Mercury and other element exposure in tree swallows nesting at low pH and neutral pH lakes in northern Wisconsin USA.
The primary objective of this study was to determine whether tree swallows (Tachycineta bicolor) demonstrate similar responses to lake pH and mercury (Hg) contamination in northern Wisconsin as do common loons (Gavia immer). Similar to common loons, Hg concentrations in the blood of tree swallow nestlings were higher, Hg concentrations in eggs tended to be higher, and egg size tended to be smaller at low (<6.2) pH lakes. In contrast to common loons, tree swallow nestling production was not lower at low pH lakes. Based on modeling associations, Hg concentrations in tree swallow eggs and nestling blood can be used to predict Hg concentrations in common loons without the invasive or destructive sampling of loons. Mean concentrations of cadmium, manganese, and mercury in nestling livers were higher at low pH lakes than neutral pH lakes. Concentrations of cadmium, chromium, mercury, selenium, and zinc were not at toxic levels.
US Geological Survey, Upper Midwest Environmental Sciences Center, 2630 Fanta Reed Rd., La Crosse, WI 54603, USA. tom_w_custer@usgs.gov
Thomas W
TW
Custer
Christine M
CM
Custer
Wayne E
WE
Thogmartin
Paul M
PM
Dummer
Ronald
R
Rossmann
Kevin P
KP
Kenow
Michael W
MW
Meyer
D000818:Animals; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis / Q000378:metabolism*; D005260:Female; D006863:Hydrogen-Ion Concentration; D060106:Lakes / Q000737:chemistry*; D008628:Mercury / Q000032:analysis / Q000378:metabolism*; D009425:Nesting Behavior; D046388:Swallows / Q000378:metabolism*; D014131:Trace Elements / Q000032:analysis / Q000378:metabolism*; D014922:Wisconsin
D004785:Environmental Pollutants; D014131:Trace Elements; D008628:Mercury