Crows.

[cupid04]

Just heard a racket outside and went to investigate where I saw about 6 crows squabbling and fighting in next doors fir tree. One of the blighters seemed to be snagged upside down on a branch but managed to free himself and they all flew off. I thought they only attacked smaller birds, not each other.
It's gone quite now. Don't usually get many crows .

[tonyav]

I have seen crows squabbling / fighting amongst themselves ( usually Magpies ).

[cupid04]

These were definitely crows...magpies are black and white...these were all black...

[tonyav]

Yes cupes but Magpies are a member of the crow family.

[Butterbun]

Maybe one wanted something another had hold of? They do fight over food.

[Chipchopper]

With crows anything go's

[jollyroger66]

//It's gone quite now. Don't usually get many crows .//

Luckily only one blown over.

[Tilly2]

That must have been murder, Cupid!

[woofgang]

If they were in a group, they were not crows but rooks. Both are corvidae but rooks flock and crows don't.
Old saying
If you see a crow with a lot of other crows, its a rook. If you see a rook all on its own, its a crow.

[RATTER15]

I'm with Woof here, I was about to quote the same verse. They were rooks.

[melv16]

In the breeding season crows are territorial birds. In autumn and winter they tend to hang around in flocks. I've seen over sixty feeding on a discarded loaf of bread in my local park.