Long-term monitoring of bird migration across the North and Norwegian Seas

Renewable energy developments are expanding offshore in order to meet the world’s energy demands, and floating structures permit previously undisturbed areas to be utilised. As a result, there are growing concerns over impacts on migrating birds, however, very little is known about the amount, timing, or position of offshore migration due to the challenges involved in obtaining such data. Long-term monitoring of offshore bird migration is necessary to be able to discriminate inter-annual variability from temporal trends in migration patterns, as well as to capture how migrating species are responding to offshore human developments and climate change.

Here we summarise the sensor and non-sensor-based approaches that are suitable for monitoring offshore bird migration in the long-term including weather and avian radars, biologging, acoustics, laser scanners, camera technology, and citizen science. Each of these sensor-based and observational-based approaches come with their own strengths and weaknesses in terms of, for example, their spatial and temporal scale and resolution. Biologging, avian radar, and satellite imagery would provide the better offshore coverage, but weather radar and citizen science data are readily available, and if combined, could provide useful information on species-specific numbers of birds migrating towards the sea. We outline a plan including core activities for long-term monitoring of bird migration across the North and Norwegian Seas, including a network of weather radars, network of offshore radio telemetry, citizen science data, and collating information from avian radars at sea. We also propose research and development activities which require piloting, but which could provide important data offshore. These activities include analysis of satellite imagery, network of offshore acoustic monitoring, and utilising LiDAR off-shore. All listed R&D activities provide offshore data on bird migration at different temporal and spatial scales and resolution as well as different levels of key information on flight behaviour. If successfully tested, these R&D activities should become part of the core activities.