Data from: Low frequency sampling rates are effective to record bottlenose dolphins
Creators
- 1. Universidade Federal de Santa Catarina
- 2. Universidade da Região de Joinville
Description
Acoustic monitoring in cetacean studies is an effective but expensive approach. This is partly because of the high sampling rate required by acoustic devices when recording high-frequency echolocation clicks. However, the proportion of recording echolocation clicks at different frequencies is unknown for many species, including bottlenose dolphins. Here, we investigated the echolocation clicks for two subspecies of bottlenose dolphins in the western South Atlantic Ocean. The possibility of record echolocation clicks at 24 and 48 kHz was assessed by two approaches. First, we considered the clicks in the frequency range up to 96 kHz. We found a loss of 0.95-13.90% of echolocation clicks in the frequency range below 24 kHz, and 0.01-0.42% below 48 kHz, to each subspecies. Then, we evaluated these recordings downsampled at 48 and 96 kHz and confirmed that echolocation clicks are recorded at these lower frequencies, with some loss. Therefore, despite reaching high frequencies, the clicks can also be recorded at lower frequencies because echolocation clicks from bottlenose dolphins are broadband. We concluded that ecological studies based on presence-absence data are still effective for bottlenose dolphins when acoustic devices with a limited sampling rate are used.
Notes
01_data_prop_freq.csv
The file contains 220 one minute samples (rows) and seven columns: dolphin_group contains a string for each group recorded, with a prefix for coastal (COAST) and offshore (OFF) recordings, and the ID of the group separated by an underline; environment contains information of the environment where the recording was made (coastal or offshore); recording contains the number of the recording file; duration contains the sample duration in seconds (up to 60 s); click_L24 contains the number of clicks only detected in frequencies below 24 kHz; clicks_L48 contains the number of clicks detected in frequencies up to 48 kHz; clicks_total contains all the clicks detected up to 96 kHz.
Data_GPS_location.csv
The file contains 18 locations of recordings, with four columns. environment contains information of whether the recordings were made in the coastal lagoon system (Lagoon_s) or offshore (Open_w); group contains the group ID for each recording in the environment; Lat and Long contains the latitude and longitude in degrees, respectively.
setup.R
R code to prepare the environment before running analysis.R, figure_seewave.R, map.R. Briefly, setup.R installs and load R packages, load custom functions and define colours to plot figures.
analysis.R
Contains the R code to run the analysis and reproduce the results.
figure_seewave.R
Contains the R code to plot spectrograms from audio samples above_24khz.wav and above_48khz.wav. plotSpectro function is loaded from setup.R.
map.R
Contains the R code to generate the maps.
detect_clicks_warbler.R
Contains the R code to apply filters and downsample the recordings.
filter_clicks_warbleR.R
Contains the R code to filter detections based on the interval of signals detected, to analyze the overlapping clicks in each downsampled frequency, and to analyze the results.
get_clicks.R
Contains the R code to run the automatic detection of clicks, with the parameters used in each frequency and for each environment.
modelling_click_detections.R
Contains the R code to consider the detections by time bins and bins with detections per minute, and to analyze the results.
validate_clickCountR.R
Contains the R code to run the 'optimize_auto_detect' funcion.
above_24khz.wav
Sound archive of a sample subset, to plot the spectrogram figure.
above_48khz.wav
Sound archive of a sample subset, to plot the spectrogram figure.
Funding provided by: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100002322
Award Number: 001
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Additional details
Related works
- Is source of
- 10.5061/dryad.4f4qrfj99 (DOI)