Louisiana Waterthrush (Seiurus motacilla), San Pedro River near the San Pedro House, Cochise County
This Louisiana Waterthrush was
discovered by Stuart Healy and on 6 November 2009 and photographed by Andrew Core on 04 December 2009.
Louisiana Waterthrush is a very sparse transient and winter resident in southeastern Arizona. Although most Northern Waterthrushes have departed by late October, there is a record for the Santa Catalina Mountains from the late date of 4 December, so caution is warranted.
Andrew Core provides these ID points:
"Most Northern Waterthrushes will have some spotting or streaking on the throat, and most Louisiana Waterthrushes have unspotted, unstreaked throats. There is some individual variation, though, such as in this bird (see second photo), so other marks should be considered as well.
Throat When facing the observer as in the fourth photo, the throat of a Louisiana Waterthrush should appear as a white oval, extending into the chest. Also the background color is always white, regardless of spotting. The throat of a Northern Waterthrush is often buffy or yellowish.
Supercilium Note the shape and color; behind the eye of a Louisiana the supercilium broadens and is always bright white (see first and second photo). In Northerns it is often narrower (occasionally the same, but not broader) and usually buffy or yellow.
Flank color An excellent mark is the color of the flanks. In Northerns the underparts can range from yellow to off-white, but in any case the underparts are uniform. Louisianas often have a distinct pink or buffy wash along the flank. While not always present, it is virtually diagnostic when it is (see third photo).
Other marks Breast streaking is variable, but generally the streaks on a Northern are denser and bolder and come together at the throat. Louisianas tend to have lighter streaks, and as noted before, heavy streaks are absent from the throat and extreme upper chest. Louisiana Waterthrushes have a longer and heavier bill, but this is a mark that requires practice and familiarity with both species and which varies geographically. Reference: The Western Bird Watcher, Zimmer 1985"
The constant tail bobbing behavior differs between the species as well.
Northern bobs just the tail up and down (the wings are not involved), while
Louisiana bobs the entire rear half of its body (including the wings) in a more
circular motion. A good mark when they are walking away from you, as they
04 December 2009, photos by Andrew CoreAll photos are copyrighted© by photographer
Submitted on 05 December 2009