The Study of Bird Migration by Radar Part 2: Major Achievements

This is a brief review of the main insights into bird migration provided by radar. Radar is the main tool to study the flight behavior of migratory birds under the influence of environmental factors, i.e., the ecology of migratory flights, ranging from the large-scale pattern of migration in relation to the distribution of land masses, geomorphology, and weather systems down to the variation of flight behavior of single birds in response to leading lines, obstacles, particular atmospheric conditions, and flight phases. Radar has revolutionized research on bird migration. It provides data on the patterns of migration in various geographical areas and is the main tool for studying the reactions of migrants to topographical features and weather, and the variation of flight behavior in time and space under the influence of environmental conditions. It will continue to play an important role, particularly for the analysis of flight and orientation strategies. This review briefly summarizes the major contributions of radar ornithology to our knowledge of bird migration. To limit the reference list I refer to review papers whenever possible. The most comprehensive synopses are [1] for migration as a whole (with an update on migratory strategies in [2]), [3] for radar ornithology, and [4, 5] for weather-dependence of migration. A methodological update is provided in [6].