From Smolen & Keller (1987): "Microtus longicaudus is a small, thick-bodied vole characterized by a long, bicolored tail that is greater than one-third the total length of the animal. Pelage color ranges from dull grayish through brownish gray to dark sepia brown. Numerous black tipped hairs occur on the dorsal and lateral portions of the animal. The sides are more grayish and the ventral surface varies from grayish-white to a dull buff (Hall and Cockrum, 1953). Ears are large and haired, and eyes are large. There are four inguinal and four pectoral mammae."
From Armstrong et al. (2010): "This is a fairly small-bodied, long-tailed vole, the tail greater than one-third the length of the head and body. Dorsal color is reddish brown to brownish gray interspersed with numerous black-tipped hairs. The ventral surface is gray to buff-gray."
External measurements
Length measurements are in millimeters (mm) and weight measurements are in grams (g), unless stated otherwise. If available, the sample size (n=) is provided. If a range is not provided and n= is not given, then the listed measurement represents an average.
Part of range
Reference
Total length
Tail length
Hindfoot length
Ear length
Mass
Arizona
Hoffmeister (1956); compiled by Smolen & Keller (1987)
males: 171.6 (n=12); females: 184.9 (n=8)
males: 52.8 (n=12); females: 57.9 (n=8)
males: 22.3 (n=10); females: 21.9 (n=8)
males: 15.8 (n=10); females: 15.8 (n=8)
Arizona (Chuska and Lukachukai mtns.)
Hoffmeister (1986)
166–199 (n=14)
55–65 (n=14)
20–22.5 (n=14)
Arizona (Graham Mtns.)
Hoffmeister (1986)
154–201 (n=32)
43–64 (n=32)
19–24 (n=32)
Arizona (San Francisco Mtns.)
Hoffmeister (1986)
157–182 (n=5)
52–62 (n=5)
20 (n=5)
Arizona (vicinity north rim Grand Canyon)
Hoffmeister (1986)
149–196 (n=51)
47–70 (n=51)
20–23 (n=51)
Arizona (vicinity of Hannagan Meadows, White Mountains)
Hoffmeister (1986)
151–195 (n=44)
44–65 (n=44)
19–23 (n=44)
California
Jameson & Peeters (2004)
155–221
50–93
20–25
11–15
21–56
California (northwestern)
Kellogg (1922); compiled by Smolen & Keller (1987)
162–194 (n=10)
56–74 (n=10)
21–23 (n=10)
California (Sierra Nevada)
Kellogg (1922); compiled by Smolen & Keller (1987)
190–221 (n=21)
55–77 (n=51
21–24 (n=51)
California (southern)
Kellogg (1922); compiled by Smolen & Keller (1987)
170–198 (n=10)
53–68 (n=10)
21–23 (n=10)
Colorado
Armstrong et al. (2010)
174–196
53–68
20–22
13–17
36–59
Nevada (northern)
Borrell & Ellis (1934); compiled by Smolen & Keller (1987)
males: 174–196 (n=10; females: 171–197 (n=10)
males: 57–68 (n=10); females: 57–70 (n=10)
males: 20–22 (n=10); females: 20–22 (n=10)
Utah (central)
Lee & Durrant (1960); compiled by Smolen & Keller (1987)
males: 162–182 (n=5); females: 155–186 (n=12)
males: 49–59 (n=5); females: 49–58 (n=12)
males: 21–22 (n=5); females: 19–24 (n=12)
males: 13–15 (n=5); females: 13–15 (n=12)
Utah (southeastern)
Durrant (1952); compiled by Smolen & Keller (1987)
males: 169–179 (n=4); females: 164–180 (n=6)
males: 52–60 (n=4); females: 56–60 (n=6)
males: 20–21 (n=4); 19–21 (n=6)
males: 13–15 (n=4); females: 13–15 (n=6)
Utah (western)
Hall (1931); compiled by Smolen & Keller (1987)
180–197 (n=10)
52–70 (n=10)
21–24 (n=10)
Variation
California, Fresno County
Colorado, Boulder County
Wyoming, Park County
Skull
From Armstrong et al. (2010): "The skull is long and flattened with large, rounded auditory bullae. The first lower molar has a large anterior lake of dentine followed by 5 triangles and a crescent-shaped posterior prism. The second upper molar has 4 triangular prisms."
Enamel pattern of Microtus longicaudus. The left pair are the upper molars (top to bottom are M1, M2, M3) and right pair are the lower molars (top to bottom are m1, m2, m3).
Similar species
From Smolen & Keller (1987): "The long tail, incisive foramina, and nasals of M . longicaudus are useful in distinguishing them from other species in the subgenus. The relatively long tail in relation to head and body length and hindfoot length separates M . longicaudus from most other species of Microtus. The head and body length of M. longicaudus is from 1.6 to 1.9 times as long as the tail, and the tail is from 2.8 to 3.5 times the length of the hindfoot. Only M. californicus (2.0–2.5 times tail length; 2.3–2.6 times length of hindfoot), M. pennsylvanicus [note: at the time of this publication, M. drummondii had not been split from M. pennsylvanicus and so the range of M. pennsylvanicus at that time included what is now the range of M. drummondii] (2.0–3.1 x tail length; 1.9–2.7 x length of hindfoot), and M. townsendii (2.2–2.4 x tail length; 2.2–2.6 times length of hindfoot) have head and body to tail or tail to hindfoot proportions that approximate those of M. longicaudus (Hall and Cockrum, 1953)."
Comparison with Microtus californicus
From Smolen & Keller (1987): "Microtus californicus is more difficult to separate if tail length proportions are not definitive (Maser and Storm, 1970).
Comparison with Microtus canicaudus
Microtus canicaudus can be distinguished from sympatric M. longicaudus by a shorter tail (both relatively and absolutely).
Comparison with Microtus drummondii
In the field, Microtus longicaudus can be distinguished from Microtus drummondii by its much longer tail. The tail of M. longicaudus is greater than one-third the length of the head and body. The four loops in M2 of M. longicaudus distinguishes it from M. drummondii that has an M2 with five loops (Smolen & Keller, 1987; Naughoton, 2012).
Microtus mogollonensis can be distinguished from sympatric M. longicaudus by a shorter tail (both relatively and absolutely).
Comparison with Microtus montanus
From Smolen & Keller (1987): "The relatively long tail in relation to head and body length and hindfoot length separates Microtus longicaudus from most other species of Microtus."
From Smolen & Keller (1987): "Incisors are hidden by nasals when viewed from above in M. longicaudus rather than being visible as in M. townsendii. Furthermore, the incisive foramina are tapered gradually or at least as wide posteriorly as anteriorly in M. longicaudus whereas the foramina are long, narrow, and constricted posteriorly in M. townsendii."
Comparison with Microtus xanthognathus
From Conroy & Cook (1999): "Microtus xanthognathus is one of the largest species in the genus Microtus, and adults have a conspicuous rusty-yellowish color about the whisker area."
References
Armstrong DM, Fitzgerald JP, Meaney CA. 2010. Mammals of Colorado, Second Edition. Denver (CO, USA): University Press of Colorado.
Borell AE, Ellis R. 1934. Mammals of Ruby Mountains region of northeastern Nevada. Journal of Mammalogy (15):12-4.
Durrant SD. 1952. Mammals of Utah: taxonomy and distribution. University of Kansas publications, Museum of Natural History (6):1-549.
Hall ER. 1931. Critical comments on mammals from Utah, with descriptions of new forms from Utah, Nevada, and Wasington. University of California Publications in Zoology 37:1-13.
Hall ER, Cockrum EL. 1953. A synopsis of the North American microtine rodents. University of Kansas Publishing, Museum of Natural History 5:373-498.
Hoffmeister DF. 1986. Mammals of Arizona. Tucson (AZ, USA): University of Arizona Press.
Jackson DJ, Cook JA. 2020. A precarious future for distinctive peripheral populations of meadow voles (Microtus pennsylvanicus). Journal of Mammalogy 101(1):36-51.
Jameson EW, Peeters HJ. 2004. Mammals of California (No. 66). Berkeley (CA, USA): University of California Press.
Kellogg R. 1922. A synopsis of the Microtus mordax group of meadow mice in California. University of California Publications in Zoology 21:275-302.
Lee MR, Durrant SD. 1960. A new long-tailed vole (Microtus longicaudus (Merriam)) from Utah. Proceedings of the Biological Society of Washington (73):167-1.
Maser C, Storm RM. 1970. A key to Microtinae of the Pacific Northwest (Oregon, Washington, Idaho). O.S.U. Book Stores, Inc., Corvallis, Oregon, 162 pp.
Merriam CH. 1888. Description of a New Species of Meadow Mouse from the Black Hills of Dakota. American Naturalist 22, 934.
Smolen MJ, Keller BL. 1987. Microtus longicaudus. Mammalian species (271):1-7.
California, Fresno County
Colorado, Boulder County
Wyoming, Park County
