I had to look up mast year, too

Very cool indeed! I have definitely noticed some years the oaks get surrounded by a carpet of acorns. Never gave it much thought. One thing that doesn't add up though is why it would make the
leaves any bigger? From what I read, mast year is about producing an abundant crop of nuts/seeds, it's not related to leaf size?
I have often wondered why chickens moult when they do.
Maybe because they should be fat from summer forage so they have enough mass to stay warm while they swap out feathers?
I am sure there's some kind of evolutionary answer.
Chickens aren't native to the US (or most other parts of the world where they are now kept), and especially cold climates, so they never really evolved to handle winter. Not as far as nature is concerned. The wild jungle fowl that got domesticated many thousands of years ago and gave rise to today's chickens lived in the tropical jungles of Southeast Asia. So they weren't meant to care about cold winters when dropping their plumage. And I bet they didn't drop it as dramatically as modern day chickens do - after all, the various wild birds of today molt, too, including cold climate birds, but they don't get naked the way chickens do - that would make them vulnerable not just to the weather, but also to predators, since it would affect their ability to fly/jump/run as well. Today's chickens are a very far cry from whatever nature intended, in lots of ways, not just plumage. They lay eggs (almost) every day for months or years at a time - something highly unnatural and totally a product of human-driven selection. In nature, a bird would only lay a handful of eggs at a time during mating season, then raise the young, and be done for the year. Humans have dramatically reshaped domesticated animals to fit their own needs. Think about sheep who don't shed/molt at all and instead their wool never stops growing, and it can overwhelm and even kill them if not shorn! The wild relatives of sheep, like bighorn sheep, don't have that problem - they shed like nature intended, and don't need to be shorn. Domesticated animals are out of sync with nature - with the surrounding nature, with their own internal nature, and no longer do what would be best for their survival. They are dependent on us.