Friday, April 2nd through Sunday, April 4th - Pine Warblers, Louisiana Waterthrushes, and Eastern Towhees returned to Powdermill during this first week of April giving us hope for some new (unbanded) captures and some new species for the spring.  Unfortunately, rain prevailed for much of the week, limiting the banding effort and even forcing us lose a full day of banding on April 1st.  Even so, we banded four new spring species during this first week (however, none of the three species mentioned above as having returned was caught and banded).  New species to band included Blue Jay (not pictured) and the following:
 

• A second-year Brown Thrasher (not very visible in the picture are the bird's three retained juvenal outer greater coverts)

• An after-second year (ASY) male Belted Kingfisher.  This bird was aged as an adult because of the fairly discernible molt limit among the primary coverts.  The bird pictured below appeared to have molted its three inner primaries, its innermost secondary and all its rectrices (not pictured), primary coverts 3, 4, and 9 (1 is not visible), and the alula.  Although its exact age based on this molt pattern is uncertain, it certainly had undergone at least one additional prebasic molt compared to an SY bird (making it at least an ASY bird).  The lack of very strong contrast between the fresher inner and unmolted outer primaries suggests that both sets of feathers may, in fact, have been "adult," which would make this bird an ATY--this is a very subjective and difficult assessment to make, however, leading to our more conservative determination of the bird as an ASY.

• An after second year Chipping Sparrow (top photo below) banded during the first week of April is complimented here (second photo below) with a picture of our first Swamp Sparrow (bottom photo) of the spring, banded a few days earlier on the last day of March.   Although they are similar looking, especially in the coloration of their caps, they do have distinct differences.  CHSPs are less robust and show a whiter stripe over the eye and a straighter, blacker eye line.  CHSP also do not have any streaking on the breast or bright reddish wing coverts as seen in the SWSP.  The SWSP was a particularly bright red-capped after second year bird, undoubtedly a male based on the combination of its bright and extensive cap color and a wing length of 64.5 mm, well above a 95% cutoff value for males (62.0mm) based on the distribution of wing lengths for known sex (i.e., females with brood patches or males with cloacal protuberances) SWSPs banded at Powdermill.

.




• For banders who may be interested, our study entitled, "Relationships among body mass, fat, wing length, age, and sex for 170 species of birds banded at Powdermill Nature Reserve," has just been published as the first monograph of the Eastern Bird Banding Association.  It contains a very extensive tabulation and analysis of morphometric data from nearly 300,000 original banding records collected here between 1974-2000.  In addition to descriptive statistics of wing length and body mass related to fat levels for the main discernable age-sex classes of 170 species, there are more involved statistical analyses of age and sex differences in mass and wing length and of mathematical relationships between fat and mass and estimated lean mass and wing length for 100 species for which sample sizes were large enough to support such analyses.  Finally, there is an appendix giving statistically determined wing length cutoff values as a provisional guide for sexing nineteen species of birds that have monomorphic or, like the SWSP, only slightly (and/or only seasonally) sexually dimorphic plumage.

.
• The monograph is being sold and distributed by EBBA and will be available for purchase for the first time at the annual EBBA meeting this weekend in New London, Connecticut.  Copies can be obtained by contacting EBBA Officers Don Mease (Treasurer) or Elaine Mease (Membership and Publications) at 2366 Springtown Hill Rd., Hellertown, PA  18055 or mailto:measede@enter.net

Wednesday, April 7th through Saturday, April 10th - Similar weather patterns continued throughout the second week of April, forcing us to close nets early on April 8th.  The weekend brought a couple dry, warm days, but still seemed to negatively impact our catches despite increased effort and the obvious arrivals of some new migrants to the area.  This made us particularly grateful and excited to add the fifth new species for the spring banding list--our one "star" from the second week of April,

• An adult male Blue-gray Gnatcatcher (female BGGNs lack the black "eyebrows"), captured on 4/9, three days after the first of its kind (maybe even the same bird) was observed just outside the banding lab at Powdermill.

---

• Finally, we've added one more image to the photo series begun last week showing the prealternate molt progression of male American Goldfinches at Powdermill.  The third (bottom) shot in the series shows an SY male banded recently that had nearly completed its spring molt (except for a couple of head feathers.)  Because it is an SY bird, it lacks the bright yellow epaulet of the ASY birds pictured above it.  The retained brownish epaulet will not be replaced during this bird's prealternate molt, but will molt to bright yellow during the bird's second prebasic molt this coming fall.

.
• A few adult AMGOs (i.e., those that have undergone two or more prebasic molts) can fail to acquire a bright yellow shoulder (i.e., resembling an HY or SY bird), and a few HY or SY birds can precociously acquire some bright yellow feathers among their lesser coverts--as always, banders must try to be careful to consider any and all ageing criteria when arriving at age determinations.

• Thanks to all those who helped with banding these two weeks:  Tim and Rachel Dellinger (visitors from West Virginia University), Randi Gerrish, David Leibmann, Annie Lindsay, and Felicity Newell.

Last Updated on 4/14/04
By Adrienne J. Leppold