1 Methodology

Naturaconsta provided the raw observations made during the Suivi Hivernal des Oiseaux Communs (SHOC). It consists of 9445 observations during 420 visits over 73 sites and 125 species. The birds are counted during a walk along at a transect. The length of the transects range from 2.62 to 6.4 km. The distance between the bird and the observer is recorded in four classes: “0-50m”, “50-100m”, “>100m” and “passing”.