A possibly relevant consideration for the recent discussion of the
origin of the Xantus's Hummingbird in B.C. is the Green Violet-ear,
another montane hummingbird of Mexico with a recent pattern of discovery
as a post-breeding disperser northward. First identified in Texas in
the 1960's, it now is found somewhere in eastern North America almost
annually, with a record now as far north as the vicinity of Thunder Bay,
Ontario. Some of the early reports, especially far from its area of
origin, were dismissed, although now the pattern of occurrence is
well-established. It perhaps is significant that there is no
stepping-stone pattern for individuals -- i.e., a bird inevitably (I
think) appears perhaps a thousand miles or more north of its range
without ever being seen en route.

The Green Violet-ear is a much more common and widespread species than
Xantus's Hummingbird, so it is unlikely that as strong a pattern of
northward vagrancy ever will develop for the latter. But the anology
seems reasonable to me, and I'd predict that eventually the locations of
Xantus's sightings will fill in. It may take a few centuries for such a
pattern to emerge.

Do birders give Records Committees (and themselves?) too much
credit for omniscience, and birds too little credit for mobility
and survival?
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P W (Bill) Smith
Grays Harbor, Washington USA
pwsmith at techline.com