Clearly I’m not asking google the right questions, because I’m finding it difficult to find the answer to this: what’s the lowest temperature feathers will burn at?
I ask because I have polymer clay that needs to bake at 250-275F for 30-60 minutes at the thickness I’d need, and I’d love to try to make my own crow like this, but with clay as the basis for the body instead of foam. But when I try to look into this via discussions about using clay and feathers, lots of people swear it’s fine, and others say they’ve burned the feathers. 
I just ran a small test, with stuff I had at hand: using my thermostat-equipped heat gun, 200 C (close to 400 F) didn’t affect the tip of a pheasant wing feather at all, while 350 C (660 F) scorched it in about 10 seconds.
Obviously, very small, thin feathers may ignite at lower temperatures. Real crow feathers have an oil to them that may affect the outcome, too. To know how things work out, I’d just put a small batch of same feathers I’m going to use in a 275 F oven for an hour and see how they turn out.
keratin - as in human fingernails and hair - presumably all of the feather, decomposes at 233 C.