Northward range expansion and breeding evidence of Crissal Thrasher, Toxostoma crissale Henry, 1858 (Mimidae), and Cactus Wren, Campylorhynchus brunneicapillus (Lafresnaye, 1835) (Troglodytidae), in Colorado, USA

Geographic distributions of many bird species have shifted in recent decades. Here, we present evidence that two desert southwest species of passerine bird, the Crissal Thrasher, Toxostoma crissale Henry, 1858, and the Cactus Wren, Campylorhynchus brunneicapillus (Lafresnaye, 1835), are expanding their breeding ranges northward into novel geographic areas in the state of Colorado.