Hummer migration is complex. The strange East-West
migrants are Anna's & Costa's. Feeder influence is
clear on Broad-billed and Rufous. Anna's have both
migrant and resident populations in both Calif & AZ.
I notice the Anna's increase in Winter in Tucson where
they fight with my now year round resident
Broad-billed hummer families. We also get Costa's in
Winter in Tucson, but they disappear in the Summer. (
I have close-ups of a male Coasta's at my snow covered
Tucson feeder last Jan.) Anna's breed year round in
N. Cal, and some migrate up-slope post-breeding into
the Sierra, where they appear at my Tahoe feeders just
as the south-bound male Rufous show-up in June. The
aggressive Rufous & Anna's drive off my breeding
Calliopes.

It's weird, but interesting.

Dick

--- ravenintherain <ccorax at blarg.net> wrote:

> Cliff Drake wrote:
> >> Overwintering in the Puget Sound area, at least
> in such predictable
> >> numbers, is an artifact of our feeding them. And
> once you start, one
> >> is therefor obliged to keeping up a good "hummer
> cafe".
> >>
> > I'm not sure I believe either point. There are
> Anna's in my yard because
> > I have a feeder out but if I didn't they'd just go
> down the block, not
> > to Mexico or wherever. I just can't believe our
> use of feeders has led
> > to the Anna's Northward migration. I had a 10
> minute chase this morning
> > around the house, lots of action in front of the
> windows. Pretty cool.
> > ====================
> > Cliff Drake
> > Seattle WA (Ballard)
> > cliff at cliffdrake.net
> >
> I checked some sources on this. Cornell's Birds of
> NA Online had the
> most information on migration, but that wasn't much.
> The discussion
> centered on the fact that the major Anna's
> population is in southern and
> central California. Post-breeding the birds move up
> into the mountains,
> east into Nevada Arizona and "north up the coast."
> None of the other
> sources (Sibley and Audubon Guides, a few ".edu" Web
> sites) say much
> more than that the species has been expanding since
> the 1950s,
> especially to the north. It has always been my
> understanding that our
> Anna's population stays around all winter eating
> arthropods with feeder
> nectar as dessert, but that's received info not
> science. It has been my
> impression that there are more Anna's around here in
> winter than in
> summer, but that may be because the trees are bare
> and the birds
> therefore more visible. Is it possible that our
> winter population is
> supplemented by migrants from the Great White North?
> Anyway, as someone
> else remarked, it's nice to have the color around in
> winter.
>
> Dale
>
> --
> Dale Chase
> (AKA ravenintherain)
> Seattle, Washington
> ccorax at blarg.net
>
>
>
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Richard Carlson
Full-time Birder, Biker and Rotarian
Part-time Economist
Tucson, AZ, Lake Tahoe, CA, & Kirkland, WA
rccarl at pacbell.net
Tucson 520-760-4935
Tahoe 530-581-0624
Kirkland 425-828-3819
Cell 650-280-2965