Sedge Wren in Massachusetts

Help with a Cistothorus Identification in Massachusetts

On 12 August 2005, a group of birders in Concord, MA, found a Cistothorus wren that has generated debate, with some believing it to be a Sedge Wren (C. platensis) and others, a juvenile Marsh Wren (C. palustris), which is much more common in the area. Glen Tepke took several photos of the bird and solicited help with the identification via the Yahoo! Birds-Pix group, of which I am a member. I posted a reply on 28 August, which is archived by Yahoo! without the accompanying photos.

Below I present the main points of my analysis along with my own photos of both species, taken in July 2005 at Baker Wetlands in Douglas County, Kansas. Both of these individuals were singing adults, but the structural characteristics and comparative differences that I describe should hold for young birds as well.

I believe the bird photographed by Tepke is a Sedge Wren for the following reasons:

1) the bill is short, relatively thick (with an arched culmen), and distinctly bicolored brownish and yellowish;
2) the auriculars are relatively pale and plain, blending smoothly with the pale throat;
3) the crown is not sharply darker than the nape; and
4) the superciliary stripe is relatively short and faint. The Marsh Wren differs from the Sedge Wren in each of these characters, as can be seen in the photos below, except for the darker auriculars often visible on the Marsh.

Matt Garvey submitted additional arguments (below Glen's photos) in favor of Sedge Wren, some of which are also demonstrated in my photos below.

Sedge Wren (Cistothorus platensis)

Marsh Wren (Cistothorus palustris)