Counts were carried out using the IPA method described in Blondel et al (1970), IBCC (1977) and Blondel et al (1981). According to the protocol, two passes with a twenty-minute data collection per listening point were carried out each year (end of April and beginning of May for early breeders and end of May and beginning of June for late breeders), in the morning, in good weather and no wind. A value of 1 is assigned to a species for any visual or auditory contact with a pair, an occupied nest, a family, an adult carrying food, or a singing male, and a value of 0.5 is assigned to a single non-singing bird. The values per species and per passage are added up to a maximum index of 5. For each listening point, the best index of the two passages was retained for the analysis. Data collection was carried out between 6.30 and 9.00 a.m. during the first pass and between 6.00 and 9.00 a.m. during the second. For more details see Michelat et al. (2023) full reference below. IPA distribution according to years and habitats Forest Marshes and peatbogs Dry grassland Water body Meadows and pastures River 1998 0 0 0 0 0 15 1999 0 0 0 0 0 20 2006 0 0 0 0 0 20 2007 0 0 19 0 0 20 2008 8 35 0 12 5 0 2009 0 35 0 0 0 0 2010 8 0 0 12 5 0 2011 0 0 0 0 0 20 2012 0 0 19 0 0 20 2013 8 36 0 12 5 0 2014 0 36 0 0 0 0 2015 8 0 0 14 5 0 2016 0 0 0 0 0 20 2017 0 0 19 0 0 20 2018 8 36 0 14 5 0 2019 0 36 0 0 0 0 2020 8 0 0 14 5 0 FILE DESCRIPTION IPA_localisation.txt id, IPA Id: digit 1-2, habitat; digit 3-4, IPA number within the habitat habitat iddom, second ID in clear commune lieu, locality long, longitude lat, latitude alt, altitude rnr, Réserve naturelle régionale (yes/no) natura, Natura 2000 area (yes/no) apb, Arrêté de protection de biotope (yes/no) Observations.txt IPA values idipa, IPA Id: digit 1-2, habitat; digit 3-4, IPA number within the habitat an, year column 3 to 144 species names (used to join with the table Species_statuts.txt) Species_statuts.txt id, id number nom, common name (in French) nomlat, latin name nomab, abridged name (used to join with the table Observations.txt). lre, European red or orange list (LR-CR, red list, critically endangered: LR-EN, red list, endangered; LR-VU, red list, vulnerable; LO-NT, orange list, nearly threatened) lre27, red or orange list in the European Union (27 countries) lrf, French red or orange list lrfc, red of orange list in Franche-Comté lr, present on at least one of 4 red lists lo, present on at least one of 4 orange lists lro, present on at least one of 4 red or orange lists hn, habitat (national) hr, habitat (regional) pref, preference mig, migratory status SUPPLEMENTARY MATERIAL IPA_distribution_map.png Map of the IPA locations in the Drugeon basin. The red line indicates the limits of the Natura 2000 Special Protection Area. BD ORTHO © cartographic background kindly provided for research by IGN. Graphics.zip Boxplots BIBLIOGRAPHY Blondel (J.), Ferry (C.) et Frochot (B.) 1970. - La méthode des indices ponctuels d’abondance (IPA) ou relevés d’avifaune par « station s’écoute ». Alauda, 38 : 55-71. Available here Blondel (J.), Ferry (C.) & Frochot (B.) 1981. - Points counts with unlimited distance. Studies in Avian Biology, 6 : 414-419. Available here IBCC 1977. - Censuring breeding bird by IPA method. Polish Ecological Studies, 3 : 15-17. Michelat, D., Dupuis, O., Vaniscotte, A., Giraudoux, P., 2023. Quarante ans d’évolution du peuplement d’oiseaux nicheurs dans le bassin du Drugeon, Franche-Comté, France. Alauda, 91 (2) : 1-80.

Data collection, for a fraction, has been supported by DREAL Bourgogne Franche-Comté.