Winter is one of the crucial periods of the bird’s year-round life cycle. Fat reserves in birds are prone to wide range of factors, with weather conditions and bird’s social status being two major ones. In our study we analysed the variation in fat reserves in birds with stable, constant access to food resources in three most common Europenian wintering species: great tit Parus major, blue tit Cyanistes caeruleus and greenfinch Chloris chloris. The highest mean value of fat score was found in greenfinch, whereas in both species of tits these values were significantly lower. For all three species the amount of fat reserve was correlated with the same factors: negatively with mean daily ambient temperature, and with the course of the daytime as well as the season-site index influenced the fat score in all the species. Contrary to many previous surveys we did not find the realation of fat score level and the individual domination status which is probably linked to the abundance of food in catching sites.