There are definitely seasonal differences for us. Chickens lay eggs in response to day length. For that reason, commercial egg farms keep lights on in their laying houses to fool the birds into laying year round. This wears the hens out in 18-24 months, and those hens are rotated out and slaughtered for processing into such useful things as pet food and school lunches...Some smaller producers will put lights on timers in their henhouses to increase the length of the day, accomplishing something similar. We don't do that. Every hen in our flock is an investment in time and feed and I want to keep them producing as many years as possible. Giving them a winter break allows them to gain weight and rest up for next year's laying. Having said that, some breeds will lay longer into the fall and even during the winter. Our Buff Orpingtons slow down, but never completely stop laying. They keep us in eggs all winter. The Aracaunas quit early, usually in late September. They are just now starting up again. Oops, looks like I've gone off base into one of my favorite rants. My apologies! Back on topic, our winter eggs have darker and richer yolks. I don't know why. The chickens still hunt and peck with the goats and sheep, but in the winter they are more dependent on bagged feed, since there is less forage for them. No tasty bugs etc. Maybe the fact that their diet changes is the key, but I doubt it's the feed. If it was the feed, you'd expect those poor commercial birds to have darker yolks, because they never get the chance to eat a bug or blade of fresh grass. Still, I think it's seasonal somehow due to diet.