Sexual difference in heavy metal contamination in the liver of tits Parus in winter

Abstract

Although tit Parus species are considered suitable as biomonitors for local contamination, sexual differences in their accumulation of heavy metals have not been studied. Here I present data on the concentration (mg kg-1 dry weight) of cadmium, copper and zinc in the liver of adult Marsh Tits P. palustris, Great Tits P. major and Blue Tits P. caeruleus caught within a restricted area in central Norway during the winters of 1993-99. The mean concentration of cadmium was slightly higher in adult males than adult females each winter, and males of all the species had significantly higher mean concentrations of cadmium, copper and zinc over the years. The sexual differences may be associated with different metabolic rates in the two sexes.