Developmental Exposure to Aroclor 1254 Alters Migratory Behavior in Juvenile European Starlings (<i>Sturnus vulgaris</i>)

Birds exposed to endocrine disrupting chemicals during development could be susceptible to neurological and other physiological changes affecting migratory behaviors. We investigated the effects of ecologically relevant levels of Aroclor 1254, a polychlorinated biphenyl (PCB) mixture, on moult, fattening, migratory activity, and orientation in juvenile European starlings (<i>Sturnus vulgaris</i>). Birds were orally administered 0 (control), 0.35 (low), 0.70 (intermediate), or 1.05 (high) μg Aroclor 1254/g-body weight by gavage from 1 through 18 days posthatch and later exposed in captivity to a photoperiod shift simulating an autumn migration. Migratory activity and orientation were examined using Emlen funnel trials. Across treatments, we found significant increases in mass, fat, and moulting and decreasing plasma thyroid hormones over time. We observed a significant increase in activity as photoperiod was shifted from 13L:11D (light:dark) to 12L:12D, demonstrating that migratory condition was induced in captivity. At 12L:12D, control birds oriented to 155.95° (South-Southeast), while high-dosed birds did not. High-dosed birds showed a delayed orientation to 197.48° (South-Southwest) under 10L:14D, concomitant with apparent delays in moult. These findings demonstrate how subtle contaminant-induced alterations during development could lead to longer-scale effects, including changes in migratory activity and orientation, which could potentially result in deleterious effects on fitness and survival