Accurately estimating the proportion of birds at collision risk height forms a key part of assessing potential collision risk at offshore wind farms. Recent advances in LiDAR and digital aerial imaging offer the potential to collect precise estimates of the altitude of birds in flight. We trialled LiDAR and digital aerial photography as an approach to measuring the flight heights of seabirds in the Outer Forth and Tay Estuaries and carried out an exercise to validate measurements of flight height gained from LiDAR. The validation exercise demonstrated that the height of birds in flight could be measured using LiDAR to an accuracy of within 1 m. This compares very favourably to other approaches used for measure seabird flight height.
We successfully collected flight height information on 2,201 birds of which 806 were believed to be black-legged kittiwakes and 377 were identified as northern gannets. These data were used to derive continuous flight height distributions. We also demonstrate how data can be used to plot spatial patterns in seabird flight heights which may be of use for the purposes of marine spatial planning. Based on our experiences, we provide recommendations for the best practice in the use of LiDAR to collect seabird flight height data as part of future studies.