Documentation of Eastern Marsh Wren

Observer Information

Reporter:  Steven Mlodinow  530 Peregrine Circle,   Longmont, CO  80504-8806
Other Observers:  Nick Moore. Spotted and ID'd bird first.

Species, Date, Time and Location Information

Species:  Eastern Marsh Wren
First Date/Time:  10/15/2014 9:21:00 AM
Last Date/Time:  10/15/2014 9:26:00 AM
Duration (total time in view):  5 minutes
County:  Yuma
Specific Location:  Wray
Number:  1
Age:  Unknown
Sex:  Male
Plumage:  Other/Unknown

Viewing Conditions

Optics:  Swarovski 12x50 bins
Distance:  10-40 feet
Light:  excellent to fair

Description of the Bird

Nick called me over stating that he'd heard an Eastern Marsh Wren sing twice. The bird was skulking very close in some emergent reeds/grass at water's edge. It popped in to the open, and it's overall dark rusty (rather than orange-buff) appearance was evident. After that, we had the bird cornered in some tree roots over the water and took a number of photos.

The bird's crown appeared blackish from the sides. From above, the center of the crown was medium dark gray. The auriculars were moderately streaked, causing the birds white supercilium to stand out prominently. The posterior portion of the supercilium was streaked brown. The throat and upper chest where white. The sides of the chest, and more broadly, sides of the belly were dull to medium chestnut brown (duller anterior, brighter posteriorly), and appeared somewhat streaky on the chest sides. The center of the belly was dull whitish washed in buff. The vent was buffy. The undertail coverts were dull white barred in buff. 

The nape was plain chestnut centrally, but on sides, was chestnut streaked lightly with darker markings. The back was black with bold white streaks. The uppertail coverts were chestnut and unmarked. The scaps and wing coverts were bright chestnut with two thick, but interupted, black bars on the coverts. The tertails were black with gold-buff notching. The secondaries were chestnut. The primaries were duller brown with white marks. The upper tail was barred black and black and chestnut, with the bars being about equal in thickness. The bill was slightly curved and appeared a bit large for a Marsh Wren. The bird's call sounded more like a "Chack" and less like a "Chet" than the MAWR's I am used to hearing; not sure if this difference was individual variation, due to the closeness of the bird, or a real difference between subspecies.

Similar Species Discussion

Interior West (and other) Western Marsh Wrens: 
The following marks seem valid, besides the diagnostic song.
1- Darker crown
2- Darker chestnut vs plain brown or buff-brown, difference perhaps most noticeable on underparts.
3- Distinctly streaked auriculars
4- Streaking on sides of nape
5- Dark barring on uppertail equal to, or greater than, pale barring.
6- More contrast on wings between secondaries and tertials and secondaries and primaries, when folded

Resources Used

Scouring photos on the Flickr from locations where ID little in question. Also, feedback from Michael O'Brien and Ross Silcock

From Michael O'Brien
Hi Steve,

I agree that this looks good for eastern. In addition to the overall brightness and darkness, I think you're right that the streaked cheeks are more typical of eastern birds. Interesting question about the call. I can't say that I've noticed much of a difference, though it's worth looking at. 


Michael O'Brien
Victor Emanuel Nature Tours

From Ross Silcock
Thanks for sending these pics.  Must say I use song to ID these forms (species?) but one thing I've noticed is that Easterns have a tricolored set of panels on the folded primaries, secondaries, and tertials ( I think I have those tracts correctly named). This tri-panel look happens I'm guessing because Easterns have more pigment in general (darker). On Easterns the tertials are blackish with internal gold markings, secondaries are pretty much rufous, and primaries are paler.  On Westerns, all three tracts are paler, to the extent that the rufous in the secondary panel is diluted to where there is little difference between its color and that of the primaries. Reminds  me a bit of the separation of Hutton's Vireo and RC Kinglet by wing panel markings.
Sorry to be so convoluted, but this feature of Easterns (rufous secondary panel, imparting a tri-panel look) shows well in your pics, especially pic 6, as well as the generally dark crowns.

From Tony Leukering
Looks good to me for Eastern.

Tony Leukering
currently Mayville, MI

Previous Experience

Extensive with western birds and eastern birds, though experience with eastern birds somewhat distant.


Notes made AFTER observation

Date Documentation Submitted

12/5/2018 9:01:00 PM
Click left or right edges of photos to move through all; click outside image to close

Location Map

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