This advanced citizen science project requires knowledge of the common native breeding bird species and participation over several years. Twice a year, the participants count all birds seen and heard at fixed points. The total of all counts is then used to calculate population trends. The available data is currently sufficient to determine meaningful trends for about 65 bird species – from 1998 onwards. Sadly, the results show how important it is to monitor our breeding bird world: more than half of the species studied are declining in numbers, whereas only about one fifth of all species show an increase. The other bird species are currently stable.
Further information and results can be found here: https://www.birdlife.at/page/monitoring