Not an accident. Firing a weapon without determining the target or what is beyond it is negligence. Especially with a rifle. If he wants to scare birds he should use a shotgun with light shot or bird bombs.
Although in his defense, he did check out the field with binoculars first. Nontheless, this was still an accident and therefor preventable.
I agree with you, the only point I was making is that this farmer obviously made a horrible mistake and now an innocent man is dead. He will have to deal with that.