Wintering Great Cormorant roost counting
The simultaneous count of Great Cormorant roosts in mid-January provides the most accurate estimation of the total number of the wintering individuals and a precise description of the wintering range of the species.
Coordinated roost census allows to count the entire population, while day counts systematically underestimate it (as birds are scattered).
This census is conducted in the same way some years in many countries and for establishing results across the range of the species.
For more information on this monitoring, download the manual counting.