Hidden forest chipmunk
The Uinta chipmunk or hidden forest chipmunk (Neotamias umbrinus ), is a species of chipmunk in the family Sciuridae. It is endemic to the United States. Formerly known as Tamias umbrinus, phylogenetic studies have shown it to be sufficiently distinct from the eastern chipmunk as to be placed in a separate genus, Neotamias. The same studies have also suggested that Palmer's chipmunk may actually be a subspecies of Uinta chipmunk, although the two are still generally regarded as separate species.
In some parts of its range, this medium-sized chipmunk is almost undistinguishable from other chipmunk species of the area. During the summer months, the Uinta chipmunk usually exhibits yellowish brown-grey to dark brown coloration with tingle; on its back, this rodent displays 3 wide, dark blackish-brown bands that stretch downwards and are alternated with 4 paler, grey to white colored bands; on both sides of its face, the chipmunk has 3 dark and 3 pale stripes. On the other hand, the winter coat of Uinta chipmunk is noticeably duller and more greyish with less prominent bands; the ears of the animal are black, while the under-parts are colored in very pale grey; the orange and black tail is fringed with paler hairs on the underside.
This rodent is mainly found in the western U.S., namely, in Nevada, Utah, northern Arizona, eastern California, northwestern Colorado, western and southern Wyoming, eastern Idaho and southern Montana. Preferred habitat of the Uinta chipmunk is margins of pine and fir forest as well as clearings, particularly near rocky areas or steep slopes.
These solitary rodents typically don't tolerate conspecifics. Individuals have home ranges of 2 - 5 hectares on average, which they fiercely defend. Within their territories, Uinta chipmunks choose a suitable place to construct a den, usually giving preference to sheltered and secluded areas and often placing their dwellings under rocks or shrubs. Throughout the winter months, these animals generally remain in their dens. During the rest of the year, they are very arboreal, foraging and finding shelters from predators in trees. Uinta chipmunks are diurnal animals. They are known to undergo relatively short periods of hibernation or a state of torpor. Before winter, these rodents store food supply. After entering hibernation in October, they wake up every several days to eat the cached food, doing this until May, although hibernation period often depends on location and elevation. Uinta chipmunks communicate with each other through a wide variety of vocalizations. The most commonly heard call of this species is a long, sharp "chip" sound, which may continue for 15 minutes. They are also known to emit lower pitched "chuck" calls, alternated with trills, squeals and "chips". The latter is produced when the animal flees from a predator.
As omnivorous species, Uinta chipmunks consume a wide variety of food such as fruit, conifer mast, maple seeds, juniper and chokecherry, supplementing this diet with pollen, buds, insect larvae, eggs of various birds as well as fungi, which they find through digging.
There is little information on mating habits and behavior of this species. However, Uinta chipmunks are thought to be polygynandrous (promiscuous), which means that individuals of both sexes have multiple mates. Mating season begins in late April-early June, when these rodents wake up from their hibernation. Females produce a single litter per year. Gestation period lasts for 30 days, yielding 4 - 5 young that are nursed by their mother for the first 1 - 2 months of their lives, whereas the father takes no part in rearing its offspring. Young disperse prior to winter and are able to produce offspring of their own in the following spring.
The population of this species in general doesn't face any serious threats, although feeding wildlife seems to be a notable concern across national parks of the U.S., where Uinta chipmunks are hand-fed by humans.
According to IUCN, the Uinta chipmunk is locally common and widespread throughout its range but no overall population estimate is available. Today, this species’ numbers are stable and it is classified as Least Concern (LC) on the IUCN Red List.
Uinta chipmunks act as important seeds dispersers due to their habit of food caching, during which they carry goods to their dens, losing some on their way. In addition, they contribute to soil aeration through their habit of burrowing.
