My brother is color blind to red (or certain shades thereof) he used to have a heck of a time trailing a deer he shot that did not drop in sight. In fact I have tracked a many deer for him through the years. He has gotten so that if it is not night time and the ground is not wet he can track fairly well ( I think damn well for being colorblind to reds) now, he studys the foliage and looks for wet/shiny spots and other things such as freshly broken limbs or folded down grasses etc. I still do alot of tracking for him when the conditions are nto perfect, but hey that is what brothers are for.