Gooseslayer..To answer your question, 10 or 12 crow decoys will do you just fine...If you want more, just set up dead crows as you shoot them... An owl is OK, but you don't really need it, and with an owl and an e- call you may end up with every crow in the area over your head at once, and then they'll be gone.. IMHO it is much preferable to simulate a feeding setup along a flyway and decoy in birds a few at a time, in smaller groups that you can handle... A hand call or e-call is handy at times, but you can decoy in and kill lots of crows with just decoys in the right spot.. Just like ducks and geese...Put the dekes in the right place and get well hidden ( cause they sure ain't BLIND) and you should get plenty of shooting..