Sunday, April 25, 2010

Metro Beach banding report - April 23 & 24, 2010

On Monday, April 19, the Metroparks conducted a controlled burn to eliminate the Phragmites that had been treated with herbicide last fall. The South Marsh was burned, which included 2/3 of the banding area, but the North Marsh was not burned as the wind apparently shifted direction before that could be done. The burn was done on a rather late date, especially so given the early arrival of warm conditions this year. How it will affect bird populations in the area will be a major focus of this banding station from this point forward. The marsh was very dry as it has not rained in some time, so it is unclear whether the numerous calling Western Chorus Frogs and Eastern Toads from last week have simply quit calling due to drought, or were negatively affected by the burn. The number of birds banded so far this April is less than half the worst year previously, so it might be difficult to get an immediate impression of the effects of the burn, but longer term may prove interesting.

In the photo below, volunteer John Bieganowski is standing in the middle of the "field" area, where before last week he would have been invisible as all the blackened areas were covered with 10-foot tall Phragmites stems. This area is a transition zone from the swamp forest and the open marsh, usually wet in spring and dry in fall, with a variety of herbaceous plants interspersed with patches of dogwood. Four (of 13) nets are in this area, and the three Field Nets have been the most productive in the entire banding area in recent years. Birds were caught in these nets on both days this week.

Four other nets were affected, as the burn apparently crossed over to the north side of the maintenance road that runs through the banding area. There isn't any Phragmites in this area, so it appears this was not intentional. Birds were caught in these nets on both days this week. The photo below shows one of the Upland-U nets with adjacent burned areas.

Captures remained low this week, for unknown reasons, so at least the burn doesn't seem to have made it worse! Hermit Thrushes and White-throated Sparrows were seen foraging on the ash on the ground and at one point one of the thrushes captured an insect when it flipped over a bit of the ash.

Banding highlights of Friday, April 23 included the first Red-winged Blackbirds captured this spring. The first was a nice after second-year male. It takes two years for the males to attain the full red epaulets and all black plumage, and this particular male had been banded in 2009 as an after second-year then, making him at least three years old.

It has been my impression that the female Red-winged Blackbirds have been later this year, by perhaps 2-3 weeks, which may be the reason for so few captures so far this spring. Now that the marsh has been burned, including the cattails, it seems likely that there will be very few more caught this spring. This second-year female (older birds have more peach color on the throat) was the second Red-wing of the day.

Interesting birds observed but not banded included 6 Common Loons flying over, a Sora calling briefly north of the road, two Purple Martins, two Northern Rough-winged Swallows, and at least one Barn Swallow (plus the Tree Swallows that have been back for some time), only one Yellow-rumped Warbler, but a single singing Pine Warbler and two different singing Northern Waterthrushes which were quite early.

Banding highlights of Saturday, April 24 included the first, and probably last Winter Wren of the spring as few of these tiny birds are captured here in May.

Yesterday's small flock of White-throated Sparrows had increased to at least a dozen, with several singing early in the morning, and the first of the season banded being a nice white-striped individual (there are two color morphs, the other being tan-striped).

One of the most common birds banded at Metro Beach is the Swamp Sparrow. In fact, probably more of these are banded here than anywhere else in Michigan. Birders are often puzzled by sparrow identification, and this is not only due to the complex brown-striped plumage that many share, but also due to the individual variation. Most look for a sparrow in the marsh (rarely in true swamps) which has a solid rufous cap and an unstreaked breast, like the one in the photo below.

But more often than not (and almost never in spring), the Swamp Sparrow does not sport such a solid rufous cap. Individuals with rufous, brown, and black are very frequent, and generally the rule in fall. Individuals like the one in the photo below.

Birds with the solid rufous caps can be confused with other sparrows, including Chipping and American Tree Sparrows. And birds with less rufous caps can be confused with, well, just about anything. But there are other field marks to look for, including the grayish line over the eye (white in Chipping), and the gray collar visible on the second bird above (lacking in Tree). On the wings, the Swamp Sparrow (in spring) has a very distinct pattern to the greater secondary coverts. They've got a large black teardrop-shaped center with broad rufous edging. This is shown well in the photo below (you'll want to click on the photo to see it full-size). One might think that this variation is based on the age or sex of the bird but, so far, no such correlation has been demonstrated.

Song Sparrows have a similar pattern on these coverts, but instead of rufous, they're brown, and of course they have a boldly striped breast with a central breast spot. Some of this doesn't apply to birds in the fall, and especially juveniles, but I'll leave that discussion for another time! Interesting birds observed but not banded included an American Woodcock flushed from one of the small remnant unburned patches of Phragmites, flyover Bonaparte's Gulls and Forster's Terns, a briefly singing (and early) Warbling Vireo, similar swallows to yesterday, three Blue-gray Gnatcatchers, at least 4 Golden-crowned Kinglets, and a couple singing Yellow-rumped Warblers.

Thanks to the volunteers who made banding on these two days possible: Elaine Attridge, John Bieganowski, Chris Charlebois, Harry Lau, Rose Lau, Tessa Lau, Jennifer Munson, and Tom Schlack.

Banding Data
THURSDAY, April 23, 2010
Sunrise (E.S.T.): 5:39
Time Open (E.S.T.): 5:45
Time Closed (E.S.T.): 13:15
Hours Open: 7.50
No. of Nets: 4.25-13.25
Net Hours: 92.375
Temperature (F): 36-59
Cloud Cover: 10-50%
Wind: NE-E @ 1-3-10 mph
Barometer: 30.03-30.06
Precipitation: None
No. Banded: 19 (plus 13 recaptured and 1 released unbanded)
No. of Species: 7
Capture Rate: 35.7 birds per 100 net hours
Volunteers: Elaine Attridge, John Bieganowski, Chris Charlebois, Jennifer Munson, Tom Schlack

Hermit Thrush - 2
[American Robin - 1 recaptured]
[Song Sparrow - 1 recaptured]
Swamp Sparrow - 2 (plus 1 recaptured)
[Northern Cardinal - 3 recaptured]
Red-winged Blackbird - 1 (plus 1 recaptured)
American Goldfinch - 14 (plus 6 recaptured and 1 released unbanded)

SATURDAY, April 24, 2010
Sunrise (E.S.T.): 5:38
Time Open (E.S.T.): 5:45
Time Closed (E.S.T.): 13:30
Hours Open: 6.25 (closed 9:30-11:00 during rain)
No. of Nets: 4.25-13.25
Net Hours: 75.813
Temperature (F): 52-61
Cloud Cover: 100%
Wind: NE-E @ 5-7-10 mph
Barometer: 30.00-29.86
Precipitation: Light rain from 9:30-11:00
No. Banded: 12 (plus 5 recaptured)
No. of Species: 7
Capture Rate: 22.4 birds per 100 net hours
Volunteers: Harry Lau, Rose Lau, Tessa Lau

[Black-capped Chickadee - 1 recaptured]
Winter Wren - 1
Hermit Thrush - 3
Song Sparrow - 2 (plus 3 recaptured)
Swamp Sparrow - 2
White-throated Sparrow - 1
American Goldfinch - 3 (plus 1 recaptured)


Laurent said...

Thanks for the pics and post about the swamp sparrow!

I wonder how the burns (even done early in the season) affect the food supply for the hermit thrushes (and other ground feeders). My local patch (Redbud in Ann Arbor) has been burned very early in the season, and although it is now completely green again, with tons of local wilflowers, I had so far only one hermit thrush, compared to the dozen or so I had at the same date last year. Any thought about it?


Allen Chartier said...

Laurent, there have been very few migrants of any kind so far this spring, so I don't know if the burns can be implicated in the reduced numbers.