FIRST DOCUMENTED OBSERVATION OF SEDGE WREN
(Cistothorus platensis) IN ARIZONA
Alan Schmierer, PO Box 626, Patagonia, AZ 85624 (email@example.com)
On 27 November 2010 the author discovered and photographed a Sedge Wren (Cistothorus platensis) on the shores of Peña Blanca Lake, Santa Cruz County, Arizona. This sighting was the first documented record of this species for Arizona.
INITIAL DISCOVERY AND CONTINUED SIGHTINGS
The initial discovery of this bird was a very brief encounter. At about mid-morning I was birding the south shore of the cove (informally called Thumb Rock Cove; see Figure 2) that is just north of the Upper Thumb Rock Picnic Area parking lot. Several double-chip notes, somewhat reminiscent of those of the Pacific and Winter Wrens (Troglodytes pacificus and heimalis) alerted me to a potentially interesting bird being present, followed by a 15 second look at the bird with binoculars (at about a two meter distance), two quick photos (a lesson for photographers to keep their cameras handy for such “bird emergencies”) and then the bird was gone.
The wren was seen while it was about 1.5 m up in bare branches close to the trunk of a small deciduous tree at the water’s edge, and it then flew across the cove to a grassy edge of the opposite shore. That brief view was enough for me to identify it as a Sedge Wren. Even as a newcomer to Arizona I knew that it was likely a very rare bird in the state, and I wanted to get the word out quickly. So I ran back to the car, drove 6-7 km back toward civilization to find cell phone service and called home to ask my wife to post it to the Arizona Bird LISTSERV as soon as possible. I then rushed back to the lake to the grassy area where I had last seen the bird. I spent the next few hours scouring that area for any sight or sound of the bird, but to no avail. That afternoon, however, it was relocated by Bill Stocku who saw it along with two other observers.
Over the next few months birders from around the state and beyond visited the lake in search of the wren. It was seen and reported only sporadically despite frequent searching, likely the result of the secretive nature of the bird and its reluctance to call. Those who were lucky did see it on their first visit, but some would not succeed until their seventh or eighth visit. In the early months of its stay the wren was rarely seen in exactly the same spot in succession, but was generally seen along the shore of Thumb Rock Cove. On 14 January 2011, Rich Hoyer (and others) reported it just east along the east shore of Peña Blanca Cove: (http://listserv.arizona.edu/cgi-bin/wa?A1=ind1101b&L=birdwg05 , item #76). For the remainder of the season it was found exclusively, and more reliably, in this more eastern area. Perhaps this was its more preferred area all along, explaining why it was seen only sporadically along Thumb Rock Cove from the outset. The last known sighting was on 5 April 2011 by the author.
With photographs taken by the author and subsequently by others, the identity of the wren was never in question (see Figures 1, 3, 4, and 5). The obvious streaking on the entire back, the checkered pattern on the wings, and the streaked crown with a rather obscure supercilium distinguish this species from the Marsh Wren (Cistothorus palustris) which is commonly found in southern Arizona in migration and winter, often in this same habitat. The marked streaking of the back and the bright and unmarked rich creamy-cinnamon throat and upper breast tones separate this wren from Winter Wren and even the brightest Pacific Wren. The shorter tail and streaked crown and back separate it from the “Brown-throated” race of the House Wren (Troglodytes aedon; Sibley 2000; or T. brunneicollis compositus; Howell and Webb 1995). The blackish streaking that is apparent on the crown extends forward of the eyes and the streaking on the rump (not seen well in the photos) would suggest that this bird is of the stellaris subspecies, the only subspecies known to occur in the North America (Howell and Webb 1995; Pyle 1997). Several Marsh Wrens were seen on a regular basis and at least one Winter Wren was periodically sighted along the same length of Peña Blanca Lake shoreline, making searching for the rarer bird more frustrating at times.
Peter Pyle indicated that he leaned to “… a first cycle (SY) based on the apparently worn and brown primary coverts (or possibly outer greater coverts) best seen in … [Figure 1], the worn-looking outer primaries and outer rectrices …, and the possibly replaced central rectrices best seen in … [Figure 3]”, but advised that the aging question should best be left open (Pyle, personal communication). On 5 April 2011 the author heard the wren give moderate to long sections of song, which would indicate that this bird was a male as only males of this species sing (Herkert et al. 2001).
Most sightings were the result of hearing the single or double chip notes, then searching patiently. Early in the season the wren called infrequently (about 5% of the observation time; personal observation). By January it was calling more regularly and was thus easier to locate. Recordings of the calls were made by Rich Hoyer on 14 January 2011 (http://www.xeno-canto.org/america/recording.php?XC=70080) and by Scott Olmstead on 4 February 2011 (http://www.azfo.org/SoundLibrary/sounds_Page8.html#Wrens,_Kinglets, Gnatcatchers). An additional recording by Molly Pollock was sent to the Arizona Bird Committee for archiving. On 5 April 2011 the author heard the wren give double and single-chip notes and periodically vocalize a full song for more than half of the 90 minutes spent listening.
The author observed the Sedge Wren for a total of about three hours over the course of five successful visits to the lake. It foraged in the grasses/sedges for about 60% of the time, generally avoiding the wettest areas. The remainder of the time it worked in and out of thickets of fine dead branches, mostly close to the ground, but often up to a meter high. It often preened while on these higher perches. Its actions and habitat preference were markedly similar to that of the Winter Wren, ducking into holes and tunnels and working through the thick debris. It appeared to be gleaning small insects. However, preys were too small to see with binoculars and did not show up on photographs. Little information is available in the literature about the dietary habits of the Sedge Wren. Spiders and insects appear to be the main, if not exclusive content of the diet (Herkert et al. 2001).
LOCATION AND HABITAT
Peña Blanca Lake is located near Ruby Road within the Coronado National Forest, approximately 26 km northwest of Nogales. The lake is less than 1.5 km in length and was created by the damming of Peña Blanca Canyon. The elevation of the lake is about 1170 m.
The shoreline of the southern part of Peña Blanca Lake where the sightings occurred is generally lined with dried grasses ranging in height from a few cm to about 60 cm, and with sparse areas of short sedges (Cyperaceae spp). The width of the strip of grasses and sedges ranges from none to about 4 m, with most areas less than 1 meter in width. Imbedded in most of the grassy edge is a thin line of small deciduous trees, bushes, and frequent brushy downed branches. Within 2-10 m of the shore the land slopes up steeply into arid grasslands with scattered live oaks and mesquites (Quercus and Prosopis spp). Figures 6 and 7 show typical vegetation of the slopes. There are sections, like that of the initial sighting, that rise into almost sheer rock cliffs within a few meters of the shore. Figure 7 shows some of the shoreline where the wren was detected most often early in the season. Figure 8 shows the area where it was most often seen after mid-January; with close-up of that habitat in Figure 9. Little is known about the winter habitat of Sedge Wrens, but it has been documented in the literature that winter habitat includes grasses (Herkert et al. 2001). In New Mexico, Sedge Wrens typically occur in wet, grassy marshes, meadows, or fields, generally characterized by dense, tall grasses and/or sedges, often with scattered shrubs or small trees (willow, Russian olive). Tall cattail or bulrush marshes apparently are avoided (Williams 2011). The cattail marshes of Peña Blanca Lake had been recently removed when the lake was drained and excavated to remove accumulated toxic mercury. This avoidance of tall cattail marshes and preference for grasses and sedges appears consistent in all the literature that the author reviewed. A USGS site is one of the most comprehensive sources of specific information about breeding habitat requirements and restoration of breeding habitat (see http://www.npwrc.usgs.gov/resource/literatr/grasbird/sewr/sewr.htm.
RANGE AND EXTRALIMITAL RECORDS IN THE SOUTHWEST
The North American breeding range of the Sedge Wren is restricted to an area that extends in a somewhat limited belt from east-central Alberta, through central Saskatchewan, southern Manitoba, Minnesota, Iowa, east to upper and western New York State, and very rarely farther east to New England. Within that range the species breeds very locally due to habitat preferences. The normal winter range generally is limited to the coastal states from extreme southern New Jersey to Texas, generally east of the Big Bend area, southeastern Chihuahua, Mexico east of the Sierra Madre, and east and south to the Gulf coast. Migration is east of the Continental Divide (Sibley 2000; Herkert et al. 2001). During migration and winter there are Sedge Wren records from several states neighboring Arizona and one from west of the Sierra Madres in Sonora, Mexico:
A map of adjoining states highlighting locations of Sedge Wren records is shown in Figure 10. The closest record to Peña Blanca Lake is that in northwest Sonora, about 300 kilometers away.
PRIOR ARIZONA REPORTS AND RECORDS
There are no accepted records of the species by the Arizona Bird Committee (ABC).
In a recent article on the Smithsonian National Zoological Park Migratory Bird Center on-line “Bird of the Month” page (http://nationalzoo.si.edu/scbi/migratorybirds/featured_birds/default.cfm?bird=Sedge_Wren), J. Smith wrote that “the Sedge Wren is one of the most widespread birds in the Western Hemisphere, and yet it is one of the most poorly understood. I've consulted references as far back as 1884 in which the author optimistically wrote that as the number of observers increase, ‘We shall, no doubt, learn more about these retiring little birds.’ Yet, the most up-to-date life history summary in Birds of North America (2001) still laments that ‘There have been relatively few field studies of this species, and thus many aspects of its natural history remain poorly known.”
Perhaps our observations of the Peña Blanca Lake Sedge Wren this winter will add some small amount to the knowledge of the winter range and habits of this fun little bird.
The author thanks “Sandy” Williams for sharing the wealth of information on Sedge Wrens in New Mexico from the manuscript for his upcoming book Birds of New Mexico, and for several very informative emails; Peter Pyle for offering his opinion regarding aging of the wren; Tony Leukering and William Schmoker of the Colorado RBC for their input; and Pierre Deviche for his editorial assistance.
Dechant, J.A., M.L. Sondreal, D.H. Johnson, L.D. Igl, C.M. Goldade, B.D. Parkin, and B.R. Euliss. 2003. Effects of management practices on grassland birds: Sedge Wren. Northern Prairie Wildlife Research Center, Jamestown, ND. Northern Prairie Wildlife Research Center Online. http://www.npwrc.usgs.gov/resource/literatr/grasbird/sewr/sewr.htm (Version 12DEC2003).
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Rosenberg G.H. and J.L. Witzeman. 1999. Arizona Bird Committee Report, 1994-1999: Part 2 (Passerines). Western Birds 30: 94-120.
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Williams, S.O. III. 2011. Sedge Wren in New Mexico, a summary from Birds of New Mexico. Unpublished.
Accepted 8 May 2011