How to identify wood pewees

In forested regions from coast to coast, in late spring and summer, some of the most characteristic sounds are the chirping of pewees. The sound changes abruptly in the middle of the continent because two species – Eastern and Western Wood-pewees – divide the lower 48 states almost exactly in half, along a line stretching from the Dakotas south to in Texas.

These clipped gray flycatchers tend to perch high, often among foliage, so they are heard more often than they are seen. That’s just as well because they differ much more in sound than in sight. Both are relatively simple, somewhat larger than the dainty Empidonax flycatchers, with wing bars but no eye-rings. No visual diagnostic mark will help you tell them apart.

In fresh plumage, typical adults of the two species have different color tones. Eastern tends towards a more greenish gray on the upperparts and whiter on the throat, and its chest band is paler in the center. Western is on average more brownish gray overall, more often with a plain gray breast band. The wingbars tend to be a bit whiter and more visible on Easterns. In both species the lower mandible is dull orange at the base and dark at the tip, but the black is often more extensive in Western. Unfortunately, there is so much individual variation that none of these differences would be reliable if either species appeared out of reach.

Adults moult in tropical wintering grounds, so they are in fresh plumage when they arrive in North America in the spring. Their feathers gradually become more worn and faded, and by late summer their wingbars may be obscure. At this stage, lacking eye-rings and wingbars, a wood-pewee might superficially resemble Eastern Phoebe, but this species has a longer tail that it wags frequently, shorter wingtips, and a sharp contrast between dark face and white throat.

In late summer, when the adult pewees look worn and dull, fresh juveniles are on the scene. They have distinct wingbars, often with a buff tone. Because they look different from adults in the same season and sometimes make strange callnotes, eastern or western birders may be tempted to identify them as the “other” species. They reflect the importance of considering a bird’s age and the condition of its plumage when trying to make a difficult identification.

Adult voices are their best pitch marks. What most distinguishes the Western Wood-pewee is a harsh, buzzing, descending pzzzzeeyeer. The clear, plaintive whistles of the eastern wood-pewee are the most distinctive: pee-yeah-peewith the first highest note and the second lowest, and a peeey-yerrr. However, it would be misleading to summarize their voices as buzzy or clear. Most of the Westerner’s other notes are clear hisses, and some of the Oriental’s calls have a dry or buzzy quality, so only the full notes described here can be considered diagnostic.

Listen to the sounds of Eastern Wood-pewee and Western Wood-pewee

Western Wood-pewee, adult. June in Mono County, California. Photo by Brian E. Small

Average differences between Eastern and Western Wood-pewees may be evident on typical individuals. The Western tends to be slightly more brownish gray above, with slightly less distinct and contrasting wingbars. The gray wash on his chest tends to be darker and more continuous. The Oriental tends to be more greenish-grey above and whiter on the throat, with more conspicuous whitish wingbars. In both species the base of the lower mandible is dull yellowish, but the dark area at the tip is usually more extensive on the western mandible. Unfortunately, there is variation in all of these points, so they do not allow certain identification of either species outside of its normal range.

Willow Flycatcher, adult. June at Lac Le Jeune, British Columbia. Photo by Brian E. Small

Most Empidonax flycatchers are easily distinguished from pewees because they have conspicuous eye rings. The exception is the Willow Flycatcher, whose eyering varies from faint to absent. Willow Flycatcher also tends to show less contrast in the wingbars than other Empidonaxes, making it even more similar to pewees. The best accolades involve structure, not brands. The willow flycatcher is a more compact bird than the pewees. In particular, its wingtips appear much shorter because its primaries do not extend as far beyond the tertials on the wing. Seen from below, the beak is also wider in the Willow Flycatcher than in the Wood-pewee. A good behavioral clue: all Empidonax flycatchers wag their tails at least occasionally; pewees do not.

Western Wood-pewee, adult. June in Mono County, California. Photo by Brian E. Small

Pewee wing patterns vary by season, and it helps to understand why. Wood pewees go through a complete moult once a year, almost entirely on the wintering grounds. When they come north in the spring they are in the coolest plumage we will see in North America, with wingbars at their most distinct. When comparing birds with equally fresh plumage, the wingbars tend to be whiter and wider in the Eastern Wood-pewee than in the Western Wood-pewee. In both species, however, the wingbars fade and wear away as spring turns to summer, and by late summer the wings may appear plain. Pewees with distinct wingbars seen in early fall are young birds still wearing their juvenile plumage.

Large Pewee, adult. April in Cochise County, Arizona. Photo by Brian E. Small

Several species of wood pewee live in the American tropics, and one of them reaches Arizona and southwestern New Mexico. The Greater Wood-pewee is locally common in summer in open mountain pine-oak forest, mainly above elevations where the Western Wood-pewee is most common, but they overlap in some places. The Greater Wood-pewee is, as its name suggests, a larger bird, and it almost always shows a visible erect crest, as in this photo. Its general color is usually a smoother gray than that of the pewee, especially on the underparts. Its best ground mark is often the bright orange lower mandible, which is quite visible from a surprising distance.

This article originally appeared in the May/June 2021 issue of BirdWatching magazine.