DOI: 10.5061/dryad.rn8pk0pks
title: Data from: Optimization of swim depth across diverse taxa during horizontal travel

description: Semi-aquatic taxa, including humans, often swim at the air-water interface
 where they waste energy generating surface waves. For marine animals,
 theory predicts the most cost-efficient depth-use pattern for migrating,
 air-breathing species that do not feed in transit is to travel at around
 2–3 times the depth of their body diameter, to minimise vertical distance
 travelled whilst avoiding wave drag close to the surface. This has rarely
 been examined, however, due to depth measurement resolution issues at the
 surface. Using satellite-relayed data for green turtles (Chelonia mydas),
 high-resolution depth-accelerometry and video data for little penguins
 (Eudyptula minor) and loggerhead turtles (Caretta caretta), and literature
 data for further sea turtle, penguin and whale species, we show that
 near-surface swimming is likely used broadly across non-foraging diving
 animals to minimise the cost of transport.
description: See methods detailed in 'Optimization of swim depth across
 diverse taxa during horizontal travel' and Supporting
 Information. 
description: ReadMe file for data associated with the paper 'Optimization of swim
 depth across diverse taxa during horizontal travel' K. L. Stokes, N.
 Esteban, P. Casale, A. Chiaradia, Y. Kaska, A. Kato, P. Luschi, Y.
 Ropert-Coudert, H. J. Stokes, G. C. Hays
 [https://doi.org/10.5061/dryad.rn8pk0pks](https://doi.org/10.5061/dryad.rn8pk0pks) The below lists files containing animal tracking data from the above publication For dive summary data and comparative literature data see Tables S1–S3 in supplementary materials 'NA' indicates data is not relevant for that cell 1\. Green turtles (Chelonia mydas) 6x2022Cm_all_dives.txt PTT: identifies the individual turtle What: "Dive" - each row is an individual dive &gt;= 5 m depth Number: "1" - the number of dives detailed in the current row Shape: "Square", "V" or "U" - describes the shape of the dive according to definition set by Wildlife Computers Date: year/month/day (UTC) Time: hours:minutes:seconds (UTC) AveLat: the average latitude calculated for that date from the Fastloc-GPS data for that turtle AveLon: the average longitude calculated for that date from the Fastloc-GPS data for that turtle HoursAhead: time difference between tag recorded time (UTC) and local time, in hours MinAhead: time difference between tag recorded time (UTC) and local time, in minutes LocalDate: converted from UTC time and date based on longitude LocalTime: converted from UTC time and date based on longitude Depth: depth reading (m) Duration: duration of that dive (s) Stage: "premig" (pre-migratory), "pelagic" (pelagic migratory), "bank" (crossing a submerged bank), "coastalmig" (coastal migratory) or "fg" (foraging ground) - the stage of migration according to the corresponding GPS data DN: "D", "N" or "C" for diurnal, nocturnal or crepuscular based on timings defined in the above publication Includes all six green turtles 6x2022Cm_all_surface.txt Columns as above, 'What' and 'Number' replaced by 'Surface' and 'Deep' Surface: time spent between 0 and 1 m depth (s) Deep: time spent between 1 and 5 m depth (s) Includes all six green turtles NB Depth categories 0–1 m and 1–5 m were collapsed owing to sensor resolution (0.5 m) and accuracy (1.01 m) 6x2022Cm_depthuse_per_depth_pelagic.txt Summarises the percentage of time spent within each depth bracket diurnally (Dpc) and nocturnally (Npc) Dhours and Nhours list the number of hours spent within each depth bracket diurnally (Dhours) and nocturnally (Nhours) Includes all six green turtles during the pelagic stage only Depths given in m 6x2022Cm_depthuse_per_stage.txt Summarises the percentage of time spent within the two depth brackets 0-5 m and 5+ m, diurnally (Dpc) and nocturnally (Npc) for each stage (pre-migratory, pelagic migratory, coastal migratory, foraging ground/post-migratory) for all six turtles Dhours and Nhours list the number of hours spent within each depth bracket diurnally (Dhours) and nocturnally (Nhours) Depths given in m 2022_Cm_229845_track_dates.txt (and files for 229846–229850) These files summarise the dates used to divide the track into the various stages (pre-migratory, pelagic migratory, coastal migratory, post-migratory) Mig_start: date of departure from nesting region; track before this date is pre-migratory Fg_start: date the turtle switched from directed movement to sharp turning angles within a final destination (foraging ground); track after this date is post-migratory Further categories divide the migration into pelagic, coastal and 'bank' if crossing a submerged bank AveLat and AveLon: average per day, used to calculate the time difference from UTC LocalDate and LocalTime: converted time and date based on longitude 229845-Behavior.csv (and files for 229846-229850) Raw depth tracking files from Wildlife Computers Dives and surface periods are quantified in terms of depth and duration See 'all_dives' and 'all_surface' files above for column descriptions and dive classification rules 229845FastGPS.txt (and files for 229846-229850) Unfiltered Fastloc-GPS data for each turtle for the duration of tracking Location estimates are given in Latitude/Longitude Number of satellites indicates the quality (error class) of each location estimate HauledOut: whether or not the logger had sufficient 'dry' readings in a row to be classified as on land 2\. Loggerhead turtles - files start with 'Cc' for Caretta caretta Cc_T1_depth_1_8pm.txt Cc_T2_depth_1_8pm.txt Cc_T3_depth_1_8pm.txt Cc_T4_depth_1_8pm.txt Depth files for the sampling period (1–8 pm on day of release, sampling rate 1 s) ID: identifies the individual turtle Depth: depth reading (m) Surface: minimum depth reading per half hour to be used for zero offset correction DepthAdj: adjusted depth value after zero offset correction Date: year-month-day (local time) Time: hours:minutes:seconds (local time) Cc_T1_diveStats_thr02.csv (and files for T2, T3, T4) Output file from diveMove (R package), applied to depth files above using a dive threshold of 0.2 m Summarises all dives between 1 and 8 pm on day of release Each row is an individual dive Includes travel dives and deep dives Columns 'divetim' and 'bottdep.mean' are dive duration and mean bottom depth of dive Descriptions for other columns can be found in the 'diveMove' documentation Means given in table S1 are for travel dives only (excluding n=2–8 'deep' dives &gt; 5 m) Cc_T1_accelerometry_shallowdives.txt (and files for T2, T3, T4) Accelerometry files for a typical period of travel dives (sampling rate 10 Hz) Date: year-month-day (local time) Time: hours:minutes:seconds (local time) Depth: depth reading (m) accX, accY, accZ: raw accelerometry values (g) in the surge, sway and heave axes DepthAdj: adjusted depth reading after zero offset correction 3\. Little penguins All_LP_ten_min_commute_depths.csv Summary depth file including ten minutes of commute diving per little penguin (sampling rate 1 s) TagID: identifies the individual little penguin Pressure: raw pressure reading (mbar) Date: day/month/year (UTC) Time: hours:minutes:seconds (UTC) Depth_m: converted depth value from pressure reading (m) xxx_gps.csv (where xxx is the identification code for each individual little penguin) Unfiltered GPS data for the duration of a single foraging trip per penguin Location data are given in the 'location.lat', 'location.lon' columns The number of satellites used to derive the location (given in 'satellites' column) gives an indication of the quality/error class of that estimate Date and time are in UTC (local time is + 11 h) xxx_depth_commute.csv (where xxx is the identification code for each individual little penguin) Depth data for the commute period (sampling rate 1 s) TagID: identifies the individual penguin Timestamp: identifies the date and time including fractional seconds X_g, Y_g, Z_g: raw accelerometry values in the surge, sway and heave axes (g) Pressure: raw pressure values used to derive depth (mbar) Date: day/month/year (UTC) Time: hours:minutes:seconds (UTC) xxx_accelerometry_commute.csv (where xxx is the identification code for each individual little penguin) Accelerometry data for the relevant commute period selected for each little penguin (sampling rate 25 Hz) TagID: identifies the individual penguin Timestamp: identifies the date and time including fractional seconds X_g, Y_g, Z_g: raw accelerometry values in the surge, sway and heave axes (g) Pressure: raw pressure values used to derive depth (mbar) Date: day/month/year (UTC) Time: hours:minutes:seconds (UTC) xxx_diveStats_thr005.csv (where xxx is the identification code for each individual little penguin) Output files from diveMove (R package), applied to depth files above using a dive threshold of 0.05 m Each row is an individual dive Columns 'divetim' and 'bottdep.mean' are dive duration and mean bottom depth of dive - values used in this analysis Descriptions for other columns can be found in the 'diveMove' documentation online at [diveMove package - RDocumentation](https://www.rdocumentation.org/packages/diveMove/versions/1.6.2) [https://www.rdocumentation.org/packages/diveMove/versions/1.6.2](https://www.rdocumentation.org/packages/diveMove/versions/1.6.2)