After doing belly crawls and stalks on a number of these ducks, I have decided they have eyesight like the Hubble Telescope!! I couldn’t believe it, even if I was in the shadows and they had the sun in their face they spotted me through thick mats of brush and grass as I was approaching and I was moving slowly enough it took me 10 minutes or more to cover 40’ on my stomach. I had to get within about 30 feet for a decent photograph and most never let me get closer than about 50(+). Uncanny I’ll tell you and I was in full camo.