About Tamias quadrivittatus (Say, 1823)
This species, the Colorado chipmunk (Tamias quadrivittatus), is the largest of the three chipmunk species found in Colorado's Front Range, alongside the smaller least chipmunk and Uinta chipmunk. Adults average around 62 grams (2.2 ounces) in weight. Unlike ground squirrels, chipmunks have a distinct stripe running across the face under the eye. There are no visible size or form differences between males and females of this species. Vocalizations play a key role in defending the Colorado chipmunk's territories. Three subspecies of Tamias quadrivittatus are currently recognized: T. q. australis is found in the Organ Mountains of New Mexico, T. q. oscuraensis in the Oscura Mountains of New Mexico, and the nominate subspecies T. q. quadrivittatus ranges across Colorado, northern New Mexico, northern Arizona, and eastern Utah.
The Colorado chipmunk primarily lives in coniferous forests of the Southern Rocky Mountains. In northeastern Colorado, competition with the higher-elevation Uinta chipmunk strictly bounds its range, and the Colorado chipmunk mainly occurs in open woodlands between 1,500 metres (4,900 ft) and 2,100 metres (6,900 ft). In southern Colorado, where Uinta chipmunks are not present, the Colorado chipmunk inhabits montane forests and meadows up to 3,200 metres (10,500 ft). Isolated populations in the Oscura and Organ Mountains of New Mexico have different habitat preferences than northern populations. Colorado chipmunks in the Oscura Mountains are closely tied to old-growth pinyon-juniper woodland, while those in the Organ Mountains rely on cool microclimates formed by arroyos.
The number of litters a Colorado chipmunk produces each year ranges from one to two, depending on the elevation of its habitat. Mating most often happens in spring, right after chipmunks emerge from their burrows. Females are only receptive to mating for a couple of days after they leave their burrows. Around one month after mating, females give birth to litters of 5 to 8 altricial (underdeveloped at birth) young. Young chipmunks are weaned between 40 and 50 days after birth.
