Flock of birds outside my home


Every morning, this flock of about thirty birds is outside my bedroom window flying continuously at high speed, turning frequently (I can only assume they're taking feed on the wing; they're flying at about 100 feet). Now the thing is I always assumed they were pidgeons but some things don't seem to gel with that; the tops and undersides of their wings catch the sunlight brightly (where pidgeons are usually grey) and their wings are swept back at the tips and pointed.

They DO have the fanned tails of pidgeons/doves though, and are about the right size. The trouble is that they're flying so fast it's difficult to see detail; and they're only close by infrequently.

Can anyone start me on features to look for as they zoom past so that we can get a better ID?