Data from: Wind, waves, wing loading and the flight energetics of giant petrels

This dataset was used to investigate the relationships between wind,
waves, and flapping rates in giant petrels (Macronectes spp.)
breeding at Bird Island, South Georgia in 2022 and 2023. It is comprised
of hourly GPS positions for 36 northern giant petrels (M. halli) and 42
southern giant petrels (M. giganteus) and contains the unique deployment
ID assigned to each individual bird, and the sex of each individual bird.
Hourly wind speed (km/h) and swell height (m) were extracted from ERA5
hourly data on single levels along the birds' foraging tracks (0.25 x
0.25 degree spatial resolution for wind data, and 0.5 x 0.5 degree spatial
resolution for swell data). Wing flaps per hour were calculated using a
LULU filter to identify peaks in the z-axis of the accelerometer data. The
dataset only contains data for times when the birds were performing
commuting flight as predicted by a Hidden Markov Model used on GPS data in
order to restrict analyses to in-flight behavior. Data points within 20 km
of land around South Georgia were also excluded to remove coastal foraging
performed predominantly by male giant petrels. Generalized Additive Mixed
Models were constructed to analyze how wind speed and swell height impact
flapping rates.