On Bonnie Brae in the Outer Sunset, two birds fervently guard their nest. Passing within ten feet once was a transgression. Passing twice was unforgivable.
Taking turns, they swooped at my head, screeching and scratching. Ducking, I turned onto Country Club Drive. They followed. In fact, they continued to follow for at least half a block until I received some advice from a neighbor.
Giving a knowing glance, he put down his trash bag and gestured with flailing arms. I followed suit, and the parents quit diving at least. But they followed for blocks, flitting from house to house, aggressively cawing and beating their wings.
If birds could learn lessons, I would have gone back to take the eggs.
Since birds can’t learn lessons, once their behavior is antisocial, it’s only logical that they must be killed for the greater good. It’s totally darwinian; the baby birds that hatch won’t live long, if they hatch at all. Bad genes, no cookie.