EXPLAINER: What's making mid-Atlantic songbirds sick?

A mysterious ailment has sickened and killed thousands of songbirds in several mid-Atlantic states since late spring. While scientists are still racing to confirm the cause, it seems juvenile birds may be most susceptible. The U.S. Geological Survey, which oversees responses to some natural hazards and risks, has recommended that people temporarily take down bird feeders and clean out bird baths to reduce places that birds could closely congregate and potentially spread disease.