While we do have fifty sets of gun and hunting laws, there are certain Federal laws that apply to all of us. Migratory game bird laws are controlled by our Federal Government, or at least they set up guidelines that each state must follow. In fact, a Federal Duck Stamp is required by anyone, in any state, to hunt these species.
One example is the use of nontoxic shot. Anyone in America that hunts ducks or geese can not have any loads contianing lead. There are other examples.
I realize that this might sound confusing, but most of us that live here still haven't figured all of this out.