Ambient noise decreases detectability of songbird vocalizations in passive acoustic recordings in a consistent pattern across species, frequency, and analysis method

Apol, Chad A.; Valentine, Ethan C.; Proppe, Darren S.

doi:10.1080/09524622.2019.1605310

Cited by 5 publications

(3 citation statements)

References 44 publications

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“…Further studies are necessary to ascertain whether the urban observation of species previously considered absent or rare in this kind of environment during the lockdowns was due to a higher abundance of individuals, to a temporal change in the availability of ecological niches as a result of the reduction in anthropogenic disturbance ( Derryberry et al, 2020 ; Rutz et al, 2020 ), to an increased detectability of birds following a decrease in environmental noise levels ( Apol et al, 2020 ), or to a reflection of a larger number of observers present. Nonetheless, we note that similar processes were observed as a result of a reduction in human disturbance on other occasions (e.g.…”

Section: Discussionmentioning

confidence: 99%

Birds seen and not seen during the COVID-19 pandemic: The impact of lockdown measures on citizen science bird observations

Basile

Russo

Russo³

et al. 2021

Biological Conservation

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In early 2020, the rapid spread of the novel coronavirus disease 2019 (COVID-19) led multiple countries to introduce strict lockdown measures to contain the pandemic. Movement restrictions may have influenced the ability of the public to contribute to citizen science projects. We investigated how stay-at-home orders affected data submitted by birdwatchers in Italy, Spain and the United Kingdom (UK) to a widely-used citizen science platform, iNaturalist, depending on whether observations were collected in urban or non-urban areas. We found significant trends in the daily number of observations in all three countries, indicating a surge in urban observation during lockdowns. We found an increase in the mean daily number of urban observations during the lockdown in Italy and Spain, compared to previous years. The mean daily number of non-urban observations decreased in Italy and Spain, while remained similar to previous years in the UK. We found a general decrease of new records during the lockdowns both in urban and non-urban areas in all countries. Our results suggest that the citizen science community remained active during the lockdowns and kept reporting birds from home. However, limitations to movements may have hampered the possibility of birdwatchers to explore natural areas and collect new records. Our findings suggest that future research and conservation applications of citizen science data should carefully consider the bias and gaps in data series caused by the pandemic. Furthermore, our study highlights the potential of urban areas for nature activities, such as birdwatching, and its relevance for sustainable urban planning.

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Section: Discussionmentioning

confidence: 99%

Birds seen and not seen during the COVID-19 pandemic: The impact of lockdown measures on citizen science bird observations

Basile

Russo

Russo³

et al. 2021

Biological Conservation

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“…Thus, more importantly, detectability increases with SNR: even though extremely low SNR microphone elements are almost non-existent, it is worthwhile to search for the highest SNR in the market of existing microphone elements. Moreover, the detection areas of our wide range of microphone elements did not reach a clear saturation point, although detection spaces are eventually limited by the ambient sound ( Apol, Valentine & Proppe, 2019 ; Darras et al, 2018a ). Crucially, the best-performance microphones can be obtained at little additional expense: as an example, the lowest signal-to-noise PUI Audio microphone element (55 dB SPL) cost us 3.10 EUR (at the time of purchase, via Digikey.com), only a little less (28%) than the highest signal-to-noise PUI Audio microphone element (80 dB SPL) that cost 4.25 EUR.…”

Section: Discussionmentioning

confidence: 81%

High microphone signal-to-noise ratio enhances acoustic sampling of wildlife

Darras

Deppe

Fabian

et al. 2020

PeerJ

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Background Automated sound recorders are a popular sampling tool in ecology. However, the microphones themselves received little attention so far, and specifications that determine the recordings’ sound quality are seldom mentioned. Here, we demonstrate the importance of microphone signal-to-noise ratio for sampling sonant animals. Methods We tested 12 different microphone models in the field and measured their signal-to-noise ratios and detection ranges. We also measured the vocalisation activity of birds and bats that they recorded, the bird species richness, the bat call types richness, as well as the performance of automated detection of bird and bat calls. We tested the relationship of each one of these measures with signal-to-noise ratio in statistical models. Results Microphone signal-to-noise ratio positively affects the sound detection space areas, which increased by a factor of 1.7 for audible sound, and 10 for ultrasound, from the lowest to the highest signal-to-noise ratio microphone. Consequently, the sampled vocalisation activity increased by a factor of 1.6 for birds, and 9.7 for bats. Correspondingly, the species pool of birds and bats could not be completely detected by the microphones with lower signal-to-noise ratio. The performance of automated detection of bird and bat calls, as measured by its precision and recall, increased significantly with microphone signal-to-noise ratio. Discussion Microphone signal-to-noise ratio is a crucial characteristic of a sound recording system, positively affecting the acoustic sampling performance of birds and bats. It should be maximised by choosing appropriate microphones, and be quantified independently, especially in the ultrasound range.

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“…Some experimental evidence indicates that species whose songs encompass many frequencies (i.e., are more complex) may have a greater chance of detection during point counts than species whose calls vary less, especially in the presence of noise interference (Koper et al 2016). Amplitude (volume) of ambient noise has a stronger masking effect on bird songs than ambient noise frequency (Apol et al 2019). Thus, the combination of the high complexity and relative loudness of Winter Wren songs makes it unlikely that all song frequencies would be effectively masked by ambient noise.…”

Section: Discussionmentioning

confidence: 99%

Accounting for point count ambient noise increases population size estimates

Ek¹,

Pf²,

Jm³

et al. 2021

Preprint

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Ambient noise is an integral component of natural environments, but it also creates challenges for avian monitoring programs. Ambient noise can mask bird vocalizations from observers during point counts, which may lead to systematic undercounting of birds in noisy environments. Here, we estimate detection probability and population size in models that either account for or omit the influence of ambient noise. We used data for four bird species, from 2228 point counts that were conducted during the 2019 Mountain Birdwatch field season. Community scientists assessed ambient noise using a simple scale. Despite relatively quiet conditions at sampling locations (x = 2.48), our information theoretical approach favored N-mixture models that incorporated ambient noise into the detection function for all four species. At the noisiest sampling locations, our models predicted detection probabilities that were as low as 10% for some species. Accounting for ambient noise resulted in a modest, mean increase of ≤3.29% in the total population size for each species. Following our approach, other researchers can easily incorporate ambient noise assessments into their field protocols and analyses, with minimal costs or added complexity, to increase the comparability of studies conducted within different acoustic environments.

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Ambient noise decreases detectability of songbird vocalizations in passive acoustic recordings in a consistent pattern across species, frequency, and analysis method

Cited by 5 publications

References 44 publications

Birds seen and not seen during the COVID-19 pandemic: The impact of lockdown measures on citizen science bird observations

Birds seen and not seen during the COVID-19 pandemic: The impact of lockdown measures on citizen science bird observations

High microphone signal-to-noise ratio enhances acoustic sampling of wildlife

Accounting for point count ambient noise increases population size estimates

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