Two or three summers ago basically every single crow around here was wiped out by the West Nile Virus. It was sad that so many birds died but it was nice to never have to hear ten thousand crows yelling at you when you walked out the door, all angry that you even looked at them and messing with your garbage cans.
Anyway I've taken up bird-watching a bit in the backyard (I feel like an old man, puttering around in the garden and sitting in an easy chair with a pair of binoculars and the Birds of Chicagoland book, getting all excited to see a goldfinch), and have never once seen a crow since the virus hit. The grackles have sort of filled the niche, but I began to wonder whether they would ever come back.
Today I heard a cawing noise, and ran outside found a single crow perched triumphantly at the very peak of our roof, just cawing and cawing and looking at me.
After it knew that I saw it, the crow flew away into the distance and it left me feeling really uneasy.