I am guessing that drones are to birds what a Martian invasion would be to us - suddenly a new species has arrived and is persistent - it can go everywhere birds can go, it has spare energy enough to make aggressive noises constantly and it completely ignores any aggressive actions and attacks made to drive the drone off.

It has arrived and taken over the territory completely - so abandon the area.

My problem is if my conjecture is true, we basically have to ban drones ... everywhere.