THE ROMAN SNAIL (HELIX POMATIA LINNAEUS, 1758) IN NORTHERN MAZOVIA

ABSTRACT: In northern Mazovia Helix pomatia L. is rare and found only in some anthropogenic habitats; in the 55 sites studied its frequency was 9%. Neither abundance nor biomass and size structure of its populations de-parted from those reported from other regions of Poland. Its rarity, the scattered localities and its absence even in apparently optimum natural habitats confirm the earlier view that it is an introduced species in the re-gion. Comparison with the earlier data indicates no expansion tendency within the last 35–40 years. The esti-mated area occupied by the species in the whole Mazovan voivodeship does not exceed 50 km2. These single populations, even when dense, may be threatened because of their isolated character; they should not be ex-ploited and deserve protection