Though they do consume mice and rats, the Black Rat Snakes also willingly consume chipmunks, squirrels, birds, and bird eggs. In captivity they have a reputation for being "vacuum cleaners," and will eat almost anything placed in front of them.
Black rat snakes are quite large and are known to reach up to 8 feet, being the largest snake found in Canada. The record length for a Black Rat Snake is 101 inches, making it (officially) the largest snake in North America. Unofficially, Indigo Snakes are known to exceed them, and one wild caught Pine Snake with a portion of its tail missing measures 111 inches.