02723naa a2200289 a 450000100080000000500110000800800410001910000150006024501170007526000090019252019660020165000150216765000140218265000130219665000130220965000210222265000170224365000130226065300080227365300090228165300160229065300110230665300120231765300180232970000170234777300690236417927652017-03-28       1996    bl ---       0--  u    #d1 aBURGER, J.  aHeavy metal and selenium levels in birds at Agassiz National Wildlife Refuge, Minnesotabfood chain differences.  c1996  aThe levels of heavy metal and selenium in the eggs and in breast feathers of adult double-crested cormorant (Phalacrocorax auritus), black-crowned night heron (Nycticorax nycticorax) and franklin's gull (Larus pipixcan) nesting at Agassiz National Wildlife Refuge in Marshall County, northwestern Minnesota were examined. Also examined were metal levels in the feathers of fledgling night herons and gulls in the feathers of adult and fledgling American bittern (Botaurus lentiginosus), in eggs of America coot (Fulica americana) and eared grebe (Podiceps caspicus) and in feathers of adult Canada geese (Branta canadensis). These species represent different levels on the food chain from primarily vegetation-eating species (geese, coot) to species that eat primarily fish (cormorant). A clear, positive relationships between level on the food chain and levels of heavy metals occured only for mercury in feathers and eggs. Otherwise, eared grebes had the highest levels of all other metals in their eggs compared to the other species. No clear food chain pattern existed for feathers for the other metals. For eggs at Agassiz: 1) lead, selenium and manganese levels were similar to those reported in the literature, 2) mercury levels were slightly for cormorants and night herons, 3) all species had higher chromium and cadmium levels than generally reported and 4) eared grebes had significantly higher levels of cadmium than reported for any species from elsewhere. For adult feathers: 1) gulls had higher levels of lead than the other species, 2) cadmium levels were elevated in gulls and adult herons and cormorants, 3) mercury levels showed an increase with position on the food chain, 4) selenium and chromium levels of all birds ata Agassiz were generally low and 5) manganese levels in adults were generally higher than in the literature for other species. Adults had significantly higher mercury levels than flegling gulls, night herons and bitterns.  afood chain  aMinnesota  aselenium  awildlife  aCadeia Alimentar  aMetal Pesado  aSelênio  aAve  aBird  aHeavy metal  aRefuge  aRefugio  aVida selvagem1 aGOCHFELD, M.  tEnvironmental Monitoring Assessmentgv.43, n.3, p.267-282, 1996.