I've got two hens that are about 9 months old, a Barred Rock and a Black Star (The General and Nugget). I live in Seattle where nights have been in the low 40's. For about the last two weeks, most nights, they have chosen to sleep on the roost in their outdoor run instead of in the "house" part of the coop. We supplement light, but only in the mornings (currently have a heat lamp in, after a cold snap earlier in Jan, could go back to a florescent). For about 5 nights I put them back in the house before I went to bed (9ish). It gets dark here by 5:30 or so. One of those nights they turned around and came back outside.
My husband mucked out the house, and put in all new wood chips. They are still going inside to lay, and are still laying at the same rate (10-12 eggs a week from the pair). They also go in and out at will during the day.
They get free range time of about 2-4 hours a day.
What else could be going on? It doesn't seem like a big deal right now when our nights are fairly warm, but I'm worried if we have a cold snap. I could put them to bed when I get home from work (6:30 or 7) and lock them in, and then let them out in the morning (about 7).
Any clue what this could be?