felling fowl

I was doing about 50 or 60 on a narrow road flanked by vegetations when two sparrows swooped low in front of my car. One sparrow narrowly skimmed over the bonnet and windshield, presumably riding on the cushion of displaced air. The other bird disappeared with a gentle "thump".

In the rear-view mirror, I could still see the poor birdie flopping around helplessly on the ground. What are the chances of that?

Probably a bit higher than my friend accidentally killing a bat while playing tennis.