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I photographed this female
Williamson's Sapsucker at the College of San Mateo on 12/29/04
between 11:00a and noon. In the photo to the left, the bird
worked briefly in a spot that allowed a reasonably clear
view. Note the brightly colored belly.
It later moved to a more obscured perch where
it sat for most of the time I observed it (below left).
It occasionally drank from an apparent sap well in the vertical
branch to its right.
The male of the species has a markedly different
plumage, and for a time, both sexes were thought to be different
species (see text below). I include an image of a male (directly
below) photographed in it's normal range in the Sierra Nevada
at Yuba Pass on 6/9/02. |
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As detailed in Arthur Cleveland Bent's "Life Histories of
North American Woodpeckers", 1939, the female of the
species was first described by John Cassin in 1852 as the
male of the "black-breasted woodpecker" Melanerpes
thyroideus, from a specimen collected by John G. Bell
in Eldorado Co., CA. Cassin described the female as lacking
the well-marked, densely black breast patch of the male.
In 1855, a Dr. Newberry collected and described the male,
which he called Picus williamsonii, at Klamath
Lake, OR.
In 1860, Cassin, Spencer Baird, and George
Lawrence, in their work on the collections from the Pacific
Railroad Surveys, described Newberry's woodpecker as the
male Williamson's Woodpecker, Sphyrapicus williamsonii.
The female was described as having a white chin. They also
changed the name of the bird Bell collected to "brown-headed
woodpecker", Sphyrapicus thyroideus. These
descriptions placed them in the current genus.
This misunderstanding continued in 1870 when
J. G. Cooper continued to use this nomenclature in his Geological
Survey of California. He also referred to the female as
the "round-headed woodpecker".
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Finally, in 1875, Henry W.
Henshaw observed the supposed males of both species in "suspicious
proximity". He felt that they were the same species
but originally thought that thyroideus was the
young of williamsonii. Eventually, the birds were
observed to mate and attend a nest cavity. Only then was
the true nature of their relationship understood.
So, the male "black-breasted woodpecker"
described by Cassin was actually the adult female Williamson's
Sapsucker, and his female was actually an immature female.
Newberry's male was, indeed, that of a Williamson's Sapsucker,
but the female described by Cassin, Baird and Lawrence was
actually the immature male. As for the scientific name,
Sphyrapicus, being the genus of the sapsuckers, was
retained, and thyroideus, being used for the first
description of the species, had priority. Hence, the binomial,
Sphyrapicus thyroideus.
This confusion is understandable with such
a disparity between the male and female plumage.
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