A total of 809 birds of 60 species
was banded at Powdermill in the past week; 259 birds and 21 species were
wood warblers, led by Magnolia (77 banded), Common Yellowthroat (43), Hooded
(24), Black-throated Blue (19), and American Redstart (18). Overall,
American Goldfinch (94 banded), Gray Catbird (85) and Swainson's Thrush
(78), along with Magnolia Warbler, were the top species this week.
Best banding days this week were September 25 (188 birds of 38 species)
and September 24 (185 birds of 43 species). Seven species, Ruby-crowned
Kinglet, Hermit Thrush, Winter Wren, Blue Jay, Yellow-rumped Warbler, Dark-eyed
Junco and White-throated Sparrow were new for the Fall 2005 banding list,
which now stands at 88 species. Most of these are shorter distance
migrant boreal species that are typical of the latter half of the fall
migration season (dare we say "harbingers of winter?!").
.
Hatching Year female Dark-eyed
Junco (top photo) and Ruby-crowned Kinglet (bottom photo)
banded on September 22--the first
of their species for our fall 2005 banding season.
Our thanks to David
Norman, Felicity Newell, Annie Lindsay, Emma DeLeon and her parents Bob
and Donna Deleon, Matt Shumar, Molly McDermott, Pam Ferkett, Jack and Shoko
Brown, and Trish Miller for their help with
the banding this week.
Highlight for
the week was an immature (hatching year; HY) female Yellow Warbler banded
on September 20 (photos below). It's a highlight because in
44 years of fall banding at Powdermill, a total of just 38 YWARs have been
banded after the end of August, and only ten have been banded as late or
later than the bird pictured below. Typically, these late migrant
YWARs appear morphologically very different from the common eastern breeding
subspecies, Dendroica petechia aestiva, being generally darker
and more uniformly green above and duller yellow below. They probably
represent one of several possible northern and northwestern races.
Determinations of the racial affinities of these individual birds is very
difficult without extensive comparative museum material. A YWAR caught
at Powdermill on September 25, 1966, however, was identified by Dr. Kenneth
C. Parkes, then the Curator of Birds at Carnegie Museum of Natural
History, as belonging to the subspecies
D. p. rubiginosa,
which ranges from the Alaska Peninsula south and east through coastal Alaska
and British Columbia.
. Interestingly, we thought the
best fit for the bird pictured below probably was D. p. parkesi.
This race breeds from northern Manitoba north and west to the western District
of Mackenzie. Among the northern YWAR subspecies, it is described
in Jon Dunn and Kimball Garrett's superbly researched, written, and illustrated
Peterson Warblers field guide as having the darkest green upperparts
with comparatively duller yellow underparts. Although our series
of photos for the YWAR banded this week did not turn out well due to low
natural lighting conditions, we posted an extensive series of photos and
measurements for a similarly late YWAR
banded in September 2002. Compared to the present bird, that
YWAR had a dull light gray-green upper back that contrasted somewhat with
a brighter olive-green head and even paler whitish-yellow underparts, more
like the western subspecies D. p. morocomi, whose range extends
from the southern Rocky Mountains north to the southern Yukon. The
bird banded this week, by comparison, had uniformly dull green upperparts
and dull yellow underparts and, therefore, likely belonged to one of the
more strictly northerly races, such as D. p. parkesi or D.
p. amnicola. Similar to the late YWAR banded in 2002, it did
not have the longer primary projection typical of D. p. rubiginosa.
Jon Dunn, if you're out there, we'd love to get your opinion on these birds!
Among the many wood warblers banded
this week were this HY female Black-throated Green Warbler (top photo),
HY male Blackburnian Warbler (middle photo) and HY male Cape May Warbler
(bottom photo).
Indigo Buntings (and Passerina
buntings, in general) have a highly variable and complex sequence of plumages
and molts. The complexity stems, in part, from the inclusion of an
extra molt, the presupplemental molt, which is well known for buntings
and which probably occurs much more frequently than is widely known in
other passerines, such as tanagers and grosbeaks. The PS molt occurs
very shortly after fledging and generally involves only the body plumage
and the lesser wing coverts. The first (in HY) and definitive (in
AHY) prebasic molts for buntings occur later in the fall and are variable
with respect to extent (in the case of the incomplete 1st PB molt) and/or
seasonal occurrence (i.e., when and where the prebasic molts occurs relative
to the breeding grounds). The prealternate molt also is quite variable
in extent both for first year and older birds.
.
Two INBUs banded this week illustrate
some of the variability and complexity in the molts and plumages of this
species. First, the wing plumage pictured below belongs to a hatching
year (HY) male INBU banded on September 23. Three feather generations
comprise the overall wing plumage (four, if you count the adventitious
molt of secondaries 1-3, which had not molted on the bird's left wing,
as a separate generation!) The retained juvenal feathers are the
middle and distal alula feathers and the primary coverts (the feathers
directly below the forefinger in the photo), primary flight feathers 1-4
and 7-9, and secondary flight feathers 4-6. The more worn and brownish
lower tier of lesser coverts and outer 1-2 median coverts are not juvenal--they
are supplemental plumage. The freshest feathers, the blue-edged lesser
coverts, the inner median coverts, all the greater coverts, the carpal
covert, the alula covert, primaries 5-6 and secondaries 7-9 (the tertials)
are first basic feathers. As mentioned above, secondaries 1-3 are
replacements for accidentally lost feathers and would not ordinary be molted
during the 1st PB molt in this species.
Importantly, on any given date in
the fall, HY INBUs can show a wide range of variation in their progress
with the 1st PB molt. Some individuals replace more or fewer feathers
at this molt, and individuals may undergo this molt before departing the
breeding grounds, at a migratory stopover site, or on the wintering grounds.
.
The next
wing photo is of an adult (AHY) female Indigo Bunting banded on September
25. Her extremely worn wing and tail plumage shows no sign of active
molt at a time of the year when many, if not most, INBUs are in the latter
stages of their complete definitive PB molt. She was molting only
a few scattered body feathers and scapulars (the dark brown edged feathers
where the wing meets the body in the photo below). It is likely that
she will not undergo further molt until she reaches a southerly migration
stopover site or her wintering grounds. Ordinarily, a female caught
this later in the season in this plumage condition would be expected to
show signs of recent breeding activity (i.e., and old, not yet refeathered
brood patch). This female did not appear to have ever had a B.P.,
the feathers on her belly being present and not obviously recently molted.
You may have noticed that the wing
plumage pictured above actually is comprised of more than one feather
generation. The two innermost primary coverts are retained from an
earlier plumage, perhaps from the bird's juvenal plumage, but more likely
abnormally retained from an earlier basic plumage. It is not all
that uncommon for adults to retain stray feathers (often primary coverts
or alula feathers), during an otherwise complete prebasic molt. Also,
an SY bird would be expected to show a block of retained juvenal flight
feathers in the middle of the wing (i.e., inner primaries and adjacent
outer secondaries). Finally, the lack of any molt limits within the
secondaries or greater coverts of this bird suggests that she underwent
no prealternate wing molt, a very different case from the adult female
pictured in the next wing plumage photo.
Like the adult female INBU pictured
above, the adult (ASY) female INBU pictured below had not undergone any
prebasic wing molt when it was banded on September 27, but, unlike the
first female, she did appear to be refeathering a brood patch. Also
unlike the first female, the female pictured below clearly underwent a
quite extensive prealternate molt, replacing most of her lesser and median
coverts, all of her greater coverts, and her tertials (the three innermost
secondaries). The amount and depth of blue color in the wing of this
female, a product of her prealternate molt earlier in the year, is about
the maximum we have seen in a female INBU.
Finally, we end this update with
photos of two of the eight Brown Thrashers banded thus far this season.
Eye color, as mentioned before on this website, can aid banders in making
correct age determinations for many species. While we, of course,
examined the wing plumage for the presence of molt limits among the greater
coverts, teritals and outer secondaries, and central rectrices, the difference
in eye color between the HY bird on the left and the AHY bird on the right
in the photos below is particularly dramatic. In general, HY/SY birds
have a gray/brown cast to their eye while AHY/ASY birds have a darker red/brown
cast. In the case of the Brown Thrasher, the gray eye color in the
immature will become brighter yellow/orange with age.
