AVIS-IBIS

Birds of Indian Subcontinent

Geographic and Seasonal Variation in Mercury Exposure of the Declining Rusty Blackbird (Variación Geográfica y Estacional en la Exposición al Mercurio de la Especie en Disminución Euphagus carolinus)

Publication Type:Journal Article
Year of Publication:2010
Authors:Edmonds, ST, Evers, DC, Cristol, DA, Mettke-Hofmann, C, Powell, LL, McGann, AJ, Armiger, JW, Lane, OP, Tessler, DF, Newell, P, Heyden, K, O'Driscoll, NJ
Journal:The Condor
Volume:112
Issue:4
Date Published:2010
ISBN Number:00105422
Keywords:Euphagus, Euphagus carolinus, Icteridae, Turdidae, Turdus, Turdus maximus, Turdus merula, United States
Abstract:Abstract. 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.
URL:http://www.jstor.org/stable/10.1525/cond.2010.100145
Short Title:The Condor
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