Xenobiotic and essential metals biomonitoring by feathers: molting pattern and feather regrowth sequence in four dominant waterfowl

The variations of some metals including nickel, iron, copper, zink, mercury, lead, and cadmium were examined in wing primaries of dominant wintering waterfowl in international wetlands near the Caspian Sea's southern basin, including graylag goose (Anser anser), mallard (Anas platyrhynchos), pintail (Anas acuta) and common teal (Anas crecca). The core question of this study is the determination of primary feathers arrangement in molting, growth pattern effects and its performance on the bioaccumulation of contamination and determining the best growth feather location for biomonitoring purposes. The metals content, overall trend lines, and correlations among the 10 primary wing feathers were compared, and molting effects and feather regrowth were investigated. The metals were measured by AMA 254 Advanced Mercury Analyzer and inductively coupled plasma atomic emission spectroscopy. In all the species, almost all primaries have simultaneous regrowth, but their growth continues irregularly. There were significant differences in metal differences with juvenile waterfowl that did not experience molting compared to adults that do. The results showed that all of the species (except common teal) have experienced molting due to the difference of Hg concentration between adults and juveniles. It seems unplanned or random selection of bird's feathers to achieve pollutants monitoring purposes by previous studies' methods can now be challenged. In order to examine the linear changes of some elements (mercury, copper, and zink), it is recommended to collect samples of middle primaries, while samples of the feather growth locations to study the linear changes of nickel, iron, lead, and cadmium are necessary.