While the common grackle seems ubiquitous, no matter where I go, the boat-tailed grackle (Quiscalus major) is a little more elusive. I have seen the female, which almost looks as if it is a separate species, at several places, including the Pond in Central Park. But mainly I see them near Jamaica Bay Wildlife Refuge and at Big Egg Marsh to the south.
These birds are omnivores, and take advantage of any opportunity to eat whatever they can get, although they love seeds of all kinds.