Actually differing color isn't as bad as the open top is.
MOvement is the other instant killer.
One year we put up some netting in front of us... in some reeds where we stood. Worked fine until later in the morning.
Took 2 hunts until at the time of the morning when it seemed the ducks would start flaring I walked out front... DUH, the sun was up high enough we were silhouetted behind the netting then....
I like the idea of local vegetation options though a LOT and try to use it when we can, but if not, we've got a few pieces of fast grass zip tied to wire fence. Each piece is hinged where the end of the fast grass is and you can put it up quick, run fiberglass rods in the ground hopefully, and then have a piece that flips over the top.
works fine on the river on the bank, on sandbars etc...
