Urocitellus columbianus Ord, 1815
All the species of Urocitellus were previously believed to belong to the much larger genus Spermophilus, but DNA sequencing of the cytochrome b gene showed that this group was paraphyletic to the prairie dogs and marmots,, and could therefore no longer be retained as a single genus. As a result, Urocitellus is now considered as a genus in its own right.
- Herron, Matthew D.; Castoe, Todd A.; Parkinson, Christopher L. (2004). "Sciurid phylogeny and the paraphyly of Holarctic ground squirrels (Spermophilus)". Molecular Phylogenetics and Evolution 31 (3). PMID 15120398.
- Helgen, Kristofer M.; Cole, F. Russel; Helgen, Lauren E.; and Wilson, Don E (2009). "Generic Revision in the Holarctic Ground Squirrel Genus Spermophilus". Journal of Mammalogy 90 (2): 270–305. doi:10.1644/07-MAMM-A-309.1. http://www.mammalsociety.org/uploads/Helgen%20et%20al%202009.pdf.
- North American Mammals: Urocitellus columbianus