Migration Info This western warbler migrates somewhat earlier than related western species (Townsend's and Hermit Warblers). Black-throated Gray Warblers usually follow the Pacific coast or pass along the lower elevations of mountain ranges. They sing during migration and are often found in mixed species flocks. This species has shown a marked shift to the north in recent years, possibly as a result of climate change caused by the buildup of greenhouse gases. Their principal winter habitat is along the lower elevation scrub-woodlands of the western slope of the Sierra Madre, Mexico.