While feral pigeons tend to get a bad rap in cities across the world, one team of researchers are enlisting the help of birds in New York City to learn more about lead pollution and children’s susceptibility to it. An ongoing problem (though NYC has put in many successful measures to curb it), lead in the blood can be critically detrimental for child development. “Little is known about the effects of low amounts of lead on human health, but recent studies have shown that lead is harmful at all levels –no matter how low– affecting intelligence, neurodevelopment, social skills, and memory,” explain Rebecca Calisi, assistant professor in the Department of Neurobiology, Physiology and Behavior at the University of California, Davis, and undergraduate student Fayme Cai, in their recently published study.

Given the fact that urban pigeons breathe the same air, walk on the same streets and, often, eat the same food as urban humans, the pair of researchers figured that our feathery neighbors would suffer from the same toxicity as us. In other words, they propose that urban pigeons could serve as timely, accurate and abundantly available bioindicators. “The combination of densely-packed buildings, an abundance of food, and ample greenery, such as that found in Central Park, make NYC an ideal feral pigeon habitat. Compared to many other urban organisms, the pigeon’s relatively long lifespan and hardiness, combined with its close relationship to humans, make it a suitable bioindicator, offering up the potential to gauge adverse environmental conditions that may affect humans and other wildlife,” reads the study.

To set about proving their hypothesis, Calisi and Cali took blood samples from 825 pigeons at NYC’s Wild Bird Fund where citizens often take visibly ill or injured birds. Between 2010 and 2015, the team set about analyzing the blood samples, categorizing them by the Manhattan neighborhood the pigeons were found in and seasonally, with birds tested in winter, summer, spring and fall. Immediately, their findings proved the efficacy and accuracy of pigeons as bioindicators – blood samples from birds correlated positively with elevated lead rates in children in the same neighborhoods.

pigeons lead toxicity

Scatter plot depicting the positive correlation between pigeon mean blood lead levels in neighborhoods in Manhattan with rates of children (per 1000 tested) younger than 18 years of age with elevated blood lead levels of 10 μg/dl or greater.

Similarly, and like what has been witnessed in children, lead levels rose significantly in the summer. Lead levels are typically higher in children during the summer months due to more outdoor activity taking place during vacations, and rising temperatures which lower the humidity of soil and thus make it easier for lead to escape from it.

While “[y]ear and neighborhood did not significantly predict blood lead levels”, there were, however, areas of NYC that presented much higher lead toxicity than others. Pigeons from the Soho/Greenwich Village neighborhood had on average the highest levels of lead in their blood, followed by pigeons from Lower Manhattan/Lower East Side and then Upper West Side