Data from: Vocal signatures affected by population identity and environmental sound levels
Data files
Apr 13, 2024 version files 5.86 MB
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AllChars_211025_Upload.csv
59.02 KB
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MatchedSW_Chars_210927_FinalMatchUpload.csv
23.28 KB
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MatchedWhistles_210624_Chron_Upload_SiteNum.csv
22.93 KB
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README.md
5.40 KB
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SoundLevel_Dates_210927_T1C0Gain.csv
5.75 MB
Abstract
Passive acoustic monitoring has improved our understanding of vocalizing organisms in remote habitats and during all weather conditions. Many vocally active species are highly mobile, and their populations overlap. However, distinct vocalizations allow the tracking and discrimination of individuals or populations. Using signature whistles, the individually distinct calls of bottlenose dolphins, we calculated a minimum abundance of individuals, characterized and compared signature whistles from five locations, and determined reoccurrences of individuals throughout the Mid-Atlantic Bight and Chesapeake Bay, USA. We identified 1,888 signature whistles in which the duration, number of extrema, start, end, and minimum frequencies of signature whistles varied significantly by site. All characteristics of signature whistles were deemed important for determining from which site the whistle originated and due to the distinct signature whistle characteristics and lack of spatial mixing of the dolphins detected at the Offshore site, we suspect that these dolphins are of a different population than those at the Coastal and Bay sites. Signature whistles were also found to be shorter when sound levels were higher. Using only the passively recorded vocalizations of this marine top predator, we obtained information about its population and how it is affected by ambient sound levels, which will increase as offshore wind energy is developed. In this rapidly developing area, these calls offer critical management insights for this protected species.
https://doi.org/10.5061/dryad.9s4mw6mq0
Acoustic data were collected between 2016 at 2018 at sites 1, 2, and 5 were located 12, 31, and 64 km east of Ocean City, Maryland, USA, respectively. Water depths at these sites ranged from approximately 20 – 42 m, and the acoustic recording instruments were deployed approximately 1 m above the ocean floor using bottom-anchored moorings.
Ambient sound levels were calculated in MATLAB (MathWorks, Natick, Massachusetts, USA) as the relative broadband (up to 24 kHz, given the sampling rate of 48 kHz) root mean square sound pressure level (SPL; dB re 1µPa root-mean-square (rms)) during the recording in which the signature whistle occurred (two or five minutes in duration).
PAMGUARD Whistle and Moan Detector was utilized to determine hours with possible dolphin presence. These hours were then manually searched for signature whistles with high signal-to-noise ratios. Signature whistles were manually identified using the SIGID criteria -in which the same whistle repeated in a pattern of two or more whistles within 1–10 s of one another and with a minimum length of 0.2 s. Whistle contours (shape of the whistle) were obtained using Beluga software (https://synergy.st-andrews.ac.uk/soundanalysis) within MATLAB (Math-Works, Natick, Massachusetts, USA). Whistles with low signal-to-noise ratio or abundant non-linear features that obscured the shape of the whistle could not be included in the analysis.
For each whistle, manual measurements were taken in Raven Pro 2.0 Interactive Sound Analysis Software (Cornell Lab of Ornithology, Center for Conservation Bioacoustics, Ithaca, New York, USA) of the duration, start, end, maximum, minimum, and delta frequencies (maximum minus minimum frequency), and number of local extrema (e.g. local minima and maxima) including the start and end of the whistle.
Description of the data and file structure
Signature whistle characteristics:
- AllChars_211025_Upload: Whistle characteristics for all signature whistles (n=357) used in the signature whistle characteristic analysis. Columns include: ID, Region, Filename, Start.freq, End.freq, Min.freq, Max.freq, Delta.freq, Duration, Extrema, sqrtStart.freq, sqrtEnd.freq, sqrtDelta.freq, logDuration, logExtrema, sqrtMin.freq, sqrtMax.freq. Sqrt indicated squareroot of the metric and log indicates that the log of the value was taken.
Characteristics of the matched whistle subset:
- MatchedSW_Chars_210927_FinalMatchUpload: Whistle characteristics for the subset of signature whistles (n=103) that reoccurred at different sites or times. Columns include: Index (of the pair), WhisNum (whistle number within the match), SiteNum, Filename, Region, Startfreq, Endfreq, Minfreq, Minfreq, Maxfreq, Deltafreq, Duration, Extrema, SPLrms. Freq indicates frequency (measured in Hz) and SPLrms indicates the sound pressure level (SPL) measured as root mean square (rms) measures in dB.
Catalog of all matched whistles in the study area:
- MatchedWhistles_210624_Chron_Upload_SiteNum: Catalog of all matched signature whistle (n=201) information. The first column title is “New Whistle” and for each matched signature whistle, the site, date, and file name for each whistle are included.
Sound levels calculated for all recording periods:
- SoundLevel_Dates_210927_T1C0Gain: Sound levels for all recording periods. SPLrms indicates the sound pressure level (SPL) measured as root mean square (rms) measures in dB.
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Variables:
Index: Identifier for each signature whistle or signature whistle pair
WhisNum: whistle number within the match
SiteNum: Site identifier
Filename: File from which the signature whistle originated
Region: Offshore, Chesapeake Bay, or Inshore region
Startfreq (or Start.freq): Start frequency (Hz) of signature whistle
Endfreq (or End.freq): End frequency (Hz) of signature whistle
Minfreq (or Min.freq): Minimum frequency (Hz) of signature whistle
Maxfreq (or Max.freq): Maximum frequency (Hz) of signature whistle
Deltafreq (or Delta.freq): Delta frequency (maximum minus minimum; Hz) of signature whistle
Duration: Duration (seconds) of signature whistle
Extrema: Number of extrema (maxima or minima) of signature whistle
SPLrms: Sound pressure level root mean square (dB)
DateTime: Date and time of signature whistle
Site: Site identifier (Sites 1-5)
sqrtStart.freq: Square root of value of start frequency (Hz) of signature whistle
sqrtEnd.freq: Square root of value of end frequency (Hz) of signature whistle
sqrtDelta.freq: Square root of value of end frequency (Hz) of signature whistle
logDuration: Log of value or duration (s) of signature whistle
logExt: Log of number of extrema (maxima or minima) of signature whistle
sqrtMin: Square root of value of minimum frequency (Hz) of signature whistle
sqrtMax: Square root of value of maximum frequency (Hz) of signature whistle
New whistle match cat: Matched whistle category
[#] sighting site: Site at which the signature whistle was recorded
[#] sighting date: Date on which the signature whistle was recorded
[#] sighting contour name: Identifying contour name from Beluga software
Acoustic data were collected between 2016 at 2018 at sites 1, 2, and 5 were located 12, 31, and 64 km east of Ocean City, Maryland, USA, respectively. Water depths at these sites ranged from approximately 20 – 42 m, and the acoustic recording instruments were deployed approximately 1 m above the ocean floor using bottom-anchored moorings.
Ambient sound levels were calculated in MATLAB (MathWorks, Natick, Massachusetts, USA) as the relative broadband (up to 24 kHz, given the sampling rate of 48 kHz) root mean square sound pressure level (SPL; dB re 1µPa root-mean-square (rms)) during the recording in which the signature whistle occurred (two or five minutes in duration).
PAMGUARD Whistle and Moan Detector was utilized to determine hours with possible dolphin presence. These hours were then manually searched for signature whistles with high signal-to-noise ratios. Signature whistles were manually identified using the SIGID criteria -in which the same whistle repeated in a pattern of two or more whistles within 1–10 s of one another and with a minimum length of 0.2 s. Whistle contours (shape of the whistle) were obtained using Beluga software (https://synergy.st-andrews.ac.uk/soundanalysis) within MATLAB (Math-Works, Natick, Massachusetts, USA). Whistles with low signal-to-noise ratio or abundant non-linear features that obscured the shape of the whistle could not be included in the analysis.
For each whistle, manual measurements were taken in Raven Pro 2.0 Interactive Sound Analysis Software (Cornell Lab of Ornithology, Center for Conservation Bioacoustics, Ithaca, New York, USA) of the duration, start, end, maximum, minimum, and delta frequencies (maximum minus minimum frequency), and number of local extrema (e.g. local minima and maxima) including the start and end of the whistle.