Acceleration and depth data on foraging behaviour of rhinoceros auklets breeding at Teuri Island
Data files
Feb 29, 2024 version files 20.57 GB
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2012_01540701_Accel.txt
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2012_01540701_DT.txt
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2012_01720621_Accel.txt
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2012_01720621_DT.txt
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2012_01730621_Accel.txt
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2012_01730621_DT.txt
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2012_01730701_Accel.txt
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2012_01730701_DT.txt
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2012_01750622_Accel.txt
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2012_01750622_DT.txt
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2012_01770621_Accel.txt
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2012_01770621_DT.txt
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2012_01780621_Accel.txt
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2012_01780621_DT.txt
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2012_01780701_Accel.txt
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2012_01780701_DT.txt
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2012_D3GT50Hz_01540701.pxp
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2012_D3GT50Hz_01720621.pxp
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2012_D3GT50Hz_01730621.pxp
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2012_D3GT50Hz_01730701.pxp
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2012_D3GT50Hz_01750622.pxp
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2012_D3GT50Hz_01770621.pxp
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2012_D3GT50Hz_01780621.pxp
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2012_D3GT50Hz_01780701.pxp
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2013_02120621_Accel.txt
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2013_02120621_DT.txt
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2013_02120701_Accel.txt
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2013_02120701_DT.txt
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2013_02130627_Accel.txt
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2013_02130627_DT.txt
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2013_02130701_Accel.txt
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2013_02130701_DT.txt
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2013_02140627_Accel.txt
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2013_02140627_DT.txt
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2013_02150627_Accel.txt
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2013_02150627_DT.txt
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2013_02160703_Accel.txt
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2013_02160703_DT.txt
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2013_02170703_Accel.txt
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2013_02170703_DT.txt
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2013_D3GT20Hz_02120701.pxp
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2013_D3GT20Hz_02130701.pxp
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2013_D3GT20Hz_02160703.pxp
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2013_D3GT20Hz_02170703.pxp
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2013_D3GT50Hz_02120621.pxp
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2013_D3GT50Hz_02130627.pxp
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2013_D3GT50Hz_02140627.pxp
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2013_D3GT50Hz_02150627.pxp
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2019_00970626_Accel.txt
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2019_00970626_DT.txt
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2019_01010619_Accel.txt
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2019_01010619_DT.txt
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2019_01010626_Accel.txt
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2019_01010626_DT.txt
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2019_01020619_Accel.txt
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2019_01020620_DT.txt
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2019_01020626_Accel.txt
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2019_01020626_DT.txt
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2019_D3GT20Hz_00970626.pxp
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2019_D3GT20Hz_01010626.pxp
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2019_D3GT20Hz_01020626.pxp
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2019_D3GT50Hz_01010619.pxp
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2019_D3GT50Hz_01020620.pxp
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2020_00970606__Accel.txt
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2020_00970606_DT.txt
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2020_00970606.pxp
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2020_00970619_Accel.txt
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2020_00970619_DT.txt
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2020_00970619.pxp
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2020_01010619-20_Accel.txt
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2020_01010619-20_DT.txt
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2020_01010619.pxp
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2020_01020606_Accel.txt
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2020_01020606_DT_.txt
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2020_01020606.pxp
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2020_01020619_Accel.txt
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2020_01020619_DT.txt
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2020_01020619.pxp
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D3GTStartTime.xlsx
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README.md
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README.md.docx
Abstract
Marine top predators are expected to adjust their foraging behaviour at multiple time scales concomitantly with changes in forage fish availability. Rhinoceros auklets Cerorhinca monocerata rearing chicks at Teuri Island, Japan Sea, fed on anchovy Engraulis japonicus in 2012 and 2013 (anchovy regime) but switched to sand lance Ammodytes spp in 2019 and 2020 (sand lance regime). Here, we studied their at-sea behaviour using the GPS locations of 33 birds and the depth-acceleration records of 26 birds, and compared their foraging behaviour between these prey regimes. At the trip scale, auklets used offshore waters (>50 m sea depth) and coastal waters in the anchovy regime but used mainland coastal waters (<50 m sea depth) in the sand lance regime. In the sand lance regime, the birds also conducted more overnight 2- to 4-day trips in 2020 and spent more time flying during 1-day trips as they fed in further areas compared to the anchovy regime. At the dive scale, auklets frequently dove to both <5 m and 20 – 30 m depths in the anchovy regime but mainly to <5 m depth in the sand lance regime. Within each dive, auklets showed a greater number of fast/strong wing stroke events in the anchovy regime than in the sand lance regime. These changes in auklet behaviour reflected the different habitats, depth distribution, and swim speed of the targeted prey species. Our study shows the behavioural flexibility of a wing-propelled flying-diving seabird in response to the inter-annual shifts in the dominant forage fish community. It also indicates the ecological constraints on the mechanisms determining nest productivity in this day-foraging/night-provisioning seabird.
README: Acceleration and depth data on foraging behaviour of rhinoceros auklets breeding at Teuri Island
Bird List and time of start recording data for each logger is in D3GTStartTime Excel file. See Supplementary Material 1 for detailed information for each bird.
Description of the data and file structure
We deployed the depth-acceleration data-logger (ORI400-D3GT, 9.0 g, 12 mm diameter×51 mm, Little Leonardo, Japan) on the back of Rhinoceros Auklets rearing chicks at Teuri Island. Igor files for Depth, temperature and 3-axis acceleration data collected by D3GT logger deployed on Rhinoceros Auklets at Teuri Island. File name is Year_data-logger_sampling interval and Bird ID. Sampling interval was 1 second for depth (Depth) and in interval of 0.02 s or 0.05 s for 3-axis acceleration; sway (XW, left-right), surge (YW, tail-head), and heave (ZW, dorso-ventral). We retrieved depth-acceleration loggers from 8 of 8 birds in 2012, 8 of 8 birds in 2013, 10 of 11 birds in 2019, and 8 of 8 birds in 2020. Because of malfunction or battery shortage in some devices we finally collected depth-acceleration data from 26 birds. Here are Igor files. You can see data and calculation processes using Igor software.
XW: X-axis acceleration (sway)
XW_psd: power spectrum density of X
ZW: Z-axis acceleration (heave)
ZW_psd: power spectrum density of Z
YW: Y-axis acceleration (surge)
YW_psd: power spectrum density of Y
DynamicXW: High frequency component of X acceleration
DynamicYW: High frequency component of Y acceleration
DynamicZW: High frequency component of Z acceleration
filteredXW: Low frequency component of X acceleration
filteredYW: Low frequency component of Y acceleration
filteredZW: Low frequency component of Z acceleration
Coef: Coefficient relating to filter
modifiedPitch: Body angle corrected by the angle of attachment of loggers that was obtained by eye for each bird referring the angle when birds were sitting on the water.
Pitch: Pitch angle calculated using filteredYW(surge)
PitchDetection: The point when modifiedPitch was changed from positive to negative
PrePitch: When filterdYW≧ 1 =1,<-1=-1”for calculating Pitch
DownStrokeWingbeat: Top convex part of curve of heave (down stroke, PreWingbeat2) but higher than threshold determined by eye to determine the peak for each bird, during dives.
PreWingbeat: Down convex part of curve of heave (up stroke), during dives.
PreWingbeat2: Top convex part of curve of heave (down stroke), during dives
Wingbeat: Down convex part of heave (up stroke, PreWingbeat) but lower than the threshold determined by eye to determine the peak for each bird, during dives.
WingBeatCount: The number of Wingbeat (up stroke) per 1-s window, during dives
WingbeatHist: Histogram of Wingbeatcount
WingbeatTable: Table of Wingbeatcount
BeatConverted: Not used
FlightMask(temporal): Not used
FlightMask(2) : Mask of time fly
FlightPreWingbeat: Down convex part of curve of heave(up stroke) but lower than the threshold determined by eye for each bird, throughout the record
FlightWingbeatCount: Number of FlightPreWingbeat over the threshold determined by eye for each bird per 1 second window. Note that WingbeatCount is for time under water but FlightWingbeatCount is for throughout the record .
FrequencyAverage: FlightWingbeatCount averaged for 5 second, throughout the record
MaxAmplitude: Maximum Amplitude of DynamicZW for each 1-s window
Amplitude Mask: Mask for time when Amplitude of DynamicZW>1.04
Amplitude 1.04: 1-s time windows when Amplitude of DynamicZW >1.04(0/1)
Amplitude 1.32: 1-s time windowswhen Amplitude of DynamicZW >1.32(0/1)
overG =1.04: The threshold of maximum amplitude to define dash
overHz =4: The threshold of WingbeatCount to define dash
over4: Mask for time when wing beat frequency was greater than 4
over4Asc: Mask for time over4 and ascent phase(”DivePhase1”=4)
over4Bot: Mask for time over4 and bottom phase(”DivePhase1”=2 or 3)
over4Des: Mask for time over4 and descent phase(”DivePhase1”=1)
over4PointAsc: over4Asc points on depth wave (1-s)to shown events of 1-s window with wing beat frequency greater than 4/s
over4PointBot: over4Bot points on depth wave (1-s)to shown events of 1-s window with wing beat frequency greater than 4/s
over4PointDes: over4Des points on depth wave (1-s)to shown events of 1-s window with wing beat frequency greater than 4/s
Dash: Mask for time 1-s windows when amplitude>1.04 and wing stroke frequency>4Hz
DashTable; Table for calculation of Dash
DashWave: Not used
DconvertedYW: Not used
Dconverted50: Depth at each point giving acceleration (sampled at 50 Hz or 20 Hz), using average depth change rate at 50 Hz or 20 Hz/
Pursuit: Mask of time dash in bottom or ascent phase
PursuitTable: Table for dash
PursuitWave: Dash event on depth wave (1-s) to show when dash occurred during the dive
VeDBA: VeDBA of DymanicXW, YW, ZW at 20 or 50 Hz
averageVeDBA: average VeDBA in 1-s window
AscentMask: Mask for time when depth change rate (/second) was negative
AscentPhase1: 80% of maximum depth of a dive to the surface
AtoD : Mask for time of 「AtoDChangePoint」(0/1)
AtoDChangePoint: the point when change ascent (depth change rate was negative) to descent(depth change rate was positive)
BottomAscent: Not used
BottomDurationTable: Table for calculating the duration of bottom phase
BottomPhase1: Mast for time bottom phase
ChangeDirection: The points when birds changed direction from descent to ascent or ascent to descent, excluding points of the maximum depth
ChangeDirectionCount: The number of the points when birds change direction for each dive deeper than 5 m
ChangeDirectionPoint: 1-s windows when there were ChangeDirections (0/1)
ChangeDirection5m: The points when birds changed direction from descent to ascent or ascent to descent, excluding points of the maximum depth for dives deeper than 5 m
Depth: Raw depth data (1-s)
D1: 0/1, Depth ≧ 1 m =1, <1 m =0
D: Corrected depth
DepthChange: Depth change rate(m/s)
DescentMask: Mask for time when DepthChange was positive
DescentPhase1: Mask for descent phase
Dive: Table for calculating dive parameter
DiveID: ID of dives
DiveMask: Mask for time diving
DivePhase1: Phase (1 for decent,2 for DeepBottomdepth bottom phase deeper than 80% of maximum depth, 3 for ShallowBottom, bottom phase but shallower than 80% of maximum depth, 4 for ascent), 2+3 = bottom phase
DiveShapeTable: Table for the number of ShallowBottom per dive
DtoAChangePoint: The point when bird changed direction from descent to ascent (positive to negative descent rate)
ShallowBottom: ShallowBottom(DivePhase1=”3”) for calculating DiveShapeTable
PhaseChangeTable: Table showing start and end time of bottom phase for each dive
PhaseDurationTable: Table showing duration of each phase
PreChangeDirection: The points of the change from descent to ascent or ascent to descent for making ChangeDirection
Sur: Surface time
Sur1: Not used
Sur2: Not used
Temp: Temperature (1-s)
Undulation: ChangeDirection but excluding those ChangeDirection occurred in the previous 3 seconds.Not used.
UndulationPoint: Mask for time with Undulation
ParameterAt5mTable: Table showing body angle, wing stroke frequency and depth change rate at 5 m depth.
ParameterAt10mTable: Table showing body angle, wing stroke frequency and depth change rate at 10 m depth.
Point5mTable: Table showing points (time ) nearest to 5 m for calculating ParameterAt5mTable.
Point10mTable: Table showing points (time ) nearest to 10 m for calculating ParameterAt10mTable.
Methods
We deployed the depth-acceleration data-logger (ORI400-D3GT, 9.0 g, 12 mm diameter×51 mm, Little Leonardo, Japan) on the back of Rhinoceros Auklets rearing chicks at Teuri Island. The sampling interval was 1 second for depth and 0.02 s (50 Hz) or 0.05 s (20 Hz) for 3-axis acceleration; sway (X, left-right), surge (Y, tail-head), and heave (Z, dorso-ventral). We retrieved depth-acceleration loggers from 8 of 8 birds in 2012, 8 of 8 birds in 2013, 10 of 11 birds in 2019, and 8 of 8 birds in 2020. Because of malfunction or battery shortage in some devices, we finally collected depth-acceleration data from 26 birds. Here are the Igor files. You can see data and calculation processes using Igor software.
We defined dives as depth greater than 1m considering the accuracy of the depth sensor (0.5m), “dive duration” as the time between the previous time the bird first attained 1 m and the following time it last attained 1m, “dive depth” as the maximum depth during each dive, and “surface time” as the time between the end of dives to the start of the next dives. We defined “descent” phase as the time from the start of the dives to the time when birds attained 80% of dive depth, “ascent” phase as the time between the last time when birds attained 80% of maximum dive depth and the end of dive, and “bottom” phase as time from the end of descent phase to the start of ascent phase as in Kuroki et al. (2003). Rhinoceros Auklets often make “rotations” where they switch from ascent to descent and from descent to ascent with a depth change rate of greater than 0.5 m s-1 (Kuroki et al. 2003). We typed dives with dive depth < 5 m as “shallow-type”, those > 5 m, with no rotation and proportional bottom time smaller than 50% of dive duration as “V-type”, and those deeper than 5 m, with no rotation and the proportion of bottom time greater than 50% as “U-type” referring to Lescroël and Bost (2005), Pütz and Cherel (2005), and Halsey et al. (2007). Dives > 5 m and with these rotations were typed as “W-type”.
During the descent phase, breath hold divers are expected to regulate body angle and depth change rate to maximize the proportion of foraging time at foraging depths by minimizing the transit time but also may search for prey (Wilson et al. 1996). To characterize the behaviour during descent, we measured body angle, descent rate (depth change per second), and wing stroke frequency (number of wing strokes per second, see next section) using depth and acceleration data. The body acceleration reflects both slow changes in the body angle and the dynamic/fast movement of the body (Yoda et al. 2001). Low frequency component of the acceleration was separated by low pass filer using Ethographer (Sakamoto et al. 2009) on IGOR Pro ver. 8.03 (WaveMetrics, Lake Oswego, USA). As the attachment position of acceleration data-logger varied among individuals, we set the critical frequency of low pass filter for each bird. The mean values of the critical frequency were 2.2 ± 0.6 Hz for tail-head (surge, Y) and 1.8 ± 0.8 Hz for dorso-ventral (heave, Z) accelerations. The fast component was derived by subtracting the low frequency component.
Body angle (θ) was calculated from the low frequency component of surge (YL, Fig. 2 a, b) as arcsinYL and incorporating attachment angle of each bird that was the body angle when the birds were sitting on the water (Watanuki et al. 2003). We compared descent body angle, descent rate, and swim speed at the 1 s-window closest to 5 m and 10 m depths between prey regimes. The body angle of >90° was assumed to be 90°. 1-s windows with the body angle of < 0° (7.7% and 7.2% of all windows for 5 m and 10 m depths respectively) were excluded from the analyses as these could be measurement errors. As the angle of trajectory was almost the same as the body angle when Rhinoceros Auklets are descending (Watanuki et al. 2006), swim speed can be estimated as r/sin θ where r was the descent rate (m s-1). Speed values faster than 2.5 m s-1 were unreliable (Watanuki and Sato 2008) and excluded from the analyses (3.5% and 3.6% of windows with speed data for 5 m and 10 m depths, respectively). Dynamic component of the heave (dorso-ventral, Z) acceleration reflects up-down body movement in association with wing stroke. The number of local minimum of the dynamic component of heave acceleration (Fig. 2 c inserted) in each 1-s window was defined as “wing stroke frequency”. The maximum amplitude of dynamic component of heave in each 1-s window was measured using IGOR (Fig. 2c). Rhinoceros Auklets stroked wings by 2-3 Hz while they were cruising in the descent phase (Watanuki and Sato 2008, see Fig. 2c). Wing-propelled seabirds often stroke wings fast during dives and these are assumed to relate to the prey chase (Ropert-Coudert et al. 2006). We categorize 1-s windows with stroke frequencies greater than 4 Hz (mean + 2 * SD of the frequency in 1-s window excluding those with no stroke, Supplementary Material 3a) and the maximum stroke amplitude greater than 1.04 g (mean + 2 * SD of the maximum amplitude in 1-s window excluding those with 0 amplitude) as “fast/strong stroke windows”, then we defined a series of the fast/strong stroke windows as “fast/strong stroke event” (Fig. 2d, e). The fast/strong wing stroke events at the start of descent could be acceleration phase to approach against buoyancy to the prey aggregation. In effect, we observed fast/strong stroke events in the descent phase mostly at the start of dives (<2 m depth) (Supplementary Material 4a). In Rhinoceros Auklets, the quick change of the depth (one of the indicators of prey chase) was observed mainly in the bottom and ascent phases (Kuroki et al. 2003) and the attack scars on the prey fish brought back to the chicks are mostly observed underside of the fish (Burger et al. 1993); indicating that they possibly chase individual prey in bottom/ascent phases. The occurrence of fast/strong wing strokes during the descent (Supplementary Material 4a) and the bottom/ascent phases (Supplementary Material 4bc), therefore, were analyzed separately. Maximum amplitude in 1-s window can be biased to be lower for acceleration sampled at longer intervals. To check this potential bias, we put sampling frequency (high, 0.02 s interval or low, 0.05 s interval) as potential explanatory factor when we analyzed the effects of regime on the duration and frequency of fast/strong stroke events.
Usage notes
IGOR Pro ver. 8.03 (WaveMetrics, Lake Oswego, USA) for the .pxp files. Txt files are provided for accessibility.