A beautiful sight caught on video in the San Pablo Bay National Wildlife Refuge, shows tens of thousands of birds flying in hypnotic unison.
The small sandpipers seem to ebb and flow over Sonoma Creek Marsh.
Andrea Jones, Director of Bird Conservation for Audubon California, tells us the birds are actually being chased by a hawk.
She says San Francisco Bay is filled with shorebirds returning from the arctic where they breed during the summer.
The Bay Area is an important stop in their migratory pattern.
Many of the birds will continue on to South America.
Video courtesy Courtney Gutman, Richardson Bay Audubon Center & Sanctuary