Dwarf found in Rocky Mountain National Park

BY ERIN MUTHS was considerably decayed when weighed. Acknowledgments he dwarf shrew ( nanus) is From these measurements, I determined the Thanks to Dave Armstrong, University one of the smallest specimen to be Sorex nanus. The specimen was of , for help with identification; in the world and is the small- also examined by D. Armstrong (University Therese Johnson, Craig Axtell, and Jeff est in the southern of Colorado) and compared to a confirmed Connor at Rocky Mountain National Park TRocky Mountains (Armstrong 1987; Sorex monticolus specimen; this shrew was and Steve Corn, USGS Biological Re- Fitzgerald et. al 1994). Rocky Mountain smaller in all dimensions. Based on measure- sources Division, for encouragement and National Park (Colorado) currently has no ments and direct comparison my identifica- support. P S information of the dwarf shrew occurring tion as Sorex nanus was confirmed. in the park although Estes Park is the type Dwarf are primarily montane in locality (Armstrong 1987) for this species. distribution and have been collected from Literature cited The holotype was collected by E. A. Preble rock slides and spruce-fir bogs (Brown Armstrong, D. A. 1987. Rocky Mountain mammals, a in 1895 at “Estes Park” and could easily 1967), alpine tundra (Hoffman and Taber handbook of mammals of Rocky Mountain National Park and vicinity, Colorado. Revised have been taken at a location now within 1960; Hoffmann and Pattie 1967), and edition. Colorado Associated University Press, the park boundaries. Additionally, shrews marsh and forest clear-cut (Spencer and Boulder. 223 pp. have recently been suggested as potential Pettus 1966). Hoffmann and Owen (1980) Brown, L. N. 1967. Ecological distribution of six bioindicators of environmental change and report an altitudinal range of “at least” species of shrews and comparison of sampling degradation by researchers at the Univer- 740-3,350 m (2,428-10,991 ft). Although the methods in the central Rocky Mountains. Journal sity of Toronto (Ray 1998) and may pro- carcass appeared intact and essentially un- of Mammalogy 48(4):617-23. vide important information for resource disturbed, it is possible that the shrew was Fitzgerald, J. P., C. A. Meaney, and D. M. Armstrong. managers in this regard. carried to the site by a bird and dropped, 1994. Mammals of Colorado. Denver Museum of I found a dead dwarf shrew at Lake but this could not be confirmed. Natural History and University Press of Colorado. Husted (UTM zone 13; 448385E, 4484207W; Rocky Mountain National Park has listed Hoffmann, R. S. and D. L. Pattie. 1968. A guide to 3,388 m; 11,116 ft) in the northeast corner the dwarf shrew in its Resource Manage- mammals: Identification, habitat, distribution and abundance. University of of Rocky Mountain National Park on 17 July ment Plan (USDI National Park Service Montana Print Service, Missoula, Montana. 133 pp. 1997. This specimen represents a new local- 1998), but the project is currently unfunded. Hoffmann, R. S. and J. G. Owen. 1980. Sorex ity for Sorex nanus and is the first reported When funding is obtained, potential tenellus and Sorex nanus. Mammalian Species within Rocky Mountain National Park1 (Jeff projects might include a simple determi- 131:1-4. Connor, Rocky Mountain National Park, nation of the abundance and distribution Ray, J. 1998. Shrews may predict environmental telephone conversation with author, 21 Janu- of the dwarf shrew in the park to provide degradation. University of Toronto press release, ary 1999). Previously, the altitudinal record baseline data for monitoring population 28 January 1998. Published on-line at for Sorex nanus was 3,350 m (Hoffman and trends; studies of the habitat requirements www.eurekalert.org/releases/utc- Pattie 1968; Hoffman, personal communi- of the shrew; studies of predator-prey in- shmpeodo.html. cation). This specimen was found 38 m (125 teractions, and the potential for visitor im- Spencer, A. W. and D. Pettus. 1966. Habitat ft) higher, at the edge of Lake Husted in a pacts on the shrew. preferences of five sympatric species of long- tailed shrews. Ecology 47:677-83. mossy area surrounded by rocky glacial de- As more people travel into the back- bris and low-lying juniper shrubs. The speci- country risks associated with human dis- USDI National Park Service. 1998. Resource Management Plan. Rocky Mountain National Park, men was intact except for a small hole in its turbance clearly increase. Even low volume Estes Park, Colorado. 696 pp. skull. I measured its total length, tail length, human activity at higher elevations can and hind foot length and examined the skull have profound effects on the delicate al- in the laboratory. pine tundra plant communities and may The shrew had brown fur dorsally with a have related effects on small mammals, such Erin Muths is a Zoologist with the USGS Biological Resources Division, Midcontinent lighter underbelly and measured < 90 mm (3.5 as the shrew, which may use these ecosys- Ecological Science Center. She made the in) total length. Its tail was 40 mm (1.6 in), and tems exclusively. Shrews exist within very discovery of the dwarf shrew while working its hind foot was 12 mm (0.5 in). The carcass small areas that must sustain them through- on a project on boreal toads funded partially weighed approximately 2.5 g (< 0.1 oz) but out their lives. Even small disturbances of by Rocky Mountain National Park. She can fragile ecosystems have the potential to be reached at 4512 McMurry Ave.; Fort 1 A dwarf shrew was documented in 1967 for disrupt individuals and perhaps to disrupt Larimer County, Colorado, just north of the park Collins, CO 80524; 970-226-9474; Fax 970- (Jeff Connor, Rocky Mountain National Park, tele- entire populations of shrews. 226-9230; [email protected]. phone conversation with author, 21 January 1999).

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