Data from: Region- and season-specific exposure to lead in a common North American songbird

The American Robin (Turdus migratorius) is a common songbird in a variety
of habitats across most of North America that could serve as an ideal
sentinel of heavy metal contamination. We evaluated how robin exposure to
lead (Pb) varied regionally, seasonally, and among demographic groups, and
assessed impacts on body condition and reproductive hormone
concentrations. We detected higher blood Pb concentrations in robins
sampled in a more urban region (Indiana) compared to a more rural region
(Alaska). Higher blood Pb concentrations in the more urban region may
reflect the robin diet of earthworms, which accumulate lead due to their
feeding behavior, and could incorporate greater ambient soil lead
contamination typical of more urban areas. Blood Pb concentrations were
also highest in spring and summer, when robins primarily forage on
earthworms. We found no relationship between blood Pb concentrations and
body condition, but blood Pb concentrations showed a negative relationship
with testosterone in male robins and with estradiol in female robins,
suggesting lead may have negative effects on reproductive
function.