Tamias senex, J. A. Allen, 1890
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publication ID |
https://doi.org/ 10.5281/zenodo.6840226 |
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DOI |
https://doi.org/10.5281/zenodo.6840621 |
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persistent identifier |
https://treatment.plazi.org/id/064D0660-FF82-ED7F-FFC3-FB62F804F47D |
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treatment provided by |
Diego |
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scientific name |
Tamias senex |
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Shadow Chipmunk
French: Tamia d’Allen / German: Allen-Backenhdrnchen / Spanish: Ardilla listada de Allen
Other common names: Allen's Chipmunk
Taxonomy. Tamias senex J. A. Allen, 1890 View in CoL ,
“Summit of Donner Pass, Placer
Co[unty]., Cal[ifornia, USA].”
This species is part of the townsendii complex, which includes 7. townsendii, 1. siskiyou, and 1. ochrogenys. Widely used subspecific name pacifica has changed for gender agreement. Two subspecies recognized.
Subspecies and Distribution.
T.s. pacificus Sutton & Patterson, 2000 — NW coast of California, in the redwood forest up to 32 km inland (USA).
Descriptive notes. Head—body 142:6-147-5 mm, tail 102-:9-107-3 mm; weight 86-94 g. Shadow Chipmunk is a large species of chipmunk with geographically variable size and coloration. Pelage of head, hips, tail, and posterior one-fourth of dorsum are washed with gray. Post-auricular patches are white to cream. There are well defined white to buff eye-stripes and eye rings, which are set off by the surrounding ocherous to red orange-brown pelage. There is a mid-dorsal longitudinal stripe that varies from dark cinnamon to sepia or black, and two lateral dorsal dark stripes, which are very faint. The dark stripes are offset by grayish white stripes, and all stripes usually fade before rump. Tail is thin and grizzled gray, suffused with reddish orange, with an ocherous ventral side and sometimes frosted with buff. Nominate senex is slightly larger, and has a light olive dorsal background color, with a pale gray wash. Venter is creamy white. It is similar to the Long-eared Chipmunk (7. quadrimaculatus), but grayer and with less white post-auricular patches. Subspecies pacificus has a dark olive dorsal background and a grayish pink ventral pelage. It is similar to the Yellow-cheeked Chipmunk (1: ochrogenys). Chromosome number of the Shadow Chipmunk is 2n = 38. Karyotype is type B for Tamias and consists of five pairs of metacentric autosomes, six pairs of submetacentric autosomes, seven pairs of acrocentric autosomes, a submetacentric X chromosome, and an acrocentric Y chromosome.
Habitat. Primary forests with closed canopy and dense brushy understory. The Shadow Chipmunk inhabits the Canadian and upper transition life zones, such as the mostly undisturbed montane conifer forests of the Sierra Nevada, at elevations of ¢.1200-1800 m, and chaparral slopes.
Food and Feeding. There is strong evidence to suggest that the Shadow Chipmunk is a truffle specialist, consuming mostly hypogeous fungi, along with small amounts of conifer seeds, flowers, and arthropods. During some parts of the year,it can feed almost exclusively on truffles.
Breeding. Mating season occurs around April, and litter sizes of usually 1-5, with young being weaned at late June.
Activity patterns. The Shadow Chipmunk is diurnal, very active, and hibernates from late November to mid-March. It is one of the most arboreal species of the group. It is sympatric with several other Tamias species, such the Yellow-pine Chipmunk (7. amoenus), the Alpine Chipmunk (7. alpinus), the Least Chipmunk (7. merriami), the Sonoma Chipmunk (7. sonomae), the Long-eared Chipmunk, the Uinta Chipmunk (7. um-
brinus) and the Lodgepole Chipmunk (7. speciosus), but it is believed to be ecologically isolated from these species due to its truffle-based diet and arboreal behavior.
Movements, Home range and Social organization. Home range is estimated to be smaller than 3-5 ha, and to vary with food availability. The “chip” vocalizations have three to five syllables per chip, and occur at an intermediate frequency compared to the vocalization frequency of other chipmunks, such as the Yellow-cheeked Chipmunk and the Siskiyou Chipmunk (7. siskiyou).
Status and Conservation. Classified as Least Concern on The IUCN Red List. The current population trend is stable and there are no specific threats. Because the Shadow Chipmunk appears to prefer areas with low levels of disturbance, increased anthropogenic alteration of landscapes within its distribution may have a negative impact on local populations.
Bibliography. Foley et al. (2008), Gannon & Forbes (1995), Gannon & Lawlor (1989), Hall (1981), Kain (1985), Linzey & NatureServe (Hammerson) (2008ab), Sutton (1987), Sutton & Nadler (1974), Sutton & Patterson (2000), Thorington et al. (2012), Wilson et al. (2008).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
