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One of the axioms of field birding is that smaller birds
tend to feed more actively and move more frequently and
unpredictably than larger birds.
How does one separate three Little Gray Jobs of similar
size and structure as they flip frenetically and silently
together through the same habitat? Here are three requirements:
Patience. Sooner
or later even Little Gray Jobs will pause to rest, preen, or
eyeball around for the next morsel.
That's how sharp images of smaller birds are ultimately
captured.
Experience. Last
fall, In the low desert of Papago Park, one of our quiz birds
was reported to me as an Olive Warbler.
Beginning birders just growing into an awareness of
habitat and probability need to realize once-in-a-lifetime
sightings rarely occur at the beginning of that lifetime.
Concentration. I
know very well a lifelong birder who writes photo quizzes who,
on his slides, mislabeled one of our quiz birds for another,
an egregious error pointed out to him by his friend Troy
Corman.
A)—Good
photo, easy bird
If you've heeded the well-worn message about the importance
of structural differences over plumage considerations but all
you're seeing is three plump little birds with the same body
shape, then you've forgotten that bill shape is part of a
bird's structure and bill shape is always a good place to
begin separating look alike species.
A close, careful look at these three photos reveals three
very different bill profiles.
Our first image shows a bill that is quite thick
compared with the other two.
That stout bill, if not the plump body, eliminates
warblers from our consideration and is the primary
characteristic of that mostly drab family of LGJs, the vireos.
Even in a family as nondescript as the vireos, our quiz bird
scores "very plain."
Five of our vireos sport "racing stripe"
eyebrow lines, but here we see only an eyering broken at the
top by a dark spot. Seven
of our vireos sport eyerings and matching lores so bright we
call them "spectacles," but here we see pale lores
not quite bright enough to connect into the eyering.
That leaves us to choose from Hutton's, Gray, or
Bell's, and it would be very unusual to find either of the
latter two in central Arizona in the winter.
The only other plumage feature in the photo, the obvious set
of bright wingbars, should wrap up our identification of this
bird as a Hutton's. Gray
Vireo wingbars are so indistinct that many guide books do not
even depict them or show only the lower one.
Wingbars on the Arizona version of Bell's Vireo are
equally obscure, though the lower bar on a bright eastern
Bell's might be this bright.
Neither Gray nor Bell's vague eyering is broken on the
top like this Hutton's
B)--Good
photo, difficult pair
Our second bird, at first glance, could pass for a Hutton's
Vireo mightn't it? Same
plump nondescript little body, same eyering broken at the top,
same wingbars. But
that bill is different. It
is thinner, flatter, and possibly even smaller relative to
this bird's head, though we can't say for sure because our
Hutton's view isn't a completely side profile.
And, except for the pale eyering, our
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second bird has a uniformly plain face without any
discernable difference in the color of the loral area.
It also has a flatter, less rounded crown.
This is not a Hutton's Vireo, but the differences are
subtle.
So subtle, in fact, that many field guides show this species
alongside Hutton's on the vireo color plate to note how
careful observers should be in separating it from Hutton's. So subtle, in fact, that this species' name is easily and
often applied to a Hutton's passing by in a hurry or to a
Hutton's image if a photographer is in a hurry to label his
slides. The converse, however, seems not to be true.
We rarely apply Hutton's name to this bird because
Hutton's is not nearly as common, as commonly seen, or as well
known and recognized as this bird.
This second quiz bird seems always to be our
"default" LGJ.
If we slow down and look carefully at those "same"
wingbars we realize they are not really the same.
In our Hutton's photo, the bright lower wingbar, which
is really the tips of the greater secondary coverts, reaches
all the way to the base of the bird's secondaries.
In this photo we see a very distinct black bar across
the base of the secondaries, not at all in the same place as,
or to be confused with, the greater coverts of the Hutton's
which appear darker than its secondaries in our first photo.
This black bar across the base of the secondaries is
the surest way to distinguish Ruby-crowned Kinglet from
Hutton's Vireo.
C)—Bad
photo, easy
pair
This grayscale image, with only two slightest hints of
color, is exactly what you would see observing the female of
this species--no face pattern, no obvious wingbars, nothing
but shades of gray. A
tough call perhaps, especially if other LGJs were about.
But there is that unique bill--tiny, thick at the base,
yet sharply pointed. It
is not a warbler bill, and if this bird were reported from
Papago Park as an Olive Warbler, you should know immediately
that a novice birder had seen the male of this species.
Actually the bird in this photograph is a male.
The dark lores are discernable here, but the touch of
darker tone at the shoulder might be your imagination without
the color slide to show you the rusty epaulet--which is often
not visible in the field anyway.
Which may account for mistaking this male Verdin for a
male Olive Warbler in the low deserts around Phoenix.
The female Verdin, lacking the male's dark lores, may well
be our plainest bird, without any apparent field marks, but
remember that behavior can be a key diagnostic feature.
Verdins' feeding mannerisms are similar to those of
kinglets, exploring nervously along branches, hanging from the
branch tip, then flipping off to the next bush.
I have seen both species hover pluck insects and I have
seen both flick their wings repeatedly for no apparent reason.
Hutton's, like all vireos, tends to feed more slowly
and deliberately than Verdins or kinglets, gleaning, pausing,
searching with the eyes rather than the body.
Here's an ultimate cautionary note for LGJ aficionados.
A male Olive Warbler spent last winter in
Boyce-Thompson Arboretum State Park! Be patient. Be
careful. Learn
from your mistakes.
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