Yes there is an element of combined probability of all that happening, inasmuch as assessing the possible genetic origins of the bird and its arrival at that point. It is those things that are still undecided (but seem fair to me). However this does not any longer need to be multiplied by the probability of being found in WA by a birdwatcher. This is because the latter event is now a known fact. Unexpected maybe but probability only exists before the event. Once it has happened, the probability of it happening (at some other random time), now becomes irrelevant, as that part is now 100%. Indeed this may have happened with other birds in the past that were never found by any observer, or more in the future, in which case the probability of them being found is relevant and can be included in the calculation. But not this one.
If I win (or don’t win) the lottery, the probability of this happening is irrelevant, after the event. The only relevant probability is would I win the next one (which until it happens is equally unlikely).
Philip
