GNSS navigation interference disrupts telemetry tracking of raptors migrating between Europe and Africa

Global Navigation Satellite System (GNSS) interference in war conflict zones can disrupt wildlife tracking for research and conservation efforts. In 2023 and 2024, we tagged Black Kites Milvis migrans in Moldova and Kazakhstan, respectively, with telemetry loggers, tracked them until September 2025 and found that 20 out of the 24 Black Kites had interfered (erroneous) geographical position fixes. The GNSS interference was obvious mainly in the border area between Ukraine and Russia, in the eastern Mediterranean, the area of the Red Sea and Sudan and was most likely caused by intentional jamming or spoofing or a combination of both influences in areas of war combat operations. In this work, we propose a methodological guide on how to proceed during the primary processing of telemetry data from areas where GNSS interference can be assumed, which allows for relatively easy removal of erroneous position data.