My thought is that birds can see colors. Otherwise, why would the males be so brightly colored? All things in nature have a purpose or God wouldn't have made them that way.
Regarding depth perception, most prey species have eyes to the sides of their heads, so they only have 2-D (height & width) vision, rather than binocular (3-D) vision like predators with front-facing eyes. This enables them to see more of their surroundings. Some prey animals have eyes more to the front than others, and therefore have a bit more depth perception. Notice the location of the eyes on predators, including birds of prey, compared with prey animals.
I think this is why turkeys are so spooky... they can just see movement but don't have any idea how close it is. Just my .02!