If you haven't yet had a chance to see Common Nighthawks, High Park is a great place to view them. I went last night for "Shakespeare in the Park" and counted at least 16 while I was waiting on the theatre's hillside; between 6:30 - 8:00 pm. They were sometimes flying quite low over the trees, giving very good views. At one point I heard the distinct nasal "peent" call coming from a large tree behind me. It must have been roosting in a branch practically over my head for almost an hour! I tried desperately to find him in the tree but no luck.
-kris