The effect of age group, sex, and body condition indices on the concentration of heavy metals (Pb, Cd) in Mallard's feather

Mallard (Anas platyrhynchos) is a suitable biological model for studying ecotoxicology in heavy metals among all the water birds. When it comes to choosing an appropriate organ, using feathers is a common biological indicator and non-lethal (non-destructive) technique in the evaluation of heavy metals pollution. Having considered the contradictory results about the variation of heavy metals concentration due to body indices, age, and gender conditions, the present study was designed. Accordingly, the sampling was accomplished in autumn and winter 2019-2020, capturing 30 mallards based on applying the Duma method in the Fereydunkenar region. The individuals were first identified regarding the beak and plumage into male/female as well as adult/immature species and then the body indexes of tarsus length, wing length, tail length, head length, body length, and body weight were measured. The digestion was conducted (putting a weight of 0.5 gr of the breast feathers into nitric acid and hydrogen peroxide) and heavy metals concentrations were afterward measured using atomic spectroscopy, MP-AES 4100 model. The results indicated there were no significant differences in heavy metals concentration referring to gender status (Cd: P= 0.558, Pb: P=0.215) and maturity (Cd: P= 0.673, Pb: P=0.214). Likewise, the body condition parameters including tail length, body length and body weight had also no significant effect on Cd (P=0.385; P= 0.299; P= 0.547) and Pb (P=0.554; P= 0.185; P= 0.337) concentrations, respectively. Concluding the results, the current study indicates Pb and Cd concentrations in Mallard’s breast feathers are not dependent on gender, age groups, and body condition indices. However, long-term studies can better clarify these effects and mechanisms in bird species feathers.