cis³owska M., Busse P. 2005. Fat reserves and body mass in some passerines migrating in The aim of the present paper is to serve with a huge data set on the fat and body mass of birds that have been caught during the field work of the Operation Baltic since 1983 (earlier data are still not available in a digitalised form). There are given fat score valuations of 38 species and correction factors for the body mass standardisation. Some comments on observed fat scores in species of different migratory habits are added. They should encourage students to continue the research process on a wider scale.