Temporal trends (1937-2006) in concentrations of toxic elements in neotropical birds from southeastern Mexico

Metals and metalloids are among the pollutants of greatest concern worldwide due to their damage to human and environmental health. Organisms such as birds are exposed to these contaminants. Mercury (Hg), lead (Pb), and arsenic (As) concentrations were analyzed in feather samples (n = 241) of five species of birds from southern Mexico (1937-2006) from scientific collections. Feathers concentrations showed relatively high concentrations of As > Hg > Pb, exceeding toxicity thresholds in birds. Carnivore species had the highest concentrations of As (x̄ 44.42 ± 6.34 SE μg/g), while the concentrations of insectivore and omnivorous species ranged from 5.71 ± 0.66 μg/g to 9.24 ± 1.03 μg/g. Temporal trends for metals and As showed the highest concentrations in the 1930s and 1960s. Mercury and As showed a significant annual increase in the 1930s and 2006. An increase in Pb concentrations was observed before 1937 and a decrease after 1979 until 2006. Some temporary trends in metals and As were similar to local and global emissions caused by forest fires, mining activities, fertilizers in agricultural practices, and the termination of the use of Pb as a petrol additive. Knowledge about metals and As was generated at sites that are currently protected natural areas and cultural historical areas. Anthropogenic activities prior to their declaration of protection and transboundary pollution may be potential sources of contaminants at these sites. The first baseline of the spatio-temporal trend in toxic element concentrations was established in five species for future research.