Different colored hairs in my beard

Why do I have different colored hairs in my beard? I have dark brown hair (practically black) but on my chin and upper lip I have stray blondes here and there(actually the color I’m unsure of, someone called them copper, another said red). They are nowhere else on my body.

I’ve noticed this in the beards of my friends too. Does anyone have an explanation for this wacky phenomenon?