How didyou positively identify it as a rooster when it was flying behind a bush? We all have choices to make in life and you made an incorrect one.
Hopefully you can learn from your error and never repeat it again. You can be thankful no warden was around and you got away with a cheap lesson.
If you cannot identify your targetand know what's beyondone doesn't shoot. It's that simple. Spend some more time at a range shooting skeet low gun. Train you eyes and reflexes. When you can call for a target and if it comes out broken and you have little of no gun movement you'll know your getting shooting discipline down.