The reason for the collective noun.

I'd known crows ate meat, and I'd assumed crows ate fresh meat if they could get it, and it wasn't until today I saw a crow eating the freshest meat possible: something it'd managed to catch and kill. Something small enough it could fly off with it safely. It'd caught another bird.

I wasn't that close and I hadn't seen it do the catching, but I was able to watch a little bit of the end of the action: the crow with someone brown and smaller than itself in its beak, other birds making a racket, the crow shaking what it'd caught and flying off into the trees to have some privacy.

It was probably a sparrow. It could've been a juvenile robin. Birds from a distance can be hard to distinguish. All I knew was I saw something wild happen, and I'm grateful that I did.