Pictorial_Highlights_100206

POWDERMILL NATURE RESERVE
PICTORIAL HIGHLIGHTS
October 2-6, 2002

Sunday, October 6, 2002: Very cool, calm, and clear overnight; foggy early AM, becoming mostly sunny, mild, and increasingly windy through the morning--strong gusting winds by noon necessitated closing most nets, but a few were left open and closely monitored in order to catch birds for a public banding demonstration at Powdermill's Florence Lockhart Nimick Nature Center at 2:00pm. There was a modest amount of nocturnal flight calling during net opening, much more than yesterday morning, but not anything we'd describe as "heavy." Although our capture total and rate for the day were no better than yesterday, there was nonetheless evidence of new arrivals, both in terms of the species composition of today's catch and the fat condition of most of the birds we caught (in contrast to yesterday, all but a few birds banded today lacked visible fat deposits). Brian Jones and Darlene Madarish helped with the banding (Darlene also gave us a hand with the public banding demonstration and took several photos while Bob Mulvihill was busy showing birds to the audience).

The birds of the day today were sparrows--41 in all, or just over half our banding total, led by Swamp Sparrow (16 banded) and White-throated Sparrow (11). We did better with our catches of several other of the later set of fall migrants (which, as we discussed earlier this week, are much later arriving than usual this fall), including six Ruby-crowned Kinglets, five each of Yellow-rumped and Palm warblers, and our first migrant Hermit Thrushes of the fall (a HETH banded back on 9/14 was a local breeding bird in heavy wing molt). The photo below, a simulated HETH in flight (a little photoediting "slight of hand," and "Look Ma, no hand!") nicely shows the primary field mark for separating this Catharus thrush from the others--it has a bright rufous brown tail and rump that contrast sharply with its dull olive brown back

Since we took the liberty of erasing the hand from the photo above "for effect,"

for a different kind of effect we left it in this picture of a Carolina Wren banded today
(we have to hand it to our banding assistant, Brian Jones--he really has a way with CARWs!)

Extending today's "hand" theme further still (at the risk, perhaps, of being "handed my hat!"),

about 70 people were on hand for a banding demonstration at our nature center this afternoon.

Children and adults of all ages enjoyed closeup,
in-hand views of several kinds of birds

including, of course...
(remember our recurrent theme for today?)

a Palm Warbler!

Saturday, October 5, 2002: Some moderate rain showers associated with the remains of Hurricane Lili occurred overnight, but the winds died down and in the hour or so before dawn it was mostly clear, calm, and mild (and much less humid). It rather quickly became cloudy and breezy after dawn (but nothing like the gusting winds yesterday!), then partly sunny and warm through the afternoon. Darlene Madarish and Carole Shanahan helped with the banding today.

The line of showers associated with Lili stretched across the Great Lakes into southern Canada 500 km or so north and west of Powdermill at about the time last evening when migrants might have been considering taking off for a nocturnal flight. Apparently, most of these changed their minds, with the result that very little or no migratory movement occurred across our region overnight. It was almost eerily quiet during net opening early this morning, with perhaps only one or two flight calls heard (where many dozens to several hundred is usual). Although we managed to band exactly 100 birds, the capture rate (24 birds/100 net hours) nonetheless was quite low for this time of year, and the vast majority of birds caught were scored as being very fat (a "2" or "3" on our scale of 0-3; i.e., they did not arrive overnight, but rather had been feeding in the local area for some time). Some may have arrived in the area yesterday morning (recall that we heard fairly heavy flight calling during net opening Friday), when weather conditions for catching them were very poor.

Bird of the day was American Goldfinch (34 banded), followed by Swainson's Thrush (12) and White-throated Sparrow (11, our best day for this species so far). Our fall 2002 total for AMGO stands at 117, which compares to nearly 800 at the same time last year! Wood warbler diversity has taken a real nosedive over the last few days--just four species were banded today, and we still have not had our first real push of Yellow-rumped (Myrtle) Warblers yet (just three MYWAs banded today).

We banded our third Hairy Woodpecker of the fall, an HY female. Below is a photo of it showing the primary tools of the woodpecker trade: a stout chisel-like beak and strong feet with long-clawed toes. Like the Chimney Swift and Belted Kingfisher pictured previously, woodpeckers have a characteristic arrangement of their toes that is very different from typical "perching birds." In woodpeckers (and also owls, cuckoos, and parrots) two toes (digits II and III) point forward and two (toes I and IV) point back. The technical name for this arrangement is zygodactyl (from Greek words meaning "to join toes"), commonly called "yoke-toed" because it resembles the old-fashioned yoke frame joining two large draft animals together at the neck for doing heavy work in unison.

We just had to take the picture of another Winter Wren banded today, because unlike most of the WIWRs that we handle, this one cooperated by holding its tail up in the quintessential wren pose.

Friday, October 4, 2002: Warm and humid, with heavy fog early AM; becoming partly sunny and unseasonably hot, with strong gusting winds by late morning. In contrast to yesterday morning, when very little nocturnal flight calling was heard during net opening, flight calls were fairly numerous this morning. Even so, the number of birds caught and the capture rate were both very low. Unlike yesterday, however, when weather conditions were ideal for banding, the heavy fog this morning dampened our nets and probably also the bird activity, and gusting winds later in the morning also reduced the efficacy of our nets for catching birds (unfortunately, not so the leaves!) With help from Carroll Labarthe, we operated 53 nets from 6:30am until just 11:15am, by which time the windy conditions made it unadvisable to continue.

We banded just 39 birds of 20 species today, none new for the fall, but including our third Marsh Wren of the season. We took pictures of just one bird today, a hatching year (HY) female Rusty Blackbird (photo below), to compare with the HY male banded Wednesday and pictured along with that day's notes. Female RUBLs are somewhat smaller than males (the female banded today had a wing length of 107.5mm and weighed 52.3g, compared to the male on Wednesday, which measured 115.0mm and 58.3g); they have dark slate gray rather than glossy black back and rump feathering and, in fresh basic (i.e., fall/winter) plumage, they have lighter buffy gray underparts, more extensive rusty or buffy brown on their head and upper back, and a much more prominent light brown eye brow stripe.

Wednesday-Thursday, October 2-3, 2002: Wednesday was mostly clear (but foggy in the early AM) and unseasonably warm. With help from Randi Gerrish, we operated 42 nets from 6:30am-12:30pm. Nocturnal flight calling was fairly heavy during net opening from 6:00-6:30am. Thursday was mostly cloudy, foggy and very mild before dawn; remaining overcast and unseasonably warm throughout the day. There was very little nocturnal flight calling during net opening on Thursday; with help from Mary Helen Chiodo we operated 55 nets from 6:30am-3:00pm (heavy rain showers began shortly after net closing).

In line with the difference in the density of nocturnal flight calling, banding activity (banding total and capture rate) was much higher on Wednesday than Thursday, but species diversity on Thursday was slightly better. One new species for the fall was banded on each day: Rusty Blackbird (an imm. male; first photo below) on Wednesday and a Brown Creeper on Thursday (second photo below).

The expected shift (by early October) in species composition to the set of later fall (typically shorter distance) migrants, some of which we associate with winter at this latitude, has been evidenced less by the conspicuous arrival of this group of birds than by the decline in numbers of the earlier (mostly Neotropical) migrants (especially several species of wood warblers). The arrival (in numbers) of several of the later fall migrant species already is more than a week later than last fall. For example, we have banded just 8 White-throated Sparrows compared to 132 by this date last year; 14 Yellow-rumped Warblers compared to 64 last fall; 14 Ruby-crowned Kinglets compared to 61; and nine Winter Wrens (photo below is of one of five--all hatching year, HY, birds--banded in the last two days) compared to 24 by October 3 last year.

We have mentioned on this website several times before that in the fall often it is valuable, even necessary, to double check the degree of skull pneumatization for confirming age determinations of birds made based on other criteria (e.g., plumage, soft part colors, molt limits). Because skull pneumatization proceeds fairly rapidly in most songbirds--in as little as 90 days in the Ruby-crowned Kinglet, based on a pioneering study by our own Robert C. Leberman (1970. Pattern and timing of skull pneumatization in the Ruby-crowned Kinglet. Bird-Banding[now J. Field Ornithology] vol. 41:121-124)--an incompletely pneumatized skull in the autumn usually signals a hatching year (HY) bird, while a bird that has finished the process can be confidently aged after hatching year, or AHY, at least until the date when ~ 5% or more of HY birds have completed the process (the unusually early cutoff for the rapidly pneumatizing RCKI is the end of September). As with everything, however, there are important exceptions, that are useful for banders to know about. Two cases in point were provided by birds banded here during the last two days.

First, on double-checking the skull condition of a Lincoln's Sparrow that appeared like an adult based on its clear gray eye brow stripe (a criterion discussed last week), we observed that it had an incompletely pneumatized skull. Importantly, the unpneumatized areas took the form of two very small "windows" visible along the midline near the top of the skull (very much like the shaded areas in first skull data card pictured below, which was drawn from what could be seen by parting the slightly wetted feathers on top of the bird's head and looking carefully though the thin, transparent skin covering its skull). In HY birds at this time of the year, the extent of pneumatization typically is much less (like the second skull data card below). Thus, LISP can have what we call "delayed" skull pneumatization. The combination, in the LISP banded on Thursday, of adult plumage traits, no wing molt limits, and a nearly, but not quite fully pneumatized skull equated not to an HY bird, but rather to an AHY bird--and probably a second year, or SY, bird (this based on the likelihood that LISPs do not retain skull windows beyond their second calendar year of life).

While delayed skull pneumatization of this kind is rather uncommon in the LISP, it is much more frequent in other passerine species, like many swallows and thrushes. In fact, even when we determine that a thrush is an AHY based on criteria like the absence of any retained juvenal wing coverts, dark red-brown rather than grayish brown eye color, and broad, blunt rectrix shape, we nonetheless routinely examine their skull. This is because we have found that a fairly high percentage of SY birds retain skull windows. In these species, however, skull windows are retained in the rear quadrants of the skull rather than on top. We have banded several SY Catharus ( e.g., Swainson's and Gray-cheeked) thrushes this fall. One SWTH banded recently, similar to the bird recorded on the data card pictured below, had prominent buffy shaft streaks on its median coverts which, at a glance, could easily have been mistaken for the retained juvenal feathers of an HY bird. Without knowing about delayed skull pneumatization in this species, a bander seeing those feathers and finding a mostly, but nonetheless incompletely pneumatized skull might arrive at the conclusion that it is an HY bird, when, in fact, it is an SY.

There's no doubt about it--the process of making sense of all our firsthand observations as banders for simply correctly identifying birds to species, age, and sex can seem, many times, like the process of disentangling them from mist nets in the first place! Equally true, the eventual recognition and organization into useful patterns of all the scattered puzzle pieces of variation in living birds that we are in a unique position to observe (and document) is one of the most engaging and invaluable things about bird banding.

If you've read to this point, then it seems fitting for us to thank you for your continued interest in this website, for indulging us in our ongoing effort to "document" observations made here at Powdermill that may be of use or value to others with an interest in the study (scientific or otherwise) of birds. Thank you!

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