Abstract
We quantified total mercury (THg) in feathers of Passeriformes from the Araguaia River floodplain (Brazil) to assess bioaccumulation and biomagnification across trophic guilds. Thirty-nine individuals from 22 non-migratory species were analyzed. Feather THg ranged from 0.05 to 2.35 mg kg(-1) (d.w.), with highest concentrations in invertivores. Invertivorous birds exhibited consistently high biomagnification factors for all invertebrate prey. Omnivorous birds showed lower and more variable biomagnification, suggesting dietary diversification attenuates Hg transfer. Herbivorous birds also showed significant biomagnification, highlighting basal compartments as relevant exposure pathways. Feathers proved to be effective non-lethal indicators of Hg dynamics in Neotropical riparian food webs.