The clause that reaches the product
On this page11
The clause
The prohibition covers "any migratory bird, any part, nest, or egg of any such bird, or any product, whether or not manufactured, which consists, or is composed in whole or part, of any such bird or any part, nest, or egg thereof".
Three widening steps in one sentence
The bird, then any part of it, then any product composed in whole or part of either. Each step closes a way the previous one could be evaded.
Composed in part is the operative phrase
A fly is mostly hook, thread and synthetic. If one feather in it came from a listed species, the fly is composed in part of that bird.
Whether or not manufactured
Which anticipates the obvious argument that working a feather into something transforms it. The Act says it does not.
And the verbs apply to the product too
Sell, barter, ship, transport, carry, possess. A box of flies is subject to the same list as a box of feathers.
Which is why this is not a theoretical page
The ordinary acts of the craft, swapping, selling, posting, travelling with a fly box, are all named in the statute.
The limit is which bird
The Act protects migratory birds as specified in four bilateral treaties, and the species are listed at 50 CFR 10.13. A feather from a bird not on that list is not reached by this sentence at all.
So the question is always about the source
Not about the fly, not about the intent, not about the quantity. Which bird did this feather come from, and is that species on the list.
Which is answerable for bought material
A supplier selling tying hackle can say what bird it is, and the common answer makes the question easy. The materials section covers that.
And harder for found or inherited material
A feather picked up on a walk, or a cape in a box from a relative, has no provenance. Our beach and field finds property covers the possession side of exactly that problem.