@OscarBeau @ADDiane Almost everything was killed by it. So yes. Most (but not all) birds were killed by it. Like most (but not all) mammals were. Like most (but not all) dinosaurs.
And yes, birds did exist at that time, co-existing with dinosaurs. (https://www.science.org/content/article/how-birds-survived-dinosaur-apocalypse)

But the premise was that the asteroid was a ‘stone’ that killed the most birds of any stone. A play on the ‘to kill two birds with one stone’ saying. So, what other ‘stone’ do you think killed more birds?