If it's so dark you need a flashlight to walk, it's too dark to shoot. I wouldn't worry about it. I don't see how it's any different than deer hunting from a stand.

Sorry about that. I was not suggesting you would shoot at them in the dark, because if they had not arrived on the scene yet, you would have no reason to fear they would be scared off. I should have been more careful with my words. I now realize (I think) that the ducks will be on the water waiting for daylight when you come along.

Red and green lights are designed to be less intrusive to animals. Not too sure about ducks though. I would have to say make a filter for your flashlight out of plastic wrap and a magic marker to try different colors. Once you get a good color that doesnt affect them let us know!!

The answer is yes. humans use red lights because the cones retract in the absence of stimulation 550 nm, which is green, and the rods are in the vast majority and are ready for seeing at night, which is a gray-level thing. Ducks have no cones, and can easily see red light.