Eeek rat(s)

Incidentally, I will put ALL food waste in the secure compost bin from now on. I had stopped feeding wild birds and son't start again now.

Air rifle.

You can get some poisons which swell in the stomach rather than make them bleed to death. If something ate the rat it wouldn't swell, unless it ate the rat's stomach and even then only if it hadn't full swollen, as its mechanical.

That said I'm not sure the risk from eating the Rat is that high unless it eats it all which is a fair old fill for a chicken! In human terms 20mg a day of warfarin would be enough to kill most humans in a week. For poisoning purposes you might want 100mg or even 1g a day just to be sure. But if you consider that a human weighs 50kg - maybe 20kg of that is bone you distribute that 1g into 30kg of soft tissue. Then think in terms of a meal - 1lb of mince feeds a family of 4 so 125g of meat is probably a reasonable meal for the day, lets assume you were really hungry and ate 300g of poisoned meat (it makes the maths easier). Thats 100th of the tissue so it contains 100th of the dose so 10mg. Most fit and healthy humans would get therapeutic effects after taking 3 days of 10mg and then would need to reduce dose.

So while you wouldn't really want to have someone take 10mg as a one off you would probably be fine unless you were daft enough to keep eating the dead human! On that basis I suspect it scales down... And bear in mind your chooks probably don't like eating dead rat... ...although I don't know what dose is actually in a rat poison...

Also worth remembering that the chooks wont go in the burrow and most rats go back to the burrow to die as its a safe place to hide when they fell rough...

Or you try and keep the chooks contained to somewhere you can see them.

If you use bait boxes chooks can't get to the poison. I don't know if they'd try a dead rat? I had two dead baby rats in the run and they didn't touch them....

I bought the chooks a lockable treadle feeder because the rats were coming out during the day to eat their food. I put down anticoagulant poison Tom Cat in a bait box and Eradibait in the back of the feeder (it is only harmful to rodents and other species can eat it without harm.) They ran all over the feeder without getting any food, but also not taking the bait. The rats are alive and well. OH is talking about getting an air gun.

My OH, sets up a little house built with bricks with an inner house that houses chicken food, that only a rat or mouse can get in via a piece of pipe. It's positioned by a wall which rats will run along. When the food has been taken he switches to rat poison. They take it back to their nest. We have never seen a dead rat in their run, sick rats will generally go to ground.
We also use a cage for catching them in the chicken run by the food. These only catch the young ones but they really work well if you are prepared to kill them.

After laying poison in a bait box and getting a lockable pedal feeder for the chickens, we no longer saw rats running round the garden. Then we found a rat corpse in the shed looking as if died as it was walking. Now we have a massive number of flies, so presume there are more dead rats we can't get to.