"S. v. sartorii of Mexico was separated from the remaining taxa of S. varia by S. fulvescens of Central America. Consequently, the Barred Owls of Mexico are a species-level taxon."
- Holt et al 1999 (HBW 5).
- Mazur & James 2000. Barred Owl (Strix varia). BNA Online 508.
"S. v. sartorii (Ridgway, 1873): Scarce (infrequently reported) resident of Mexico along montane Pacific slope (Durango south to Guerrero) and interior montane areas along Atlantic slope from Puebla, Veracruz, and Oaxaca (Peters 1940, Howell and Webb 1995). Toes feathered basally as nominate varia, but coloration darker, with stripes on underparts black to blackish brown and markings on upperparts more numerous and whiter; larger than nominate varia, with relatively larger bill and feet (see measurements in Ridgway 1914)."
- Steve Howell, 2009: ""Obvious" and "new" species now (if not when I wrote the Mexico guide) include... the Mexican population of Barred Owl (whose voice I finally recorded this year),..."