"No Country for Old Men" question

[Doyle]

Antoine Chugar is driving across a bridge and takes a shot at a crow that is perched on the side railing. He misses at near point blank range and the bird flies off. I found this to be an odd scene. For someone who is an incredibly proficient killer, he misses an easy shot at the bird. Is this scene unnecessary and meaningless or does it mean something I don't get?