[Tern?] Tracks on the Mud Flats

[bird tracks on the mud flats behind Coast Guard beach, August 2004...are they terns, or some other type of bird?]

I took these pictures during the August 2004 Citizen Science trip, while walking barefoot through the mud at low tide. The mud was the consistancy of a very heavy pudding, the color of cement at the surface, but black underneath. My own feet sank a foot or more into the muck at each step. I noticed the bird tracks above describing weird patterns across the surface of the flats; I was paying attention to the meandering designs the tracks were making, and so I didn't think to take a close-up photo of the tracks in order to identify the species of bird.

Here is a shot I took of my own tracks, behind me: