STATUS OF THE LEAST CHIPMUNK (TAMIAS MINIMUS) SUBSPECIES T. M. OREOCETES AND T. M. SELKIRKI IN BRITISH COLUMBIA by D. Nagorsen Illustration © Michael Hames Victoria, B.C. Wildlife Working Report No. WR 116 December 2004 i Wildlife Working Reports frequently contain preliminary data, so conclusions based on these may be subject to change. Working Reports receive little review. They may be cited in publications, but their manuscript status should be noted. Copies may be obtained on-line from http://www.env.gov.bc.ca/wld/ or from the Ministry of Environment, Ecosystems Branch, P.O. Box 9338 Stn. Prov. Govt., Victoria, BC V8W 9M1. © Province of British Columbia ISBN 978-0-7726-6289-7 Date: May 6, 2010 British Columbia. Ministry of Environment. Status of the Least Chipmunk (Tamias minimus) subspecies T. m. oreocetes and T. m. selkirki in British Columbia Citation Nagorsen, D.W. 2004. Status of the Least Chipmunk (Tamias minimus) subspecies T. m. oreocetes and T. m. selkirki in British Columbia. B.C. Ministry of Environment, Victoria, BC. Wildlife Working Report No. WR 116. 37pp. ii DISCLAIMER In cases where a Wildlife Working Report or Bulletin is also a species’ status report, it may contain a status recommendation from the author. The Province, in consultation with experts, will determine the official conservation status and consider official legal designation. The data contained in the status report will be considered during those processes. NOTE: The content of this report was completed in March of 2004 and reflects the state of our knowledge of this species at that time. It has not been updated prior to publication April 2010. Information on current status of native species in British Columbia can be found through B.C. Species and Ecosystems Explorer http://www.env.gov.bc.ca/atrisk/toolintro.html iii ACKNOWLEDGMENTS This status report was funded by the British Columbia Ministry of Water, Air and Land Protection. Mark Fraker, who initiated the Kootenay chipmunk research project in 1996, collected some of the specimens and habitat data that provide a basis for this report. Nick Panter assisted with field work in the Kootenay chipmunk research project, and prepared the voucher specimens and genital bone preparations used for identification. Ian Parfitt created the range map and provided a digital file of the map; Dana Diotte created the map of coalfields. Dave Grieve provided information on coalfields in the Kootenay region of British Columbia. I thank Laura Friis, John Krebs, and Ted Antifeau for their support. The following museums provided the author with their museum records and specimen loans of Least Chipmunk s from British Columbia: American Museum of Natural History, New York; Canadian Museum of Nature, Ottawa; Museum of Vertebrate Zoology, University of California, Berkeley; Royal British Columbia Museum, Victoria; Cowan Vertebrate Museum, University of British Columbia, Vancouver. iv SUMMARY The Least Chipmunk (Tamias minimus), found throughout the boreal forest and western Cordillera, has the largest distributional area of any chipmunk. Twenty-one subspecies are recognized; four occur in British Columbia. Two subspecies, T. m. oreocetes and T. m. selkirki, are confined to alpine areas in the southern Rocky and Purcell Mountains and are of conservation concern. They are the only subspecies of the Least Chipmunk that are confined to alpine. Although inadequate samples prohibit definitive conclusions about their taxonomic status, their divergence in male genital morphology, disjunct distributions, and restriction to alpine suggest they qualify as distinct units for management, conservation, and ranking. T. m. selkirki has probably been isolated in the Purcell Mountains since the early postglacial, and it may represent a phylogeographic lineage separate from Least Chipmunks in the Rocky Mountains. T. m. oreocetes inhabits a small area in the Rocky Mountains of Glacier National Park, Montana and the southern Rocky Mountains of British Columbia and Alberta where its range extends as far north as the Bow River and Kicking Horse Pass. In British Columbia, it inhabits the subalpine-alpine from about 1945 to 2320 m. Krummholz tree islands and talus are the preferred habitat. Its narrow elevational range is largely the result of competition with the Yellow-pine Chipmunk (Tamias amoenus) and Red-tailed Chipmunk (Tamias ruficaudus), larger chipmunks that exclude the Least Chipmunk from forest. T. m. selkirki is known from only two localized areas in the southern Purcell Mountains of British Columbia: Springs Creek basin and Mount Brewer. T. minimus appears to be absent from the northern Purcell Mountains and the Selkirk Mountains. T. m. selkirki is known from a narrow elevational zone of about 2134 to 2380 m where it inhabits tree islands and talus similar to T. m. oreocetes. T. minimus is a facultative hibernator. Rather than accumulating heavy fat reserves, it depends on seeds stored in its burrow for winter survival. T. m. oreocetes and T. m. selkirki demonstrate several adaptations for survival in a harsh alpine environment—a small body size, lower metabolic rates, reduced fecundity, and wary behaviour. Breeding begins shortly after animals emerge from hibernation in spring. Females produce only one litter in the breeding season; only 25–50% of yearling females will breed. There are few threats to these subspecies. They are not affected by forest harvesting or forest fire, and are tolerant of human activity associated with ski developments or wilderness camping. Open pit coal mines in the Rocky Mountains have altered some alpine talus habitats, but these mines represent an insignificant portion of the range of T. m. oreocetes. Off-road vehicles are active in the Springs Creek basin, but T. m. selkirki is associated with talus areas above the old roads and open meadows. The British Columbia Conservation Data Centre currently ranks T. m. oreocetes as S2S3 because of its limited range and few occurrences. Although it has a restricted range in British Columbia (extent of occurrence is 150 km2 and includes 10 known occurrences), much of its Canadian range occurs within provincial and national protected areas along the Continental Divide. Except for the localized v effects of open pit coal mines, no threats are known. There is no evidence of habitat or population declines. Populations of T. m. oreocetes in British Columbia are connected to populations in Montana and Alberta. About 40% of the distributional area of this subspecies is in British Columbia, and 90% is in Canada. A Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assessment of this subspecies will have to include data from the Alberta population. T. m. selkirki is ranked as S1S3 by the British Columbia Conservation Data Centre; it is ranked as Vulnerable in the International Union for Conservation of Nature and Natural Resources (IUCN) Red Book. It is endemic to British Columbia, and its distributional range is restricted to two localized areas in the southern Purcell Mountains (extent of occurrence is about 30 km2 and includes about five occurrences). The area of occupancy is probably less than 100 km2, and the number of mature animals is less than 1000. No threats are known other than stochastic extinction events associated with small, isolated populations and possible future mining activity. Priorities for conserving and managing T. m. oreocetes include molecular studies to verify the taxonomic validity of this race, and inventories in the mountains west of the Flathead River valley to determine the limits of its range. More inventory is essential to determine if T. m. selkirki is present in the Purcell Wilderness Conservancy and to what extent the Springs Creek and Mount Brewer occurrences are isolated subpopulations. Future mining activity and off- road vehicle activity at the Paradise Mine site near the Springs Creek basin should be monitored for their possible impact on T. m. selkirki. vi TABLE OF CONTENTS SUMMARY .................................................................................................................................... ii ACKNOWLEDGMENTS .............................................................................................................. iv TABLE OF CONTENTS .............................................................................................................. vii LIST OF APPENDICES .............................................................................................................. viii LIST OF FIGURES ...................................................................................................................... viii 1 SPECIES INFORMATION ..................................................................................................... 1 1.1 Name and Classification ................................................................................................... 1 1.2 Description ........................................................................................................................ 2 1.3 Nationally Significant Populations ................................................................................... 3 2 BIOLOGY ................................................................................................................................ 3 2.1 General .............................................................................................................................. 3 2.2 Reproduction ....................................................................................................................