Swans in California

There are many identifications in California of “Tundra Swans”. Most of those identifications do not show the yellow dot towards the end of the birds beak, towards the eye. I’m skeptical these are all Tundra Swans could they not be juvenile Mite Swans or Trumpeter Swans??what’s the likelihood of all of these Tundra Swans coming to California? I’m here to learn so please keep it civil