Tamias alpinus Merriam 1893

187. Alpine Chipmunk Tamias alpinus French: Tamia de montagne / German: Sierra-Nevada-Backenhornchen / Spanish: Ardilla listada alpina Taxonomy. Tamias alpinus Merriam, 1893, “Big Cottonwood Meadows,...just south of Mount Whitney, altitude 3,050 meters or 10,000 feet,” Tulare County, California, USA. This species is monotypic. Distribution. Higher elevations of the Sierra Nevada in SC California, from Tuolumne to Tulare counties (USA). Descriptive notes. Head-body mean 104-6 mm (males) and 106-4 mm (females), tail mean 69-5 mm (males) and 75-5 mm (females); weight mean 35-8 g. Pelage of the Alpine Chipmunk is pale, with four whitish stripes on dorsum and an orangish venter. Lateral stripes are wide and white, but sometimes pale. The Alpine Chipmunk is smaller than almost all sympatric (or parapatric) species, such as the Yellow-pine Chipmunk (7. amoenus), the Colorado Chipmunk (7. quadrimaculatus), the Shadow Chipmunk (7. senex), the Lodgepole Chipmunk (7. speciosus), and the Uinta Chipmunk (7. wmbrinus). The only exception is the Least Chipmunk (7. minimus). The Alpine Chipmunk can be distinguished from the Least Chipmunk by its shorter tail, larger ears, and skull. Chromosome complement of the Alpine Chipmunk is 2n = 38, FN = 48. Karyotypeis type B for Tamias and consists offive pairs of metacentric autosomes, six pairs of submetacentric autosomes, seven pairs of acrocentric autosomes, a submetacentric X chromosome, and an acrocentric Y chromosome. Habitat. Elevations of ¢.2300-3900 m, primarily in alpine biotic zone but also Hudsonian and Canadian biotic zones. The Alpine Chipmunk is a highly insular species, whose prevalence and occurrence probably depends on the physical structure ofits habitat, which consists primarily of meadows, talus slopes, boulderfields, open stands of lodgepole pine (Pinus contorta, Pinaceae), and small patches of whitebark pine (P. albicaulis). Habitat is generally xeric, as it is exposed to full sun, but maximum daily temperatures do not exceed 20°C. Food and Feeding. Diet of the Alpine Chipmunk consists heavily of small seeds of sedges, grasses, and forbs, with a small amount of pine seeds. Most information on its diet is based on cheek-pouch contents, which can contain up to ¢.5000 seeds, in extreme cases. [tis assumed that the Alpine Chipmunk is a larderhoarder,like other chipmunk species; however, early natural-history observations also suggest scatterhoarding behavior. It is a predator of avian eggs and nestlings, and has been suggested to have limited the breeding distribution of the Asian rosy-finch (Leucosticte arctoa). Breeding. Breeding occurs in early summer, with young becoming active by late July to early August, and reaching adult size by October.Litter size appears to be 4-5 young. Activity patterns. The Alpine Chipmunk is diurnal, and spends a considerable amount of time in rocky areas, which may allow a quick and efficient escape from predators. It is reported to enter hibernacula in late October and emerge in June, when its habitat is still covered in snow. This early emergence allows time for territorial establishment and subsequent foraging during the short growing season in its habitat. Movements, Home range and Social organization. Distribution of the Alpine Chipmunk overlaps with those of five other Tamas species, but only the Lodgepole Chipmunk is fully sympatric with the Alpine Chipmunk. It is territorial, and performs variable aggressive displays toward conspecifics, including vertical tail displays and vocalizations described as high-pitched calls, lower-pitched “chucks” and “chips.” Distribution of the Alpine Chipmunk is limited at lower elevations by territorial exclusion by the larger Lodgepole Chipmunk, which is reported to be more aggressive, more successful in territorial disputes in the wild, and more efficient at foraging in dense vegetation where the two species are sympatric. However, the Alpine Chipmunk in captivity appears more aggressive and dominant over the Lodgepole Chipmunk, which suggests that the outcome of aggressive encounters in the wild is partially influenced by habitat structure. Status and Conservation. Classified as Least Concern on The IUCN Red List. The Alpine Chipmunk can be locally common in some areas but population levels vary. Current population trend is stable. There are no major threats to the Alpine Chipmunk; however, it is restricted to a small area of highlands, which could make it vulnerable to habitat loss and climate change. Bibliography. Clawson et al. (1994a), Davis et al. (2008), Hayssen (2008a, 2008b, 2008c¢), Linzey & Nature-Serve (Hammerson) (2008ai), Piaggio & Spicer (2000), Thorington et al. (2012).

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