One of our favorite birding things to do in August is to try to find a flock of what bird book author Roger Tory Peterson famously described as “confusing fall warblers.”

Debate swirled for years as to whether Roger had done a disservice and made people think that identifying warblers in the fall was hard or that he had been honest and taught people the simple ways to identify birds that were hard to tell apart.

You don’t hear the phrase “confusing fall warblers” much anymore, which probably means that in general most of us who teach people about birds have decided not to hype the “confusing” part of fall warbler identification.

Unfortunately, most field guides also no longer use some of the brilliant system that Roger Tory designed to help identify those fall warblers. The plates in Peterson’s field guides that he did indeed label “confusing fall warblers” were organized so that one page had warblers that had wing bars and the other had all of those without wing bars.

This taught the inexperienced observer that one of the first things to look for when trying to determine the identity of a “fall” warbler was to see whether or not it had wing bars. If it did, then there were 15 possibilities and 12 other species immediately ruled out. From there one might check to see if it had a yellowish rump. If it did then the choices would be narrowed down to four possibilities. Did it have white spots in the tail? If so, you had just figured out that it was a magnolia warbler!

It turns out most warbler species, even if sporting their immature plumage, look generally quite similar in the fall from the way they look in the spring. Yes, the immatures are generally duller and adults can be worn or even starting to molt into a drabber plumage that they may wear for the winter.

But a northern parula is still a rather small and dainty, short-tailed warbler that is bluish above and yellow on the throat. And a yellow-rumped warbler (or Myrtle warbler as it was labeled in the old Peterson field guides) is still a rather large warbler with a bright yellow rump — a feature for which birders lovingly call it the “butter butt.”

Sure, there are  a few warbler species that sport a very different looking plumage pattern in their immature or winter plumage. Don’t look for the reddish sides and lemon yellow cap on an immature chestnut-sided warbler, for example. Instead you will find a beautiful, but very different, bird with glowing lime green upperparts and a white eye ring. The immature blackpoll warbler will not be sporting the black cap of the male in spring but instead will be a greenish streaky creature (with wing bars!) with distinctly yellow legs or feet. There are today, several field guides devoted just to the identification of warblers including the newest one, “The Warbler Guide,” put out by Princeton University Press, which is a veritable warbler identification bible!

In the fall, migrating warblers will often join resident chickadee flocks to forage for food during their daily stop-overs. It is a wonderful treat to find one of these mixed species flocks and look through it to see what different species of those fabulous fall warblers you can find. Enjoy it while it lasts!

Dr. Jeff Wells is the senior scientist for the Boreal Songbird Initiative. During his time at the famed Cornell Lab of Ornithology and as the Audubon Society's national bird conservation director, Dr. Wells earned a reputation as one of the nation's leading bird experts and conservation biologists. Jeff's grandfather, the late John Chase, was a columnist for the Boothbay Register for many years. Allison Childs Wells, also formerly of the Cornell Lab of Ornithology, is a widely published natural history writer and a senior director at the Natural Resources Council of Maine. Together, they have been writing and teaching people about birds for decades. The Maine natives are authors of the highly acclaimed book, “Maine's Favorite Birds.”