POWDERMILL NATURE RESERVE
PICTORIAL BANDING HIGHLIGHTS
Wednesday-Thursday, July 23-24,
of the new species banded on the second to last day of the season was an
adult Northern Mockingbird (photo below).
We had observed the bird the evening
before it was banded, when it surprised us by singing loudly outside the
banding lab door. NOMOs are rare in the mountains of southwestern
Pennsylvania--we have never seen one at Powdermill before in summer, and
we've never observed a singing
The next morning we netted
it just in time to serve as the highlight of a banding demonstration given
to some 25 five- and six-year-old children attending Powdermill's popular
summer nature day camp program, "Adventures at Powdermill" (photo below).
Although we band very few NOMOs
at Powdermill (only ten others have ever been banded here), and most of
those caught here have been hatching year birds in fall, the eye color
of this after second year male (age based on the lack of molt limits among
its comparatively fresh, dark dusky and bright white wing feathers; sex
based on cloacal protuberance) struck us as being unexpectedly dull and
grayish (photo below), i.e., compared to the more richly and/or brightly
colored adult eye colors we see in the closely related Gray Catbird
(adult irises in this species are are dark plum-colored vs. gray in young
birds) and Brown Thrashers (adults have bright yellow-orange eyes; young
have dull grayish yellow irises). Typical adult eye color in NOMO
is described in Peter Pyle's (1997) Identification Guide to North American
Birds as "greenish yellow to yellowish orange," but with the caution
that "[adults] occasionally can retain grayish or greenish irises," as,
apparently, did this bird.
Wednesday-Sunday, July 16-20,
of the other new species to band this week was the bird pictured below
in nearly full juvenal plumage--looking just at this tightly cropped photo
of its head and beak, you may find it a little tough to put your finger
on what this bird is (or, for that matter, even what kind of bird it is!).
The second photo below should help.
Hint: When banded on 7/18,
it already was molting the first two primaries of each wing.
It's a Red-bellied Woodpecker
The third new species for the summer
also was mostly in very fresh juvenal plumage. Banded on 7/18, this
hatching year Grasshopper Sparrow (first photo below) only slightly resembled
the GRSP caught earlier this spring (second photo below). The more
worn but also more brightly colored bird banded here this spring, showing
no sign of having any retained juvenal plumage, could have been either
a second year (SY) or an after second year (ASY) GRSP, because both age
classes of this species have a complete prebasic molt. It was, therefore,
simply called after hatching year (AHY) when it was banded back in April.
Wednesday-Sunday, July 9-13,
species banded this week were new for the summer 2003 banding list:
(the bird pictured below from last week was a returning banded bird,
not a new capture) and Belted Kingfisher. We banded a total of three
this week, all hatching year birds, including this relaxed HY female.
Female BEKIs have a prominent rufous
lower breast band, and HY BEKIs of both sexes have their gray upper breast
band tipped with brown.
This closeup of the wing plumage
of an HY Kentucky Warbler banded this week shows the very last stages of
its partial first prebasic molt--the small proximal feather of the three-feather
alula group, the so-called alula covert, is just coming out of its sheath.
Molt limits created by the partial replacement of wing coverts during the
first prebasic molt in many warblers are sometimes very difficult to discern
early on because of the still very fresh appearance of the retained juvenal
feathers. For this reason, especially after adults of these same
species begin to show signs of approaching the end of their complete post-breeding
or prebasic molt, it is always a good idea to confirm age determinations
by additional criteria, such as skull pneumatization.
At this time of year, however, it
usually is the case that the birds in completely fresh feather (or perhaps
in the very late stages of molting their body plumage and some wing coverts)
are young of the year, while those in very worn plumage and/or concurrently
molting body plumage, wing coverts, AND flight feathers, are adults.
In the second photo below, a second year (SY) adult male American Redstart
was caught together in the net with a full grown and freshly molted HY
male American Redstart that it may very well have still been providing
with some parental care. Molt-breeding overlap (especially overlapping
molt with the dependent fledgling stage) is fairly common among neotropical
migrants, particularly in the case of birds that nest later in the season
(e.g., birds renesting after earlier nest losses and/or double-brooded
Last week we posted a closeup showing
the head plumage and bill shape of a juvenile Swamp Sparrow. We snapped
a quick photo of a juvenile Song Sparrow this week, and edited the two
pictures together for a quick side-by-side (O.K., top-to-bottom!) comparison.
The juvenile SWSP (top bird below) has a thicker bill and a much less distinct
malar streak (the dark line running back from the corner of its mouth or
gape) compared to the juvenile SOSP (bottom bird below).
of the week, by far, was
American Redstart (24 banded). Prior to
20 June virtually all of the AMREs we banded were SY males (20 out of 23,
the other three being SY females), and none of these was in the company
of juveniles. Since then, only four SY males have been banded compared
to 11 ASY males (plus another three recaptured ASY males)--the majority
of the latter have been accompanied by one or more recently fledged juveniles.
Presumably, the earlier push of SY AMREs represented birds that were failed
breeders, while the latest movement has been of successful nesting birds
(mostly ASY males and about equal numbers of SY and ASY females) drawn
to the productive and protective wet shrub-scrub habitats in our banding
area for the critical post-fledging and molting periods.
Two ASY males captured just
one day apart this week provided another example of just how variable the
degree of wear and timing of molt can be between individual birds, even
within the same age/sex class. The top male in the photo below (a
five year old male originally banded as an SY male on 6/18/99) was in exceedingly
fresh plumage for the date, and had not yet begun its prebasic molt, while
the bottom male was both more worn to begin with and in a rather advanced
stage of molt. Overall, this week we banded ASY male AMREs with molt
scores ranging from zero (not yet begun) to 23 (about one quarter finished).
Interestingly, even the male in the most advanced stage of molt apparently
was still providing parental care to the hatching year bird caught alongside
it in the net.
We banded three more Scarlet Tanagers
this week, including our first ASY male. Although we posted a picture
or two of comparatively brightly colored SY male SCTAs earlier this summer,
we just couldn't resist taking (and showing) a picture of this guy!
Swamp Sparrows are interesting in
that we often are unaware of their nesting at Powdermill until the first
juveniles appear in our nets (on July 4th in the case of the bird pictured
below). Because we probably band 20 or more juvenile
for every juvenile SWSP, we have to be careful not to miss the first comparatively
SWSP that we catch, not infrequently in the same net
along with juvenile Song Sparrows! (Click
here for previously published discussion and photographs of the subtle
differences between juvenile Song and Swamp Sparrows).
We banded our first hatching year
Hummingbird of the season, a female. There are various criteria for
ageing hummingbirds, but, as shown in the photo below, the prominent scaley
appearance resulting from the light buffy edges on the feathers of the
head and nape is an unmistakable feature of both males and females in fresh
Because a key molt limit for many
species of birds occurs between the small proximal alula (the so-called
alula covert) and the larger middle and distal alula feathers, and because
these feathers are among the very last to be replaced during the complete
prebasic molt, adults in heavy prebasic molt can often still be identified
as SY or ASY until the diagnostic alula feathers are lost.
The top photo below shows an ASY Yellow Warbler. There is no contrast
among the as-yet-unmolted alula feathers, all of which, although worn,
are too brightly colored to be juvenal feathers. The bottom
photo is an SY American Redstart. Even with the heavy overall degree
of plumage wear, a molt limit is still visible visible between the slightly
darker and more greenish-edged alula covert and the retained and very worn
dull brown juvenal middle and lower alula feathers. Within another
week or so, both these birds would have to be aged simply AHY.
Many of the birds we banded this
week were very worn, heavily molting, or both, but our first Veery
of the season on 3 July, a returning 5 yr. old male (originally banded
as an SY male on 8 July 1999), like the unusually well-preserved 5 yr.
old male American Redstart pictured at the top of this week's account,
had not yet begun to molt and yet was in exceptionally fresh-appearing
plumage for the date. Based on this sample size of two, can we say
that forest-nesting songbirds are in the prime of their life at age five?!
Finally, our last note and photo
highlight for this week is of a female Hooded Warbler. Ordinarily,
we carefully count the primaries and secondaries on the wings of birds
that we band in summer, in order to detect the onset of molt (i.e., the
shedding of the first, or innermost primary). When we counted the
wing feathers on this female, it might have appeared based on her having
just eight primaries that she had, indeed, begun her molt. More careful
examination, however, showed that there was no gap between her outermost
secondary and innermost primary. She simply had only eight, instead
of nine, primaries on each of her wings (count 'em for yourself).
Truly, it seems as though a banding day does not go by that we don't observe
something a little bit different or altogether new!
to Past Pictorial Highlights