I'm just guessing, but if you are looking for nutrition ( survival ), I'd say simmer the cleaned carcass's, when meat is done, pick it off bones, add to liquid, along with cooked internal organs ( heart, liver, etc ). Crush remaining bones, simmer those in a tied-off piece of cloth in the broth, then eat/drink. Adding any vegies to the mix would be a plus.
During WW2 in England, from what I've read, thier "blackbirds" ( not like our blackbirds, nor crows ) were a welcome addition to the kitchen.
<Mark