Friday, August 20, 2010

Metro Beach banding report - August 18, 2010

The warblers have arrived! For many years, the date August 25th has been stuck in my mind as the first day around which the first significant influx of migrant warblers can be expected in southeastern Michigan. Well, this year it was August 18, as a weak cold front had moved through the state overnight and into the morning.

Banding highlights on Wednesday, August 18 included ten species of warbler, the most interesting including Blackburnian, Chestnut-sided, Tennessee, and Wilson's. Four Ruby-throated Hummingbirds and four Empidonax flycatchers (three "Traill's" and one Least) were additional highlights. The majority of the birds banded today were captured in the first two net runs, after which the nets had to be closed temporarily due to light rain (NOT predicted!). Once the nets were open again, the activity had subsided considerably.

Typically, the earliest Tennessee Warblers are adults that are in heavy molt. That was the case with today's adult male, which was showing lots of pinfeathers, symmetrical wing molt, and was missing his tail entirely.

Adults of many species are the first to migrate, and this was also the case with one of the two Mourning Warblers banded today, an adult male with his freshly molted body feathers and heavily gray-fringed black bib.

Magnolia Warblers are often among the earliest warblers to arrive in fall, but can also pass through into mid-October, which results in their being one of the most frequently banded warblers at this site.

Wilson's Warblers also arrive early, and can be confused with immature Yellow Warblers, but note the olive crown contrasting with the yellow eyebrow and lack of spots in the tail, all distinguishing characters for female Wilson's.

Chestnut-sided Warblers in juvenile/fall plumage are perhaps the most distinctive species that consistently confuses birders. At first glance, it appears fairly nondescript, but no other fall warbler has such a bright green crown and back, gray cheek with bold white eyering, and yellow wing bars.

Another early species, which is banded irregularly at Metro Beach, is the Blackburnian Warbler. It was surprising to come upon two of these in the Field Nets right next to each other. Not the habitat they've been caught in before here. It seems likely that a mixed species flock of warblers dropped into Point Rosa Marsh just before sunrise this morning.

The migration of Yellow Warblers is at or just past peak, but we are still catching small numbers of them. One unusual capture was this adult female with one primary feather completely yellow. Apparenly, when this feather needed to be grown in, the bird was not able to produce melanin for some reason. That's my best guess anyway.

In contrast to warblers that are peaking in migration, American Goldfinches are just finishing nesting and won't really begin to migrate for another two or three weeks. The juvenile below is perhaps the youngest goldfinch ever banded at Metro Beach, as it's small bill and short tail shows.

Another American Goldfinch, an adult male, was very interesting. It was a recapture, with a band on its left leg. I normally band on the right leg, so thought that perhaps it had some foot pox and I banded it on the other leg. Once home, I checked the number and came up empty. It was a foreign recapture! Querying other local banding sites got a match. He was banded in November 2007 by Julie Craves in her Dearborn yard as a hatch-year male, a distance of about 27 miles to the northeast.

Interesting birds observed but not banded today included three additional warbler species, Bay-breasted, Black-and-white, and American Redstart, as well as a calling Yellow-bellied Flycatcher. Not heard since early spring, a begging call of a Great Horned Owl was heard at mid-day.

Banding could not have been done today without the able assistance of David Boon and Tom Schlack.

Banding Data
WEDNESDAY, August 18, 2010
Sunrise (E.S.T.): 5:42
Time Open (E.S.T.): 6:00
Time Closed (E.S.T.): 13:45 (closed from 8:15-10:15 due to light rain)
Hours Open: 5.75
No. of Nets: 4.25-13.25
Net Hours: 67.938
Temperature (F): 65-79
Cloud Cover: 100-10%
Wind: SW @ 1-3-10 mph
Barometer: 29.78-29.73
Precipitation: Light rain from 8:15-10:15
No. Banded: 60 (plus 10 recaptures)
No. of Species: 19
Capture Rate: 103.0 birds per 100 net hours
Volunteers (worked 10.0 hours, 6:00-16:00): David Boon, Tom Schlack.
Ruby-throated Hummingbird - 4
Northern Flicker - 1
"Traill's" Flycatcher - 3
Least Flycatcher - 1
Black-capped Chickadee - 4
[House Wren - 1 recaptured]
[American Robin - 1 recaptured]
Tennessee Warbler - 1
Yellow Warbler - 5 (plus 1 recaptured)
Chestnut-sided Warbler - 1
Magnolia Warbler - 5
Blackburnian Warbler - 2
Ovenbird - 1
Northern Waterthrush - 2
Mourning Warbler - 2
Wilson's Warbler - 2
Canada Warbler - 1
Song Sparrow - 5 (plus 3 recaptured)
American Goldfinch - 20 (plus 3 recaptured)

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