Mercury Content in Feathers of Swedish Birds from the Past 100 Years

Abstract

By means of activation analysis the mercury content in feathers of the following bird species has been studied: Phasianus colchicus, Perdix perdix, Lagopus lagopus, Falco peregrinus, Haliaetus albicilla and a small material of Emberiza calandra, Asio otus, Strix aluco, Buteo butec, and Circus cyaneus. The material, drawn from skins and mounted specimens in Swedish collections, and from living or freshly killed birds, covers a period of more than the past hundred years. Possible sources of post mortem contamination of the specimens are discussed. Allowance being made for such cases, the activation method as applied to the analysis of mercury in feathers appears reliable: a) Roughly constant Hg levels are encountered in each of the investigated species during the period 1840-1940, although with considerable variation between the species. b) Differences of position within the food chains seem to be the main cause of the differences in Hg level between species. c) A well-documented increase of Hg concentration, amounting to at least 10-20 times the previous level, appears in the 1940's and 1950's, with some time-differences between the species in the available material. The appearance of increased mercury accumulations in birds mainly in the beginning of the 1940's indicates that alkyl-Hg compounds used as seed dressings are chiefly responsible for that increase. Pe3IoMe