As far as I understand, deer are colorblind.  This is why hunter's\ncamoflage is red and black - it has the same values of dark and light as\nmilitary forest camoflage, so colorblind animals have a hard time seeing\nit.  Most people, at least those who are not red-green colorblind, can\neasily pick out the red color among the forest greens and browns.  So as\nlong as hunters only shoot at what they see, it reduces the chance of being\nin the line of fire.