Fall 2005 Pictorial Highlights  August 1-14

• I returned to Powdermill just in time to kick off the start of the fall migration season.  Banding notes and photo highlights for the first half of August are given below.  But first, for those of you who might be interested, we'll begin this update with a look back at "How Adrienne spent her summer..."

In an effort to restore nesting tern populations along the coast of Maine to what they once were, the U.S. Fish and Wildlife Service acquired islands with suitable nesting habitat (forming the Maine Coastal Islnads National Wildlife Refuge), made efforts to attract terns to them at the onset of the breeding season, and then continued to maintain tern colonies through directed research and conservation management practices.  I spent the summer supervising a small field crew on Metinic Island, where the research focus was geared not only toward monitoring populations of three species of terns (Common, Roseate, and Arctic), but also species like Common Eider and Black Guillemot, which have additionally benefited from the restoration efforts on behalf terns.

Historical use of feathers as part of the millinery trade (for use in fashion) at the turn of the 20th century, as well as rapid human population expansion in the last fifty years along the eastern seaboard, together have caused serious declines to nesting seabirds along the Maine coast, bringing many populations to the brink of extinction.  The passing of the Migratory Bird Treaty Act in 1918 protected these birds from the direct threat of hunting for the millinery industry, but ongoing human population expansion carries with it a number of other indirect threats.  For example, the spread of landfills and other artificial food resources has caused populations of Herring and Greater Black-backed Gulls to explode.  These are much larger, more agressive seabirds that encroach upon and easily outcompete terns for nesting sites, and which also negatively impact terns by preying heavily on their eggs and young.

Ongoing research being conducted on islands in the Gulf of Maine has led to successful management strategies for benefiting terns and discouraging gulls and other predators, all in an effort to restore the distribution and numbers of breeding terns to historical levels.

For more information on tern restoration efforts in the Gulf of Maine, or to find out ways you can help, please visit Maine Coastal Islands NWR or Friends of Maine Seabird Islands. (Note: you will have to use your browser back button to return to this page from the above links.)
 

>Click here to see Adrienne's Maine 2005 Summer Seabird Slideshow<

• I said goodbye to terns attacking my head in Maine, only to be welcomed back to Powdermill by a Belted Kingfisher attacking my fingers.  The edges of a Belted Kingfisher's bill are razor sharp, a great adaptation for holding onto slippery, wriggling prey like fish and frogs, and for defending themselves against bothersome banders!  On just my second day back to banding on August 6, this young female proved, once again, the great lengths (and pains!) that Powdermill bird banders go to for good photo ops.

• Thankfully, not all the catches this week were out for blood.  Certainly not this harmless handful of hatch year Eastern Kingbirds.

 

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• Early this month, we banded our ninth ever fall Orchard Oriole, a hatching year (HY) male (note: its sex was determined based on its wing length; the black chin characteristic of second year males is a product of the first prealternate molt).

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• Distinctive breeding plumage, for the majority of species to which this applies, is most commonly acquired through prealternate molt.  The adult male Purple Finch banded this period, however, was an exceptional example of the few species for which a distinctive breeding plumage actually is acquired solely by wear rather than molt (House Sparrow and European Straling are other examples).  This phenomenon is eloquently described by Jonathan Dwight, Jr. in his classic work, The Sequence of Plumages and Moults of the Passerine Birds of New York:

"Adult nuptial plumage acquired by wear produces a plumage largely bright rosy carmine...
There is no pigmentary change...the whitish barbules of the reddish feathers of the winter dress, especially of the head and throat, have worn away, leaving the resistant carmine barbs bare and glistening...Wear is considerable by the end of the breeding season and loss of edgings helps intensify the reddish tints."

• Dwight's description is well-illustrated by the photos below.  On the left is an adult (ASY) male banded on August 3 in very worn breeding plumage; on the right is an adult (AHY) male banded in October in fresh definitive basic (non-breeding) plumage.

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• Our first two Blue-headed Vireos for the fall proved to be a male and female pair of second year (SY) birds (presumably a mated pair),  caught together in the same net.  The photo below was taken to show the different progression of prebasic molt in each individual.  The bird in the foreground, the male (larger and more brightly colored), was much further along with his prebasic molt (inner five primaries molted or molting) than the female, which showed active molt only among her first three primaries.  In many passerines that have biparental care, the female typically initiates molt later than her mate.  This may be a result of average earlier emancipation from parental care for males (ordinarily, there is little or no overlap between molt and parental care, because both are very energy demanding activities);  it also may be due to  physiological differences between the sexes in the way in which sex hormones interact with environmental cues to stimulate molt onset.

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• Finally, we end Page 1 with a quiz.  The wing pictured below is of an adult male Indigo Bunting that we aged conservatively as an ASY, but it could have been aged accurately as an ATY--Why?

• The flight feathers of this bunting's wing are the product of three different molts.  The three innermost secondaries (the terials; upper left corner of the picture) with the bright blue edging were grown during the prealternate molt.  The next six secondaries were molted last fall during the prebasic molt.  The next feather, primary 1, which is visibly much more worn than the surrounding feathers, was molted during a previous prebasic molt (i.e., two falls ago), and the outer eight primaries were molted during the same prebasic molt as the outer six secondaries.

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If this bird had been an SY male last fall, then its innermost primaries would have been juvenal prior to its prebasic molt (i.e., because HY birds retain their juvenal innermost primaries during their incomplete first prebasic and first prealternate molts).  Because the abnormally retained primary 1 clearly is not a juvenal feather (which would be very brown and far more worn), this bird had to have been an ASY bird when it underwent its prebasic molt last fall, making it an after third year (ATY; at least fourth year, or 4Y) in this calendar year.  Had the abnormally retained primary 1 been a juvenal primary, then the bird could be correctly and precisely aged as TY, or third year.

Last Updated on 08/30/05
By Adrienne J. Leppold