He is now going potty on bushes.  During our morning walks thru the desert he backs himself into a bush and stands himself up tall and does his business into the bush.  There's black matter trapped in the bush.

I've never seen or heard of such a thing before. 

Dude, my GSP Buck is the same way.  He will not poop unless he has backed himself up into a bush, tall grass, flowers, whatever.  He always poops that way.  Every single time.

BOTH OF MY MALE GSPS DO THIS THEN THEY SCRATCH TO MARK AND SHOW HOW BIG THEY ARE

I had a GWP and a GSP that both do the same thing.