To shoot (a sitting bird), engage in the practice of shooting sitting birds—freq in combs specifying where the bird is sitting, as ground-swat, road-~, tree-~, water-~; hence agent nouns swatter, ground-swatter, road-~.
1951 WI Conserv. Bulletin 16.8.4, There is no grander upland game bird in North America than the ruffed grouse, and yet ground-swatting road-hunters will never know about that unless they get out in the brush and hunt on a sporting basis. 1960 Racine Jrl.–Times Sun. Bulletin (WI) 9 Oct sec 3 4/3, Even the road swatters were drawing blanks. Road or ground swatting is the ancient but somewhat disapproved practice of driving the fire lanes slowly until the grouse is seen crossing the road or scurrying along a ditch. Everyone jumps out then and opens fire. 1968 DARE FW Addit PA, In Pennsylvania, one who ground-sleuths is a ground-swatter. 1989 Ibid ceNY, NEng (as of 1970s), He wasn’t a real partridge hunter, he was always ground-swatting birds. 1992 Furtman Wild Goose 129, Poached geese are baited; lured to their death in ponds or fields baited with grain. Baiting is always illegal. Swatting—shooting at a flock of sitting geese—is reprehensible. 2005 DARE File—Internet MD, Frankly, I’m surprised to see the number of “swatters” that have posted. I remember reading a similar thread, a couple of years ago, where it seemed that the majority of the posters were passionately against “swatting”. Ibid NC, I admit that I swatted (sluiced) my first duck, a woodie. I eventually swatted fewer as my shooting has improved over the years. And, this past two seasons, I have not swatted at all. 2011 WI State Jrl. (Madison) 30 Oct sec D 16/4, Most readers saw nothing wrong in “potting,” “sluicing,” “ground-swatting” or “tree-swatting” stationary grouse. Here are some of their observations: “I once said something to a college fiend [sic] . . after he ground-swatted a rooster pheasant. He replied: ‘What’s wrong with that? He had one leg up.’ ” 2011 DARE File—Internet CA, Shooting a duck on the water—also known as “sluicing” or “water swatting”—is considered by some to be unsportsmanlike. 2014 Ibid LA, But I don’t mind others swatting birds on my pond, if they’ve [sic] of a mind to, as long as they let them clear the decoys. . . And if the shooters are very young or old, I don’t mind repairing a few decoys, either.