I'm wondering if great piles of leaves, from raking leaves in the fall, would count as "tree hay." The chickens would scratch around in them and eat what they pleased, and if they were deep enough, would shelter the bugs that the chickens desire, at least for a while into winter. I'm planning to try this, hopefully under cover if I can get the plastic to stay in place over hoop cattle panels. I've tried it before, but underestimated the strength of the wind vs my attempts to secure the plastic. However, if it works, I imagine the plastic trapping enough heat and the leaves being insulating enough that....well, that's as far as my imagination can take it. Good things happen, that's my hope.