This endangered hummingbird is found only in a small region of Peru. Much of its habitat has been destroyed, but populations remain near the Río Marañon in La Libertad and in the Chusgon Valley. It favors partially open areas of Andean slopes that feature alder trees (Alnus) or shrubs, and it primarily feeds on nectar of flowering mistletoe (Tristerix longebrachteatum) and insects. Purple-backed Sunbeams appear mostly dark brown with white on the upper chest, lower throat, and face. Their lower backs are purple in good lighting.