IBRC 67-B-09

IDAHO BIRD RECORDS COMMITTEE
RARE BIRD REPORT FORM

SPECIES: Chestnut-sided Warbler, Dendroica pensylvanica
HOW MANY: one immature

REPORTER: Ron Martin 16900 125th St. SE Sawyer, ND 58781 701-624-5241
REPORTER EMAIL: jrmartin@srt.com
OTHER OBSERVERS: Found by Ron Martin Other observers: Jay Carlisle, Narca Moore-Craig, several other student banders at the station.

DATE REPORT PREPARED: 11/28/2009
DATE SIGHTING OCCURRED: Sept. 10, 2009
LOCALITY OF OBSERVATION: Idaho Bird Observatory, Boise Ridge, Lucky Peak Banding Station. HABITAT: Brushy draw with Bitter Cherry, some tall pine canopy.
CONDITIONS: 10:15-10:30 am. Clear, wind light, sun mostly to rear of observers. Also seen with sun at about 70 degrees to observers. 8X binocs at 10-20 meters.

DID YOU TAKE NOTES?: Yes, later the same day
DID YOU CONSULT FIELD GUIDE OR OTHER REFERENCES?: Yes, another day after the observation
WHAT GUIDE(S) OR REFERENCE(S) DID YOU CONSULT?: National Geographic Guide to the Birds of North America

DESCRIPTION: Warbler, small, active; small, thin darkish bill. Dark legs. Underparts white, side of face light gray. White eye ring. White undertail coverts with white tail spots on ventral portion of tail. Dark wings and tail, wings with two yellowish-white wing bars. Top of head, nape, and back all bright, light green. Green extended down to eye.
BEHAVIOR: Feeding actively on small branches and leaves of scrubs. About 1-2 meters above the ground. No other birds in immediate vicinity.

HOW AND WHEN DID YOU POSITIVELY IDENTIFY THE BIRD, AND WHAT CLINCHED THE IDENTIFICATION FOR YOU? I immediately knew the ID as soon as I saw the bird. I am not aware of any other N.A. bird that has the unique green color on the back that this species has in imm. and basic plumage.
HOW DID YOU ELIMINATE SIMILAR SPECIES, AND WHAT WERE THEY? Warbling Vireos in the area, thicker bill, no wing bars, and no eye ring. Other warblers in the area were Orange-crowned, Yellow-rumped, Wilson's, and MacGillivray's. Also Ruby-crowned Kinglets. No other warbler has this combination of field marks with the unique green back color.

EXPERIENCE WITH THIS SPECIES (AND SIMILAR SPECIES): I have seen hundreds of CSWA in this plumage in ND and other eastern states. I have some experience with all of the regular species of warblers in North America.
GENERAL BIRDING EXPERIENCE: I have been birding since 1979. I have birded in most of North America. I have also birded in Mexico, Central America and the Philippines. I have been the Northern Great Plains editor for North American Birds journal for 18 years. I have conducted Breeding Bird Surveys for 28 years. I am an experienced birder.

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