GPS tracking brings new precision to determining the flight routes and behaviour of birds in the joint offshore wind farm project of Metsähallitus and Vattenfall in Korsnäs. The new study complements the birdlife surveys that have continued since 2021 and provides valuable information for environmental impact assessment.
Extensive birdlife surveys have been carried out in connection with the Korsnäs Offshore Wind Farm project since 2021. The surveys have focused particularly on monitoring spring and autumn migration, observation of resting birds and mapping of nesting birds. Observations have been made both on the mainland and in the sea area.
In 2025, the studies expanded further. In March, bird mappings made from a small aircraft were launched with the University of Aarhus. The current GPS-tracking-based study aims to provide a more accurate picture of bird movement and behaviour in and around the project area. Avescapes Oy, which specialises in bird expert services, is responsible for the GPS tracking.
GPS tracking focuses on providing accurate information on the movements, feeding areas and flight paths of the lesser black-backed gull and the razorbill. The lesser black-backed gull is classified as an endangered species under the EU Birds Directive. The razorbill, classified as Least Concern, is another important species nesting in the surroundings of the project area.
“GPS tracking provides detailed information on flight routes and altitudes, the time spent in feeding areas and the diving depths of the razorbill, among other things. We also get a picture of moving patterns outside the nesting season,” says Heini Passoja, Project Manager at Metsähallitus.
The study uses transmitters suitable for and as safe as possible for bird species. A GPS-UHF transmitter is attached to the feathers of the diving razorbills, and it will detach naturally in connection with the moult. A harness-mounted GPS-GSM transmitter, commonly used in gull studies, is installed on the back of the lesser black-backed gulls, which can produce data for several years. The installation of the transmitters requires catching the birds. Its timing and methods are designed to minimise disturbance to nesting colonies and individual birds.
Birdlife surveys are an essential part of information gathering related to the environmental impact assessment of Metsähallitus’ and Vattenfall’s offshore wind farm project. They help to identify the ecological characteristics of the area and ensure that the ranges and habitats of birds can be adequately considered in project development.