American coots, that is, otherwise known as Fulica americana.  In the background of the photos are visible some American white pelicans (Pelecanus erythrorhynchos) and some double-crested cormorants (Phalacrocorax auritus), although neither of those species was in focus or range when I took these photos.  Finally, there are a few mallard ducks (Anas platyrhynchos) visible in the smaller of the two photos; they’re mixed in with the covert of coots.

[btw, the collective noun for coots is ‘covert,’ hence its use in that last statement]