It's too bad that you can't ask the question from the birds' point of view. I would think that if the question could be asked of the bird, "what was the first thing that went through your mind when you hit the airplane"? His answer most likely would have been, "MY Ass".
On a more or less serious note, several years ago a 727 on climbout from an Alaskan airfield frightened an eagle carrying a large salmon. The bird dropped the salmon and it impacted the 727 just above the passenger door making a loud bang and leaving a considerable dent in the metalwork.
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The Cat