DOI: 10.5061/dryad.1ds1q
title: Data from: Three dimensional tracking of a wide-ranging marine predator: flight heights and vulnerability to offshore wind farms

description: A large increase in offshore wind turbine capacity is anticipated within
 the next decade, raising concerns about possible adverse impacts on birds
 as a result of collision risk. Birds’ flight heights greatly influence
 this risk, yet height estimates are currently available only using methods
 such as radar- or ship-based observations over limited areas. Bird-borne
 data-loggers have the potential to provide improved estimates of collision
 risk and here, we used data from Global Position System (GPS)-loggers and
 barometric pressure loggers to track the three-dimensional movements of
 northern gannets rearing chicks at a large colony in south-east Scotland
 (Bass Rock), located &lt;50 km from several major wind farm
 developments with recent planning consent. We estimated the foraging
 ranges and densities of birds at sea, their flight heights during
 different activities and the spatial variation in height during trips. We
 then used these data in collision-risk models to explore how the use of
 different methods to determine flight height affects the predicted risk of
 birds colliding with turbines. Gannets foraged in and around planned wind
 farm sites. The probability of flying at collision-risk height was low
 during commuting between colonies and foraging areas (median height 12 m)
 but was greater during periods of active foraging (median height 27 m),
 and we estimated that ˜1500 breeding adults from Bass Rock could be killed
 by collision with wind turbines at two planned sites in the Firth of Forth
 region each year. This is up to 12 times greater than the potential
 mortality predicted using other available flight-height estimates.
 Synthesis and applications: The use of conventional flight-height
 estimation techniques resulted in large underestimates of the numbers of
 birds at risk of colliding with wind turbines. Hence, we recommend using
 GPS and barometric tracking to derive activity-specific and spatially
 explicit flight heights and collision risks. Our predictions of potential
 mortality approached levels at which long-term population viability could
 be threatened, highlighting a need for further data to refine estimates of
 collision risks and sustainable mortality thresholds. We also advocate
 raising the minimum permitted clearance of turbine blades at sites with
 high potential collision risk from 22 to 30 m above sea level.
description: Gannet GPS, air pressure
 and temperature telemetry dataZip file contains (1)
 GPS data collected by tracking adult breeding northern gannets from Bass
 Rock at either 2 minute or 1 second intervals. File names correspond to
 logger deployment day and bird ID. Fields: TIME in UTC; LON = longitude;
 LAT = latitude; GPS_ALT = height recorded by GPS (m); GPS_SPD = speed
 recorded by GPS; TRIP = foraging trip number; DIST = distance travlled
 since previous fix (m); SECS = interval elapsed since previous fix (s);
 CALC_SPD = speed derrived from previous two varibales (m/s); COL_DIST =
 distance by sea from colony (km); STATUS = in colony (COL), in flight
 (FLIGHT) or on water (WATER). (2) ambient pressure and temperature data
 collected using loggers deployed on adult breeding northern gannets from
 Bass Rock. File names correspond to logger deployment day and bird ID.
 Fields: TIME in UTC; P = pressure (Pa); T = temperature
 (C).P_T_GPS.zip