Empty Skies

Abstract

Pick the right night and you will hear them. A September night, perhaps, when a northwest wind has swept the clouds from the sky and the stars are out in full force. As midnight approaches, find a quiet spot away from the rumbles and groans of urban life and listen carefully. Soon you will hear soft chirps and whistles drifting down from the sky. These are the calls of migrating songbirds. A thousand feet above you, extending for hundreds of miles in all directions, is a vast highway of little birds—millions of thrushes, warblers, flycatchers, tanagers, vireos, and sparrows—heading south. A few skilled birdwatchers can distinguish the call notes of the different species. A high, clear “chip” marks a northern parula warbler en route to the Caribbean; a sharp buzz identifies a blackpoll warbler headed for the Amazon basin; a gentle whistle denotes a veery traveling from Canada to Colombia. The sky is alive.