pbjosh
missing the neotropics

Back to the original question, I've never had Whooper Swans come up as a subject of conversation with any British friends, but all of the Americans and non-native speakers I've ever heard pronounced the w- and not the h-, so wooper more or less. I should guess the original / correct pronunciation would be hwooper or something like that, as per the RSPB video above. These sorts of things are very hard to "enforce" as English spreads around the world and evolves. Given that it's not a word in general use, though, it's pretty far down the list of words that will be pronounced differently / mispronounced in different parts of the world 