Tiring = A tough piece of meat and bone that will keep a bird occupied for a long period of time. This usually also has the quality of conditioning the beak and exercising the neck and back muscles, although not necessarily. A chicken or pigeon wing removed at the shoulder, a rabbit or duck head, or a rabbit foreleg with much of the meat removed, make an excellent tirings as they have very little meat distributed over a large surface making it difficult to get ahold of the edible parts. The bird will work and work on a tiring for a period of time. In absolute correct terms, a tiring is from a mammal, such as a rabbit foreleg, and a plumage is from a bird, such as a pigeon wing.
I use tiring quite a bit. I believe it is awesome for conditioning your birds beak and for general manning. I do a lot of duck hunting and have many friends that duck hunt. The all save me the duck wings which I freeze to use as tirings. It takes my birds roughly 30 minutes or more to pick every feather off and all the connective tissue. They’re lucky if they get a total of 20 grams of bone, feather and meat from the wing.