Why have my chickens stopped laying ?

Laying is  mainly dictated by the amount of light a bird is getting. As winter approaches laying decreases and usually mid to late February it starts to pick up again as the days get longer and warmer.
This does vary slightly due to age and breed. First year hybrids will continue to lay well through their first winter, whereas in their second winter will virtually stop apart from the odd egg perhaps.
Pure breeds take a little longer to kick start their laying in the spring.
Hope this helps, what sort of hens do you have?

hi, if they are around the same age I would say your black rock, followed closely by the light sussex