Cat or fox?? Carnage in our front garden ??

Yes, they were young starlings, they didn't have the shiny feathers yet

Callistemon your brown birds are young starlings probably which are quite pretty but not black and fool many people.
The carnage sounds more like fox than cat as we have both come to our garden and in the past once had 6 cats of our own. But I agree a sparrowhawk is a definite possible and we also have had a peregrine here.

Whatever it is its nature for one creature to hunt another. Even cats. Even dogs given free roaming. Cats don't kill for fun, they don't have that instinct. They will kill for food but then realise they are not hungry enough to eat it.

Possibly a Sparrow Hawk. I saw one take a big fat wood pigeon on our back lawn. Looked like someone had burst a pillow - feathers everywhere.

I used to work at a premises in central Bath, an area which has a large number of pigeons and also sparrowhawks. We often found small amounts of Pigeon remains in the grounds, and one morning a member of staff came in rather shaken, as a sparrowhawk had literally swooped in on a Pigeon at her feet in the car park, and carried the unfortunate victim off! So I am guessing, comparing the OP's post with the remains we used to find, that her instance was a bird of prey.

Sparrowhawks pluck the feathers from their prey and they scatter in a complete state around the kill. Whereas foxes and cats tear at prey with teeth so, if it's messy with many broken feathers, I would say that it's likely a cat or fox. If a lot of the carcass is left, it is probably a well-fed cat; cats are disastrous for wild life.

Could be a sparrowhawk doing the pigeon shredding.

Round here, if a fox gets into a chicken run, they just bite the heads off the birds and leave them, bar 1 or 2 which they carry away

Sparrowhawk. They make a terrible mess like that. I don't know about foxes really but cats generally drag their kill away to eat it in a more private place, behind bushes or something.

I think a sparrow hawk is responsible. They always leave feathers everywhere in a large circle. A fox would carry its prey away.

We invariably see so many red kites on the way to dd’s in Oxford - often drifting on thermals above the M40, presumably with an eye open for roadkill - that I was astonished to see a TV prog not long ago, about how they had been so scarce or endangered.

Margiknot it was just so unusual to see them after all these years, I did say 10 years but it's probably much longer than that and it's interesting that they're back.

Do you have red kites about? I ve seen them go for smaller birds but don’t know if they would kill a pigeon. Redkites are intimidatingly large birds! I’ve seen the local cat stalk pigeons but it’s better at catching mice!
Callistermon- agree sounds like young starlings- they are dull brown and peck and chatter together in groups. We had lots in our garden pecking away this morning.

I very often get pigeons gong into the glass, usually when I haven't filled the bird feeder and they're trying to tell me, but the sparrowhawk always aims for the brickwork.

Savvy

Our local sparrowhawk likes to slam his prey into the side of the building. Its loud, but very effective, all that we see is a cloud of feathers.

If its just left the feathers it sounds like either a bird of prey or possibly a magpie has chanced upon the carcass and had a feed. If it was killed by a fox, they tend to carry off their prey and bury it for later, unless they are disturbed.

I've heard a pigeon slamming into the window then seen a sparrowhawk demolish it in the garden.
Pigeons leave a perfect imprint on a window if they hit it, usually they fly off none the worse.

There are suggestions here that the carnage might have been caused by a cat, fox or sparrow hawk. The pigeon's feather shafts might provide a clue.
Predators with teeth, such as foxes and cats, leave feather shafts which have been broken/nibbled whereas birds, such as sparrow hawks, pluck feathers from victims so the shafts remain tapered and whole.
You've commented that virtually all of the pigeon has been eaten. Sparrow hawks don't waste much. There's a graphic image on Google; if you type in 'What killed this pigeon?' an RSPB warden intern answers and comments.
A sparrow hawk hunts in my garden (at up to 50kph) and is quite predictable in her flight path and the time she arrives. She has been known to leave prey then return to eat.
Of course, the pigeon having been killed by a cat, could well become a meal for others as Savvy says. I've seen crows enjoying road kill. Setting up a camera might be the sole way to arrive at an answer.

We have a local Sparrowhawk I see him and the Red Kites often I’ve seen the Hawk dive on a pigeon full pelt then follow the injured bird down to the ground to finish it if it’s nor already dead.

Our local sparrowhawk likes to slam his prey into the side of the building. Its loud, but very effective, all that we see is a cloud of feathers.

If its just left the feathers it sounds like either a bird of prey or possibly a magpie has chanced upon the carcass and had a feed. If it was killed by a fox, they tend to carry off their prey and bury it for later, unless they are disturbed.

I'm trying to add a pic of the sparrowhawk - it's not a good one as it's a bit fuzzy but it should be clear what it is. If this works -

We have trees down the back but the garden is fairly open apart from a few bushes. I've never seen the sparrowhawk in action so don't know how it approaches. It was sitting in the middle of the garden eating when it got the woodpecker.

I do know that one year, before we had ever seen the sparrowhawk, I was sitting in the garden under the umbrella on a very hot day when I felt/heard a rush of air pass my head and a 'clunk' on the fence behind me. I turned around but couldn't see anything. It was like a large missile had passed by me. My OH had said a few days earlier that he thought he saw some sort of hawk briefly, but couldn't be sure. It was months later before we first saw the sparrowhawk for long enough to identify it.

I’ve never seen red kites around here (outer SW London) but there are masses around Oxford, where a dd lives.

The suggestion of a sparrow hawk is interesting. We’ve hardly ever seen any kind of hawk in our very small back garden - maybe it feels too enclosed for them - there are several mature trees at the back. But the front area is much more open - don’t they prefer more open spaces?

I don’t think it can have been a cat, anyway - I doubt that any of the spoiled moggies around here would have felt the need to eat virtually everything but the feathers. The cat we used to have could never manage more than half a small woodmouse - that is if she ate any of it at all, and didn’t just bring it in to drive us mad trying to catch the poor little thing.

Only last week I watched a large seagull bring down a pigeon. I couldn’t believe it.

The sparrowhawk that got a woodpecker in our garden ate some of it but took the rest away. Just a couple of feathers were left.

Our trail cam has videos on it from a few nights ago of a cat chasing a mouse around the garden. It went on for quite a few minutes as it played with the mouse, then it killed it and took it away. We think it was the same cat that chased a fox out of the garden one afternoon. He's not our cat but seems to think our garden is his - the poor fox was having a snooze in the sun and the cat sat down about two feet away until it woke up. When the fox got up the cat charged it and chased it out of the garden.

Aldom

I think young starlings too. I have several families of starlings in my garden every year.

I don't think I've seen any in our garden for about 10 years, Aldom. Who'd have thought I'd get so excited about starlings!
We did have a lovely juvenile woodpecker visiting yesterday.

Red Kites are much bigger than a Sparrow Hawk and don't hunt they eat carrion. So it was probably the Sparrow Hawk.