White-eared Hummingbird occurs in forested montane regions from the extreme southwestern United States south to Nicaragua. White-eared Hummingbird is resident across most of its range, but the northernmost populations are migratory; it withdraws entirely from the United States in the winter, and most if not all individuals in the north central part of the range (e.g. Sonora, Chihuahua and Nuevo Leon) also withdraw in the winter (October-March) (Howell and Webb 1995, Russell and Monson 1998). In the southern populations, there are some (local?) altitudinal movements following breeding, although the extent of these movements is not well documented.
In the United States, White-eared Hummingbird is most regular in southeastern Arizona, where it first was detected in 1894 (Fisher 1894); however it was not documented at all in Arizona between 1933 and 1961 (Phillips et al. 1964). Currently it is an uncommon but regular summer resident, although breeding in Arizona was not detected until 1989, and the first occupied nest in Arizona was not discovered until 1996 (Williamson 2001, Corman and Wise-Gervais 2005). It also is reported from New Mexico (Hubbard 1978) and Texas (Lockwood and Freeman 2014), although it is much less frequent in both of these states. White-eared Hummingbird also is a very rare vagrant to Colorado, Michigan, Mississippi, and Alabama.
The elevational range of White-eared Hummingbird is 1200-3500 m (Howell and Webb 1995).