Pollution lowers birds' ability to deal with stress.
Franceschini MD, CM Custer, TW Custer, JM Reed and LM Romero. 2008. Corticosterone stress response in tree swallows nesting near polychlorinated biphenyl and dioxin contaminated rivers. Environmental Toxicology and Chemistry. Published online May 13, 2008.
When stressed, tree swallows living in areas polluted with PCBs and dioxins make less of a critical hormone needed to overcome the trauma. This weakened ability to mount stress responses can interfere with their ability to thrive by hampering growth, reproduction and survival. This work suggests that birds living in polluted areas are less able to deal with stress than birds in areas with relatively little chemical pollution. Similar findings are reported for amphibians and fish, and it could likely occur in humans. In this research, adult female birds from polluted and non-polluted regions were studied during a two-year period. To assess stress responses, animals were placed into bags for 30 minutes. The researchers found that most birds from the polluted areas could not increase stress hormone (corticosterone) levels but birds from non-polluted regions could.