We see two species of terns in the Toronto area at this time of year.
The Caspian Tern is about the size of a Ring-billed Gull and I usually identify them by size and the raucous call they make which sounds like a bandage being ripped from a wound.
Common Terns are considerably smaller and have a distinctive “tee-arr” call.
I photographed several this morning and realize that size doesn’t help identification when you are looking at a photo.
The Caspian has a large red bill:
The bill of the Common is smaller and has a black tip:
Rattray Marsh has a very high water level at the moment so I did not see any of the marsh species that might be there when the water level is lower.
Here are photos of the marsh, rocky beach and some birds:
As the stars that shall be bright when we are dust,
Moving in marches upon the heavenly plain;
As the stars are starry in the time of our darkness,
To the end, to the end they remain. – Laurence Binyon (1869–1943)