I have a Sweeter Heater. https://www.sweeterheater.com/products
I've had mine for a couple years, but one member here has had one for over 8 years. And they're completely sealed and waterproof.
Keeping animals involves dealing with sick animals. There's no way around it. It's not just chickens. But you see a lot of sick chickens here because there are a lot of chicken owners here with a lot of chickens without chicken vets or the money to afford a chicken vet. If you can't deal...
Just caught another mouse in the snap trap and one in the bucket trap. That's five in the last few days. The amount of mouse droppings in the chicken feed and their other frequented areas is significantly less. No poison used so I can leave the dead mice out for the owls and other wildlife to...
Yup, foxes are very beneficial. Rodents seem to be the primary food of the foxes here. This year we had one (I assume a vixen with kits) regularly hunting in our overgrown pasture. I saw it leave with a mouthful of voles.
Surprisingly, having just one snap trap makes a noticeable difference in my coop. I guess it also helps that we have lots of wildlife here that eat rodents.
I set up a snap trap near a mouse nest in a wall cavity in the coop that cannot be accessed by the chickens. The trap catches rodents regularly. I got a mouse today, in fact. I check it daily and reset with chicken feed as the bait.
I do not quarantine young chicks from hatcheries or most NPIP certified breeders. All others I'd quarantine. I did a very strict 4-week-long quarantine when I added my ducks (they came from a hobby backyard breeder in the city).
How old is he? If he's under a year old you should supplement his duck feed with brewer's or nutritional yeast to make sure he's getting enough niacin.
It can be in the winter, especially if you have open water and not a nipple waterer. Humidity is not as much of a problem in the warmer months. I keep a waterer in the coop 24/7, but I do not put heated waterers in the coop. I did it once and the walls and ceiling near the waterer were coated...
Most likely another chicken is plucking her rear feathers out. This can stem from things like boredom (coop too small, etc.) and nutrient deficiency (low protein feed, etc.).
I think sand on concrete is a recipe for stinky bacteria buildup. I'd suggest a very absorbent bedding (wood pellets, shavings, hemp) perhaps over vinyl sheet flooring.