IDAHO BIRD RECORDS COMMITTEE
RARE BIRD REPORT FORM

Rare Bird Report #: 78-B-07

SPECIES:

Curve-billed Thrasher

HOW MANY:

One (1), probable hatch year

REPORTER:

J. Harry Krueger
5107 W. Ponder Street
Boise, ID 83705-1136
208-407-2786

REPORTER EMAIL:

hkrueger@idahobirds.net

OTHER OBSERVERS:

J. Harry Krueger...no other observers known

DATE REPORT PREPARED:

30 July, 2007

DATE SIGHTING OCCURRED:

28 July, 2007

LOCALITY OF OBSERVATION:

Indian Creek Reservoir, Ada County (west side of reservoir area)...(specific directions and location on IBLE Message #13131)

HABITAT:

Sagebrush with some crosote bush high desert bordering permanent water impoundment

CONDITIONS:

Equipment Used: 10x42 Bausch & Lomb Elite binoculars; 20-60x Swarovski Habicht AT80 spotting scope

Weather: Mostly sunny with some clouds, temp. 100 degrees F., little to no wind

I first sighted the bird sitting on top of a sage while slowly driving down the dirt road which parallels the back side (west end of the reservoir). I had just finished viewing available water birds, had driven past the area of the bird's appearance down to the old spillway and was doubling back to check out the ravine beginning at the west end and stretching out into the flatlands. I was almost at the head of the ravine when I made my initial observation. I quickly looked at the bird through the car windshield, slowly opened the door to have a more unobstructed and undistorted view. It was immediately evident that this was a "long-billed" and long-tailed thrasher. I was able to view the bird from about 50-60 feet through my binoculars as it sat motionless sideways to me on the sage for about 90 seconds to 2 minutes. The sun was still high in the sky (4:15 PM), partially over my shoulders. It then flew to a bush about 10 feet away (further from me) again alighting at the top. It stayed here for only about 15 seconds before dropping down to the ground and disappearing to my view. I immediately stopped the car engine and proceeded to search the area with no success. I continued my search by foot for approximately an hour, not relocating the bird again. At that time it unexpectantly reappeared, flying into a bush about only 30 feet from the original sighting and immediately dropping to the ground next to the bush but still in full, although shaded, view. This time it was closer to the water on a small rise. I again viewed the bird for about 2 minutes until it walked quickly away from me and my view. Again searching I was unable to relocate it. After considerable time searching on foot and wandering far afield from the original spot, I went back to my car and turned on the air conditioner to find some relief from the heat. I also took the time to write out notes in my notebook and make a few sketches. (As is my practice, I did not have a field guide with me). I had eliminated the other thrashers, all of which with which I was familiar, and settled on either Bendire's or Curve-billed Thrasher. I could not remember which of the two had the all black bill and indistinct underparts. I could not get a signal to use my cell phone to call anyone, and I considered going to the nearby truck stop (about 1 mile), but did not want to leave the area while re-sighting the bird was a still a possibility. While still in the car (which I had repositioned to have a clear view of the whole area), the bird reappeared (it was now a bit after 7 PM), flying onto a sagebrush bush. I immediately focused on the bird with my scope (which I had readied), having a clear view out of the driver's side window at from approximately 30x to 50x plus. The bird was about 60-70 feet from me at this point, in good light (some clouds reduced any glare), facing me from a front/side position. A was able to view the bird in this manner from inside the car for about at least 4 minutes. It again dropped onto the ground...and I again could not find it on foot. Returning to the car, I took additional notes. I then thought I might have better cell phone reception standing on a rise next to the reservoir. I though that there was still enough time before sundown for someone else to come and see the bird, so I called Cliff Weisse on his cell, and although the reception was not the best, we did communicate. He looked up the difference between Bendire's and Curve-billed Thrasher in his NGS North American Guide and confirmed that I most likely had seen a Curve-billed Thrasher. He also promised to call Lisa immediately to post re: the bird with directions.

DID YOU TAKE NOTES?:

Yes, during the observation

DID YOU CONSULT FIELD GUIDE OR OTHER REFERENCES?:

Yes, another day after the observation

WHAT GUIDE(S) OR REFERENCE(S) DID YOU CONSULT?:

Tweit, R. C. 1996. Curve-billed Thrasher (Toxostoma curvirostre). In The Birds of North America, No. 235 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists’ Union, Washington, D.C.

England, A. S. and W. F. Laudenslayer, Jr. 1993. Bendire’s Thrasher (Toxostoma bendirei). In The Birds of North America, No. 71 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists’ Union.

Kaufman, Kenn 1990. A Field Guide to Advanced Birding. Boston, Houghton Mifflin Company.

Sibley, David Allen 2003. A Field Guide to Birds of North America. New York, Alfred A. Knopf.

DESCRIPTION:

(The following is a composite of notes and sketches taken at the site, before and immediately after the last viewing...see above):

Overall impression: a comparatively (at one point seen in direct comparison to Western Meadowlark at base of same bush) large bird (approximation of about 12 inches from tip of tail to tip of bill) with long tail held parallel to body plane) and long, very slightly decurved bill (almost straight). I immediately recognized this to be of the thrasher family, but larger than a Sage Thrasher (bill, "heavy" body, and tail) which I had already seen two or three that day.

Flight: with quick wing beats, never flying high off the ground and only to a close-by bush or gliding to the ground. Movement on the ground was a "fast walk" (no hopping seen).\

Upperparts: Uniform reddish-brown all the way through the nape and onto the top of the head, while perhaps slightly more reddish [my notes say "reddish," Tweit calls it "chestnut") toward the rump area.

Underparts: a washed out brownish-yellow, with stronger brownish-yellow with a reddish tinge in the vent/undertail area as well as on the side/ flank and to a lesser degree across the breast. There were darker brownish spots, though quite faded (rounded) with no apparent pattern on the breast, becoming even more faded, and barely discernible, toward the belly area.

Head: Sloped from bill, while at rest almost giving a flat-headed, slightly domed appearance, especially when bird was open-mouthed, as it was briefly while at rest on sagebrush during the its "first appearance." Head color was as upperparts, with very slightly darker reddish-brown on auricular area and also somewhat darker lores.

Wings: same coloration as upperparts, with no discernable wing-bars, although visible tips of greater and median coverts very slightly lighter than rest of wing. Tips of primaries extended to base of tail.

Bill: All black (both upper and lower mandible blending into dark brown of lores. Almost straight (very slightly decurved upper mandible), and from side profile, length equal to width of head.

Eyes: Yellowish-orange (not pale yellow or even pale orange).

Narrow dark brown malar stripe, with some pale gray feathers bordering.

Throat: Grayish, blending into underparts, with no distinct border.

Tail: Seemed to be the same color as upperparts, but I did not see this as well as rest of bird. Long, about two-thirds of body length, with smooth, rounded tip.

When in flight, did not any whitish tips to tail, although these could have easily been missed. The overall impression was a long-tailed, long-billed bird, contrasting darker above and lighter underneath.

Legs: color not noted.

BEHAVIOR:

Vocalization: silent while observing, but distinctive and repeated two note (Sibley says three) call..."wheet-wheeeet," second note higher than first, slightly accented. Unlike any other Idaho bird, and confirmed by listening to CD (see above).

Flight pattern: (see under "Description" above)

Direct comparison to Western Meadowlark was noted (see above).

HOW AND WHEN DID YOU POSITIVELY IDENTIFY THE BIRD, AND WHAT CLINCHED THE IDENTIFICATION FOR YOU?

Upon first view of the bird, I narrowed the possibilities to Bendire's or Curve-billed Thrasher. (I was aware of the Idaho records of Curve-billed Thrasher.) I knew that one had an all black bill with indistinct breast markings, while the other had a pale base to the bill (lower mandible). I decided this was a Curve-billed Thrasher during my conversation with Cliff Weisse and confirmed the identification when the vocalization was heard. Tweit also confirms that even in juvenile plumage, only the Curve-billed Thrasher has an all black bill.

HOW DID YOU ELIMINATE SIMILAR SPECIES, AND WHAT WERE THEY?

Eliminated:

Bendire's Thrasher - see above

California Thrasher - dark eye, dark eye-line, more white about head area, more distinct border between light throat and rest of underparts

LeConte's Thrasher - Much lighter overall coloration, contrast with darker tail

Sage Thrasher - smaller overall, streaked underparts, short bill

EXPERIENCE WITH THIS SPECIES (AND SIMILAR SPECIES):

I am familiar with all the North American thrasher species, having seen this particular species numerous times (both subspecies groups) in both Arizona and Texas. I have had to differentiate between Bendire's and Curve-billed Thrashers on numerous occasions.

GENERAL BIRDING EXPERIENCE:

38 years of active birding, with 4 years of casual birding before that. Birded across entire continent of North America (and on 4 other continents), having lived and birded in New York, California, Michigan, Maryland, Guam, and Idaho.

I would consider myself a "very knowledgeable" field ornithologist. I have also done audio recording of bird vocalizations for the past 18 years.

WERE PHOTO(S), VIDEO, AND/OR AUDIO OBTAINED BY YOU?:

None