Effective conservation of migratory birds requires gathering information about their population trends, typically acquired using migratory bird counts. This often happens at migratory bottlenecks, where people with binoculars or telescopes count birds as populations pass by. Researchers looked at counts of steppe eagles and black kites at two bottlenecks and compared them with GPS tracking data to verify the conservation value of the data. The authors found that the migration bottleneck in Eilat, Israel is not a good location for understanding population trends of endangered steppe eagles, since there was high variability in migration route and most of the population didn’t pass within view of the counting station. In contrast, Batumi, Georgia was a good location for counting black kites. Bird counts are important for keeping track of population trends and identifying which species and landscapes may need protection. This study highlights the value of combining bird count information with GPS tracking to ensure the accuracy of data from bird counts.    

Efrat, R., Lehnardt, Y., Berkowic, D., Dor, R., Bragin, A.E., Bragin, E.A., Katzner, T.E., and Sapir, N., 2025, Using GPS tracking data to validate the conservation value of bird migration counts: Biological Conservation, v. 302, 110959. https://doi.org/10.1016/j.biocon.2024.110959