[Tweeters] Anna's Hummingbird

Eugene and Nancy Hunn enhunn323 at comcast.net
Tue Feb 17 11:19:36 PST 2009


Hal, Dave, et al.,

I have to agree with David and Hal, though without careful consideration of
records. Anna's first arrived in Washington about 1965 and by the 1970s was
well established in certain (but not all) urban areas as a non-migratory
species (Hutch conducted some of the early censuses of Anna's in the
Magnolia neighborhood), clearly heavily dependent on ornamental plantings,
feeders, etc. Rufous Hummers have always preferred such native habitats as
salmonberry thickets and the like (to the point that Michael Hobbs believes
they emerge each spring from salmonberry buds!). Rufous Hummers have
retreated as our built environment has hardened and expanded. I believe the
House and Purple Finch distributional changes show a very similar dynamic.
House Finches, of course, have expanded all across the US in part by virtue
of introductions, such as on the east coast and in the 1930s, I believe, on
Vancouver Island, though it is most likely Washington was invaded by a
"natural" expansion from California, the historic core territory of the
House Finch (and Anna's Hummingbird) in the US. Brown-headed Cowbirds show a
similar pattern in the late 20th century. I don't believe global warming was
a factor in any of those cases, at least not in any direct way.

Gene Hunn
18476 47th Pl NE
Lake Forest Park, WA
enhunn323 at comcast.net

-----Original Message-----
From: tweeters-bounces at mailman2.u.washington.edu
[mailto:tweeters-bounces at mailman2.u.washington.edu] On Behalf Of Hal
Opperman
Sent: Monday, February 16, 2009 9:13 PM
To: tweeters at u.washington.edu
Subject: Re: [Tweeters] Anna's Hummingbird

Tweets:

Following on David Hutchinson's recent posting, he and I have compared
notes on the evolving status of hummingbirds in the Seattle area. Dave
has suggested that I share my observations on Tweeters as he has done
with his. Our experiences, while different, complement one another.
However, unlike Dave's carefully controlled study, my evidence is
anecdotal and I have been obliged to dredge it up from memory rather
than from carefully tended written records; nonetheless it is
suggestive.

I moved to the Seattle area in 1967 and have always lived in what the
real estate industry has decided to call West Bellevue - at first near
the southeast corner of the then rather modest, spread-out business
district, and since 1975 in Medina, a residential community one-plus
mile west of the city center now dominated by closely packed tall
buildings. During the first part of this four-decade period Rufous
Hummingbird was a familiar yard bird from April into early summer. By
about 1980 it was becoming scarcer, although one still found it
regularly in large areas of suitable habitat such as Mercer Slough.
Well before 1990 it had essentially disappeared from our suburban
parks and gardens. Today I see Rufous Hummingbird in my neighborhood
only very rarely, on spring passage.

Anna's Hummingbird began turning up in our yard in the 'nineties. At
first it was a novelty: single birds now and then. Before long,
though, a pair set up residence; it or a successor pair has nested
ever since, sustained by the many shrubs and perennials in bloom in
our garden in all seasons. Other Anna's regularly test the limits of
the resident pair's territory.

In brief, Rufous has effectively been gone from West Bellevue as a
summer resident for about 25 years. If one had good data I am certain
one would find a 1:1 correlation between declining numbers of this
species and increasing density of urban development.

Anna's has been an established permanent resident for about 15 years.
This means that Rufous had been essentially extirpated for a decade
before Anna's arrived and settled in. Anna's did not drive Rufous out.
Rufous had already retreated to the farther-out suburbs, or indeed the
forested foothills, where it could still find acceptable habitat.

I believe, by the way, that a similar dynamic is in play for the
colonization of Seattle by the House Finch, and the deceptively
synchronous disappearance of the Purple Finch from the urban core,
beginning in the 1950s. Unfortunately, it is too late to gather data
to test this hypothesis in a scientifically respectable way. I do know
that Purple Finch was a common feeder bird at our house into the late
'seventies, although outnumbered 2:1 or 3:1 by House Finch. Purple
Finches then disappeared abruptly. I now see one in our garden every
three or four years, never for longer than a few minutes.

Wouldn't it be nice if we had long-running bird census data for these
and other species along transects crossing rural, suburban, and urban
zones from the Puget Sound shoreline to (say) the 1,000-foot contour
of the Cascades and Olympics? Data that could be quantitatively
compared with measurements of land-use changes and concomitant habitat
alteration over the years? How much more human population growth can
the Puget Trough stand before we wake up to discover that Rufous
Hummingbirds and Purple Finches are nowhere to be found because we
have converted the lowlands to House Finch and Anna's Hummingbird
habitat?

Hal Opperman
Medina, Washington
hal at catharus.net_______________________________________________
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