My young duck's laid in the winter still no problem. I do know the decrease in daylight can affect laying but I haven't experienced that yet with either my duck's or chickens. I live in Washington and we get sunshine 3 months out of the year if we are lucky. It's mostly cold, wet, and rainy here. Someone just told me a couple of days ago that you can place any light in their coop such as an LED bulb and it will work to compensate for the lost daylight. I thought for some reason it would have to be a special type of light but I guess not! I'm not 100% sure if it works on ducks but placing ceramic fake eggs or a golfball even in their nesting boxes/area they lay at will help remind them to lay their eggs there too.