Terns of Two Types

I saw a flock of Caspian terns today. 

 I have not seen the Common tern for a while as the DNR has said they are an endangered species. 

The common tern has a forked tail while the Caspian tern has a fan like tail and is larger, about the size of a sea gull. They are very elegant, but their voices are gravelly.

Here is more information:What the bird sounds like