Mercury contents in blood and feathers of Streaked Shearwaters

Abstract

Feathers of birds are used for monitoring mercury pollution. We measured total mercury contents ([Hg]) in the blood cells and feathers of 32 adult Streaked Shearwaters Calonectris leucomelas captured at their nesting site during the chick-rearing period. Males had higher [Hg] than females in their blood cells and in body feathers growing at the time of blood-sampling, but not in the chest feathers or in the innermost primary feathers (P1) that are replaced possibly during the early breeding period and in the migration/wintering period, respectively. The growing body feather [Hg] depended linearly on blood cell [Hg], but P1 [Hg] and outermost tail feather (R6) [Hg] did not. Levels of [Hg] in chest feathers and growing body feathers were higher than in P1, and lowest in R6. These results indicate that [Hg] of molting feather is balanced with that of the blood [Hg] and that feather [Hg] reflects seasonal changes in the excretion of mercury through molting, and possibly through egg-laying. The lack of significant correlations between [Hg] of the feathers that were replaced during the separate periods may indicate that there is little consistency of feather [Hg] of individuals across the periods.