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An overview of eastern fall warblers |
This article is adapted from a
presentation by Marcel Gahbauer to Bird Protection Quebec, December 2006
The "fall warblers" are one of the classic
identification challenges for North American birders, perhaps
immortalized best by Roger Tory Peterson's compilation plates of
"confusing fall warblers". However, despite the large number of
species involved overall, the situation need not be as daunting as it
sometimes seems. In reality, the full suite of fall warblers can
be broken down into several smaller groups, within which specific
features can be looked for to further narrow down the identification.
The material presented below is not intended to be authoritative, but
rather by offering a somewhat light-hearted approach to the subject from
a different perspective than some other references, may help provide
some useful memory tricks to apply when faced with a "mystery warbler"
in the field.
The WFTU approach
One of the keys to identifying fall warblers (or any birds for that
matter) is to know what to look for - there are myriad body parts that
you can commit to memory or jot down notes about, but in reality only a
few of those tend to provide really diagnostic information about
species. WFTU is a useful acronym to remember, as it stands for
two useful messages. One, focus on What Feathers
Tell Us - for the majority of warblers, and also many other
species, looking closely at particular feather tracts is where you
should concentrate your attention. Which ones? Wings,
Face, Throat, and Undertail are particularly useful
for warblers.
Simplify the search
It's easy to feel overwhelmed by the challenges of identifying an
unknown bird, especially if you are relatively new to birding. The
key to remember is that there are never really as many options as there
might appear to be at first. There are 2041 species in North
America ... but only 925 in the United States and Canada. Within
Canada there are just 661, and only 464 of those in Quebec.
Narrowing the scope further to the Montreal area, i.e. the pool of birds
that might potentially be encountered at MBO, the total drops to 357.
Numbers will be different for any particular location in North America,
but the general principle will hold for most - right from the beginning
you can ignore half or more of the birds in a North American field guide
(conveniently ignoring for the moment that vagrants can occur anywhere,
but the intent of this article is to focus on identifying the regularly
occurring species, so that's a topic for another time).
From that suite of local species, narrow the
field of options further again by identifying the general group of birds
to which the candidate belongs, such as warblers or sparrows, or more
generally waterfowl and songbirds. The key to this process is to
gradually weed out birds you are certain are NOT what you're looking at,
until left with a relatively small group of similar species is left to
consider ... and at that point the WFTU system can hopefully take over.
Know the locals
As alluded to above, vagrants can turn up anywhere, and of course their
discovery can lead to a lot of excitement. But in reality, the
vast majority of birds you encounter will be the regularly occurring
species in your area. Sometimes the ability to identify those gets
taken for granted, but in reality, if you are really familiar with those
species and their key characteristics, it will make it all the easier
for you to recognize a rarity when it does appear, and to be confident
that it IS in fact something different (even if you don't immediately
recognize just what it is). Practice looking for the key features
of common birds, and the differences will jump out at you much more
obviously when something doesn't fit.
The not-so-confusing fall warblers
Many references have broken down fall warblers into those featuring
wing bars and those without, but some further subdivisions are useful in
breaking up the species further. The table below summarizes such a
further subdivision for the 30 warbler species seen with some regularity
in southwestern Quebec and eastern Ontario. Below that, the WFTU
approach is applied to each group in turn. Refer to the
MBO Photo Identification Gallery for pictures
of some of these species, along with further detail on determining the
age and sex of individuals once species has been identified. Note
that some of the descriptions below are overly simplified as there is
quite a bit of variation within species by age and/or sex; again, this
is not meant as a definitive guide, but rather as an alternative
approach that may help you focus on important features, in combination
with tips from other sources.
With wing bars |
Without wing bars |
"True wingers" |
Golden-winged, Blue-winged |
|
"Pale 'n'
plain" |
Tennessee, Orange-crowned, Yellow, Black-throated
Blue (F) |
|
"Greenish
streakers" |
Bay-breasted, Blackpoll, Pine |
|
"Yellow-bellies" |
Nashville, Wilson's, Mourning, Connecticut, Canada,
Common Yellowthroat |
|
"Yellowish
streakers" |
Yellow-rumped,
Cape May, Palm |
|
"Mini-thrushes" |
Ovenbird, Louisiana Waterthrush, Northern
Waterthrush |
|
"Unique faces
of the bar" |
Magnolia, Chestnut-sided, Blackburnian,
Black-throated Green, Cerulean, Prairie,
Black-and-white, Northern Parula |
|
"Upstart
redstart" |
American
Redstart |
|
"True wingers"
These two species are easy to distinguish, especially by the wings and
throat (in this and other tables below the easiest / most reliable
distinguishing features are highlighted in bold)
|
Wing bars |
Face |
Throat |
Undertail |
Blue-winged
Warbler |
white |
black eyeline |
yellow |
white |
Golden-winged
Warbler |
yellow |
black cheek |
gray/black |
white |
"Greenish streakers"
These three are among the most confusing of the 'classic' confusing fall
warblers. Focus especially on the facial pattern and undertail, as
the wing bars are white on all three, and the throat is about as
variable within species as it is between them. Also check the back
- it is streaked on Bay-breasted and Blackpoll, but unmarked on Pine.
|
Wing bars |
Face |
Throat |
Undertail |
Bay-breasted
Warbler |
white |
slight eyering |
buffy |
buffy |
Blackpoll
Warbler |
white |
dark eyeline |
grayish |
white |
Pine Warbler |
white |
pale eyeline |
gray-yellow |
whitish |
"Yellowish streakers"
These species generally have a yellowish or brownish overall appearance
in fall. The face in combination with undertail are the best
features to focus on, though the more brownish wing of the Palm if often
an easy giveaway.
|
Wing bars |
Face |
Throat |
Undertail |
Yellow-rumped
Warbler |
white |
white eyering |
beige |
white |
Cape May Warbler |
white |
dark eyeline |
streaked |
white |
Palm Warbler |
brownish |
dark eyeline |
gray-yellow |
yellow |
"Unique faces of the bar"
These are 8 species with prominent wing bars that share little else in
appearance - each has a unique facial pattern though, more pronounced in
spring, but remaining distinctly recognizable in fall. In many
cases the throat can also be used to help confirm identity.
|
Wing bars |
Face |
Throat |
Undertail |
Black-and-white
Warbler |
white |
striped |
white/black |
white |
Blackburnian
Warbler |
white |
yellow-orange supercilium |
yellow/orange |
white |
Cerulean Warbler |
white |
whitish supercilium |
greenish |
white |
Northern Parula |
white |
partial eyering |
yellow |
white |
Magnolia Warbler |
white |
white eyering |
yellow |
white |
Black-throated
Green Warbler |
white |
yellow supercilium |
yellow - black |
whitish |
Chestnut-sided
Warbler |
yellow |
white eyering |
white |
white |
Prairie Warbler |
yellow |
dark eyeline |
yellow |
yellow |
"Pale 'n' plain"
These species are generally a pale yellowish/greenish/grayish overall.
The Black-throated Blue is more readily recognizable if it has white
wing patches (on the primaries, below the primary coverts), but not all
females show this. The Tennessee and Orange-crowned can be
particularly problematic, and for them the best feature to look for is
the colour of the undertail.
|
Wing bars |
Face |
Throat |
Undertail |
Orange-crowned
Warbler |
none |
partial eyering |
yellowish |
yellow |
Tennessee
Warbler |
none |
dark eyeline |
yellowish |
white |
Yellow Warbler |
none |
plain face |
yellowish |
yellow |
Black-throated
Blue Warbler (female) |
none |
pale supercilium |
whitish |
buffy |
"Yellow-bellies"
These species all have bold yellow underparts, but are different enough
in the face and/or throat that they can be fairly easily separated.
|
Wing bars |
Face |
Throat |
Undertail |
Nashville
Warbler |
none |
white eyering |
yellow |
yellow |
Mourning Warbler |
none |
partial white eyering |
yellow/gray |
yellow |
Connecticut
Warbler |
none |
white eyering |
gray/brown |
yellow |
Canada Warbler |
none |
white/yellow eyering |
yellow |
white |
Wilson's Warbler |
none |
yellow supercilium |
yellow |
yellow |
Common
Yellowthroat |
none |
brownish/black cheek |
buff/yellowish |
yellow |
"Mini-thrushes"
Brown above and spotted or streaked below, these three warblers look
like smaller versions of the Catharus thrushes. The face
and throat provide easy ways to distinguish among them.
|
Wing bars |
Face |
Throat |
Undertail |
Ovenbird |
none |
white eyering |
white |
white |
Northern
Waterthrush |
none |
buffy/pale supercilium |
streaked |
white |
Louisiana
Waterthrush |
none |
white supercilium |
streaked |
white |
"Upstart redstart"
The only warbler in this region lacking wing bars and also entirely
different in appearance from the preceding three categories.
|
Wing bars |
Face |
Throat |
Undertail |
American
Redstart |
none |
gray or black |
white or black |
white |
Concluding thoughts
Everyone's learning approach and memory techniques are different.
The information presented in this article has proven helpful for some
birders, and not for others. Regardless of which category you fall
into, remember that there is no substitute for experience - spend enough
time watching the common warblers in your area, and you can develop your
own unique personalized ways of identifying each species.
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