Monday, September 10, 2012

Metro Beach banding station report - September 6-7, 2012

Conditions for migration in the week before these two banding days was improved over previous weeks. While we were gathered in the darkness along the shoreline of Lake St. Clair each morning before heading back to the banding area, migrants were heard calling overhead as they came into the park from offshore, many of them Swainson's Thrushes. The number of nocturnal flight calls heard was greater on Friday (Sep 7) than on Thursday (Sep 6). But clearly the banding results can sometimes be the opposite as you'll see from the summary below.

The station was closed early on Thursday due to a personal emergency. I want to thank the following volunteers for making banding possible on these two days: Dave Lancaster, Marie McGee, Kathy McDonald, Tom Schlack, and Blanche Wicke.

Highlights of the 44 birds banded on Thursday, September 6 included a number of warblers. A good omen for the day was the very first bird captured, a Connecticut Warbler. This was the 5th at this station since 2004, all of them in fall. This compares with a total of 8 banded by Ellie Cox (the previous bander here) from 1989-2000, with 2 in spring and 6 in fall. So the capture rates seem to be similar.

Hatch-year female Connecticut Warbler

Hatch-year female Connecticut Warbler

The second bird captured today is one that has been nearly as infrequently captured, a Cape May Warbler. This was only the 6th banded here since 2004, all in fall since 2010. This contrasts with a total of 16 banded from 1989-2000, with 7 in spring and 9 in fall.

Hatch-year male Cape May Warbler

Hatch-year male Cape May Warbler

Another uncommon warbler captured today was Mourning Warbler, with two banded. From 2004-2011, an average of 5.4 per season have been banded (range 1-10), and the two today brought the season total to 5. The hatch-year bird showing a nearly complete, but still broken eye ring, provided a good comparison to the Connecticut Warbler (remember to click on the photos for an enlarged view).

Hatch-year Mourning Warbler

The other Mourning Warbler was a bit of a surprise, as it was an adult male, which made the day feel more like spring with his plumage being brighter than all the Mournings we've banded this fall.

After hatch-year male Mourning Warbler

The final warbler highlight came in the form of a commonly observed, but irregularly banded species, the season's first banded Palm Warbler.

Hatch-year Palm Warbler

Interesting birds observed but not banded included two American Woodcock flushed from different parts of the banding area...we'll catch one eventually! Only two Ruby-throated Hummingbirds were observed and sadly none banded, which is very unusual at this peak time of their migration. Also, warblers observed but not banded included Nashville, Chestnut-sided, Black-throated Green, and Ovenbird.

Highlights of the 23 birds banded on Friday, September 7 included 5 Ruby-throated Hummingbirds. Normally, I'd be banding 10-15 per day this time of year, but the past two days have come up empty so it is nice to see a few in the area.

Hatch-year male Ruby-throated Hummingbird

Typically, more than 90% of the Ruby-throated Hummingbirds banded at this site are hatch-year birds. It is not clear why that is, but the park's habitat does not support more than a couple breeding pairs, so most are assumed to be migrants here. Determining the age of these birds is accomplished by looking at the surface of the upper mandible (maxilla) with a 10x magnifier. Hatch-year birds show "corrugations", sometimes faint, along most of its length. This is difficult to show to others, and is not easy to photograph, but I did manage one today and it is posted below (again, click on it to enlarge).

"Corrugations" on maxilla of hatch-year
Ruby-throated Hummingbird (also note buffy
fringes on forehead and crown feathers)

Determining the sex of these hatch-year birds is accomplished by measuring the wing chord; males are smaller than females with very little overlap in size. Other characters that observers can use, that are less reliable than wing chord, include the "5-o'clock shadow" effect of dense spotting on males, as on the bird above. And sometimes young males show stray iridescent red throat feathers. Another character that is still being explored is the pattern of white on the second rectrix (third from outside), with males tending to have white on the tip only on the inside of the shaft, with females having more extensive white. Also, the shapes of the male's tail feathers are subtly more pointy than females.

Hatch-year male Ruby-throated Hummingbird
with white mainly on inside web of second

Interesting birds observed but not banded included two Red-breasted Nuthatches, and a calling Marsh Wren. Warblers observed but not banded included: Tennessee, Magnolia, Black-throated Blue, Palm, Blackpoll, and American Redstart.

I had hoped to provide photos of the progress of the Monarch chrysalis discovered along the side of the road last week, but unfortunately the park decided to mow a wide swath down both sides of the banding area...puzzling to me as this is a nature trail in the natural area.

Banding Data
THURSDAY, September 6, 2012
Sunrise (E.S.T.): 6:02
Time Open (E.S.T.): 5:45
Time Closed (E.S.T.): 10:15 (personal emergency forced early close)
Hours Open: 4.50
No. of Nets: 4.5-13.5
Net Hours: 53.75
Temperature (F): 66-73
Cloud Cover: 50%
Wind: NW @ 3-5-7 mph
Barometer: 29.90-29.97
Precipitation: None
No. Banded: 44 (plus 4 recaptured)
No. of Species: 15
Capture Rate: 89.3 birds per 100 net hours
Volunteers (worked 7.00 hours, 5:00-12:00): Dave Lancaster, Kathy McDonald.

Swainson's Thrush - 1
Tennessee Warbler - 2 (plus 1 recaptured)
Magnolia Warbler - 1
Cape May Warbler - 1
Black-throated Blue Warbler - 1
Palm Warbler - 1
Blackpoll Warbler - 4
American Redstart - 1
Northern Waterthrush - 2
Connecticut Warbler - 1
Mourning Warbler - 2
Common Yellowthroat - 8
Song Sparrow - 6 (plus 2 recaptured)
Swamp Sparrow - 2
American Goldfinch - 11 (plus 1 recaptured)

FRIDAY, September 7, 2012
Sunrise (E.S.T.): 6:03
Time Open (E.S.T.): 5:45
Time Closed (E.S.T.): 12:45
Hours Open: 7.00
No. of Nets: 4.5-13.5
Net Hours: 87.50
Temperature (F): 64-75
Cloud Cover: 50-100%
Wind: NW-SW @ 1-3-5 mph
Barometer: 29.91-29.93
Precipitation: None
No. Banded: 23 (plus 2 recaptured)
No. of Species: 10
Capture Rate: 28.6 birds per 100 net hours
Volunteers (worked 9.5 hours, 5:00-14:30): Marie McGee (8.0 hrs), Tom Schlack, Blanche Wicke.

Ruby-throated Hummingbird - 5
Least Flycatcher - 2
House Wren - 1
Swainson's Thrush - 3
Nashville Warbler - 1
Northern Waterthrush - 2
Common Yellowthroat - 1 (plus 1 recaptured)
Wilson's Warbler - 1
Song Sparrow - 3 (plus 1 recaptured)
American Goldfinch - 4

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