You'll need to pay special attention to your town's roads, as you'll see the giant Pigeon walking around with a yellow question mark above its head. Note: You might need to refresh your game a few times, or simply wait a few minutes for it to appear.
Once you find the Pigeon, he'll have goals for you to complete, similar to the "citizen rewards" feature that was released earlier this year. For instance, your first goal might be "collect from 10 residences." Another goal might ask you to collect from your City Hall (regardless of its upgrade level).
As you complete these goals, you'll receive prizes like coins, experience points and free energy. Just make sure you have a lot of energy on hand to begin with, as some of these tasks require quite a bit of it to complete. Good luck finishing all of these mini-goals before the Pigeon flies the coop!
What do you think of this Giant Pigeon Attack feature in CityVille? Were you expecting a more literal prank from Zynga for April Fool's Day? Sound off in the comments.