Hi -
I am pretty confident the birds alan saw were Aleutians.
In the last decade before leaving Oregon, I put in quite a bit of effort trying
to identify "Cackling" Geese migrating along the coast. My method was to
photograph flocks as they went by, then examine them for neck bands and for
breast color. Of course Aleutian birds of the year usually lack neck bands, so
all flocks would have lots of birds without. Flocks that had multiple birds
with white neck bands I called Aleutians (ssp. leucopareia ). Flocks with none
visible were "other" Cackling Geese. Overall my conclusions were that when
there were big movements along the beach, bluffs, etc. they were consistently
Aleutians. I think most of the "real" Cackling Geese (ssp. minima ) go inland,
and do not follow the coast. The Willamette Valley is now the primary wintering
area for ssp. minima, although some still go farther south into California.
And of course other subspecies (e.g., hutchinsii) also winter in the Willamette
Valley, and might sound different.
I have never been satisfied that the AOU (now NACC) completed the job with
white-cheeked geese. They have been downplaying the inconvenient fact that
minima breed adjacent to other, larger "Cackling" Geese without interbreeding.
The minima population breeds in a small area on the coast of the
Yukon-Kuskokwim Delta, abutting larger " hutchinsii " type breeders. As any
careful birder in the Willamette Valley can see, minima also behave somewhat
different in winter: When feeding they form much tighter flocks, such that
these flocks are recognizable at a distance by how tightly packed they are.
Over a decade ago, Steve Mlodinow responded to a post of mine on goose taxonomy
stating that minima and leucopareia (Aleutian ssp.) were almost identical
genetically, so that if minima were separated from other mainland "Cackling"
Geese, the Aleutians would need to be placed with minima . I have observed
Aleutians feeding in the dairy pastures in the Smith River bottoms north of
Crescent City CA, and the "Semidi" Aleutians at Pacific City, and to my eyes
they do not seem to pack together as tightly as minima do around Finley,
Baskett Slough, and Ankeny NWRs.
Speciation in birds is usually a somewhat drawn-out process, requiring long
periods of differentiation of allopatric populations, but it seems clear to me
that there are several groups of birds where "special circumstances" (unusual
combinations of behavioral and genetic traits) allow much faster
differentiation and speciation, without the gradual changes in "neutral" gene
markers that are usually used to assess species status. Bird groups subject to
such "special circumstances" include northern geese (Anserini), prairie grouse,
crossbills and perhaps some other finches, perhaps Empidonax flycatchers,
certain groups of petrels, and probably a few more.
For the geese, in addition to the "Cackling" group, rapid differentiation is
evident among the forms Canada Geese, of Bean Geese, of White-fronted Geese,
and of Brant. To put this in good temporal perspective, remember that much of
the current complex pattern of geographic differentiation in breeding
distribution is on land that was glaciated 10-15 thousand years ago.
For geese, the behavioral "special circumstances" include migration in
sub-population specific flocks with migration routes determined by tradition
rather than genetics, long-term monogamous pair bonds, and pairing within these
flocks on the winter range. The genetic "special circumstances" include rapid
responsiveness to selection for larger or smaller body size (in general,
inverse relationship between body size and length of migration), and for
differences in bill morphology responding rapidly to diet differences. Geese
also tend to follow Gloger's Rule - I'm not sure how relevant that is, but it
does speak to evolutionary plasticity.
So bottom line for me; minima are the "real" Cackling Geese, and should be
recognized as their own species. I would not be upset if Aleutians were
included with them, but suspect they should be treated as a separate species as
well.
[For prairie grouse the primary driver of rapid speciation likely is the lek
mating system and resulting extreme sexual selection on external appearance.
For crossbills, it seems to be the combination of nomadic travel in groups of
close relatives, use of vocal differences to recognize close relatives, and
rapid selective responses in bill morphology to differences in cone size and
toughness.]
Wayne
From: "Phil Pickering" <philliplc@xxxxxxxxxxx>
To: "obol" <obol@xxxxxxxxxxxxx>
Sent: Friday, October 22, 2021 5:56:59 PM
Subject: [obol] Re: Lane coast birds
I saw several flocks of Aleutians angling inland
over Lincoln City in the rain this morning, possibly
hitting the coast right at this latitude before turning
south.
Phil
