The aim of this study was to determine the concentration of 12 elements in the livers of 14 different species of birds from East Poland, as well as factors affecting their accumulation. The greatest amount of Cd was found in the livers of woodcocks. Analyses showed that Cd accumulation in the liver was associated with the consumption of soil invertebrates. Our data show that some corvids were the most vulnerable to the effects of lead bullets. In the livers of some of them, lead levels exceeded 6 mg/kg. Expansion of food niches in the direction of omnivorous species limited the accumulation of Hg and Cu, which resulted in low concentrations of these elements in omnivorous species. On the other hand, deep specialization in catching fish favored accumulation of Hg and Cu. Accumulation of Mg and Mn may occur due to foraging in wetlands. Liver concentrations of Se that may result in sublethal effects and reproductive impairments were found in grey herons, cormorants, and mallards.