Are deer are color-blind? Is this why hunters can wear bright orange clothing and the deer don’t seem to notice?
Yes, deer have a form of color blindness. All mammals have a retina located in the back of the eye that consists of two types of light sensitive cells called rods and cones. Rods function in the absence, or near absence, of light and permit vision in darkness. Cones function in full light and permit daytime and color vision. Deer have more rods (nighttime cells) and fewer cones (daytime and color cells) than humans. Therefore, deer have better nighttime vision than humans but poorer daytime and color vision. Deer lack red cones so they can't distinguish between green, yellow, orange, red or brown. All of these colors appear as shades of yellow. So the blaze orange color hunters wear appears yellow, as does almost everything else to a deer.