1 Methodology

Naturaconsta provided the raw observations made during the Suivi Temporel des Oiseaux Communs (STOC). It consists of 52726 observations during 6446 visits over 123 sites and 214 species. The birds are counted during a fixed period at a stationary point. The distance between the bird and the observer is recorded in four classes: “0-25m”, “25-100m”, “>100m” and “passing”. These distance classes were too broad to estimate a distance based detection function. Especially the lack of an upper bound makes this very hard. Therefore, we aggregated all the distances classes into a single class. One observation in the data contain the total number of bird of a given species at a given point and at date.