Why aren't they laying anymore?

[linders]

Our four hens are 9 months old and all summer we got 3 or 4 eggs a day. Exactly one month ago they abruptly stopped laying and we had no eggs for two weeks. Then after those two weeks we started getting one egg every other day.
This is our first year of chickens, so could this be due to molting (we have noticed more feathers in the coop but the birds aren't looking drastically different) or shortened days or..??? Any thoughts? Nothing else has changed in terms of feed, water, etc.
Thanks!

 

[ChickenCanoe]

Usually day length.
If you need eggs soon, add light.

 

[McGobs]

Mine are doing the same thing. Feathers everywhere, and the egg production is way down. Molting and the shorter days are most likely the culprit. Adding a light inside the coop to snap on a few hours before daylight will get them laying again. But at the same time, they need to grow feathers back, so forcing them to lay might slow the feather growth down, and I know its getting pretty cold here.