Week 5:  August 29 - September 4, 2005

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This week brought MBO far more vireos than ever before.  By far the most numerous were
 the Red-eyed Vireos, shown at bottom left with an after-hatch-year male on the left and a
 hatch-year sex unknown on the right.  On Friday, net G2 contained not only a Red-eyed
Vireo, but also the week's only Blue-headed Vireo (top left) and one of two Philadelphia
Vireos (top right).  As for the bird at bottom right ... it too is a Philadelphia Vireo,
although much less distinctly marked than the other.  (Photos by Marcel Gahbauer)


# birds (and species) banded 281 (40) 847 (53) 1580 (78) 2501 (88)
# birds (and species) repeat 48 (13) 117 (21) 362 (28) 540 (35)
# birds (and species) return 8 (6) 15 (7) 46 (12) 46 (12)
# species observed 79 107 147 161
# net hours 414.9 1013.5 2668.3 3642.8
# birds banded / net hour 67.7 83.6 59.3 68.6

Note: table does not include nocturnal banding (owls)

Bander-in-charge:  Marcel Gahbauer
Assistants:  Pierre Bannon, Jean Demers, Christina Donehower, Barbara Frei, Gay Gruner, Marie-Anne Hudson, Barbara MacDuff, Betsy McFarlane, Lynn Miller, Chris Murphy, Guillaume Passavy, Kristy Putnam, Crissy Ranellucci, Steven Skipper, Clémence Soulard, Vince Spinelli

Notes:  This was our first week of full operation for the fall season, so it is not surprising that with six days of good weather we set a new weekly record with 283 birds banded.  Wednesday was washed out with the leftover rain from Hurricane Katrina, which somewhat replenished the low water level in the ponds, but seemed to have little effect on the mix of birds present.  Tuesday and Sunday the migration was quite slow, allowing us to get some much needed site maintenance done, but otherwise the level of activity was medium to high every day.

Even more than the past few, this was the week of the warblers.  19 species were banded this week, including a high of 15 on Friday.  They accounted for 61% of all the birds banded this week, and up to almost 80% on a couple of days.  Without exception, the most numerous species every day this week was the Magnolia Warbler, with a total of 53 banded.  Though in distant second place with 27, the Red-eyed Vireo also deserves honourable mention for being unusually abundant this week.

This week we banded our first ever Philadelphia Vireo, and also added another three species to the list of birds banded this fall with Cedar Waxwing, Western Palm Warbler, and an early Slate-coloured Junco on August 29.  

In addition to these, several other species were seen for the first time this season.  The Connecticut Warbler on Sunday's census was only the second ever observed at MBO.  The day before, a Great Horned Owl hooted at sunrise, and the first few Canada Geese flew past overhead.  Belted Kingfisher, Scarlet Tanager, and American Kestrel rounded out the week's new additions.  Overall it was the most diverse week yet this fall, with 79 species observed.

As the later migrants begin to trickle in, we're already saying goodbye to some of the early ones.  It seems that the last of the Eastern Kingbirds have already left, and the numbers of Yellow Warblers, Baltimore Orioles, Indigo Buntings, and Rose-breasted Grosbeaks have tapered off to the point that we expect them to soon disappear altogether as well.  We are still seeing at least a couple of Ruby-throated Hummingbirds in the nets daily, but they too are likely to move on before long.  In the meantime though we continue to enjoy their irrepressible spirit, highlighted by one on Saturday which pursued a crow over quite a long distance! 

We sometimes get asked what benefit there is in looking closely at birds recaptured within a
few days or weeks of when they were banded.  Often little will have changed, but sometimes
in fall an increase in fat and/or weight will be evident over time.  Occasionally, as with the
 second-year male Tennessee Warbler above, we have the opportunity to document the
progression of a moult.  The top right photo was taken on August 22, and the bottom right
photo 13 days later on September 4.  It shows that in less than two weeks, the final four
juvenal secondaries (brown and worn in the top photo) have all been dropped, and are in the
process of being replaced.  Visible in the top right corner of both photos is the alula - a pale
brown and worn juvenal feather two weeks ago, and a fresh dark feather now.  Moult processes
 in many species remain poorly understood, so documentation of such cases can be of great value.
(Photos by Marcel Gahbauer) 




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