Hexachlorocyclohexane in Non-breeding Populations of American Kestrel (Falco sparverius) in Central Mexico.

We studied the concentration of hexachlorocyclohexane (HCH) and isomers in blood samples of American kestrels (Falco sparverius) during the non-breeding season in agricultural fields across two states of central Mexico. The majority of the 36 kestrels we sampled were females (72%). In both, Tlaxcala and Hidalgo, the mean concentrations of ∑HCH were 0.07 µg/mL, and the presence of this contaminant did not vary between sexes, nor within or between states. We also detected the isomers β-HCH and γ-HCH (lindane) in most samples (97 and 80%, respectively), while α-HCH was the only other isomer found in a single sample. Our results confirm the presence of HCH in the non-breeding, overwintering populations of American kestrels in central Mexico. This report warrants further investigation of the timing, sources, and intake pathways of these contaminants in this migratory raptor.