Sterna hirundo
This barge was man-made just for these birds -- there were dozens of them! The 2nd and 3rd shots are heavily cropped and over sharpened, but I'm hoping will make an ID easier.
Leslie Street Spit.
I think they look most like Common Terns, Sterna hirundo:
http://en.wikipedia.org/wiki/Common_Tern...
They look like a species of Tern. They look comfortable. :) Do you have any closer views of the birds themselves?
Lat: 43.63, Long: -79.32
Spotted on Jul 4, 2009
Submitted on Sep 12, 2012