At the risk of sounding smart***ed, are their feathers falling out? Also, they could have stopped because of winter and shorter days. It's really difficult to tell the age, even 18 mo. old chickens will stop laying in winter often.
At the beginning of a molt, it's easy to tell because there will be loose feathers everywhere. But after that phase, you can tell by looking the bird over and spotting the feather quills of the new feathers coming in. With some birds going through a fast molt, you can feel it just by picking the bird up. She'll feel almost like a porcupine with all the quills. In the final phase of the molt, it's harder to tell. The papery sheaths of the quills will have dropped off, and the new feathers won't be easy to distinguish. But the bird will still be recovering from the stress of producing all those new feathers and her body won't be ready to produce eggs yet. Of our flock of nine bantams, six of them are in that final phase of molt and aren't laying. One has finished her molt and gone back to laying, and two continued laying right through their molts. But they're also all pretty young, only 1 and 2 years old.
