I just took a pot of rendered deer fat out of the oven and made up some bird blocks with black sunflower seed and the rest getting about three pounds of creamy peanut butter stirred in thoroughly. Woodpeckers, nuthatches and chickadees love the stuff. The cracklings that are strained out of the liquid fat get packed into plastic one pound coffee canisters. When cooled and the fat set, the canisters get sliced on two sides and the cracklings are put in a round cage. Woodpeckers will sit on that for an hour chipping away.
I had about 18 pounds of deer fat all trimmed nice with little meat attached and put it in the oven at about 10 this morning and took it out at 2, at 325 degrees. The house smells like a good roast in the oven. The birds will be happy this winter.