Black Skimmer at the San Diego River mouth

Black Skimmer. Mission Beach, California. June 1, 2019.

A flock of about a dozen Black Skimmers were feeding in the San Diego River mouth on June 1st, where I was able to get these flight shots.

To fly low and plow the shallow, calm waters with their knife-like bills, skimmers flap from horizontal to highly vertical, not below the horizontal in this feeding flight. The flock feeding flight appears choreographed and synchronized at times (upper photo). At other times flocks appear uncoordinated and chaotic (photos below).