free roaming hens not laying

Judging from what you're saying, I would try providing them with some more protein. This can be anything from soy or cottonseed meal to bugs and worms. You may be losing some laying due to daylength, and some due to age and background of the birds, but not all of it. They seem to be getting a varied diet, and I see green stuff in the photos (fresh greens are very important....and the first thing I ask about when thinking about unhappy chickens). But because it's winter, they might not be able to find enough bugs, etc. to maintain.....

Alder brings up all the main points. While "happy hens lay happy eggs", I find that feed, water, light, breed, and age are the main factors. Gee, even crammed together battery hens lay plenty of eggs.

Length of light.....most hens stop laying in the winter until the length of daylight increases. Commercially they control the amount of light so that hens stay at top production.
Age.....the older the hen, the less eggs they produce. After three laying seasons, you don't get many eggs from most hens.
Breed of the hen....some breeds are longer layers than others. And often mongrel hens are poor layers, in my experience.
Diet.....super important. Protein in, protein out. They can't produce eggs if they are deficient in their diet. Unless they have a large, well supplied area to forage in, you need to bring the food to them. And never let them run out of food. Letting the bowls go empty really cuts into egg production. And so does dramatically changing their diet, say going from a daily supply of meat and greens to a diet of pellets, or vice versa. They need more than just a spattering of this and that.
Water....they need a constant supply of water especially if fed dry feed. During the winter water can freeze, so that's a problem that needs to be addresses. Never let them run out of water because producing an egg uses up a lot of water.
Stress...things that upset them will stop egg production. I've had egg laying drop dramatically when a neighbor's dog began visiting the pen daily. A friend told me her egg production dropped dramatically when the land next to her got bulldozed for 7 days in a row.

All that being said, my own flock is at the ebb of production this time of year. Very short days here right now. What surprises me is that there are some who haven't quit yet. But most of the hens have molted by now so that after the first of the year I should start seeing the number of eggs gradually increase.

How long are your days? A fresh young pullet may lay eggs with less that 12 hours of daylight, but older birds rarely do!

My own laying flock quit laying about 1 month ago: I am hoping they will start laying again in early February. Some years I use electric lighting to give them more hours of light in the day but this year I did not with to bother! My daughter was the big egg eater of the family but she moved to Texas, and it is simpler to just buy an occasional dozen and wait for the birds to come back into lay.

Your birds are lovely, by the way!

We find the tricks to getting eggs are: feed, light and low stress. For feed ours forage in the warm months and we feed them meat in the winter. 14 hours of light makes a huge difference. Doesn't have to be all that bright.

Different chickens have different times of starting to lay. Just give them a bit more protein, then placed a couple of golf balls or those fake eggs in the nest boxes. In fact, I didn't get my first egg until after I did so. Apparently they decided not to lay for lack of a good area lol. Besides, this is the season for moulting, they really don't lay well during that time.