Sorry for your loss too. That’s sounds so similar to what happened to me today. Three feather, with a small bit of poop. Its only my second time with a broody so I was so shocked. I’m glad its not common & I hope it never happens again here.I just had this happen a couple of months ago. I never had even considered this a hazard, but it turned out fatal for one of my chicks.
My Black Ameraucana had 3 feathers held together by a tiny piece of dried poop.
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The chick obviously came up through the stuck together feathers and wrestled trying to get lose. He must have fought trying to get free and couldn’t. I found him a couple of feet away from the broody with the feathers all wrapped around his neck, the feathers had been pulled out in the struggle. I’m not sure if he strangled himself or broke his neck, but needless to say I was upset. View attachment 2236676