The Empidonax Challenge Looking at Empidonux by Bret Whitney & Kern Kaufman Part IV: Acadian, Yellow-bellied, and Western Flycatchers (Empidonax virescens, E. fiviventr& and E. difSilh, respectively). Acadian Flycatcher (Empidonax virescens) (Plates 1 - 3) Voice The song is a loud, explosivepeef-see&or investigation. The tail is fairly long, and pee'-&@, or pee'-trup. The first syllable is tends to be uniformly wider than that of usually accented, but there sometimes seems other species when in a relaxed attitude. to be no accent on either syllable. The call is also rather loud but lacks tonal quality (very Plumage "flat") and is similar to the first syllable of The wing-bars and tertial4ghgs of adult the song: peellorpick.! No other Empidonax Acadians (except after wear, mid-tdate has a call like this. A onesyllabled call of summer) are welldefined, ranging in hue Yellow-bellied Flycatcher is clmst, being from white (second spring and older?) to about the same pitch and with a similar buffy-white (first spring?) in spring, and piercing quality, but ako with a falling, buffy-whiteto rich buff in fall. All juveniles, more "musical" inflection. and perhaps all adults after the post-nuptial molt (which is usually completed before the Structure birds leave the U.S.), have buffy wing-bars. Acadian is a large, long-winged Empid Adult Acadians in spring and fall typically with a lot of bill and tail. The bill averages show a neat whitish or yellowish-white eye- the broadest basally of any species, and also ring of uniform thickness, or thickness averages longest (but see Similar Species). slightly concentrated around the posterior The lower mandible is virtually always edge. In some individuals (a somewhat entirely pinkish-yellow or yellow but rarely higher percentage of worn summer birds), has a small dusky tip. the eye-ring is essentially lacking. Like Least The primary extension of Acadian averages Flycatcher, Amdian is characteristically quite the longest of all Empids, with a sabre-like uniform from crown to nunp, showing curve on the folded wing, long and straight essentially no contrasts in the upperparts or on the drooped wing. In fact, the wing may head. Aside fiom Yellow-bellied and Western be so long as to make the tail appear Flycatchers, Acadian shows brighter green proportionally rather short. The length of in the upperparts than does any other the primary extension on a short-winged Empidona species. This green is perhaps Acadian can be overlapped by those of best seen in the face and malar region. The ' Alder and Willow, and can rarely be green of the head and malar region, from matched even by Least, according to where it borders the sides of the whitish specimen measurements obtained by K. V. throat, runs posteriorly to the sides of the Rosenberg! The extent to which the primary breast, where it takes on a darker olive hue. extension might vary during molts needs This olive in the sides of the breast usually Volume XVIII, Number 6 Plate 1: Acadian Flycatcher (E. virescens). Note the Plate2 Acadian Flycatcher (E. virescens).A very long primary extension, and drooped wing. This viewing angle and lighting aspect on the bird showm D individual appears to have a small dusky tip to the Plate I. Long wings evident, and a hint of green in k lower mandible. Fresh spring plumage shows a typical face and sides of upper breast is visible even st tLk even, yellowish-white eye-ring, and whitish wing-bars distance, imparting a rather weak facdthroat m and edges to the tertials. Plumage generally suffused Note that the tail, which would normally hang so& with a delicate greenish hue, uniformly through upper- lower, is propped up by a branch. Photo by Onik Aria parts and paling on to face and sides of upper breast. The throat and belly might be said toshow a very pale yellowish tinge, but one can imagine how whitish the underparts will look after a month or two of wear. This individual was fluffed to keep warm on a cold mid- May morning at Point Peke National Park, Ontario. Photo by Onik Arian washes almost through the center to impart junction with structural and other plumage a faint olive breast-band. characters. Adult Acadians are often largely white or Juvenile Acadian Flycatchers posses a grayish-white below, especially individuals very distinctive plumage. The upperpam with weak breast-bands or worn summer are bright green, many of the crown, nape. birds. On fresh spring arrivals, the underparts and upper wingcovert feathers (lesser and may be seen to bear a very pale, delicate median) with conspicuous buff tips. The greenish wash as ephemeral as the new wing-bars and tertialdgings are rich buff. opening of the spring leaves. The majority of The throat usually shows a light yellow adult Acadian Flycatchers have a whitish wash. The underparts typically bear a fairly throat. Following the fall and spring molts, conspicuous greenish breast-band which is however, Acadian may show a pale yellow often washed with clear lemon yellow that or greenish wash on the throat. This ap- runs posteriorly to the undertail-coverts. parently wears to whitish within a month or The center of the belly, however, is often so, but could cause confusion with Yellow- white. Unfortunately, this beautiful plumage bellied Flycatcher if not considered in con- is largely molted out by early September. BIRDING, December 1986 C= Plate 3: Acadian Flycatcher (E. ~irescem).Yote the Plate 4: Yellow-bellied Flycatcher (E /laviwnlris). very long primary extension and relaxed wing. Even in Although focus is so& this plate is good for a typical very subdued Lighting (in the rain). the neat yellowish- protile impression of Yellow-bellied Flycatcher (small, white eyering and whitish aiog-bars and tertial- with round head and proportionally short tail). Note edgings indicative of besh spring plumage are evident. the rather short primary exteasion, bold whitish eye Stronger apparent face/thrmt contrast on this bird (as ring (obsolete bottom edge on this individual), and compared to Plate 1) is perhaps owing to a somewhat blackish wing with whitish wing-bars (upper not as whiter throat and darker sides of upper breast. (Third white as lower) and tertialcdgings. This is as pale and week of April, at Corpus ChiJu Texas.) Photo by John "colorless" (above and below) as a spring Yellow- Awin bellied is likely to appear, although sunlight will bring out more green in the upperparts at least. This bird apparently had not completed its pre-nuptial molt. (Mid-May, in Austin, Texas.) Phm by B. Whitmy. and is unlikely to be seen far from the width. But when excited (for example, when breeding area. patrolling territory or trying to impress a mate), Acadian can be a spritely little bird, Behavior wing- and tail-flicking with the best of them. Acadian seems to be a relatively lethargic bird, sitting still for longer than the other Molt Empids, and doing less wing- and tail- Acadian is the only "eastern" Empid in flicking. The tail is flicked now and then, but which the adults typically undergo a complete the wings are very seldom flicked except for molt (the pre-basic, or post-nuptial) in late the first couple of seconds after settling on a summer before they begin their southward perch. In a relaxed mood, Acadian seems to migration. This molt can be underway as hold the wings and tail "at ease" much of early as late July and can be completed by the time, allowing the long wing-tips to early September, although in some indivi- droop below the tail. The tail is characteris- duals it is later. Juveniles have a partial tically parallel-sided (no basal constriction), molt, replacing mostly the body plumage and allowed to expand to its full, relaxed (thus losing the distinctive buff tips on the Volume XVIII, Number 6 crown, back, and perhaps some of the wing- Acadians showing neat, uniform eye-ings covert feathers), beginning about the time and others having virtually none. they become independent, and generally Plumage-points to keep in mind when completed by early September. Thus, the faced with an Acadian/''Traill'sW are th vast majority of Acadians seen in fall will be most adult Acadians are very whitish below in fresh plumage, with buff or burn-white (except soon after molts), while most juvenile wing-bars, and often a noticeable yellow "Traill's" are lemon-yellow on the belll;, wash on the belly. (See the precautionary appear noticeably green on the back (especi- notes in the Similar Species section con- ally in direct sunlight), and have bufFy wing cerning the effects of wear on late-summer bars. Through spring and summer, both adults.) Acadian and "Traill's" show whitish wing- Spring molts are partial (wing and tail bars, sometimes with a buff tinge, but in fa4 feathers retained) and take place on the strong buffy wing-bars are the norm for wintering-grounds. Acadians of all ages. Onlyjuvenile "Train's" have buff wing-bars at this season; the wing- SiSpecies bars of adults (which have not molted are Acadian Flycatcher is most similar to thin and dingy whitish, showing evidence of "Traill's" Flycatcher (Alder/Willow pair). the summer's wear. It is important to remain It can be readily separated from "Traill's" conscious of predictable age- and m&- by either the song or the call. The bill related plumage variation in looking at structures and lower mandibles are very Empidonax-it can work for you (or similar, but Acadian's lower mandible against you!). averages both broader throughout its length and longer than "Traill's".