Sedge Wren at South San Francisco, California

Sedge Wren (Cistothorus platensis)
South San Francisco, San Mateo County, California
16 January 2005
Joseph Morlan

This morning, I arranged to meet Dan Singer and look for the Sedge Wren which had been found by Ron Thorn at South San Francisco on 9 January 2005 and seen several times since. I arrived at the parking lot behind 260 Littlefield Rd. around 11am and noticed a group of about a dozen birders looking intently in the vegetation along the Bay Trail. Merry Haveman pointed out the bird to me and I eventually got fairly good, but brief views as the bird skulked under dense vegetation, almost at our feet. It called a few times, giving a low harsh "chtsump" with a sucking quality, lower and more throaty than the similar call of the Marsh Wren . Eventually Dan Singer arrived as viewing continued periodically. Dan and Richard Hall took some pictures. About noon Al Jaramillo arrived, and made digital recordings of the bird's call-notes. Click here to listen to Jaramillo's recording. Peter LaTourrette also photographed the bird when it came out into the open about 12:30pm.

Description

I spent about 2 hours with the bird, but total viewing time was probably about 5 minutes with many of the views fairly brief and obstructed. However, towards the end of my visit, the bird perched repeatedly in the open after capturing a grub. The accompanying photos were taken at this time. Another time the bird preened in the shade.

It was a small wren. It was mostly by itself but it seemed smaller and more compact than Marsh Wren (Cistothorus palustris). It was similar to Marsh Wren in its back pattern. The back was blackish with extensive white streaks. These streaks were more numerous, but finer than those on Marsh Wren. The crown was also prominently streaked with white. The supercilium appeared buffy in the shade, but grayer in sunlight. Likewise the unmarked underparts appeared rich buff in the shade, but a paler grayish-buff in occasional sunlight as in these photos. The undertail coverts appeared to be very rich buff. The throat was grayer and paler than the rest of the underparts. A faint buffy, very narrow eyering was visible at close range. The buffy coloration of the underparts wrapped around the back of the neck separating the strongly streaked back and crown with a brownish collar.

We had excellent studies of the wings and tail; both were heavily barred with black and buff, with spots of pale buff on the tertials and tail. The barring included all the wing coverts including the lesser, median and greater coverts. Likewise the visible primaries were barred with dusky and buff.

The bill was short and thin, slightly curved and pointed. The entire lower mandible appeared pale yellow throughout its length. The feet and legs were dull pinkish. The eyes were dark.

Discussion

I have posted an additional photo (video-grab) taken last week by David Vander Pluym here.

This is the fourth Sedge Wren I have seen in California and the second I have seen in San Mateo County. The first was in December 2002. I posted an account of that bird here along with a list of other records.

Update

Two photographs taken by Marcel Holyoak along with an account of the observation by Richard Hall have been posted here.