# Screening of Mercury Bioaccumulation in Birds (Passeriformes) from a Major Wetland of the Brazilian Cerrado

## TL;DR

This study measured mercury levels in birds from a Brazilian wetland to understand how mercury accumulates in different bird diets.

## Contribution

The study reveals how mercury biomagnifies in different trophic guilds of non-migratory birds in a Neotropical wetland.

## Key findings

- Invertivorous birds showed the highest mercury concentrations and biomagnification factors.
- Omnivorous birds had lower and more variable mercury biomagnification due to dietary diversity.
- Feathers are effective non-lethal indicators of mercury dynamics in riparian food webs.

## 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.

The online version contains supplementary material available at 10.1007/s00128-026-04186-2.