Spring 2006 Notes and Highlights for May 16 - 31

• During the last two weeks of May, we banded 10 new species for the season and 968 birds, giving us an above average spring season total of 3481 birds and 106 species.  Cape May, Blackpoll, and Bay-breasted Warbler were three of the ten new species banded for spring during the last two weeks of May.  Large catches of Cedar Waxwings on five days this period pushed this species into the number one spot (155 total) for the two-week period and turned what might have been one of the worst spring catches for the species (just one banded prior to the current period) into the fifth highest spring total ever!  For the period, Magnolia Warbler (104) was the second most commonly banded bird, followed by American Goldfinch (87).  For these species, the strong late spring showing matched their generally very good spring flights.

 

 
 
 

We thank Paul Pieper, Rosemary Spreha, Fred and Carol McCullough, Pam Ferkett, Brent Worls, Sandy and Gary Lockerman, Sandy Teliak, Trish Miller, Jessica Scopel, Jessica Maggio, and Lauren Schneider for their help with banding this period.

• In only the first few days of the period, we added two new vireo species to our season list: Philadelphia Vireo (top photo below) and Warbling.  While Philadelphia Vireos are much more common through Powdermill on migration, we usually can expect at least one Warbling Vireo each spring.  Superficially, a pale PHVI can closely resemble a WAVI (and vice versa).  In the hand, however, identification becomes unmistakeable because P10 (the outermost primary flight feather) on a PHVI is so reduced it is nearly absent, while on WAVIs, P10 is as long or longer than the primary coverts (bottom photo below).

• The orange color on the throat of the Tennessee Warbler in the photo below actually is a stain from pollen of the various flowers whose nectar this species feeds upon on its wintering grounds from Mexico to Colombia.  As pointed out in Dunn and Garrett's (1997) in their exceptionally detailed and well written Peterson Field Guide to Warblers, "[Tennessee Warblers] that spend much time foraging at flowers on the wintering grounds often become stained by red pollen on the head; some of this staining may persist during the northward migration in spring."  Apparently, the vine Combretum fructicosum is especially favored, but Tennessees also will probe the flowers of Inga, Erythrina, and Eucalyptus for their nectar and for small insects.  A dietary switch, at least in part, from insectivory to nectarivory and/or frugivory between the breeding and wintering season is characteristic of many species of wood warblers.

• More than a few times on this website we have pointed out that in many dimorphic species, accurately (and precisely) determining the age of a bird is an important prerequisite to correctly assigning the same bird to one sex or the other.  This is because hatching and/or second year males tend to have much less well-developed masculine plumage traits at the same time that adult (AHY/ASY) females can have unusually (and sometimes surprisingly!) well-developed male-like plumage.  Field guide depictions of males and females necessarily are drawn to represent the most typical, or average, plumages, but nature is all about variation!

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At Powdermill, we have observed (and previously discussed on this website) extremes of female plumage variation (adult females closely resembling males) in two of the three Wilsonia wood warblers: Hooded and Wilson's.  Before this spring, however, we had not observed a similar case in the congeneric Canada Warbler.  The plumage of an adult (ASY) Canada Warbler banded on 20 May certainly was male-like, but more like the plumage we'd expect for a SY male.  The very fact that the bird was clearly an ASY based on absence of expected wing molt limits for an SY immediately gave us pause.  We came to a full halt when the birds wing measured 63.5mm, well short of the average for an adult male.  Although subtle, there can be  consistent differences in the appearance of the cloaca between sexes of many species even outside of the breeding season (see Svensson's classic Identification Guide to European Passerines), and we have been opportunistically evaluating the usefulness of this for sexing birds at Powdermill.  The cloacal morphology for the Canada Warbler pictured below was as we have seen in many non-breeding female wood warblers.  So, based on the age, size (wing length), and cloaca of the bird, we provisionally identified it as a female.

Adult (ASY) probable female banded 20 May 2006

• For comparison, the next photos show a second year (SY) male, which would be the most likely other candidate for a CAWA with plumage traits like the female above, and an ASY male.

• Compared to our putative male-like ASY female CAWA, the plumage of an ASY male in spring is characterized by a broader (i.e., deeper), more well-defined "necklace" of black streaks, more extensive black around (especially behind) the eyes and on the top of the head.   Importantly, we will officially report the sex of the ASY CAWA banded on May 20 as "U," while retaining notes about our opinion of the bird's sex (and the reasons for it) in our own banding database.  The opportunity to study subtleties of plumage in living birds is one of the great things about banding, and one of the most important opportunities for banders.

• Another thing that made May 20 an important banding day was the capture of our very first hatching year (HY) bird for 2006--a "squab" Mourning Dove.

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• This Cape May Warbler, the first and only to be banded this spring season, was an SY female that had undergone only scattered prealternate body molt.  Notice the extreme wear on scattered brownish basic head feathers of her crown.

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• Amidst the odd plumages, new species, and firsts for the year on 20 May, we welcomed 90 or more members of the Pennsylvania Society for Ornithology which held its annual meeting at Powdermill and nearby Ligonier.  During the meeting, our banding lab door was always open, and many attendees took advantage of meeting breaks to pay us a visit.  Our good friend Doug Gross (Endangered Species Biologist for the Pennsylvania Game Commission), is the leading authority on one of Pennsylvania's rarest nesting songbirds, the Yellow-bellied Flycatcher, a denizen of relict boreal forested wetlands in the state.  During the meeting he got the chance to admire a migrant individual of this species, which he nicknames the "Moss Tyrant" for the verdant setting in which he finds most of its well-concealed ground nests.

• Our thanks to all who participated in this three day meeting event and especially to Greg Grove, Shonah Hunter, and others on the PSO committee for selecting Powdermill as the venue for this year's meeting.  We had requested this as one way to kick off a year-long 50th anniversary celebration for Powdermill Nature Reserve.   Our thanks to Cokie Lindsay, Assistant to the Director, and Theresa Rohall, Coordinator of Education, for handling many of the meeting logisitcs at Powdermill.  Thanks also to Powdermill's own Trish Miller, Annie Lindsay, and Mike Lanzone, and to Dr. Todd Katzner (The National Aviary), Dr. Terry Master (East Stroudsburg University), Dr. Stacy Small and Kim Van Fleet (Pennsylvania Audubon) for their excellent and interesting contributions to the meeting's scientific program.  Last but not least, Len and Linda Hess from the Westmoreland Bird and Nature Club handled field trip arrangements and several members of the WBNC led those trips.

• We finally banded this SY male Orchard Oriole on 23 May.  One (probably this very bird) had been seen and heard around the banding lab for a week or two prior.

• Two days later we were happy to finally see a bird that we thought might turn out to be a "conspicuous miss" this spring--our first Scarlet Tanager.  This was our 5th latest first spring capture of a SCTA at Powdermill.

• Later the same day we caught the second of our two Savannah Sparrows banded for the season, making   May 25th the latest spring capture date (by 13 days) for this species at Powdermill.   In fact, this bird proved to be a male in breeding condition--most likely a wanderer from some neighboring hayfield habitats a quarter of a mile to the north of our banding area.

 

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• There may not appear to be anything particularly special about the adult male Cedar Waxwing in the photo below, but in actuality, he is about the most handsome individual of his kind we have ever seen!

• Not only did he have larger and more extensive wax tips than we've ever seen (wax tips on all nine secondaries, with hints of wax on three inner primaries), he also had a completely orange tail band with prominent wax tips on every rectrix.  The orange tail band variation in waxwings is something we usually see only in immature (HY/SY) waxwings that have been fed a heavy diet of tartarian honeysuckle berries.  When we do see this plumage variant in adults, the orange coloration typically is less dark and uniform.  The close up tail band photo shows the very wide, very colorful orange tail band with its waxy tips.  Tail wax tips, only rarely seen (fewer than 50 CEDWs banded at Powdermill out of >16,000 banded are noted as having wax tips on their tail; only three of these have been HY or SY birds), usually are greatly reduced in size compared to wing wax tips and usually occur on just one or two pairs of rectrices.

• The photo below is of the tail of a Cedar Waxwing banded a few days later.  While the wing wax of this bird was not unusually extensive, and the tail band was the usual yellow color, the unusually extensive wax tips on the tail were very large, even in comparison to the bird in the photos above.

Last Updated on 06/22/06
By Adrienne J. Leppold and
Robert S. Mulvihill