Holy chrome, Steve.
It's time to try the varied deterrents I know of, and each one may or may not work, but I'm unfamiliar with Buffalo Gnats, but they sound terrible!
#1 Flowers of Sulfur- it can be obtained from any pharmacy, though you may need to ask for it. It's a couple of bucks and the yellow powder can be applied directly to birds like Sevin. It is used directly on the skin in this area to prevent chigger bites, and though chiggers are a mite, it also deters mosquitos, so who knows?
#2 Vanilla- it deters flies and mosquitos and can be put directly on the skin, the feathers, or even sprayed onto surfaces with a small spray bottle or dabbed with a cotton ball. I staple cotton balls saturated with it in unseen places all over my yard...
#3 Repel's Lemon Eucalyptus Insect Repellent- it smells nice and can be applied directly or used to saturate wood on the coop or brooder. The effect is long-lasting.
Try each of these things before making them a permanent application, but I think it's worth a shot....
I'm so sorry!!