Squirrels have dichromatic color vision. This means that squirrels can distinguish red and green from other colors but cannot tell red and green from each other. This kind of color vision closely resembles red-green color blindness in humans. Now since orange is a combination of red/yellow, and some humans with red/green color blindness have a hard time seeing Blaze Orange, it's my guess that squirrels have a hard time seeing it, or at least distinguishing it from green camo. With squirrels the type of fabric the orange is on seems to make a difference as well as the amount of light available. Many times with game animals, until a color is associated with danger, they tend to ignore it as long as there is not movement involved. But, some fabrics and detergents with color brighteners will attract attention to hunters, even when they are motionless. Around here, the DNR suggests wearing Blaze orange while moving during Turkey Hunting and to tie a orange rag somewhere close to you when sitting in camo while turkey hunting. But I can tell you without a doubt, that turkeys see orange and identify the color with humans. Once the gun deer season has started around here, turkeys will go out of their way to avoid anything Blaze Orange. We have deer seasons that extend into the late fall turkey season so blaze orange must be worn while hunting. It is impossible, at least where I hunt, to get a wild turkey within shotgun/bow range when wearing the legal amount of blaze orange.
