The Great-tailed Grackle breeds from Mexico and the Gulf Coast of Texas north to central California, central Nevada, Utah, Colorado, Kansas, and Iowa (Sibley 2014). This species is a year-round resident throughout the southern portion of its range (Sibley 2014). In Montana, the Great-tailed Grackle has only a few observations, including three records with direct evidence of breeding in Dillon in 2014, 2015, and 2016, and a single record with indirect evidence of breeding at Bowdoin National Wildlife Refuge in 1996 (Marks et al. 2016, Montana Bird Distribution Committee 2012).
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.