Seasonal Differences in Contaminant Accumulation in Neotropical Migrant and Resident Songbirds.

For many years, it has been hypothesized that Neotropical migrants breeding in the United States and Canada accumulate organochlorine pesticides (OCPs) while on their wintering grounds in Latin America. We investigated the seasonal accumulation of persistent organic pollutant (POPs) in migrant and resident passerines in Texas, Yucatán, and Costa Rica collected during the fall, winter, and spring from 2011 to 2013. A total of 153 birds were collected, and all contained detectable levels of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and OCPs with dichlorodiphenyldichloroethylene (DDE) being the most predominant pesticide.