Back in the 80's I hunted the Delaware River for ducks. Boy was it difficult to call in those Greenheads. On the films the "Experts" made it sooooo easy. I'm damn sure they were all on private grounds. In fact, once at a waterfowl festival I challanged one of those so called "Experts" to accompany me for a hunt on the Delaware. Of course he ignored me. Back then he was seling his hand made calls for $75. I think SALES were his primary interest, much as are the DVD's of today.