Metro Beach banding report - September 11 & 13, 2009

Since the beginning of September, the weather across southern Michigan has been "nice". There has been little or no rain, few clouds, little wind, and moderate temperatures. So far no strong cold fronts have passed through with the result that the migration, and resulting banding, can be characterized as "slow". I've been keeping an eye on radar observations of migrants as well as postings to a new chat group I've joined of people who monitor night flight calls of migrating songbirds. Both of these sources have shown quite clearly that significant songbird migration has been going on for the past two weeks. Such conditions are clearly great for the birds, most of which end up over-flying us or, when they land, are not bunched up and crowded into a few small patches of habitat so instead may be more dispersed. Thus the total of only 73 birds banded over the two days we recently opened the nets, Friday September 11 and Sunday September 13.

Banding highlights on Friday, September 11 included two Ruby-throated Hummingbirds, and this Yellow-bellied Flycatcher shown below. Empidonax flycatchers are coming through in good numbers this fall, for a change.

Hatch-year Yellow-bellied Flycatcher

A Mourning Warbler was the 10th so far this fall, a good total. Nashville and Wilson's Warblers continue to be steady captures. Among the warblers, this Magnolia Warbler was perhaps the most colorful.

Hatch-year Magnolia Warbler

The Bird Banding Lab does not allow banders to sex hatch-year Magnolia Warblers. The threshhold for any criteria to be used is that it must be 95% reliable. These birds are quite variable in a number of characters which makes them quite challenging to determine the sex. On the bird above, one could determine that it is a hatch-year based on the relatively pointed tail feathers and the fresh plumage overall. But no criterion, or set of criteria, has been published that reliably can be used to determine the sex of hatch-year Magnolia Warblers. There may be a tendency for females to have shorter and males to have longer wings. There may be a tendency for males to have large black centers on the back feathers and females to have none (with many intermediates). There may be a tendency for males to have bolder black flank streaks and females to have less or none (again with many intermediates). There may be a tendency for males to have large black centers on their upper tail coverts and females to be mostly gray (once again with many intermediates). One older publication suggested that the size and/or shape of the white spot on the second tail feather (second out from center) could be used to determine sex, but after examining hundreds of known-sex Magnolia Warblers in spring it is clear to me that this character is at least as variable as all the others, if not more! So, how do some of the "experts" determine the sex of an "immature" Magnolia Warbler from photos or in the field? I'd personally love to know, since nothing concrete has ever been published on the subject. Or, is the threshhold in the field much lower than 95%?

Interesting birds observed but not banded included two flyover Green Herons, two flyover Sharp-shinned Hawks, an American Woodcock flushed from the Field Net area before we set up, and a juvenile Great Horned Owl begging in the woods.

Banding highlights for Sunday, September 13 included 6 Ruby-throated Hummingbirds, one of which I'm releasing in the photo below.

Hatch-year male Ruby-throated Hummingbird
(Photo by Jerrry McHale)

The first Ruby-crowned Kinglet of the fall was a surprise as it seems a little early for them.

After hatch-year male Ruby-crowned Kinglet
(Photo by Jerry McHale)

Another surprise was an Indigo Bunting, which we only rarely catch in the fall and infrequently catch in spring as well. This dull bird was a real head-scratcher for most of the banding assistants as hatch-year females are quite nondescript.

Hatch-year female Indigo Bunting

Interesting birds observed but not banded included a Cooper's Hawk, two Common Nighthawks over the woods while we were setting up in the field, a Gray-cheeked Thrush overhead in the dark while in the field along with a few Swainson's, single Magnolia and Black-throated Blue Warblers, a few flyover Bobolinks, and at least two Purple Finches in the tree at the center of the Field Nets.

I would like to thank the volunteers who made banding on these two days possible: Chris Charlebois, Dave Furi, Jean Gramlich, Thierry Lach, Jerry McHale, Tom Schlack, and Sue Wright.

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Banding Data
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FRIDAY, September 11, 2009
Sunrise (E.S.T.): 6:07
Time Open (E.S.T.): 6:00
Time Closed (E.S.T.): 12:00
Hours Open: 6.00
No. of Nets: 5.00-13.25
Net Hours: 75.188
Temperature (F): 63-73
Cloud Cover: 50-25%
Wind: NE-SE @ 1-5 mph
Barometer: 30.22-30.29
Precipitation: None
No. Banded: 35 (plus 11 recaptured and 1 released unbanded)
No. of Species: 14
Capture Rate: 62.5 birds per 100 net hours
Volunteers: Chris Charlebois, Jean Gramlich, Jerry McHale, Tom Schlack, Sue Wright

Ruby-throated Hummingbird -2 (plus 1 released unbanded)
Yellow-bellied Flycatcher - 1
Black-capped Chickadee - 1
House Wren - 1 (plus 4 recaptured)
Swainson's Thrush - 6
Gray Catbird - 1 (plus 1 recaptured)
Nashville Warbler - 5
Magnolia Warbler - 2
Ovenbird - 1
Mourning Warbler - 1
Common Yellowthroat - 7 (plus 2 recaptured)
Wilson's Warbler - 3
Song Sparrow - 2 (plus 4 recaptured)
American Goldfinch - 2

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SUNDAY, September 13, 2009
Sunrise (E.S.T.): 6:09
Time Open (E.S.T.): 6:00
Time Closed (E.S.T.): 12:00
Hours Open: 6.00
No. of Nets: 5.00-13.25
Net Hours: 74.063
Temperature (F): 55-75
Cloud Cover: 20-0-50%
Wind: Calm-NW @ 0-5-7 mph
Barometer: 30.18-30.17
Precipitation: None
No. Banded: 38 (plus 9 recaptured and 1 released unbanded)
No. of Species: 13
Capture Rate: 64.8 birds per 100 net hours
Volunteers: Dave Furi, Thierry Lach, Jerry McHale

Ruby-throated Hummingbird - 6
Least Flycatcher - 2
[House Wren - 2 recaptured]
Ruby-crowned Kinglet - 1
Swainson's Thrush - 5
Gray Catbird - 1
Nashville Warbler - 3
Ovenbird - 2
Common Yellowthroat - 8 (plus 4 recaptured)
Wilson's Warbler - 2
Song Sparrow - 4 (plus 4 recaptured and 1 released unbanded)
Swamp Sparrow - 3 (plus 1 recaptured)
Indigo Bunting - 1