The bird in the photos from MDI is a juvenile Swamp Sparrow. Two things, among others, suggest this.
First, the wing coverts and edgings are too reddish for Lincoln's Sparrow, which is more of an ochraceous brown. Second, the two broad crown stripes are essentially solid and dark (there may be obscure internal streaks but the overall pattern is different from juvenile Lincoln's, which is obviously streaked. The plain throat and blurry streaks on the breast are fine for Swamp, and the bird looks like it is already progressing with its prebasic molt, showing plain brown flanks. Both juvenile Lincoln's and Swamp are streaked below, and the amount of streaking on the chin and throat is variable (plain is a tendency in Swamp; streaked a tendency in Lincoln's--but there is overlap). Given these new, unstreaked feathers on the flanks, the ID becomes unambiguous as Swamp. Simply based on geography, this is the most likely option as Janet pointed out.
Below is a link to a paper by Chris Rimmer on the identification of juvenile Lincoln's and Swamp Sparrows. Additional characters that a bander might note are mouth color (yellow in Swamp, gray in Lincoln's, but intermediates and some overlap exist), and wing formula (Lincoln's more pointed with 9th primary longer than 4th, the reverse in Swamp). The plate in this paper shows how similar birds in juvenal plumage of these two species can be. The MDI bird has advanced beyond this; so the plain underparts with only blurry streaks on the breast is clearly Swamp.
Louis Bevier
Fairfield
On Aug 4, 2013, at 5:12 PM, Janet Leavens <janet.leavens1@gmail.com> wrote:
Hi all,My husband and I just spent a week birding Mount Desert Island and came across a bird that we thought was a possible candidate for Lincoln's Sparrow (see attached photos). We found the bird perched in a tree bordering a large, overgrown field on Norway Drive. As there were definitely Swamp Sparrows in the vicinity (in the same tree, even), we wanted to make sure that we weren't looking at a juv. Swamp Sparrow or unusually streaky Swamp.Here's why we think the bird might indeed be a Lincoln's: Not only is there fine streaking across the breast and down the sides, there is also a buffy breast band contrasting with a white belly. There is also a relatively bold, buffy eye-ring as well as a buffy malar stripe. If you look carefully in the 2nd photo, you can make out some fine streaking on the sparrow's crown. We know that juvenile Swamp Sparrows can show fine streaking below, but are under the impression that this streaking is not on a buffy breast band.Here's why we think it might just be a streaky Swamp Sparrow: We realize that the Lincoln's Sparrow has rusty edges to its flight feathers, but this bird's wings and tail look just a bit too red for a Lincoln's. These photos also do not show fine streaks on the white throat (although I remember seeing very fine, light streaking here when I was in the field). While the streaking on the breast seems too fine for a Swamp, it doesn't seem *very* fine, although this might be a problem with the photo image (we only use a 300 mm lens, not a 400 mm). Finally, Sibley's, Crossley's and Birds of North America all show the breeding range of the Lincoln's Sparrow ending slightly to the North of MDI. (On the other hand, Lincoln's Sparrow has been not infrequently eBirded for MDI all through the summer.)Ideas?Thanks in advance,Janet LeavensOviedo, FL--
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<Lincoln's_or_juvenile_Swamp_cropped.JPG><Lincoln's_or_juvenile_Swamp_2.JPG>
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