Estimating colony sizes of emerging bats using acoustic recordings

Kloepper, Laura N.; Linnenschmidt, Meike; Blowers, Zelda; Branstetter, Brian K.; Ralston, Joel; Simmons, James A.

doi:10.1098/rsos.160022

Cited by 45 publications

(39 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The platform was used to record Brazilian free‐tailed bat Tadarida brasiliensis flight during morning re‐entry (0330‐0500) outside of a lava tube cave on private land in Sierra County, New Mexico (Kloepper et al., ). During our seven mornings of recordings from May 24–June 5, 2017, we hovered for two replicates (swapping batteries in between) of 1 min each at 5, 10, 20, 30, 40 and 50 m height.…”

Section: Resultsmentioning

confidence: 99%

The Chirocopter: A UAV for recording sound and video of bats at altitude

Kinniry

Kloepper

2018

Methods Ecol Evol

Self Cite

View full text Add to dashboard Cite

Abstract1. Most recordings of bats are conducted with fixed equipment, which relies on opportunistic data collection. Unmanned aerial vehicles (UAV; such as drones) are considered inappropriate for recording bats due to ultrasound noise constraints.2. We developed a UAV system that physically isolates UAV noise, so we can record, with 3D manoeuvrability, ultrasonic audio and spatial thermal data of bat flight at altitude.3. We tested the noise of our UAV with various payloads and microphone configurations to characterize the ultrasonic noise of our system, physically isolate drone noise from the microphone, and maximize UAV flight performance.4. Over 84 min of recordings, we captured 3,847 echolocation signals from bats with corresponding thermal data of bat flight. Our system provides a feasible mechanism to capture both acoustic and video data of bats aloft at flexible locations and altitudes.5. We include information on how to extend our method to apply to acoustic recordings in the audible (20 Hz-20 kHz) range for recording sounds of other taxa. K E Y W O R D Sbats, thermal data, UAV, ultrasound This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

show abstract

Section: Resultsmentioning

confidence: 99%

The Chirocopter: A UAV for recording sound and video of bats at altitude

Kinniry

Kloepper

2018

Methods Ecol Evol

Self Cite

View full text Add to dashboard Cite

show abstract

“…Autonomous sound recording systems are gradually being adopted by ecologists for surveying animal biodiversity. These passive sampling systems are most often used to survey birds (Shonfield & Bayne, 2017) and marine mammals (Sousa-Lima, Norris, Oswald, & Fernandes, 2013); but primates (Heinicke et al, 2015), bats (Kloepper et al, 2016), insects (Lehmann, Frommolt, Lehmann, & Riede, 2014) and amphibians (Measey, Stevenson, Scott, Altwegg, & Borchers, 2017) are also commonly monitored. Autonomous sound recorders are capable of collecting huge amounts of data in a cost-effective, efficient and standardized manner.…”

Section: Introductionmentioning

confidence: 99%

Comparing the sampling performance of sound recorders versus point counts in bird surveys: A meta‐analysis

Darras

Batáry

Furnas

et al. 2018

Journal of Applied Ecology

115

126

View full text Add to dashboard Cite

Autonomous sound recording is a promising sampling method for birds and other vocalizing terrestrial wildlife. However, while there are clear advantages of passive acoustic monitoring methods over classical point counts conducted by humans, it has been difficult to quantitatively assess how they compare in their sampling performance. Quantitative comparisons of species richness between acoustic recorders and human point counts in bird surveys have previously been hampered by the differing and often unknown detection ranges or sound detection spaces among sampling methods. We performed two meta‐analyses based on 28 studies where bird point counts were paired with sound recordings at the same sampling sites. We compared alpha and gamma richness estimated by both survey methods after equalizing their effective detection ranges. We further assessed the influence of technical sound recording specifications (microphone signal‐to‐noise ratio, height and number) on the bird sampling performance of sound recorders compared to unlimited radius point counts. We show that after standardizing detection ranges, alpha and gamma richness from both methods are statistically indistinguishable, while there might be an avoidance effect in point counts. Furthermore, we show that microphone signal‐to‐noise ratio (a measure of its quality), height and number positively affect performance through increasing the detection range, allowing sound recorders to match the performance of human point counts. Synthesis and applications. We demonstrate that when used properly, high‐end sound recording systems can sample terrestrial wildlife just as well as human observers conducting point counts. Correspondingly, we suggest a first standard methodology for sampling birds with autonomous sound recorders to obtain results comparable to point counts and enable practical sampling. We also give recommendations for carrying out effective surveys and making the most out of autonomous sound recorders.

show abstract

“…Both methods deploy arrays of many microphones to record and locate vocalizing animals. But how to deal with data from single recorders, which many practitioners are limited to in monitoring programs and impact assessments ? Kloepper et al (2016) estimate the colony size of emerging cave-dwelling bats using only one ARU.…”

Section: Introductionmentioning

confidence: 99%

Estimating population density of insectivorous bats based on stationary acoustic detectors: A case study

Milchram

Suarez‐Rubio

Schröder

et al. 2020

Ecology and Evolution

View full text Add to dashboard Cite

Automated recording units are commonly used by consultants to assess environmental impacts and to monitor animal populations. Although estimating population density of bats using stationary acoustic detectors is key for evaluating environmental impacts, estimating densities from call activity data is only possible through recently developed numerical methods, as the recognition of calling individuals is impossible. We tested the applicability of generalized random encounter models (gREMs) for determining population densities of three bat species (Common pipistrelle Pipistrellus pipistrellus, Northern bat Eptesicus nilssonii, and Natterer's bat Myotis nattereri) based on passively collected acoustical data. To validate the results, we compared them to (a) density estimates from the literature and to (b) Royle–Nichols (RN) models of detection/nondetection data. Our estimates for M. nattereri matched both the published data and RN‐model results. For E. nilssonii, the gREM yielded similar estimates to the RN‐models, but the published estimates were more than twice as high. This discrepancy might be because the high‐altitude flight of E. nilssonii is not accounted for in gREMs. Results of gREMs for P. pipistrellus were supported by published data but were ~10 times higher than those of RN‐models. RN‐models use detection/nondetection data, and this loss of information probably affected population estimates of very active species like P. pipistrellus. gREM models provided realistic estimates of bat population densities based on automatically recorded call activity data. However, the average flight altitude of species should be accounted for in future analyses. We suggest including flight altitude in the calculation of the detection range to assess the detection sphere more accurately and to obtain more precise density estimates.

show abstract

Estimating colony sizes of emerging bats using acoustic recordings

Cited by 45 publications

References 15 publications

The Chirocopter: A UAV for recording sound and video of bats at altitude

The Chirocopter: A UAV for recording sound and video of bats at altitude

Comparing the sampling performance of sound recorders versus point counts in bird surveys: A meta‐analysis

Estimating population density of insectivorous bats based on stationary acoustic detectors: A case study

Contact Info

Product

Resources

About