Mercury in tree swallow food, eggs, bodies, and feathers at Acadia National Park, Maine, and an EPA superfund site, Ayer, Massachusetts.
We monitored nest boxes during 1997-1999 at Acadia National Park, Mt. Desert Island, ME and at an old-field site in Orono, ME to determine mercury (Hg) uptake in tree swallow (Tachycineta bicolor) eggs, tissues, and food boluses. Also, in 1998-1999 we monitored nest boxes at Grove Pond and Plow Shop Pond at a U.S. Environmental Protection Agency Superfund site in Ayer, MA. We recorded breeding success at all locations. On average among locations, total mercury (THg) biomagnified 2 to 4-fold from food to eggs and 9 to 18-fold from food to feathers. These are minimum values because the proportion of transferable methyl mercury (MeHg) of the THg in insects varies (i.e., 35%-95% of THg) in food boluses. THg was highest in food boluses at Aunt Betty Pond at Acadia, whereas THg in eggs was highest at the Superfund site. A few eggs from nests at each of these locations exceeded the threshold (i.e., 800-1,000 ng/g, wet wt.) of embryotoxicity established for Hg. Hatching success was 88.9% to 100% among locations, but five eggs failed to hatch from 4 of the 11 clutches in which an egg exceeded this threshold. MeHg in feathers was highest in tree swallows at Aunt Betty Pond and the concentration of THg in bodies was related to the concentration in feathers. Transfer of an average of 80%-92% of the Hg in bodies to feathers may have enhanced nestling survival. Residues of Hg in tissues of tree swallows in the Northeast seem higher than those of the Midwest.
Longcore
Jerry R
JR
U.S. Geological Survey, Patuxent Wildlife Research Center, 5768 South Annex A, Orono, ME 04469-5768, USA. Jerry_Longcore@usgs.gov
Haines
Terry A
TA
Halteman
William A
WA
D000818:Animals; D000831:Animals, Newborn; D017753:Ecosystem; D004531:Eggs / Q000032:analysis*; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000032:analysis* / Q000633:toxicity; D005241:Feathers / Q000737:chemistry*; D020387:Food Chain; D005843:Geography; D049673:History, 20th Century; D008404:Massachusetts; D008628:Mercury / Q000032:analysis* / Q000633:toxicity; D008767:Methylmercury Compounds / Q000032:analysis / Q000633:toxicity; D009425:Nesting Behavior; D011157:Population Dynamics; D018570:Risk Assessment; D046388:Swallows / Q000196:embryology / Q000502:physiology*; D014018:Tissue Distribution
D004785:Environmental Pollutants; D008767:Methylmercury Compounds; D008628:Mercury