Back to collared doves - never seen a sparrowhawk (or any raptor) take one, but I have seen a collared dove nearly kill another collared dove. Presumably a dispute over territory, mating rights, food, or whatever. The stronger bird had the weaker in a complete stranglehold, holding it down with its wings so that it couldn't breathe. When I realised what was going on, I ran out into the garden and chased off the attacker, but the weaker bird was so badly hurt it couldn't fly away, just crawl into some bushes, and I found it dead on the lawn next day. It looked like the finishing touch was from a cat.