Little Ruddy, I'd also like to think they are a bit smarter than scaup too! Ha, but they also many times commit too easily- and you wonder how they made it down this far south the flyway unscathed- but Gunner's migration observation explains that in large measure...I just found an old call in my arsenal that I had ignored- it is very guttural sounding- and that is what I am looking for, to try and sound like the real thing, but you are right that most times you can get away with any mallard call. From my 37 year experiences in the southernmost marshes of the continental U.S. (not a boast, hoping it is a fact), the drake ringer is usually more vocal. That staccato burl/burl can be assessed as both a "here I am", "follow me" or "danger, be careful", so I am very selective when using it. Many of you will agree that your particular decoy spread, motion decoy, or encouraging your buddy to stand up and relieve himself are perhaps more of a guarantee to bring them in. Your are dang right about hearing the wind shearing sonic boom before you see them- if they are riding the breeze I let them pass and their return arc is much slower and so a bit of patience usually leads to more clean kills.