Recent evidence suggests that mercury exposure has negative effects on the health of songbirds, and species that forage in wetlands may be at a greater risk of bioaccumulation of mercury than are those of other habitats. We examined mercury concentrations in blood and feathers from the wetland obligate and rapidly declining Rusty Blackbird (Euphagus carolinus) from five regions across North America: three wintering areas in the contiguous United States and breeding areas in the western boreal forests of Alaska and the Acadian forests of northeastern North America. In blood, mercury concentrations in Rusty Blackbirds from the Acadian forest (geometric mean 0.94 µg g-1; n = 59) were >3× than in those from Alaska (0.26 µg g-1; 107). Wintering birds had blood mercury levels approximately an order of magnitude lower than those of breeding birds (0.07 µg g-1; 332). In feathers, mercury concentrations in samples from the Acadian forests exceeded published minimum levels for adverse effects on birds (8.26 µg g-1; 45) and were 3× to 7× those observed from the other regions. The mercury concentrations we report in blood and feathers of the Acadian forest population of the Rusty Blackbird are among the highest reported for wild populations of passerines at sites without a known local source of mercury. Mercury should be considered as a potential contributor to the species' dramatic population decline in New England and the Maritime provinces and in other areas where bioavailability of mercury is high.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 112 • No. 4