Mercury is one of the most serious environmental contaminants, which can be found as inorganic and organic compounds in air, soil and water. Studies have shown that birds that access to these three sources are more at risk than other group of animals. Birds absorb methylmercury directly from water, air and from eating smaller organisms that contain methylmercury. Greater amounts of methylmercury are found in higher food chain which tend to eat other small birds and organisms. In present study, the accumulation of total mercury (Hg) were measured in tail and breast contour feathers of five museum species of owls that are distributed in Iran; Sistan (8 individuals), Isfahan (10 ), Mazandaran (7), Azarbayjan (6), and Khuzestan (9). All museum samples have been collected and skinned from the same provinces after 1995. Using AMA 254 atomic absorption mercury analyzer, concentrations of mercury (ppb=nanograms Hg/g dry weight) was analyzed and compared to the body size of studied species. Results show that breast contour’s feather showed higher concentration of mercury than tail. Body size for owls was classified in 3 ranges: small (<25cm), medium (between 25cm and 40cm), large (>40cm). The highest levels of Hg concentrations have considered in small owls with 1475 ppb. Medium owls have shown intermediate bioaccumulation with 1078 ppb absorption and least concentration for large owls with 838 ppb. The negative relation was appearing between body size of owls’ species and Hg levels. Paired samples t-test showed that the concentrations of mercury were significantly higher (p<0.001) in the breast feathers than tails. Breast contour feathers had 2.6 times as much more than tails. Other studies in Iran showed that the concentrations of mercury were significantly higher (p<0.001) in the tail feathers (0.86 ppb) than secondary (0.45 ppb). It seems that usage of breast contour feathers are better for heavy metals monitoring.

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