Mystery chicekn deaths

[LaBelleDameSansPatience]

I wonder if anyone has any suggestions.
We have had seven chickens, living in a run in the garden, shut up at night (although the door probably has a 1" gap and the floor of the house is slatted.) Have had them for years, never any problems.
Now in the last week we have lost three. Each is found dead in the house in the morning. There is a little damage on the bodies, close to the vent or on the back - two or three bloody holes about the size of a teaspoon. There are also a few drops of blood around the next box (where they tend to perch, producing very dirty eggs).
What could be doing this? I wondered about disease - we had bought a new pullet a fortnight before, who died first. The second one did maybe look a bit 'tucked up' beforehand, but certainly not terribly ill. Would the other chickens have attacked a carcass in the night? Could it be rats? I don't know how big a space they'd need to get into the house. We have put down poison, just in case. Any large animal a) couldn't get into the house and b) would have eaten the carcass.
Any ideas at all??

Sorry to hear of your chx. Not sure what this could be. I doubt if the others would peck in the night, but might once it got light before they're let out.
Not sure about rats - sounds logical tho.
Have you tried posting on the poultry page of the allotment org site? I find they are the font of all wisdom for all things chicken on there.

The 1" gap is big enough for a rat to get in through, but agree is best to seek more knowledgable advice.

A weasel could easily get in to a tiny space and kill the hens like that.

If possible spread some sand around the area to see if you can pick up a print.

Rats are buggers. How big are your chickens? Doubt a rat could take down an Oprpington, but a Peking would be likely. We had a brood of chicks killed by a hedgehog once too. Would never have believed it if I hadn't seen it!

Check the live ones and make sure they haven't got similar damage round their vents. I'm wondering if it could be red mite? Obviously mite wouldn't cause the visible damage, though I'm guessing the damage isn't bad if you're wondering about disease. Mite infestation could cause them to peck at themselves.

I did see a similar story on a poultry forum and it was down to red mite. Someone had five chickens die in one night.

Whatever it is you need to give your hen house a really thorough scrub tomorrow. Get some poultry shield if you can and clean with that. Put ivermectin drops on your chickens to kill lice and will also worm them. If you can get some apple cider vinegar put some of that in their water as a health boost.

It sounds like rats to me but could be a weasel. Dsis had a number killed by a rat and found the enormous bastarding rat tucked up sleeping in one of the nest boxes

I've had a few die through red mite Viva (while I was on holiday) but you really don't see any damage in the way the OP is describing also it's still too cold for redmite to get to high levels atm.

Thanks for ideas. DH has barricaded the sleeping quarters and so far so good ... but it is always a bit makeshift and the chicken themselves are breaching the defences already. Hadn't thought rats would fit through such a tiny space. Keeping fingers crossed.

Could be redmite, or fly-strike maybe? Hope the others are all ok.

I'd agree with the rat / weasel theory (although frankly rats are more likely). Red mite wouldn't cause visible damage like that, and comes with other telltale symptoms like a reluctance to return to the coop at dusk and being able to see (and be bitten by!) the little bastards at night.

Now you've got rats (probably), you need to get rid of them.
a) Remove any sources of food. Don't scatter food on the ground and (although I wouldn't normally recommend it) remove the feeder overnight.
b) Block up any holes in the coop (properly!)
c) Put down traps. Unless you're using a poison like eradirat (see www.eradibait.com/ ) then I'd avoid poison altogether. With anticoagulant poisons, you run the risk of a rat dying either (a) in the coop / run, the chickens eating it (yes, they will) and then dying from secondary poisoning, or (b) the kids doing roughly the same thing. Plus, anticoagulants just aren't pleasant - they cause incredibly painful internal hemorrhaging whereas eradirat kills through dehydration IIRC. If you call environmental health, then they'll use the anticoagulants.