These aren't the best shots, as the birds were somewhat distant. But it's not as common to see avocets at the coast at this time of year, so the photos will serve as a record.
I started wondering if this might be an adult and two juveniles. But I don't have any experience aging avocets. If you have thoughts about this, I'd appreciate feedback!
The two smaller birds generally stayed close together and behaved in similar ways. They seemed paler on the head, face, and breast. And there were hints of white edges on some of the dark feathers (see picture below — I'm referring to the two birds that are preening).
It also seemed as though the larger bird was keeping a somewhat "watchful eye" on the smaller birds.
The larger bird occasionally called. Most of the time it gave a clear, single note. But occasionally it was two syllables. Here's a rough recording if you'd like to hear an example. It was windy at the time, but if you turn up your volume I think you'll be able to hear the avocet just fine. Listen for two single notes, then a two-syllable phrase, then 3 single notes. [If you're reading this in an e-mail, click on the title of the post above to see the sound file below.]
amav2 by nhbh
P.S. On 7 July 2013, among the other shorebirds in Bodega Harbor, I also saw and heard a single Black-bellied Plover and two Greater Yellowlegs.