The problem i see is going to be identifying the bird. They are related to but not the same bird as the trumpeter swan which is federally protected. You would need to get pretty close to the bird in order to tell them apart. Tundra or whistling swans have a small amount of yellow in the beak which are almost all black near the eyes where trumpeters beaks are all black with no yellow. Their call is different.. other than that its very easy to mistake one from the other. Kill a trumpeter you're looking at a heavy fine.. somewhere north of $20k. I personally wouldn't hunt them .
1, they are huge.. wont fit in any conventional oven whole if you plan to eat it
2 they are tough.. unless its a young bird, the best way to consume one is to grind it and use it like burger meat so i am told.