Unlike uccelli, if the main menu lists osei, it really does means little birds such as thrushes and larks. They are spit roasted with sage until they are crunchy and can be eaten whole, including the bones, and laid out a mound of polenta. Probably the main reason that hunting bans appear periodically on the ballot.
The dish is, or was, so popular that in Bergamo (especially) they also make little cakes of the same name, with pan di spagna, filled with cocoa flavoured cream and rum, and topped by little marzipan birds and honey.
Images by: Mike Rosenberg, Creative Commons License