This is a flock of late spring stragglers. Most of the individuals in this flock are heavily worn, but all can fly well.
Brant are small arctic breeding geese which tend to migrate and winter along the coast. This species has declined as a winter visitor in California but it still can be locally common during spring migration where many thousands stage at favored locations such as Humboldt Bay.
Depending on the authority, four subspecies are usually recognized. This is the race B. b. nigricans formerly called the Black Brant and formerly considered a separate species. It breeds in the Russian Far East and Alaska winters in China and Mexico. Note the white band around the neck connects in front in this race.
Top photo digiscoped with Panasonic DMC-LZ5 | Nikon FieldScope 3 | 30X WA | hand-held (no adapter). Bottom photo showing all 11 birds taken with Panasonic DMC-LZ5 alone.