Also known by some as the Boat Tailed Grackle, it resembles the crow - albeit smaller. The most obvious differences between the crow and the Great Tail are the tail and eyes. The male grackle usually flies with its tail vertical, using it like a rudder on a boat. Its eyes are yellow, whereas the crow's are black. The males are overall black, and somewhat irridescent. Females are smaller with dark brown back and wings, and the head and frontal areas are a lighter brown/bronze. Females generally fly "normally" - with their tails horizontal.
This is the male Great Tailed Grackle.
This is the female Great Tailed Grackle.
(Note: Some books list the Great Tailed Grackle and the Boat Tailed Grackle as two different species. Those that do show them to be almost exactly the same, in appearance and behavior/eggs/traits. The Audubon society book I have only lists the Great Tailed Grackle. I have always considered it to be two names for the same grackle.)