Bird Identification: CLOSED: Black Tern? Forster's Tern?, 5 by P_Edens

P_Edens wrote:
Can these first three all be the same type of bird? And are they Black Tern?

Saw a bunch of similar birds yesterday (13 Sep 2012) flying along a canal of brackish water, plunging in for fish periodically. These were the best shots I was able to get with the storms rolling in.

Are the last two shots Forster's Tern? I saw this bird on the same day from the Hawk Watch Tower at Smith Point on Galveston Bay.