Recoveries of Ringed Red-Footed Falcons (Falco vespertinus) in Germany - An update documentation

Bird ringing is used for a long time for scientific investigation of migration routes and to better understand breeding events as well as population ecological aspects. It is applied as an inexpensive method although the well-known and major disadvantage of bird ringing is the usually low response rate. In the case of rarer species such as the Red-Footed Falcon (RFF), however, this quota could be higher due to the exclusivity and greater attention of observers. Motivated by own field observations of color-ringed RFF south of Brunswick, Germany in 2019 and no clear and comprehensive publication of verified additional recoveries and ringings, we did further research regarding this issue by following methods: 1) Contacting European Bird Ringing Centers and associated projects, 2) Query and comparison of files with the three national German Bird Ringing Stations, 3) Expanded literature research, 4) Evaluating reports in the citizen science platform ornitho.de, 5) Checking websites of ringing projects (in particular satellite tracking programs) and 6) Own observations. Surprisingly, this study revealed 18 recovered RFF ringed in foreign countries (14 Hungary, 3 Italy, 1 Romania (GPS tracked bird)) during migration or post-nuptial pre-migration time. Additionally, 1 RFF that was caught and ringed in Germany was recovered abroad. This result updates and increases the number of recoveries of RFF in Germany compared to the actual published state on the order of 18 (so far none) and on the order of 6 concerning ID-encoded RFF (GPS-bird excluded) compared to documentation state of the three Bird Ringing Centers in Germany (so far 3 at Beringungszentrale [BZ] Hiddensee, 1 at Institut fur Vogelforschung [IfV] Heligoland). Our research and evaluation of raw data succeeded to a 100% identification rate of the birds origin countries (n=18) while the rate of ID-encoded RFF by color ring codes revealed 58.8% (n=10, GPS-bird excluded). The reported-by-observer response rate was 41.2%. Interesting data of about the phenology, age and origin of the RFF recovered in Germany are presented. Questions and considerations about the recent reporting system of ringed birds and the increased numbers of RFF during the last years in Germany are discussed.