Who are the animals told that is visiting animal farm Nightly?

In George Orwell's "Animal Farm," the animals are told that Mr. Jones, the former farmer, is visiting the farm nightly. This claim is used by the pigs, particularly Squealer, to manipulate the other animals into believing that they need to be vigilant and that their leadership is necessary to protect them from the threat of Jones's return. This tactic serves to maintain control over the animals and reinforce the pigs' authority.