The Italian seabirds dataset consists of data from different sources. Counts of wintering birds were extracted from the database of the International Waterbird Census (IWC) monitoring scheme coordinated by ISPRA at the national level. As far as nesting seabirds are concerned, the data come largely from other ISPRA database and to a lesser extent from external sources such as National Parks/Marine Protected Areas monitoring schemes, ISPRA collaborators and (in 2017 only) from CNR monitoring activities.

As far as the spatial coverage is concerned, it partially or fully covers the three marine sub-regions and the criteria of the "new decision", with the exception of criterion D1C1 (bycatch), for which no data are available. In particular the data about wintering birds and those referring to breeding Ichthyaetus audouinii can be considered complete at the national level.

Breeding birds estimates are shown as minimum and maximum estimates of the breeding population ("breeding pairs"); those of wintering birds are counts (individuals) annually obtained at fixed coast sections during the IWC project. The coordinates associated to wintering birds refer to wetland complexes; data of nesting birds are referred to a square grid of 50x50 km, since they are considered as "sensitive data".