Environmental cycles often influence the presence of animals, creating patterns at different temporal scales, which may mean that their effects overlap and/or interact. Interactions between diel and seasonal cycles have been reported to influence fish behaviour but little is known about such interactions in marine top predators. Here, we studied the combined effect of seasonal, tidal and diel cycles on the occurrence of bottlenose dolphins (Tursiops truncatus) within a Marine Protected Area in Scotland. Our analyses were based on echolocation detections from passive acoustic devices (CPODs) deployed at three coastal sites between 2010 and 2016. We described patterns of dolphins’ occurrence using circular statistics and then used generalised additive mixed models to explore the relative importance of each cycle and any interactions between them. We found site-specific cyclical patterns of presence that remained constant across years. There was a highly significant interaction between seasonal and diel cycles at two sites around deep channels, where occurrence was diurnal in summer but became nocturnal in autumn. The study demonstrates the highly plastic behaviour of bottlenose dolphins and shows a previously unreported behaviour that has management implications for this and other marine protected areas.
Readme text file detailing data packages: Readme.txt file for data packages associated with paper on “Fine scale spatial variability in the influence of environmental cycles on the occurrence of dolphins at coastal sites”. Data were collected by the University of Aberdeen and collaborators under a series of grants and contracts from DECC Offshore Energy Strategic Environmental Assessment Programme, Marine Scotland, Moray Offshore Renewables Ltd., The Crown Estate, Highlands and Islands Enterprise and Beatrice Offshore Wind Ltd. Contact for queries is Oihane Fernandez, email@example.com
Data on CPOD deployments: Data on the CPOD deployments. Filename = "FineScale_Deployments_OFB2019.txt" Four columns = Dep_no, Deployment_date, Retrieval_date, Data_end_date. Dep_no is the unique number assigned to each CPOD deployment. Deployment_date is the date when that CPOD was deployed at sea. Retrieval_date is the date when that CPOD was retrieved at sea. Data_end_date is the date when the data on the CPOD’s SD card ended.
Zip folder with data files on click details of bottlenose dolphins: Zip folder with 67 CPOD data files on click details of bottlenose dolphins. Filename = "Exported click details - cropped.zip" Each file has the click details data from a single CPOD deployment, cropped to remove data up to 23:59 on the day of deployment and from 00:00 on the day of retrieval. Each file has twelve columns = time, minute, microsec, cycles, SPL_a, kHz, Bandwidth, end kHz, Qn, TrN, Location, deployment.no. time is the start time as dd/mm/yyyy hh:mm minute is the start time for each click, given as two columns: the minute (= number of minutes since the start of 1900) and the number of microseconds in the minute (below). microsec is the number of microseconds in the minute for the start time of each click. cycles is the number of cycles for each click. SPL_a is the sound pressure level within the click. kHz is the frequency of the click, a single value representing the dominant frequency based on zero-crossing intervals. Bandwidth is the bandwidth of the click. end kHz is the end frequency of the click, a single value derived from the last zero crossing interval. Qn is the Quality of the click: High or Moderate (1:High, 2:Moderate). Trn is the unique identifier for the train. Location is the numeric identifier for the location at which that CPOD was deployed. deployment.no is the unique number assigned to each CPOD deployment.
Exported click details - cropped.zip
Data on tide times: Data on tide times from Cromarty and Lossiemouth ports. Filename = "FineScale_Tides_OFB2019.txt" Six columns = date, datehtide1, datehtide2, dateltide1, dateltide2, port. date is the date as yyyy-mm-dd datehtide1 is the date and time of the first high tide of the day as yyyy-mm-dd hh:mm:ss. datehtide2 is the date and time of the second high tide of the day as yyyy-mm-dd hh:mm:ss. dateltide1 is the date and time of the first low tide of the day as yyyy-mm-dd hh:mm:ss. dateltide2 is the date and time of the second low tide of the day as yyyy-mm-dd hh:mm:ss. port is the reference port.
Data on dolphin encounters: Rayleigh test: Data on dolphin encounters (from CPODs) for the Rayleigh test (see Fig.2, Fig.3, Table 2, Table S3 & Table S4). Filename = "FineScale_Dataset_RayleighTest_OFB2019.txt" Six columns = site, date, mid.encounter, dayangle_deg, tideangle_deg, seasonangle_deg. site is the location name. date is the date as yyyy-mm-dd. mid.encounter is the mid point of each dolphin encounter. dayangle_deg is the angle of each encounter for the diel cycle (degrees). tideangle_deg is the angle of each encounter for the tidal cycle (degrees). seasonangle_deg is the angle of each encounter for the seasonal cycle (degrees).
Data on dolphin encounters: GAMM: Data on dolphin encounters (from CPODs) for the GAMM modeling (see Fig.4, Fig.S2). Filename = "FineScale_Dataset_GAMM_OFB2019.txt" Six columns = site, hourly, presence, year, julianday, dayangle_deg, tideangle_deg, seasonangle_deg, PresLag1, day.num, mh. site is the location name. hourly is the datetime as yyyy-mm-dd hh:mm:ss. presence is the dolphin presence as 0: absent, 1: present. year is the year. julianday is the julian day. dayangle_deg is the angle of that hour for the diel cycle (degrees). tideangle_deg is the angle of that hour for the tidal cycle (degrees). seasonangle_deg is the angle of that day for the seasonal cycle (degrees). PresLag1 is the dolphin presence during the previous hour. day.num is the day number. mh is the hour of the day.
Zip folder with 68 CPOD data files: Zip folder with 68 CPOD data files (raw .cp3 files). Filename = "CPOD CP3 files.zip" Each file has the data from a single CPOD deployment. The name of each file contains information of the deployment: the first 3 digits correspond to the deployment number and the following three digits to the location ID (001:Sutors, 002:Chanonry, 004:Spey Bay).
CPOD CP3 files.zip
This work is licensed under a CC0 1.0 Universal (CC0 1.0) Public Domain Dedication license.