How do Red Stags get antler colour New Zealand

A huge Red Stag rubs his antlers removing any velvet and making his territory pre rut. While doing this they also stain their antlers, so the type of vegetation they rub on predicts the colour of their antlers. known to be the largest antlered deer in the world New Zealand Red Stags are second to none in antler size, New Zealand Safaris has some of the highest quality deer with heavy mass, long main beams, and alot of red stags have drop Tynes and kickers off their crowns.