If you're hunting ducks that have been in an area for an extended period (as opposed to migrators) and have been subjected to considerable hunting pressure, not calling may be the best option. Hunting "stale" or heavily pressured birds Just pick up your shotgun, stay hidden, and get ready to shoot. As long as ducks are coming, there's no reason for any vocal persuasion. Why risk messing up a good thing? If ducks are locked up and descending, why add a new variable into the equation? The birds obviously like what they see (and don't hear), or they wouldn't be dropping toward the decoys. In these conditions, ducks can more easily detect when the spread, blind, or calling isn't completely natural.
This may be because these conditions enable the birds to get a better look at the decoys and blind (no glare, no shadows, no buffeting from wind, etc.) and to hear calling more clearly.
On warm, calm, and dark days, ducks often seem especially wary and unresponsive to calling. These conditions are generally the least fruitful for calling ducks. In the following situations, less calling may be better, and none may be best: Warm, still, overcast days Thus, a big part of being an effective caller is knowing when to be subtle-or totally silent-and let the ducks work themselves. In certain hunting situations and weather conditions, silence can truly be golden, whereas overcalling will send up warning flags to circling ducks. Through the years, however, I've learned that sometimes just a little calling or none at all can be better than aggressive calling. Job one is getting and holding their attention. In such a situation, calling ducks is like being a kindergarten teacher. I grew up hunting on a highly competitive public area where if you didn't call aggressively, somebody else would get the birds. No one ever accused me of being timid with a duck call.