I’ve had 800-1000 chickens at a time for the farmers’ market business. One old wives’ tale I think does work is adding ground cayenne pepper to the water 1/4 tsp to a gallon) or red pepper flakes to their feed. In the feed, it helps has the added bonus of deterring vermin.
I’ve always been wary of heat lamps. Doubly so after a beautiful historic bank barn near our old house caught fire from one falling onto bedding. Killed a sow &’ her piglets & a bunch of other animals that were FFA kids’. Premier 1 does make some kick a$$ sturdy lamps meant to withstand lambs & kids more than chickens. I splashed out on a couple of those when we had bottle baby goats. And I’ve seen a really clever idea where someone made a ‘UFO’ lamp houses.with a 55-gallon plastic drum. Currently, we have a rooster who lives alone because he can’t play nicely with others. I put hand warmers in his little coop for him on very cold nights.
That sucks about the wildlife.
I love opossum. They’re so delicate & prone to frostbite even in regular mid-Atlantic winter temps. Seems like a glitch in the Matrix that they are like that. We had one that lived under our deck in the winter of 2019. I finally put a cat igloo out there with a body heat reflecting pad in it for it.