American Tree Sparrow (Spizella arborea)
- Photos, identification tips, Christmas Bird Count map, and taxonomy chart.
- http://www.mbr-pwrc.usgs.gov/id/framlst/i5590id.html

Brewer's Sparrow (Spizella breweri)
- Identification tips, photos, range map, and taxonomy chart.
- http://www.mbr-pwrc.usgs.gov/id/framlst/i5620id.html

Chipping Sparrow (Spizella passerina)
- Illustration, sound file, and description of this bird's nesting and diet.
- http://birds.cornell.edu/BOW/CHISPA/

Clay-colored Sparrow (Spizella pallida)
- Close-ups photos of this species.
- http://birds.cornell.edu/crows/claycolor.htm