• August 27-31, 2003:  With 49 banded, Ruby-throated Hummingbird was by far the commonest bird banded this week.  We catch comparatively very few adult male RTHUs at this time of year, but we banded four this week, and three of the four showed unusually extensive and heavy molt of their iridescent red gorget feathers.

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• Collectively, with 31 banded, Empidonax flycatchers were the second most comonly banded birds this week after hummingbirds.  Among these, as usual for us at Powdermill, migrant Yellow-bellied Flycatchers were the most numerous (16 banded).

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Although it is a very common breeding bird at Powdermill, Acadian Flycatcher actually is the least common Empid species at the banding station.  Two ACFL were banded this week (both hatching year, HY, birds), including one (bird on right in the photo below) with an exceptionally yellow belly (actually a much yellower lower belly than a YBFL caught with it--the bird on the left holding onto the photographer's thumb).  Note, however, the whitish, rather than yellowish chin and throat of the ACFL.  To add to the possible confusion concerning identification of this yellow-bellied ACFL, it had a very bright orange mouth lining color (second photo below), rather than the light pink to pale yellowish color often attributed to the species.

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• Among the 75 wood warblers of 15 species banded this week was our first Yellow-breasted Chat of the season (photo below).  It was an HY bird showing the "eccentric" first prebasic molt pattern typical of this species (second photo below:  several outer primaries molted, these contrastingly darker with blacker shafts, but all primary coverts retained juvenal).

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• We banded two Mourning Warblers this week,including this adult female.  Like AHY males of this species in fall, adult females have a distinctive definitive basic plumage that cannot be confused with HY birds of either sex (thin broken whitish eye ring, somewhat variable, but always with a solid grayish white hood and throat)--banders really do not have to examine the skull or wing molt limits to accurately determine the age and sex of adult MOWAs in fall.

This second photo makes a nice companion to that of the  adult male MOWA  from 8/17

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• The same net round on 8/31 produced this "pair" of HY Blue-winged Warblers (male left/ female right, in both the top and bottom photos).  A blacker eye line and contrastingly bright yellow forehead distinguish hatching males from hatching year females of this species.

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• August 20-24, 2003:  Among the birds banded this week was a very late Louisiana Waterthrush on 8/20.  Only eight other LOWAs have been banded at Powdermill as late or later than this week's bird, the latest ever being a hatching year (HY) bird banded on 9/9/78.  In fact, all the LOWAs banded at Powdermill after mid-August (about 20 birds) have been HY birds.  We have never banded an adult LOWA after the end of July, and only a few previously banded adults have ever been recaptured in August.

• We appreciate getting comments from visitors to this website about the quality of our bird photos.  Lest anyone should think that we put our birds under some kind of magic spell that lets us capture them unfailingly in serene and artful poses, below is one of our (many!) attempts to get a side-by-side-by-side photo of Least, Traill's and Yellow-bellied Flycatchers (the last being the first of its species to band this fall).  Now you know why the YBFL is our favorite Empidonax!

• We did finally manage to get the side-by-side comparison of the hatching year LEFL and TRFL that we were after, but not using our conventional posing.  The thing that was interesting about these two birds (LEFL left, TRFL right) was how similar they were in size, including their bills.  The TRFL's bill was noticeably wider, but it was probably the shortest we have ever measured in this species, at 7.2 mm from nares to tip.  Its tail also was very short at 50.5mm.  Both birds had wing lengths of about 65mm, leaving little doubt that the LEFL and the TRFL were a large male and a small female of their respective species.

• Another new species for the season was Tennessee Warbler--we banded a HY (top photo) and and AHY (bottom photo) male in the same net round on 8/23.  Adult TEWAs typically differ from HY birds by being more grayish and less yellowish below.

• Not a migrant, but nonetheless another new species for this fall season was a juvenile male Northern Cardinal banded on 8/24.  The very bright orange-red bill of this very young male (note it still has its very loose juvenal head feathering) is completely uncharacteristic--usually, the bill of a juvenile or HY NOCA remains dusky, or even blackish, well into its first fall (see inset photo of a more typical juvenile NOCA).  A bright bill coloration like that on the young NOCA we banded this week ordinarily is seen only in adults.

• August 7-17, 2003: It has continued to be seasonably warm and surprisingly wet at Powdermill.  We have several net lanes that ordinarily dry up completely by early May which have remained virtual quagmires all spring and summer long.  It would seem that after perhaps 15 years of below average annual precipitation, the water table finally has risen back up to pre-drought levels.  Earlier in the summer, we posited that the abundant moisture might actually benefit songbird reproduction by promoting lush foliage and healthy herbivorous insect populations, as well as good yields on wild fruiting trees and shrubs.  While this may well be true, we have begun to see some negative consequences of excessive moisture in the form of more than the usual number of cases of fungus- and/or pox-related lesions on the bills, legs and feet of a wide variety of birds.   Such pathogens undoubtedly are more virulent and spread more easily in the continually moist environments in which many birds have found themselves this year.

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• We're not sure what to blame this Red-eyed Vireo's "bad feather day" on, but perhaps it, too, is somehow related to the weather (perhaps a worse than usual ectoparasite load has plagued many birds this summer).  After photographing this bird on 8/12, we have banded three others much like it.  This naked headed condition is pretty regularly seen in Blue Jays and Northern Cardinals, but we have not seen such a extreme case before in this species.  Has anybody else been observing something similar, either in the field or in their nets?

• Although it is the fall season by our banding calendar, it is still the nesting or post-nesting season for many birds.  We continue to catch large numbers of recently fledged juvenile Gray Catbirds and Song Sparrow (photo below) from second (or third?) broods.

Note:  the two conspicuous light-colored feather growth bars near the tip of this young SOSP's tail (see photo detail below) tell us that this bird probably was not well fed for two consecutive days, perhaps the first two days after it fledged from its nest.  Because the so-called "fault" bars are near the tips of all the bird's rectrices, they formed when the tail was just a short stub, which is the usual length for most open cup nesting passerines when they leave the nest at about 10 days of age; development of wing feathers in nestlings is more rapid, with recently fledged birds typically having at least half grown wings, capable of supporting short fluttering flights, when they leave the nest.  The period of interrupted nutrition, evident as fault bars near the tips of the tail feathers, would, therefore, show up much farther from the tips of the same bird's wing feathers.
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Rainy weather may have played a role in making it difficult for the parents of this young SOSP to provide adequately for all of their recent fledglings.  In any case, this fledgling survived its early nutritional bottleneck and appeared quite fit when we banded it!  An extreme case of unquestionably even fault barring, such as seen on this SOSP, can be useful as an ageing criterion (juvenal wing and tail feathers are grown concurrently, while adult wing and tail feathers ordinarily are grown in a staggered pattern), with the important caveat that adults do sometimes lose all of their tail feathers at once accidentally.  When such accidentally lost feathers are regrown adventitiously (outside the normal molt cycyle), it is not unusual for such adult replacement rectrices to have prominent fault bars like those more often seen in juveniles (because they necessarily grow their wing and tail feathers while being entirely dependent for their nutrition--the energy and proteins necessary for feather synthesis--on the food delivered by their parents).
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In contrast to the fairly fresh feathered juvenile SOSP above (completely covered in its recently grown, loosely textured juvenal plumage), the adult male SOSP caught with it looked exceptionally worn (its tail feathers, in particular).

The shape (apparently rather pointed) and condition (extremely worn) of this bird's rectrices alone might cause a bander to think they were looking at a second year (SY) bird with retained juvenal tail feathers.

To the contrary, the SOSP pictured above, a recapture on 8/15, was originally banded in July 1997 as an HY bird, making it six years old!  In assessing a bird's overall plumage to determine how many feather generations are present and what those generations are (e.g., juvenal, first basic, definitive basic, etc.) many criteria have to be used in combination.  There simply are far too many cases of unusually unworn SY birds and atypically heavily worn ASY birds for feather wear condition alone to be a reliable age indicator.  Banders (and birders) attempting to separate the various age classes of birds must carefully examine the whole bird, always armed with a thorough understanding of what the plumage cycles for that species are known (or, at least, supposed) to be, and then make a judgement (if one can be made at all) based on the totality of available information--importantly, for the welfare of each and every bird, only so much time should be taken in arriving at a correct (and not necessarily the most precise possible) determination.

There's a saying that "assume" makes something out of you and me, and that pitfall needs to be actively avoided by us all!  Recaptured birds, like the ASY SOSP pictured above, frequently provide banders with great opportunties for learning--opportunities that should NEVER be passed up!  The best banding guide always will be the one written based on a bander's (or birder's) own very careful observations, especially when those observations are cross-referenced with the published literature.
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• Adults of many species, like the female Blackburnian Warbler (top), male Magnolia Warbler (middle), and Acadian Flycatcher (bottom) pictured below were still in heavy molt during our second banding week of the fall.  Their breeding seasons may be over, but they clearly are in no condition to migrate yet!

• Interestingly, among the eastern Empidonax flycatchers (Least, Willow, Alder, Yellow-bellied, and Acadian), only the ACFL completes it's definitve prebasic molt on the breeding grounds--therefore, an Empidonax flycatcher banded in eastern North America in normal wing molt (photo below) is unequivocally an ACFL.  It is interesting to speculate on what species' differences in breeding, migration, and/or winter ecology may have led to the evolution of such a different molt timing in this species compared to its eastern congeners (adults of some western Empidonax species, e.g., Hammond's and Buff-breasted, apparently also undergo prebasic molt on the breeding grounds).

• Although many adult birds may still be undergoing molt, most of the young of the year they have produced are now in freshly grown first basic plumage.  Some, like the hatching year female Cerulean Warbler pictured below, banded on 8/12, qualify as "confusing female warbler" at any season,

while others, like this HY male Chestnut sided Warbler (next photo), has a much different appearance this fall (first basic plumage) than it will have next spring (first alternate plumage)--i.e., making it one of the truly "confusing fall warblers."    This individual has perhaps a greater amount of chestnut coloring on its sides than average for a first year male, but it (and also adult males in basic plumage) lacks entirely the dark black facial pattern and bright yellow forecrown so conspicuous in alternate plumaged males (and to a lesser degree in spring females).

It is a surprise to some banders and birders that the majority of warblers in first basic plumage, like the HY male Black-throated Green Warbler below, aren't very much different in terms of brightness of color and pattern than the respective adults of their species in spring.  Furthermore, the adults of these same species are almost equally as bright in fall plumage as they are in spring--this includes, among others, Golden-winged, Blue-winged, Hooded, Wilson's, Black-throated Blue, Cape May, and Blackburnian warblers.

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• Compared to the series of worn and motley adults pictured above, a few adults of Powdermill's local breeding species, like this AHY male American Redstart, have completed their definitive prebasic molt and are now in just as fresh a feather as any HY bird.   Because there is delayed plumage maturation in this species, we cannot confuse this AMRE with an HY male of the same species, but very careful examination of wing plumage for molt limits, combined with assessment of the degree of skull pneumatization, is needed for separating the adults and young of many species (e.g., those listed in the preceding paragraph) once prebasic molts have been completed in both age classes.

• By the last few days of the period covered by these notes, we had even begun to catch birds, like this well-fattened adult male Mourning Warbler banded on 8/17, that are strictly passage migrants at Powdermill.   As with the adult AMRE above, an adult male MOWA cannot be confused with an HY male, which looks much like a female (i.e., there is no need to skull a MOWA in fall that looks like this bird pictured below); however, unlike HY male AMREs (which retain a female-like appearance for more than a year), HY male MOWAs acquire a more or less adult male-like appearance by their first spring.