It's been a few years since I've hunted or played woods paintball but when I did, my favorite shirt was a tan flannel with narrow grey plaid. In paintball I was told that when I stopped moving, I disappeared, and the only way they could spot me was by my blue jeans. That great tip made me quit wearing jeans to paintball... Also, I had 2 deer feed within 4 feet of me while sitting at the base of a tree. Unfortunately that was sooo close I couldn't move to get a shot.
I would give right arm to find that shirt again. Or even to find a similar pattern. It makes sense though, as the color was close to that of a deer, but slightly lighter.
My experiences with that shirt were in the woods of Ohio, so not sure how it would translate to CA.