These behaviors give the impression that disturbance is minimal, which is what I hope for. I am using a 400 mm lens while lying stationery on the beach and the images I have posted here are cropped, making the subjects appear closer than they were in the moment. As you look at some of the images, however, you will notice that in several of them, the bird is looking at the camera. When a wildlife subject is looking at you, you have disturbed it.
Next: The rest of my first day at Stinson Beach--the Dipsea Trail.
Links and resources:
Cornell on the Snowy Plover
Stinson Beach, CA
Birds of North America