It might have just brought the wing in. My two have been known to do this. If they do bring a bird in it's usually alive & they dump it by their food bowls. I like the think they're puss philanthropists, helping out needy birds (instead of dumping bird by food bowls as snack for later).
Our most recently deceased cat used to eat small birds and mice whole. He used to suck down the tail like spaghetti - it was quite amazing. We now have 2 new cats one of whom is a killing machine- 2 or 3 corpses a day at least. The other one has a large lampshade collar on to stop him scratching his scabby wounds- yesterday I saw somwthing in it and a closer inspection confirmed that he had a dead shrew stuck down at the neck bit- with the head bitten off. It was completely stuck flat to the plastic like a comedy cartoon character- it really was rank. It must have been there a few hours. Gross.