On my computer screen, in caps, "Northern Beardless-Tyrannulet" measures five inches. That's half an inch longer than this tiny, nondescript tropical flycatcher which reaches the northern limits of its breeding range in southern Arizona and whose name gives credence to non-birders' notion that bird names are nonsensical. Who shaves these guys, anyway?
Camptostoma imberbe is widespread through most of Mexico south to Costa Rica, but qualifies as an Arizona special species, species found only here or more easily here than in any other state, because the only other place it can be found in the states is the lower Rio Grande Valley of Texas, where it is
rare and hard to find. In southern Arizona it is not rare, but it is hard to find unless you are familiar with its ringing, plaintive, descending "Dee, dee, dee" call, and it is hard to see well unless you are patient.
NB-T is a member of the tyrant flycatcher family, most of which have rictal bristles, the specialized, stiffened, barbless feathers around the base of the bill which swallows and nightjars use in flight to funnel insects into the mouth. Flycatchers however, which capture insects with the tip of the bill, are thought to use these bristles in some other tactile function. The Beardless's species name, imberbe, refers to the lack of these rictal bristles which may account for its spending much more time gleaning insects from foliage than actively flycatching.
More often than not NB-Ts are heard before they are seen, but even more frequent scenarios are hearing one and never seeing it, or seeing one without hearing it and passing it off as a Verdin or an unidentifiable Empidonax. Oddly enough for one who still has trouble distinguishing between Ash-throated and Brown-crested Flycatchers, I own NB-T. To me they always appear cresty, and compared to the peripatetic Verdins and the snappy empids, the NB-T jizz is passive, sluggish, vireo-like.
In Arizona NB-T is a bird of scrubby, open, wooded areas, often near running water. As unique as its distinctive voice, this species' nest is a small, hanging, globular mass of plant debris, entrance on the side, often well disguised in a mistletoe clump or tent caterpillar web.
Recent reliable spots for Northern Beardless-Tyrannulet in southern Arizona have been Agua Caliente Park on the far east side of Tucson, the area around George West Waterfall below Proctor Road in Madera Canyon, the first pond at Kino Springs, and the Patagonia Rest Area. I have never failed to see an NB-T family feeding through the Arivaca Cienega refuge when I have visited there in late summer where the accompanying photo was taken in August 1995. This was one of a pair of adult birds escorting three young of the year through the mesquite. Learning the call will greatly enhance your search efforts.
Despite this bird's diminutive size and reputation for blandness, watch the electricity that surges outward from a veteran tour guide's body language through his group of out-of-state birders when he hears an NB-T calling. As the call always seems somewhat ventriloquial, binoculars will swing frantically in all directions, often right past the culprit several times because NB-Ts are slow, methodic gleaners, sometimes sitting quite still in the mottled greenery as if in deep contemplation of their next move.
Once the bird is located and its correlation with the signature call begins to dawn on the observer, it becomes apparent this is no Verdin or Empidonax. Bushy crest, black over flesh-to-orange two-tone bill, buff wingbars, lemon yellow secondaries, belly, and undertail coverts, and black legs mark a bird that is subtly but certainly more colorful than the species for which it is often mistaken.
If you lose contact with the call series, but begin hearing softer, intermittent, single "Dee" notes, know you have somehow stumbled into proximity with the bird and it is probably within sight if it will just move for you. If you begin to hear a second syllable, "Dee-hic," just as if the bird has the hiccups, stand still. The bird is probably directly overhead or within arms' reach. This is an unobtrusive bird but it is not a particularly shy one.