A warbler the color of the clear blue sky hops sky high through the upper canopy of eastern forests. That’s the male Cerulean Warbler, a brilliant blue songbird with a cerulean neck band and streaks down the sides. Females are equally well-dressed, wearing a dusky hue of blue-green. These long-distance migrants breed in mature eastern deciduous forests and spend the winters in the Andes in South America. Their populations have declined dramatically due to habitat loss.