@article {52613, title = {Catching insects while recording bats: impacts of light trapping on acoustic sampling}, journal = {Remote Sensing in Ecology and Conservation}, year = {2018}, month = {Apr-01-2020}, abstract = {

Collecting information on bat prey availability usually involves the use of light traps to capture moths and flies that constitute the main prey items of most insectivorous bats. However, despite the recent awareness on the adverse effects of light on bats, little is known regarding the potential impacts of light trapping on the bat sampling outcomes when passive acoustic sampling and light trap- ping are implemented simultaneously. Using a before\–after experimental design that involved the installation of a 6 W actinic light trap 1 m away from the bat detector, we tested the predictions that (1) slow-flying bat species will be less active when the light trap is present, while the opposite will be true for fast-fly- ing species; and (2) bat species richness will be lower at lit conditions compared to dark ones. Our results suggest that the use of light traps in combination with bat detectors may considerably influence the outcomes of acoustic sampling. Although the activity of fast-flying bat species did not differ between the two treatments, we found that the activity of slow-flying ones such as Rhinolophus ferrumequinum and Rhinolophus hipposideros decreased significantly at lit condi- tions. Furthermore, we recorded fewer bat species when the light trap was deployed. To overcome this issue, we strongly recommend either (1) placing light traps at a considerable distance from bat detectors; or (2) using light traps during the night that follows the bat sampling if sampling needs to be at the same position; or (3) deploying non-attractant insect traps such as Malaise traps if Lepidoptera is not the main order targeted.

}, doi = {10.1002/rse2.71}, url = {http://doi.wiley.com/10.1002/rse2.71}, author = {Froidevaux, J{\'e}r{\'e}my S. P. and Fialas, Penelope C. and Jones, Gareth}, editor = {Pettorelli, Nathalie and Merchant, Nathan} } @article {48152, title = {An Aerial-Hawking Bat Uses Stealth Echolocation to Counter Moth Hearing}, journal = {Current Biology}, volume = {20}, year = {2010}, month = {Jan-09-2010}, pages = {1568 - 1572}, abstract = {

Ears evolved in many nocturnal insects, including some moths, to detect bat echolocation calls and evade capture [1, 2]. Although there is evidence that some bats emit echolocation calls that are inconspicuous to eared moths, it is difficult to determine whether this was an adaptation to moth hearing or originally evolved for a different purpose [2, 3]. Aerial-hawking bats generally emit high-amplitude echolocation calls to maximize detection range [4, 5]. Here we present the first example of an echolocation counterstrategy to overcome prey hearing at the cost of reduced detection distance. We combined comparative bat flight-path tracking and moth neurophysiology with fecal DNA analysis to show that the barbastelle, Barbastella barbastellus, emits calls that are 10 to 100 times lower in amplitude than those of other aerial-hawking bats, remains undetected by moths until close, and captures mainly eared moths. Model calculations demonstrate that only bats emitting such low-amplitude calls hear moth echoes before their calls are conspicuous to moths. This stealth echolocation allows the barbastelle to exploit food resources that are difficult to catch for other aerial-hawking bats emitting calls of greater amplitude.

}, issn = {09609822}, doi = {10.1016/j.cub.2010.07.046}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0960982210009917}, author = {Goerlitz, Holger R. and ter Hofstede, Hannah M. and Zeale, Matt R.K. and Jones, Gareth} } @article {47292, title = {Testing the performances of automated identification of bat echolocation calls: A request for prudence}, journal = {Ecological Indicators}, volume = {78}, year = {2017}, month = {Jan-07-2017}, pages = {416 - 420}, abstract = {

Echolocating bats are surveyed and studied acoustically with bat detectors routinely and worldwide, yet identification of species from calls often remains ambiguous or impossible due to intraspecific call variation and/or interspecific overlap in call design. To overcome such difficulties and to reduce workload, automated classifiers of echolocation calls have become popular, but their performance has not been tested sufficiently in the field. We examined the absolute performance of two commercially available programs (SonoChiro and Kaleidoscope) and one freeware package (BatClassify). We recorded noise from rain and calls of seven common bat species with Pettersson real-time full spectrum detectors in Sweden. The programs could always (100\%) distinguish rain from bat calls, usually (68\–100\%) identify bats to group ( Nyctalus/Vespertilio/Eptesicus, Pipistrellus, Myotis, Plecotus, Barbastella ) and usually (83\–99\%) recognize typical calls of some species whose echolocation pulses are structurally distinct ( Pipistrellus pygmaeus , Barbastella barbastellus ). Species with less characteristic echolocation calls were not identified reliably, including Vespertilio murinus (16\–26\%), Myotis spp. (4\–93\%) and Plecotus auritus (0\–89\%). All programs showed major although different shortcomings and the often poor performance raising serious concerns about the use of automated classifiers for identification to species level in research and surveys. We highlight the importance of validating output from automated classifiers, and restricting their use to specific situations where identification can be made with high confidence. For comparison we also present the result of a manual identification test on a random subset of the files used to test the programs. It showed a higher classification success but performances were still low for more problematic taxa.

}, keywords = {Biosonar, methodology, software, species identification, ultrasound}, issn = {1470160X}, doi = {10.1016/j.ecolind.2017.03.023}, url = {http://linkinghub.elsevier.com/retrieve/pii/S1470160X17301401}, author = {Rydell, Jens and Nyman, Stefan and Ekl{\"o}f, Johan and Jones, Gareth and Russo, Danilo} }