If you are like me, you've never thought much about bird cannibalism. I think it was mentioned as one of the many problems experienced in raising fowl in a book I used to read about poultry management because it reminded me how little I knew about things.
I once watched this Marabou Stork eating a dead nestling that had fallen into the moat surrounding a Heron rookery in Kenya, but it didn't strike me as cannibalism at the time, maybe because a different species was involved. It seemed more like a Timber Wolf eating a Caribou at the time. Take a look at the picture and see how it strikes you.
A few years later though, I felt a little like Clarice when I watched Hannibal Magpie eating one of his own, maybe even a relative or mate. This was in the Badlands though, where food is very scarce, so when you look at the pictures you might be reminded more of the Donner-Magpie Party near the end of their trip.