A black, raven-sized raptor with a white band at the base of the tail and chestnut colored upper shoulders best describes a . . .

The description of a black, raven-sized raptor featuring a white band at the base of the tail and chestnut-colored upper shoulders fits the Harris's hawk perfectly. This raptor is known for its distinct coloration and size, making it easily identifiable among hawks.

Harris's hawks are unique in their social behavior as well, often found hunting in family groups, which is not as common among other hawk species. Their adaptability to different habitats, along with their striking appearance, makes them a favorite among falconers.

In contrast, the other species mentioned have different physical characteristics that do not match the described features. For instance, Cooper's hawk is slimmer and has a more elongated shape, lack of chestnut coloring on the shoulders. The Red-shouldered hawk typically exhibits a more barred breast and lacks the solid black color. The Broad-winged hawk tends to have a broader shape and may not have the same coloration at the tail base. Understanding these distinctions is key for identification in field observations or falconry practices.