Analyses of 69 collections of the tawny owls' pellets (28 containing over 100 prey items) revealed the presence of three rare mammal species on several localities in central and northeastern Poland: Muscardinus avellanarius (11 localities), Sicista betulina (3), and Crocidura leucodon (2). The obtained results supplemented data on their distribution close to the borders of continuous ranges. The Kampinos Forest was confirmed as important refuge of M avellanarius, and the lower basin of the Biebrza Valley for both M. avellanarius and S. betulina.