The potential thresholds refer to the intensity of bird migration, which can be measured by radar. Data on nocturnal bird migration in the German Exclusive Economic Zone of the North Sea and Baltic Sea have so far been collected almost exclusively by "ship radar". However, this radar system does not meet the technical requirements to implement threshold-based avoidance measures in the offshore area. Automated real-time detection of bird migration is fulfilled by radar systems specialised in bird detection.
So far, however, it is not known to what extent there is a direct comparability between the results of such radars and the measurements of marine radars. The aim of the study was to check the concordance between the migratory intensities detected by a marine radar and those of a bird detection radar. The main question was whether there is a high degree of concordance between the radar systems with regard to threshold violations. This question would be of central importance for the radar-based implementation of threshold-based measures.
Welcker, Jorg. Vergleichbarkeit verschiedener Radarsysteme zur Erfassung des Vogelzugs. Husum, BioConsult SH, 2021 (in German only)