zoology - What is this crow eating, and is it a common part of the corvid diet?

Here's a picture (by Rob Curtis) of a crow carrying and eating the corpse of what looks a bit like a small hawk or falcon:

Other pictures clearly show the crow is eating the dead bird. This image shows the underside of the head and beak; this one shows its legs, which are grayish.

1. What bird is being eaten?


2. Is this bird a usual part of the corvid diet? Or did the crow just opportunistically scavenge a dead bird?