local phenomena

At this time of year the Vaux's swifts gather in Portland, Oregon. They arrive in the evening, thousands of whirling wings fill the sky in dizzying swirling motion. Then, shortly after sunset, an unseen signal and they tumble downward into a chimney to roost for the night. What had seemed to be chaos turns into funneled harmony. In awe I watch a behavior that follows its own language, speeds and spacial awareness.
Soon they will migrate south, another journey taking place way above my head.