I shot a big drake mallard here at work a few weeks ago with my bow. I snuck up on the little pond to twenty five yards out as I'm pulling back the mallard climbs out of the water and is standing on the opposite shore. I think to myself perfect. I won't have to get wet getting the bird or arrow. I steadied my aim and released, I smacked that bird as hard as a bird could get hit and it flew off with the rest of the flock. I kept an eye on it waiting for it to fall, but it vanished into the distance with the rest of the birds. When I investigated, I lost my arrow and found a huge pile of feathers and blood.
I had mixed feelings very excited to say I shot a duck with my bow, but disgusted to know I wounded an animal and couldn't do nothing to finish the job. I was expecting my arrow to stick that bird to the bank, boy was I wrong.
My advice is to try and take the wings out or head shot.
You've got to stand for something or you will fall for anything...