January 2, 2009 - Last November we were surprised to
see a white throated sparrow foraging by double scratching in the dried
leaves under the far feeders. This one had the black and white stripe on
his head.
The latest snow and ice blew in a small flock of white throated sparrows
dancing like mad in the gentle snow drifts trying to unearth seeds and
goodies. They happily mixed with the cardinals, juncos, house finches,
and mourning doves. As can be seen from these photos, the mourning doves
learned quickly, that the sparrows could easily uncover hidden corn and
seed. The doves would follow the sparrows around and jump into the holes
they created in order to find the larger seeds that didn't appeal to the
sparrows. Good times for all.
Our latest crowd of sparrows consisted of both types of white throated
sparrows (the black and white stripes and the brown and tan version).
In
late November 2008 we
saw a white throated sparrow foraging on the ground under the
feeders with some juncos. This version had the black and white head
(sure stands out in a crowd) and, of course, the yellow spot at each
eye. Our backyard is located at the line between migration and
summer, which makes him a surprise visitor, but always more than
welcome.
This distinctive sparrow has two bright yellow spots from the
base of the beak to the top of each eye. The white throated
sparrow is polymorphic ( two color variations). The stripes on his
head are dark with either white stripes or with tan stripes. For
an as yet undetermined reason, studies show that a white striped sparrow
will only mate with a tan striped bird (white striped male with tan
striped female or tan striped male with white striped female).
Early observers (cited in old bird books) believed that the tan
striped versions were the juveniles of the white striped ones. In
researching information on the white throated sparrow I even found a
reference that stated all tan striped sparrows were the females.
But the most astonishing theory was, while the opposite colors
"almost always" mate, all males (whether white or tan) prefer
females with white stripes. Both types of females prefer males of
tan stripes. (Who did that survey, anyway?) The white striped
version is more aggressive than the tan, so the white female will select
the tan male. While the other two may mate by default, studies
show that the tan female is more nurturing than the white striped one.
And only the white female will
sing, as do both versions of the male. This might be one of nature's
strange trade-offs.
Our backyard falls in the migration transition between only summer
and only winter stays . We first saw the white throated sparrow on
April 25th. That and later sightings on May 3rd and 6th were all of the
white striped version. It wasn't until I was ready to do this
introduction and after some research, that I realized I had pictures
taken on May 12th of the tan striped morph along with, oddly enough, a
white crowned sparrow. Their migration time had overlapped in our
yard. Sure hope we don't miss a return pass through.
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Size:
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Length: 6-7 in
Weight: .9 oz
Wingspan: 8.75-10
in
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ID:
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Male: Gray underparts with some darker gray streaking; back,
wings and tail streaked brown and black; bright yellow
supraloral stripe
(area between the eye and the base of the beak); two separate
morphs (white and black striped head; the other tan and brown
striped head); white or tan throat matching head stripe; two white wing bars; beak short,
dark gray and sharp; pinkish brown anisodactylous feet (three
toes point forward and one toe points backward)
Female and Juvenile: Head pattern less bold than male; dull
yellow lores; grayer throat; streaking on breast more
pronounced
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Habitat:
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Mixed woodland undergrowth; thickets and bushes; residential
areas in winter
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Diet:
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Insects, spiders, seeds (at ground feeders), and berries;
forages on ground and in vegetation by double scratching (slight
hop forward with both feet, then a sweep backward kicking aside
debris exposing any food); loves sunflower seeds
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Family Behavior:
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Mating Habits: Monogamous and solitary; each breeding pair
consists of one white morph and one tan one; 1 brood per year
Local Breeding Period: Mid to Late May
Nests: Cup-shaped; female builds; made of coarse grass, twigs
and wood chips, and conifer needles; placed at edge of clearing
concealed by low shrub or log
Eggs: 4-6 greenish white to bluish white with reddish brown
markings; female incubates 11-14 days
Nestlings: Born altricial (helpless, naked, eyes closed) and
stay in nest 7-12 days; male and female feed
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Social Activities:
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Joins mixed species flocks in winter
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Range:
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Breeding: Across Canada to extreme north east US
Winter: Mid to southern US
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Vocalization:
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Clear whistled rhythmic pattern of notes that begin with two
notes on one pitch and next 3 or 4 on another; call a loud,
sharp chink for alarm or tseet in flocks
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Lifespan: |
Up to 10 years |
