From NYT:
"Amid reignited fears about lead poisoning nationwide, the key to identifying solutions could lie in the common city pigeon.
A study published on Monday in the journal Chemosphere found that Manhattan neighborhoods that had many children with elevated blood lead levels also had pigeons with elevated lead. The research suggests that scientists may be able to use the birds to predict lead contamination in the environment.
The principal author of the study, Rebecca Calisi, who was an assistant biology professor at Barnard College when the research was conducted, examined data on 825 pigeons from various neighborhoods from 2010 to 2015. Dr. Calisi found that elevated lead levels in pigeons from Greenwich Village and SoHo, for example, correlated positively with elevated lead levels in children in those neighborhoods, as identified by New York City’s health department.
The link indicates that pigeons could be used to detect areas of pollution across the country, particularly in urban areas."