Monday, October 25, 2010

Metro Beach banding report - October 20 & 23, 2010

The number of birds banded this week was about half of last week, and continues to be dominated by sparrows, though one warbler reminded us that their migration isn't quite over yet. The weather on Wednesday, October 20 was cool in the morning to warmer than normal at mid-day, with winds picking up by closing time. On Saturday, October 23, intermittent light rain starting around 10:15 forced net closure, with a brief (1/2 hour) period when they were opened again, before the rain became more of a drizzle and banding was cut short for the day.

Highlights of birds banded on Wednesday, October 20 included the 300th White-throated Sparrow of the season...the single season record of 285 was surpassed late last week. When photographing this bird, I noticed that it had "fault bars", which are one way that banders can age songbirds. Note the subtle band across the middle of the tail in the photo below.

During feather growth, these areas where the feather is less dense are formed during periods of poor nutrition, and in the case of a nestling it may represent a day when the adults were unable to feed the nestling sufficiently. This occurs in adults too, but since they molt their feathers in pairs, not growing them all in at once like fledglings, these fault bars would be staggered, or evenly across all the tail feathers. Another explanation is that this bird lost its tail and is growing a new one, but the relative pointiness of the tail feathers indicates to me that this is a hatch-year bird.

Another highlight was the five Fox Sparrows banded today, which is a one-day record here for the species.

One Fox Sparrow was also showing fault bars that were even more conspicuous than the White-throated Sparrow above.

Interesting birds observed but not banded included a Winter Wren still in the area, as well as two flyover Purple Finches and a Pine Siskin out in the field.

Highlights of birds banded on Saturday, October 23 included the first American Tree Sparrow of the season, which is the earliest this species has been banded here.

This species can be identified even if the central breast spot cannot be seen (and some individuals lack it entirely). The bicolored bill, black above and yellow below, is shared in our area only with the Fox Sparrow. The rufous crown distinguishes it from Chipping Sparrow, which does not show this in winter plumage, and the gray cheek and broad rufous line behind the eye further distinguish American Tree Sparrow from Field Sparrow, which has a pink bill.

The Lincoln's Sparrow banded today was the latest here by about a week, and the two White-crowned Sparrows pushed the record season further along, and generated yet another same-season recapture for the species, which is the first season ever for this species to be recaptured.

A hatch-year male Orange-crowned Warbler was the latest ever banded here, by four days. There could still be one or two out there yet to be observed or captured.

Almost never seen in the field, the orange in the crowns of males (only) is at the bases of the crown feathers, so remains hidden most of the time, unless a banding assistant helps us see it as in the photo below.

An American Robin was the first one in several weeks. I always enjoy the head pattern on these hatch-year birds.

Black-capped Chickadee is a common resident species, which normally generates longevity records not migration records. But it is well known that every 3-4 years, chickadees undergo irruptive movements, often in large numbers. This year is an irruption year, and I've been watching the daily posts from the Holiday Beach Migration Observatory in Ontario, Canada, where I banded from 1997-2003 (and counted hawks and passerines from 1976-1996). Several chickadee irruptions have been documented there, and typically these movements begin around October 25. But this year seems different, as daily counts of 100-300 have been noted most days for the past two weeks (apparently starting around October 16), and a couple days this past week have noted 600+ per day. Already, nearly 2000 Black-capped Chickadees have been reported flying from east to west past the hawk tower at Holiday Beach! What's coming in the next month?

Chickadee irruptions have been noted in Michigan as well, but the phenomenon seems to be most prevalent along the shorelines of the Great Lakes. It has not been documented at Metro Beach Metropark, which of course is right on the shore of Lake St. Clair, but prior to 2004 banding has only rarely been conducted later than October 10. So far this year, a record of 23 Black-capped Chickadees has been banded, including the one banded today, but this is far short of what is expected if they are moving through this area. Perhaps the final week of banding next week will turn up a few more chickadees.

Banding could not have been done this week without the following volunteers: John Bieganowski, David Boon, Terri Chapdelaine, Dave Lancaster (both days!), and Tom Schlack.

Banding Data
WEDNESDAY, October 20, 2010
Sunrise (E.S.T.): 6:50
Time Open (E.S.T.): 5:45
Time Closed (E.S.T.): 12:45
Hours Open: 7.00
No. of Nets: 5.00-13.25
Net Hours: 74.625
Temperature (F): 43-66
Cloud Cover: 50-20-80%
Wind: SSW-SW @ 7-10-15 mph
Barometer: 29.54-29.39
Precipitation: None
No. Banded: 45 (plus 13 recaptures and 3 released unbanded)
No. of Species: 11
Capture Rate: 81.7 birds per 100 net hours
Volunteers (worked 9.0 hours, 6:00-15:00): David Boon (5.5 hrs), Dave Lancaster, Tom Schlack.

[Mourning Dove - 1 released unbanded]
Black-capped Chickadee - 1 (plus 1 recaptured)
Golden-crowned Kinglet - 1
Ruby-crowned Kinglet - 2
Hermit Thrush - 2
Yellow-rumped Warbler - 1
Fox Sparrow - 5
Song Sparrow - 2 (plus 1 recaptured)
Swamp Sparrow - 2
White-throated Sparrow - 16 (plus 3 recaptured and 2 released unbanded)
White-crowned Sparrow - 3 (plus 5 recaptured)
Northern Cardinal - 2
American Goldfinch - 9 (plus 3 recaptured)

Saturday, October 23, 2010
Sunrise (E.S.T.): 6:54
Time Open (E.S.T.): 5:45
Time Closed (E.S.T.): 11:30 (rain forced early closure)
Hours Open: 5.25
No. of Nets: 5.00-13.25
Net Hours: 64.375
Temperature (F): 49-57
Cloud Cover: 70-100%
Wind: SSW-SW @ 5-7-10 mph
Barometer: 29.74-29.76
Precipitation: Int. Lt. rain 10:15-10:45, Steady Drizzle 11:15-12:00+
No. Banded: 47 (plus 9 recaptures and 2 released unbanded)
No. of Species: 14
Capture Rate: 90.1 birds per 100 net hours
Volunteers (worked 8.0 hours, 6:00-14:00): John Bieganowski, Terri Chapdelaine, Dave Lancaster.

[Mourning Dove - 1 released unbanded]
Black-capped Chickadee - 1 (plus 1 recaptured)
Golden-crowned Kinglet - 1
Hermit Thrush - 3
American Robin - 1
Orange-crowned Warbler - 1
American Tree Sparrow - 1
Fox Sparrow - 3
Song Sparrow - 7
Lincoln's Sparrow - 1
Swamp Sparrow - 2
White-throated Sparrow - 15 (plus 3 recaptured and 1 released unbanded)
White-crowned Sparrow - 2 (plus 1 recaptured)
American Goldfinch - 9 (plus 4 recaptured)

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