Research says a coyote sees the blue spectrum and can't see red well. I've also read a poll of hunters using green, white, and red with similar results. Red is better for human eyes at night, but dome lights and headlights hurt your night vision temporarily anyway.
What I've found is while you need every advantage, nothing is more important than good woodsmanship. I'm not sure what's going on in Texas where the coyotes run up to the truck like a house dog amidst all the clanging, banging, fist bumps, and "booyahs!" They don't do it here.
I have more success at noon when it's hot than anytime at night. I think because at night you're hunting at your natural disadvantage and the coyote has every advantage. He can see clearly, always has the wind direction, can hear you stumbling in the dark. That a coyote is active doesn't mean he's easier to find or hunt, it means he's on his game.
I use red. Good luck!
