Saturday, October 11, 2014

Fall Warblers - You've gotta love 'em.

   With the changing of the seasons comes the departure and the arrival of many bird species. Most birders seem to think "warblers" as the winds shift to the North and the sky puts on its glorious, clear, blue uniform. You can take that group of warbler-thinking birders and further divide it into two smaller groups: those who are confident when it comes to identifying these small, quick passerines, and those who are intimidated by them. Hopefully this post will help those with a lack of confidence in warbler ID.
   I, fortunately, have never felt intimidated when encountering a warbler in fall dress. Nevertheless, no matter how experienced in birding you are, you cannot avoid the challenge that comes with warbler ID. You can face these challenges in a different way, though, and often the result is increased confidence and even a new, enjoyable style of birding.
   Before I dive into the core of this post, we have to discuss how to locate a warbler. After all, at this time of year, most birds are not even singing, resulting in a bit more difficulty finding them. When searching for warblers, I usually listen for their calls, which usually sound like a simple "chip." I'll also listen for their flight calls, and these often come in the form of "seet's" or "zeet's" (for lack of better description). Warblers are frequently found with chickadees and titmice too, so if you ever come across an active flock of either species, definitely keep your eyes open for warblers. Finally, be on the alert for movement in the tree tops or in the understory, which may be a foraging warbler.
   So now, back to identifying warblers...  

   1. Consider location and habitat.

    I recommend that the first thing you do when faced with a warbler is consider the bird's location. Is the bird foraging in the canopy? Or is it quietly moving in the understory? Nearly every Setophaga warbler is found high in the trees, while warblers of genus Geothlypis and others are almost always seen low to the ground. Narrowing down your mystery bird to a tree top or ground-loving forager definitely helps shorten the identification process. Also, ask yourself about the habitat. Is the warbler in an evergreen or deciduous tree? Habitat questions are also somewhat helpful, but please remember that many warblers will stray from their primary habitat during migration, so don't solely rely on habitat to aid identification.

    2. Try to get a look at the bird's face.

   You can identify any warbler by simply paying attention to the details of the bird's face. Does it have an eye-ring? If so, is the eye-ring complete? Is it thick or thin? Little details like this are incredibly powerful field marks.
Despite the shadows cast by the cedar, you can still see the basic face pattern of this
Black-throated Green Warbler.

   3. Study the warbler's underside.

   Unfortunately, many warblers remain high in the trees, giving us views of only their undersides. As frustrating as it is, the coloration of a bird's throat, breast, or belly can be somewhat useful in identification. For example, Yellow Warblers are, of course, completely yellow on the throat, breast, and belly, but their close relative, the Chestnut-sided Warbler, is mostly gray in the same areas during the fall. Whatever you do, don't pass up a look at a warbler's underside, dismissing it as useless.

   4. Pay attention to the bird's wings.
   This is especially helpful with warblers that have similar face patterns and undersides. A good example would be Tennessee and Bay-breasted Warblers. A head-shot of both would result in two very similar birds, but then, if you move down to the undersides, you might notice peachy sides on the Bay-breasted Warbler (depending on the bird's age/sex). This coloration should be absent on Tennessee Warbler. Finally, if the birds turn, notice that the Tennessee's wings are practically the same shade of greenish-yellow as the rest of its body, while the Bay-breasted's wings are black with two white wing bars.

Even looking away, the wings and sides of a Bay-breasted Warbler easily separate it
 from the somewhat similar Tennessee Warbler.

    5. Don't ignore the under-tail and the undertail coverts.

    Believe it or not, the under-tail of a warbler is an extremely useful field mark. One of the most common fall warblers in Eastern North America is the Magnolia Warbler, and, incredibly enough, you can identify this species by just the pattern on its under-tail alone! If you ever get a look at just a bird's under-tail, don't ignore it. I'll repeat: this can be a surprisingly useful clue to the species' identity.
    Also, pay attention to undertail coverts. This, too, aids in separating similar species. Orange-crowned and Tennessee Warblers are both very similar, but one difference is that Orange-crowned Warblers have yellow undertail coverts while Tennessees have white undertail coverts. So never dismiss either of these parts of a warbler.

The under-tails and undertail coverts of a few warblers.

    6. Carefully judge size.

     Size is something to note with all birds - not just warblers. This is best done when you have two birds to directly compare. Whenever you encounter a large group of warblers, survey the flock with the naked eye, and then use your binoculars to more closely observe birds that look larger.  

   7. Watch its behavior.

    Observing a bird's behavior takes a bit of practice, but over time you may notice a particular species acting differently than others. Black-and-White Warblers, for instance, forage like nuthatches, while other warblers normally don't feed in this way. Another example would be the tail-pumping of a Palm Warbler versus the tail-flicking of a Wilson's Warbler. If you come across a warbler that seems to be acting "strange," I would certainly give it a check.

Black-and-White Warbler acting in the typical nuthatch-fashion.

    8. Listen for calls and flight calls.

    This is easily the hardest part in warbler identification. Fortunately, you don't have to base identification on the calls or flight calls of warblers. There are, however, a few species with distinct calls, such as Northern Waterthrush, American Redstart, and more. If you hear a warbler calling but you don't know what it is, try to record it - even if you have to use your phone. Later, compare your recording to various warbler recordings online. Arguably the best website with bird vocalizations is Xeno-Canto.

    By now you should see that, if you take the correct approach to fall warbler ID, it isn't as hard as you first thought. And I truly hope that those of you who needed a confidence boost in warbler ID got it from this post. Now, it's time to get outside and put what you've learned to practice! (Warning: Looking for warblers may result in neck pain, often referred to as "warbler neck." Use caution!)

*Note: Two outstanding books on warblers are the aforementioned A Field Guide to Warblers of North America (Peterson Field Guides) by Jon Dunn and Kimball Garrett, and The Warbler Guide by Tom Stephenson and Scott Whittle.

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