Bird identification is easy, except when it isn’t. For the next month, birders who look beyond their backyard feeders may be tormented by “confusing fall warblers” in the treetops.
Roger Tory Peterson coined the phrase “confusing fall warblers” in his original 1934 field guide. It remains the standard way to refer to all those pesky warblers that change plumage in autumn.
Identifying a warbler in June is relatively easy. They are brightly colored, although many are unhelpful variations on yellow. They establish nesting territories and sing to confirm their locations and identities. They stay put.
By mid-August, all bets are off. Before birds migrate, they prepare to migrate. Once their offspring can nourish themselves, parents are free to pack on their own calories, fueling up for the long flight ahead. Untethered from their nesting territories, warblers wander in search of food, sometimes in mixed flocks. As the season progresses, our local birds are joined by northern birds heading southward. In short, confusing fall warblers can show up anywhere.
Many birds molt before migrating, sometimes into muted plumages. When neotropical migrants arrive in Maine in springtime, they wear their finest colors to attract a mate. But in the fall, when it’s time to return to a Central American jungle full of predators, bright colors attract trouble. In autumn, drab is fab. The seasonal change is drastic for some warblers.
Starting with Peterson’s original guide, and in virtually every guidebook since, the author devotes entire pages to fall warbler plumage comparisons, pointing out their unique field marks. Users are expected to select the correct picture from 27 choices. I wish that worked.
I suggest that rather than trying to find the correct bird, first toss out all the incorrect birds. Many species aren’t confusing. Black-and-white warblers barely change at all, yet they still get consideration in the guidebook. Throw them out, so you’re dealing with a smaller set of candidates.
Some of the remaining warblers have wing bars. Some don’t. Whatever your mystery bird is, it’s in one of those two piles, and the other pile can be thrown out.
Most of the warblers without wing bars are still familiar-looking in fall, just duller. In this group, the Tennessee warbler is probably the hardest to identify. Canada, Nashville and black-throated blue warblers can be a little tricky. Yellow warblers and common yellowthroats are easy.
Warblers with wing bars are tougher. Fortunately, some in this bunch may look strange, but they don’t resemble any other bird. Chestnut-sided warblers lose most of the chestnut and take on a spooky facial appearance. But no other warbler looks like that in the fall, so they’re not very “confusing.”
Magnolia warblers are distinctly marked in the spring. The same breast streaks are there in the fall, but they’re indistinct. The field marks on yellow-rumped warblers also fade, but don’t disappear. Black-throated green warblers lose the black throat, but otherwise look the same as they did in spring. And so on.
There’s really only a handful of warblers that deserve to be called “confusing,” because they all resemble each other. Male Blackburnian warblers have bright orange throats in early summer, while females have yellow throats. In fall, their throat color nearly disappears. Cape May warblers have a yellow, streaky breeding plumage, but lose almost all the yellow in the fall. Bay-breasted warblers lose the bay. Blackpolls turn dingy, taking on a slightly green tint in some plumages. They all become dark, streaky warblers with white wing bars. Frequently, the challenge isn’t to identify which of 27 warblers you’re looking at. It’s figuring out which of these four similar species is flitting around up there. It’s confusing.
It gets worse. In spring, males are competing for attention. They are thus much easier to see. Females are shyer before starting to nest, and downright antisocial once they are. Birders mostly admire the easy-to-identify males. In spring, there are no immature birds to worry about, and there won’t be any until nondescript fledglings leave the nest later in summer. By autumn, drab females are as plentiful as drab males, and their youngsters are virtually unrecognizable.
So, this month, take the pressure off yourself. Concede that some fall warblers are more confusing than others, and do the best you can. Look for wing bars to help sort out possible identifications. Practice on those four troublesome warblers that look too much alike. Forgive females and youngsters for making life difficult. Forgive yourself for not getting every identification right, because I don’t either.
