When I first heard of the bird when it was in Tennessee, I immediately thought is was an escape and not worth chasing. However, as the story unfolds, it seems the bird could be wild. There are valid agruments for and against.
Hooded Cranes are not numerous in captivity in North America, numbering only a few dozen. A check has apparently revealed that all but the Idaho birds are accounted for. The four Hooded Cranes that escaped from a private collection in Idaho a few years ago were all female, so breeding in the wild (which could conceivably have produced the bird in question) would have been impossible. Three of the four had leg bands, and all were surgically pinioned, which means their outer primaries were permanently removed and long-distance sustained flight would therefore be impossible. The bird that's being seen here has no leg bands, has all of its primaries, and has no trouble flying.
However, for this bird to be wild, it would have to do a "reverse migration" in order to join the Siberian Sandhill Cranes on their migration to North America. It would have to fly about 1,200 miles northeast from its natural summer range in Mongolia and central Siberia, rather than south to China, Korea, and Japan, which is its natural wintering range. Birds do get lost all the time during migration though.
So who knows? It's up to two state checklist committees and the ABA Checklist Committee to hash it all out. I also sure hope they do decide it is wild.
Dave