In this photo by Steve Matherly, you can see the distinctive pattern on the upper wing surfaces and the very long hand characteristic of Ferruginous Hawks. The upper primary coverts are dark, where as light Krider's or immature light morph Red-tailed Hawks show a large white square of light feathering here, that includes these upper primary coverts. The white also extends well out onto the individual primaries on Ferruginous as you can see here on the upper surface of the lower wing.