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1. Sensorimotor Integration in the Biosonar System of Horseshoe Bats

   Sutlive, Joseph; Riquimaroux, Hiroshi; Mueller, Rolf (November 2017, Society for Neuroscience symposia)

   Bats have evolved unique methods of perception to navigate and catch prey using ultrasonic sounds. It has been observed that the greater horseshoe bat (Rhinolophus ferrumequinum) rapidly move their pinna and noseleaf structures in coordination with pulse emission and echo reception during echolocation, with everything occurring on a 100ms time scale. Sensorimotor integration is not uncommon in neural systems but bats provide a unique case for auditory processing coinciding motion in the periphery. We have developed biomimetic robotic models to replicate the dynamic emission and reception elements of bat echolocation; current data have shown these dynamics introduce time-variant effects which encode information to inform object identification and location. We have planned experiments to understand how motor and auditory systems are integrated, which will be done by recording midbrain responses interacting with stimuli. These recordings will consist of field potential measurements taken from the inferior and superior colliculi; we hope this work will provide physiological events associated with sensorimotor integration for echolocation. 

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2. Ecomorphology and sensory biology of bats

   https://doi.org/10.1002/ar.25314  

   Smith, Timothy D; Santana, Sharlene E; Eiting, Thomas P (November 2023, The Anatomical Record)

   Abstract This special issue of The Anatomical Record is inspired by and dedicated to Professor Kunwar P. Bhatnagar, whose lifelong interests in biology, and long career studying bats, inspired many and advanced our knowledge of the world's only flying mammals. The 15 articles included here represent a broad range of investigators, treading topics familiar to Prof. Bhatnagar, who was interested in seemingly every aspect of bat biology. Key topics include broad themes of bat development, sensory systems, and specializations related to flight and diet. These articles paint a complex picture of the fascinating adaptations of bats, such as rapid fore limb development, ear morphologies relating to echolocation, and other enhanced senses that allow bats to exploit niches in virtually every part of the world. In this introduction, we integrate and contextualize these articles within the broader story of bat ecomorphology, providing an overview of each of the key themes noted above. This special issue will serve as a springboard for future studies both in bat biology and in the broader world of mammalian comparative anatomy and ecomorphology. 

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3. The evolution of sanguivory in vampire bats: origins and convergences

   https://doi.org/10.1139/cjz-2022-0115  

   Riskin, Daniel K.; Carter, Gerald G. (April 2023, Canadian Journal of Zoology)

   Blood-feeding (sanguivory) has evolved more than two dozen times among birds, fishes, insects, arachnids, molluscs, crustaceans, and annelids; however, among mammals, it is restricted to the vampire bats. Here, the authors revisit the question of how it evolved in that group. Evidence to date suggests that the ancestors of phyllostomids were insectivorous, and that carnivory, omnivory, and nectarivory evolved among phyllostomids after vampire bats diverged. Frugivory likely also evolved after vampire bats diverged, but the phylogeny is ambiguous on that point. However, vampire bats lack any genetic evidence of a frugivorous past, and the behavioural progression from frugivory to sanguivory is difficult to envision. Thus, the most parsimonious scenario is that sanguivory evolved in an insectivorous ancestor to vampire bats via ectoparasite-eating, wound-feeding, or some combination of the two—all feeding habits found among blood-feeding birds today. Comparing vampire bats with other sanguivores, the authors find several remarkable examples of convergence. Further, it was found that blood-feeding has been ca. 50 times more likely to evolve in a vertebrate lineage than in an invertebrate one. The authors hypothesize that this difference exists because vertebrates are more likely than invertebrates to have the biochemical necessities required to assimilate the components of vertebrate blood. 

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4. Noise distracts foraging bats

   https://doi.org/10.1098/rspb.2020.2689  

   Allen, Louise C.; Hristov, Nickolay I.; Rubin, Juliette J.; Lightsey, Joseph T.; Barber, Jesse R. (February 2021, Proceedings of the Royal Society B: Biological Sciences)

   null (Ed.)

   Predators frequently must detect and localize their prey in challenging environments. Noisy environments have been prevalent across the evolutionary history of predator–prey relationships, but now with increasing anthropogenic activities noise is becoming a more prominent feature of many landscapes. Here, we use the gleaning pallid bat, Antrozous pallidus , to investigate the mechanism by which noise disrupts hunting behaviour. Noise can primarily function to mask —obscure by spectrally overlapping a cue of interest, or distract —occupy an animal's attentional or other cognitive resources. Using band-limited white noise treatments that either overlapped the frequencies of a prey cue or did not overlap this cue, we find evidence that distraction is a primary driver of reduced hunting efficacy in an acoustically mediated predator. Under exposure to both noise types successful prey localization declined by half, search time nearly tripled, and bats used 25% more sonar pulses than when hunting in ambient conditions. Overall, the pallid bat does not seem capable of compensating for environmental noise. These findings have implications for mitigation strategies, specifically the importance of reducing sources of noise on the landscape rather than attempting to reduce the bandwidth of anthropogenic noise. 

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5. Habituation of common vampire bats to biologgers

   https://doi.org/10.1098/rsos.211249  

   Kline, Emma; Ripperger, Simon P.; Carter, Gerald G. (December 2021, Royal Society Open Science)

   Rapid advancements in biologging technology have led to unprecedented insights into animal behaviour, but testing the effects of biologgers on tagged animals is necessary for both scientific and ethical reasons. Here, we measured how quickly 13 wild-caught and captively isolated common vampire bats ( Desmodus rotundus ) habituated to mock proximity sensors glued to their dorsal fur. To assess habituation, we scored video-recorded behaviours every minute from 18.00 to 06.00 for 3 days, then compared the rates of grooming directed to the sensor tag versus to their own body. During the first hour, the mean tag-grooming rate declined dramatically from 53% of sampled time (95% CI = 36–65%, n = 6) to 16% (8–24%, n = 9), and down to 4% by hour 5 (1–6%, n = 13), while grooming of the bat's own body did not decline. When tags are firmly attached, isolated individual vampire bats mostly habituate within an hour of tag attachment. In two cases, however, tags became loose before falling off causing the bats to dishabituate. For tags glued to fur, behavioural data are likely to be impacted immediately after the tag is attached and when it is loose before it falls off. 

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