst bats was empirically determined to be a linear function of population density and mean emission rates. Consequently as group size increased, small reductions in emission rates spread across the group partially mitigated the increase in interference rate. Drawing on lessons learned from communications networking theory we show how modest decreases in pulse emission rates can significantly increase the net information throughput of the shared acoustic space, thereby improving sonar efficiency for all individuals in a group. We propose that an automated acoustic suppression of pulse emissions triggered by bats hearing each other\&$\#$39;s emissions dynamically optimizes sonar efficiency for the entire group.

}, doi = {10.3389/fphys.2013.00140}, url = {http://journal.frontiersin.org/article/10.3389/fphys.2013.00140/abstract}, author = {Jarvis, Jenna and Jackson, William and Smotherman, Michael} } @article {53068, title = {The acoustic gymnastics of the dwarf dog-faced bat (Molossops temminckii) in environments with different degrees of clutter}, journal = {Journal of Mammalogy}, volume = {99}, year = {2018}, month = {Nov-29-2018}, pages = {965 - 973}, abstract = {

Molossops temminckii is the only species of the Molossidae capable of exploring background-cluttered space. We tested the hypothesis that M. temminckii uses the clutter rejection strategy in cluttered environments and determined whether the echolocation calls of this species show large-scale geographic variation. We recorded echolocation calls of 10 individuals of M. temminckii using 4 treatments with different degrees of clutter. We compared individuals recorded in Venezuela with individuals recorded in Brazil to verify geographic variation in calls. In the cluttered environments, M. temminckii emitted short downward frequency-modulated calls with short pulse intervals. In the uncluttered environments, M. temminckii emitted long upward frequency-modulated calls with longer intervals and shorter bandwidth. The decreased pulse duration and interval in cluttered environments support the hypothesis that M. temminckii uses the clutter rejection strategy. Additionally, we found that in Brazil, M. temminckii emits shorter calls with higher minimum frequency compared with bats recorded in Venezuela, indicating large-scale geographic variation, probably because of environmental factors.

}, keywords = {bat echolocation, Brazil, Cerrado, Molossidae, vocal plasticity, vocal repertoire}, issn = {0022-2372}, doi = {10.1093/jmammal/gyy070}, url = {https://academic.oup.com/jmammal/article/99/4/965/5071805}, author = {Oliveira, Thiago F and Ramalho, Daniel F and Mora, Emanuel C and Aguiar, Ludmilla M S} } @article {15200, title = {Echolocation and body size in insectivorous bats: the case of the giant naked bat Cheiromeles torquatus (Molossidae)}, journal = {Le Rhinolophe}, volume = {11}, year = {1996}, pages = {27{\textendash}38}, abstract = {

Recent hypotheses propose that the maximum size of aerial insectivorous bats is limited by properties of their echolocation system. According to these hypotheses large bats would (A) have to use low call frequencies which may only allow the detection of large prey. However, large prey may be too scarce to meet a large bat\’s energy requirements. Large bats would (B) have low wing beat frequencies and due to energetic reasons also low call repetition rates. These low call repetition rates, however, many not be sufficient for prey detection. Both hypotheses were tested by analysing the echolocation behaviour of Cheiromeles torquatus (150-200g), the largest aerial insectivorous bat.

Cheriomeles searches for prey by alternating calls with the lowest frequencies at 20 and 28 kHz (call duration 30 and 24 ms respectively) at a repetition rate of 6.3Hz, and a duty cycle of 18\%. The data are discussed in relation to the foraging behaviour of Cheiromeles.

The call parameters of Cheiromeles are far removed from predictions made in both models When the data of Cheiromeles and some other large bats are included in an allometric version of model (A) the prediction of the model changes distinctly indicating that call frequency might only be a weak constraint on body size, if at all. Call repetition rate seems to be correlated to call frequency and not directly to body size as is assumed in model (B). In nay case, large bats have lower call repetition rates than wing beat rates and the difference increases with body size. Therefore other factors have to be sought to explain the size distribution of aerial insectivorous bats.

}, url = {https://www.researchgate.net/profile/Klaus-Gerhard_Heller/publication/257655672_Echolocation_and_body_size_in_insectivorous_bats_the_case_of_the_giant_naked_bat_Cheiromeles_torquatus_(Molossidae)/links/0deec52b5d412785f3000000.pdf}, author = {Klaus-Gerhard Heller} }