I've mentioned this B-4, but when you're outside you always look around & listen; however, it's always important to look up. As a student glider pilot I learned to keep an eye out for birds that thermals to show me where there was lift. The hawks [& even the vultures] will allow a sailplane pilot to follow & stay aloft. Pilots learn about birds, the  clouds & weather. Human eyes see 3 primary colors; from a nature show [didn't see the entire episode] I heard that hawks see 5 primary colors which aids them in finding their prey among its background that humans do not perceive. Can anybody elaborate?