You'd have to have a really hot fire going, and it would still smell awful. And the bones probably wuldn't burn, unless heated for a REALLY long time.
I know because I lost several chickens in a wildfire last year. During the evacuation pandemonium, I opened up all of the pens to give everyone a chance to run away.... evacuation of every one of the animals just was not happening, not enough time. When I came back and looked for them, there were what looked like roasted chickens everywhere, very little meat left, bones still intact. They still smelled yuck. And the chicks were turned into little chicken nuggets scattered everywhere. That fire burned through HOT, it melted metal into little rivers and decimated everything in its path.... but the bones were still there.
This is not an easy thing to deal with. We live in a very unpopulated area, so when we lose a bird we take it out into the forest and put it where it can return to the earth and to nature. Yes, it means scavengers take care of it, but this is nature's way and it works for us. I hope you find a solution that works for you.
