Well, I have done is lots of times with quail and dove, just hold the body in one hand and the head in the other and pull real hard, the heads come off.
I can tell you exactly what not to do with ducks, true story and the statute of limitations has long since run. So, buddy and I are duck hunting on a typical duck hunting day, very few birds, wind about 45 mph, white caps about 4 feet tall, hiding in a shore blind a couple mallards fly over, about 85 mph considering they were going with the wind, one came down, I called it mine, it was. So, it hit the sand and runs, who knew ducks could run on the sand? I did not want to blast it again on the ground, I do not do that, shoot ducks on the ground, so the chase is on, except the 45 mph wind is now blowing snow/rain and general dark and dreary misery and the duck runs toward the water.
Wait, I have a Smith and Wesson 22 pistol, I will head shoot the running duck before he hits the water in the 45 mph wind, sleet, snow and rain. I take a head shot not 50 feet away at the running duck, and miss, my buddy is yelling, why is he yelling, I am trying to shoot a duck before it gets to the water, I miss and he yells some more, so I shoot again, and so on as I chase the surely dead soon duck, until I have one round left and the duck is nearing the water and my buddy is yelling even louder in the 45 mph wind and.....there is a truck coming, some fool driving out on the dry lake bed, that is illegal, and stupid.... and so I run after the duck and forget the darn head shot, I am out of wind now, and one round left, I shoot him center of mass and my buddy is yelling and I finally hear him, that is the game warden you fool.
Anybody know if it is illegal to shoot ducks with a 22? It is, so lucky me. We walk back to my truck and pass by a Game Warden, stuck in the sand, he said something like, you boys are in a heap of trouble, more than you ever know. OK, fine, so you want me to get my truck and pull you out? Game Warden, yea, in the 45 mph wind and blowing snow, and rain and sleet...
So, we go get the truck, could have drove off and left him out there, but didn't, he had clue who we were, so we pulled him out. And we just stood there in the 45 mph........and he said, thanks, ya'll have a nice day. So, I looked it up, it is illegal to shoot ducks with a 22 on the ground.....true story...
And there is an old retired game warden somewhere telling his great grand=kids about some fool chasing a duck a 1/4 mile shooting and missing and shooting and missing.... prolly did not tell them about being stuck a 1/4 mile lake bed.....hunting stories you just never forget. So I have no idea, carry a machete and chop them off would work...