eWestern BirdsThe Quarterly Journal of Western Field Ornithologists
Vol. 43, No. 2
Western Field Ornithologists
Irruptive Migration of Chestnut-backed Chickadees to Southwestern Idaho
Jay D. Carlisle
ABSTRACT: I document irruptive movements of the Chestnut-backed Chickadee to Lucky Peak in southwestern Idaho, over 80 km from its regular range. Chestnut-backed Chickadees were captured and/or observed at Lucky Peak in 2000, 2004, and 2008. To evaluate the context for this phenomenon, I also examined data on capture of all chickadees and other irruptive species at Lucky Peak and numbers of irruptive species recorded on Idaho Christmas Bird Counts (CBC) from 1997 to 2011. Though CBCs in the winter of 2004–05 (following the largest movement of Chestnut-backed Chickadees at Lucky Peak in fall 2004) found high numbers of many irruptive species, relatively low numbers of Chestnut-backed Chickadees were detected on Idaho CBCs that winter. Overall, I observed little correspondence between capture totals at Lucky Peak and Idaho CBC data for potentially irruptive species in general, and little correspondence between years with Chestnut-backed Chickadees and patterns of any irruptive species in CBC data for the the subsequent winter. The seasonal movement patterns of this species, their regularity, and their causes warrant greater attention.
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