Summer 2006 Notes and Highlights for the month of July   click here for season totals

• The end of July marked the end of our summer banding season.  An above average total of 539 birds of 50 species was banded over the course of eighteen banding days during the month.  The busiest banding day was July 15 (52 birds of 19 species).  As usual, most birds banded at Powdermill in July are locally breeding adults and their young.  For example, topping our July banding totals was Gray Catbird (82 banded), followed by American Redstart (47), Wood Thrush (37), Red-eyed Vireo (35), and Song Sparrow (22).  Only the catbird and sparrow nest commonly in the shrubby habitats where our mist nets are situated; the others regularly move into this habitat from the surrounding forest after they have finished breeding, presumably because it provides more abundant food (especially fruits) and better cover during the critical post-fledging and molting periods for adults and their fledglings.  Our July totals are supplemented, however, by birds, like Veery and Chestnut-sided Warbler, that breed in forest habitats at higher elevations (>1,700 ft.) than the banding station (1,300 ft.), but which routinely exhibit an altitudinal post-breeding (pre-migration) dispersal to lower elevations in late summer.  Again, the likely attraction is heavier cover and more abundant food--in the case of Veery, especially early ripening fruits of naturalized non-native honeysuckles and autumn olive.

 

 
 
 

In addition to local breeding birds and birds that have begun dispersing following breeding, July banding usually produces our first true fall migrants--i.e., species that do not breed anywhere near Powdermill or birds of local breeding species that have moderate or heavy pre-migratory fat deposits.  This July, Least Flycatcher, Northern Rough-winged Swallow, and Yellow warblers were examples of such early fall migrants.

We are grateful to the following volunteers for their help with the banding in July: Lauren Schneider, Eliza Frazer, Jessica Scopel, Lauren McFarland, Chris Meny, Cokie Lindsay, Pam Ferkett, Keri Parker, and Trish Miller.

• July is always a good month to study the molts and plumages of local breeding species.  For example, it is a chance to examine the comparatively short-lived juvenal plumage of birds like Red-bellied Woodpecker.  In the photos below, the juvenal plumage of a locally hatched male and female are compared.  Like most woodpeckers, the juvenile males (left hand photo) have more red on their juvenal crown (and, in this species, also on the nape) than juvenile females (right hand photo).

• Even more fleeting is the juvenal plumage of many wood warblers, like this very recently fledged Yellow Warbler, banded on July 9.  The first prebasic molt replaces the mouse-gray juvenal plumage of this species within just a couple of weeks after fledging.

• July produces an array of plumages, from juvenal or mostly juvenal (like the YWAR above) to fresh first basic, to worn alternate, through the various stages of molt leading to fresh definitive basic (i.e., fall or non-breeding) plumage.   The hatching year male Chestnut-sided Warbler banded on July 7 was already in its freshly molted first basic plumage.

• On the same day that we banded the freshly molted "confusing fall" HY male CSWA above, we banded an adult (ASY) female in very worn alternate (i.e., breeding) plumage.

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• Many adult warblers, however, are actively molting in July, especially earlier nesting species or those that may not have succeeded in nesting at all.  Pictured below are two second year (SY) male American Redstarts banded on July 6-7 in very different stages of molt.  The much earlier stage of molt for the bird in the top photo suggests the possibility that it did indeed attempt nesting, while the male in the middle photo, whose molt must have begun 3-4 weeks earlier (in early to mid-June) almost certainly failed to even attract a mate in its first breeding season.  The SY male Black-and-white Warbler (bottom photo), although in a similarly advanced stage of molt as the second AMRE, was banded two weeks later, on July 20, in all likelihood following at least an attempt at nesting.

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• Mentioned in the introduction, we often band Veeries in July, despite the fact that they breed only at high elevations near Powdermill.  It is typical for us to catch family units of this species composed of one parent and one or more dependent fledglings (it is possible that this species, like many, divides the brood following fledging, with the male parent taking charge of some of the young and the female taking charge of the others.  In the photos below, note that both the juvenile (top photo) and the adult (ASY) female have a very "babyish" looking gape, which is accentuated in the adult by the loss of feathers around its beak.  These "bald" spots probably resulted more from ectoparasites than molt, because the same bird had a literally "lousy" looking tail!

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• Also mentioned in the introduction to this update was our banding in July of a few early fall migrants, like this adult (SY) Least Flycatcher, which had moderately heavy fat deposits when it was banded on July 9.

• Another probable fall migrant was this HY Northern Rough-winged Swallow banded on July 9.  It is no coincidence that, with few exceptions, flycatchers and swallows forego their prebasic (post-breeding) molt until after they've reached their wintering grounds, which facilitates their much earlier migration schedule compared to most other passerines.

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• Concluding this July update are pictures and notes of a few summer "babies" banded this month.  First, and for no other reason than to show off the great picture of this cute White-eyed Vireo....

• Second, a Tufted Titmouse, pictured below, that was excessively "fault-barred."  The presence of barring on its wing coverts and body feathers, as well as near the tip of its tail and flight feathers, suggests that it experienced significant energetic/nutritional stress midway through the nestling stage (i.e., when the wing and tail feathers are just braking sheath).   In the bottom photo, the deficiency of pigmentation in its tail feathers (note how easily the hand holding the bird can be seen through the rectrices and how much darker the rectrices are at the very tip) suggests that whatever caused the initial deficit, in fact, persisted through the nestling and fledgling periods as these feathers continued to grow.

• And third, this juvenile male cardinal banded on July 29 was unusual in having a very bright orange-red bill at such a young age.  The bill of  juvenile cardinals usually is partly to mostly dusky, becoming more brightly colored over fall and winter.

Last Updated on 08/08/06
By Robert S. Mulvihill