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Pelagic seabirds reduce risk by flying into the eye of the storm

Citation

Lempidakis, Emmanouil et al. (2022), Pelagic seabirds reduce risk by flying into the eye of the storm , Dryad, Dataset, https://doi.org/10.5061/dryad.2z34tmppj

Abstract

Cyclones can cause mass mortality of seabirds, sometimes wrecking thousands of individuals. The few studies to track pelagic seabirds during cyclones show they tend to circumnavigate the strongest winds. We tracked adult shearwaters in the Sea of Japan over 11 years and find that the response to cyclones varied according to the wind speed and direction. In strong winds, birds that were sandwiched between the storm and mainland Japan flew away from land and towards the eye of the storm, flying within ≤ 30 km of the eye and tracking it for up to 8 hours. This exposed shearwaters to some of the highest wind speeds near the eye wall (≤ 21 m s-1), but enabled them to avoid strong onshore winds in the storm’s wake. Extreme winds may therefore become a threat when an inability to compensate for drift could lead to forced landings and collisions. Birds may need to know where land is in order to avoid it. This provides additional selective pressure for a map sense and could explain why juvenile shearwaters, which lack a map sense, instead navigating using a compass heading, are susceptible to being wrecked. We suggest that the ability to respond to storms is influenced by both flight and navigational capacities. This may become increasingly pertinent due to changes in extreme weather patterns. 

Methods

Methods are detailed in the manuscript.

Usage Notes

Summary of Attributes

StormDt: Storm date (UTC) from IBTrACS for each eye location.

StormID: Storm ID from IBTrACS for each storm.

StormID is given in IBtracs codes and corresponds to the storms:

  • 2010240N15142 ->  "Kompasu"
  • 2010243N12146 ->  "Malou"
  • 2010249N24125 ->  "Meranti"
  • 2014260N13135 ->  "Fung-Wong"
  • 2015226N12151 ->  "Goni"
  • 2015249N18142 ->  "Etau"
  • 2017252N14147 ->  "Talim"
  • 2018228N13145 ->  "Soulik"
  • 2018230N13156 -> "Cimaron"
  • 2018239N13159 -> "Jebi"

Date: Date of each hour of observations (UTC).

flghtID: Flight ID of each hour of observations.

StrmLng: Storm longitude for each storm eye location from IBTrACS. 

StormLt: Storm latitude for each storm eye location from IBTrACS.      

StormDirHourly: Storm eye direction of travel for each IBTrACS location.    

HourDate: Date and hour (UTC) for each hour of observations.

Hour: Hour of observations (UTC).

IntPolLng: Interpolated longitude of bird locations based on all longitudes within each hour of observations.

IntPolLat: Interpolated latitude of bird locations based on all latitudes within each hour of observations.

StrmSideHourly: The side at which the storm eye was located for each hour of observations. This is: “West” when the storm eye was located over the Sea of Japan, “JapanWest” when the eye was located over the West side of Japan and over land, “East” when the eye was located over the Western Pacific at the East of Japan and “JapanEast” when the eye was located over the East side of Japan and over land.

BrdSideHourly: Same as “StrmSideHourly” above, but for bird locations.

Spd_m_sHourly: Mean ground speed (m s-1) based on the bird GPS observations per hour.

airspeedHourly : Mean airspeed (m s-1) based on the bird GPS observations per hour.

dstnc_mHourly: Mean geodesic distance (metres) covered by a bird based on the GPS observations per hour.

BirdStormDist: Mean distance (km) between a bird and the storm eye based on all GPS observations and the location of the eye of the storm (IBTrACS), per hour.

BirdLandDist: Mean distance (km) between a bird and land based on all GPS observations and the closest location on land (for each GPS observation), per hour.

ColonyPresence: Binomial variable indicating whether a bird was located at the colony in Awashima Island (“YES”) or not (“NO”).

WindSpeed: Mean wind speed (m s-1) at bird locations estimated using ERA5, per hour.

WindDirHourly: Mean wind direction (°) at bird locations estimated using ERA5, per hour.

flWndAn360Hourly: Mean angle (°) between a bird’s flight headings (GPS) and wind’s directions at the bird’s locations (ERA5), for all GPS observations per hour. This ranges from 0° to 360°, with 0° indicating tailwind, 360° headwind, 90° crosswind coming from the right side of the bird and 270o crosswind coming from the left side of the bird.

flWndAnHourly: Same as “flWndAn360Hourly” but converted to 0°–180°. 0o indicates tailwind,180° headwind and 90° crosswind from either side of the bird. 

RelFlghtStrmDirHourly: Mean bird flight direction in relation to the storm eye’s location for each hour indicating whether a bird travelled straight towards the eye (0°), straight away from the eye (360°), perpendicular straight to the right of the eye (90o) and perpendicular straight to the left of the eye (270°).

RelFlghtStrmDirHourly180: Same as “RelFlghtStrmDirHourly” but converted to 0°–180°. 0° indicates flight straight towards the eye’s location,180° straight away and 90° away (perpendicular) to the left or to the right of the eye.

StrmAngHourly: Mean angle (°) that a bird would have to travel from each current GPS location to fly straight towards the eye’s location, per hour of observations .

RelBrdPosStrmDirHourly: Mean angle (°) between a bird’s locations (GPS) and the direction the storm eye was travelling (IBTrACS), for all GPS locations per hour. This ranges from 0° to 360°, with 0° indicating that a bird was located directly in front of the eye (i.e. the eye was travelling straight to the bird’s location), 360° indicating that a bird was located straight behind the eye (i.e. the eye was travelling straight away from the bird’s location), 90° indicating that the bird was located at the right (i.e. at the East) with the eye travelling perpendicular to the left of the bird (i.e. towards the West) and 270° indicating that the bird was located at the left (i.e. at the West) of an eye, with the eye travelling perpendicular to the right (i.e. towards the East).

BirdPosRelToStormDir: : Same as “RelBrdPosStrmDirHourly” but converted to 0°–180°. 0° indicates that a bird is located straight in front of the direction that the storm eye was travelling,180° straight behind the direction that the storm eye was travelling and 90° perpendicular either to the left or right.

flAsiaAn360Hourly: Mean angle (°) between a bird’s flight headings (GPS) and the closest location on land, for all GPS locations per hour. This ranges from 0° to 360°, with 0° indicating flight straight towards the closest point on land, 360° indicating flight straight away, 90° flight straight to the right of the closest point on land and 270° flight straight to the left of the closest point on land (perpendicular).

FlightDirRelToLand180: Same as “flAsiaAn360Hourly” but converted to 0°–180°. 0° indicates flight straight towards the closest point on land,180° straight away and 90°away (perpendicular) to the left or to the right of the closest point on land.

SampleSize: Number of GPS fixes per hour.

SampleSizeNormalised: Normalised number of GPS fixes per hour. This attribute was estimated by dividing the “SampleSize” of each hour, with the mean sample size of all hours of observations.   

StormLandDist: Geodesic distance (km) between the eye of a storm at a specific hour (IBTrACS) and the closest point on land.

StormDirRelToLand180: Mean angle (°) between an eye’s direction of travel (IBTrACS) and the closest point on land, for all storm’s eye locations per hour. This ranges from 0° to 180°, with 0° indicating a storm eye of the storm travelling straight towards land, 180° indicating an eye travelling straight away and 90° indicating that an eye was travelling perpendicular to the closest location on land either to the left or to the right.

RightOrLeft: This variable is included in the datasets of the agent-based model simulations. It indicates whether an agent was predicted to move to the right of the storm eye, indicated by a value of “1”, or to the left with a value of “0”.

Funding

H2020 European Research Council, Award: 715874

Japan Society for the Promotion of Science, Award: Grants-in-Aid for Scientific Research 24681006

Japan Society for the Promotion of Science, Award: Grants-in-Aid for Scientific Research 16H01769

Japan Society for the Promotion of Science, Award: Grants-in-Aid for Scientific Research 16H06541

Japan Society for the Promotion of Science, Award: Grants-in-Aid for Scientific Research 16K21735

Japan Society for the Promotion of Science, Award: Grants-in-Aid for Scientific Research 21H05294