Why exactly does an egg do so much damage.
It's the enzymes in the egg as well as the acid in bird .
I don't think the egg comes out of the same hole in the bird as the bird $hit! And when would a bird lay an egg on your car? At high velocity too.
Autoglym did a recent study that about bird poop and found that the acidity of the bird poop had little to do with the amount of etching that takes place, The etching happens when the bird poop lands on a sun heated panel. The sudden sun blocking effect the bird poop causes the once very hot paint underneath to cool and it ends up molding its self to the shape of the bird poop. The grainier the bird poop the more textured the etching will look. That's why sometime bird poop won't do anything at all and sometimes it will etch in no time at all. If it hands on the car at night in cool temps, probably not much would happen. In the middle of the day on full sun exposed panel, it will happen very quickly.
Always best to remove it as quickly as possible and hope you're lucky in the future that the next time a bird relieves himself on your hood that the conditions are in you favor.