Npc birds would make the SP2 archipelago feel more alive and it would present a new hazard for aircraft making sure you can fly high enough to avoid them or they would damage your parts and explode into feathers. The amount of NPC birds can be lowered or raised in the settings and bird collisions can be disabled as well. https://www.youtube.com/watch?v=rSafRuLB0c0
Trent 900 engine is tested by ingestion a bird. The video showed the damage in blade number 21.