2009 NOTES 167

Hughes, A. L., iUld M. K. Hughes. 1986. Paternal inve~tmenl Pyle, P. 1997. Identification guide to North American birds. and sexual size dimorphism in North American passerines. Slate Creek, Solinas, California. Oikos 46: 171-175. Semenchuk, G. P., Editor. 1992. The atlas of breeding birds Jonsson, P. E., and T. Alerstam. 2008. The adaptive signifi­ of Alberta. Federation of Alberta Naturalists, Edmonton, cance of parental role division and sexual size dimorphism Alberta, Canada. in breeding shorebirds. Biological Journal of the Linnean Szekely, T., J. D. Reynolds, and J. Figuerola. 2000. Sexual Society 41: 301-314. size dimorphism in shorebirds, gulls, and alcids: the Kissner, K. J., P. J. Weatherhead, and C. M. Francis. 2003. influence of sexual and natural selection. Evolution 54: Sexual size dimorphism and timing of spring migration 1404-1413. in birds. Journal of Evolutionary Biology 16: 154-162. Webster, M. S. 1992. Sexual dimorphism, mating system Lovich, J. E., and J. W. Gibbons. 1992. A review of tech­ and body size in New World Blackbirds (lcterinae). Evo­ niques for quantifying sexual size dimorphism. Growth, luti0n. 46:1621-1641. Development & Aging 56: 269-281. Witmer, M. C. 2002. Bohemian Waxwing (Bombycilla gar­ Mosher, J. A., and P. F. Matray. 1974. Size dimorphism: a rulus). Number 714 in The Birds of North America Online. factor in energy savings in broad-winged hawks. The Edited by A. Poole. Cornell Lab of Ornithology, Ithaca; Auk 91: 325-341. retrieved from the Birds of North America Online: http:// Murphy, M. T. 2007. A cautionary tale: cryptic sexual size bna.birds.comell.edu/bna/species/714. dimorphism in a socially monogamous passerine. The Auk 124: 515-525. Received 9 June 2008 Accepted 5 April 2010

Complete Albinism in a Northern Red-backed Vole, Myodes rutilus, in Alaska

JACKSONS. WHITMAN

Alaska Department of Fish and Game, Division of Wildlife Conservation, Nongame Program, 1300 College Road, Fair­ banks, Alaska 99701 USA; e-mail: [email protected]

Whitman, Jackson S. 2009. Complete albinism in a Northern Red-backed Vole, Myodes rutilus, in Alaska. Canadian Field- Naturalist 123(2): 167-168. During a study of small mammal abundance and species composition in interior Alaska, I collected a Northern Red-backed Vole (Myodes rutilus) showing complete albinism. This report documents that extremely rare occurrence, with notes on habitat and morphometrics. Key Words: Myodes ruti/us, Northern Red-backed Vole, albino, Alaska.

True albino, or amelanistic individuals are caused by I9: 14 (total:tail:hind foot:ear). In a sample of I I 1 indi­ a genetic trait and are completely devoid of melanin. viduals captured during 2007, weights averaged 20.9 Characteristicly they have unpigmented pink eyes. g, with extremes from 7.9 to 36.7 g. Standard meas­ Mammals with this trait display white pelage. Albi­ urements from this population sample show means of nism, either partial or complete, is rarely documented 120.0:29.7:18.9:14.4 (Whitman, unpublished data). in wild populations, thus detailed observations are This specimen was submitted for curation to the Uni­ noteworthy. versity of Alaska Museum of the North (UAM 85050). I captured a single complete albino Northern Red­ During 2003-2007, 7926 trapnights using unmodi­ backed Vole (Myodes rutilus) in a Museum Special fied Museum Special snap traps resulted in captures of snap trap (Woodstream Corporation, Lititz, Pennsyl­ 925 Northern Red-backed Voles. An additional 107 vania, USA) baited with a combination of peanut but­ individuals were captured in 980 pitfall trapnights (I ter and rolled oats on 2 August 2007 on Minto Flats capture/8906 trapnights; I albino in 1032 M. rutilus State Game Refuge, central Alaska (64.9052°N, captured= 0.097%). No other Northern Red-backed 149.0309°W). Dental characteristics and skull mor­ Voles showed any degree of albinism. A check for albi­ phology confirmed the initial species classification. nism amongst 1653 Northern Red-backed Vole records The albino Northern Red-backed Vole had complete in the University of Alaska Museum of the North re­ white pelage and pink eyes, with standard body mea­ vealed six specimens, two of which appeared to be surements well within the norm displayed by other complete albinos. However, I suspect any inference conspecifics in interior Alaska. Testes were non-scro­ to natural population incidence is negated by the fact tal, indicating a juvenile male individual. Weight was that pelage morphs are more likely to be curated than 17.4 g, with standard measurements (mm) of 119:29: "normal" specimens. 168 THE CANADIAN FIELD-NATURALIST Vol. 123

Habitat from which the albino Northern Red-backed L. Olson and B. Jacobsen at the University of Alaska Vole came was interior boreal forest at 110 m eleva­ Museum of the North kindly accepted and expertly tion. No notable logging or other anthropogenic curated this and other specimens. A. Greenblat of changes have occurred within l 0 km of the site. Over­ Shadow Aviation in Fairbanks provided timely and story vegetation was composed of an open mixed for­ safe transportation. L. Whitman, T. Jung, and one est of Alaska Paper Birch (Betula neoa/askana) and anonymous reviewer provided helpful editorial com­ White Spru~e (Picea glauca) with approximately 50% ments. canopy closure. The understory (stems per 1-m-radius plot frame) was comprised of Labrador Tea, Ledum Literature Cited groenlandicum (90 stems, 59% of total stems), Moun­ Barrett, G. 1975. Occurrence of an albino Microtus penn· tain Cranberry, Vacciniwn vitis-idaea (30, 20%), Bog sy/vanicus in Ohio. Journal of Mammalogy 75: 102. Blueberry, Vaccinium uliginosum (22, 14%), and minor Bowman, J., and R. M. Curran. 2000. Pa1tial albinism in amounts of grass, Calamagrostis sp. (5, 3%), Horse­ the red-backed vole, Clethrionomys gapperi, from New Brunswick. Northeastern Naturalist 7: 181-182. tail, Equisetum sp. (4, 3%), and Red-fruited Bastard Brewer, S. R., M. F. Lucas, J. A. Mugnano, J. D. Peles, Toadtlax, Geocaulon lividum (2, 1% ). Plant system­ and G. W. Barrett. 1993. Inheritance of albinism in the atics and nomenclature follows Hulten ( 1968) with meadow vole (Microtus pennsy/vanicus). American Mid­ updates provided by Viereck and Little (2007). Habi­ land Naturalist 130: 393-396. tat suitable for Northern Red-backed Voles occurs in Hutten, E. 1968. Flora of Alaska and neighboring territo­ a continuum on the north side of the Alaska Range ries: A manual of the vascular plants. Stanford University through Alaska and eastward into Yukon Territory, Press, California. I 008 pages. Canada, thus, this individual was not likely from a Jannett, F. J., Jr. 1981. Albinism and its inheritance in pop­ geographically isolated population. ulations of the montane vole. Journal of Heredity 72: 144­ 146. Although there are numerous references to albinism Owen, R. D., and R. M. Shakelford. 1942. Color aberrations in various microtine populations (Microtus montanus: in Microtus and Pitymys. Journal of Mammalogy 23: 306­ Warren 1929; Pinter and Negus 1971; Jannett 1981; 314. M. ochrogaster: Pinter and Negus 1971; M. pennsyl­ Parsons, G. J., and S. Bondrup-Nielsen. 1995. Partial albi­ vanicus: Owen and Shakelford 1942; Barrett 1975, nism in an island population of meadow voles, Microtus Brewer et al. 1993, Parsons and Bondrup-Nielsen 1995; pennsylvanicus, from Nova Scotia. Canadian Field-Natu­ M. pinetorum: Schantz 1960; Paul 1964; Clethriono­ ralist I 09: 263-264. mys (Myodes) gapperi: Bowman and Curran 2000), Paul, J. R. 1964. Second record of an albino pine vole. Jour­ the incidence (captures/100 trapnights or percentage nal of Mammalogy 45: 485. Pinter, A. J., and N. C. Negus. 1971. Coat color mutations of total catch) of albinism is rarely reported. As well, in two species of voles (Microtus mmztanus and Microtus most references are of partial albinism or leucism, ochrogaster) in the laboratory. Journal of Mammalogy 52: with few completely albino references. I can provide 196-199. no plausible argument to suggest that albinistic indi­ Schantz, V. S. 1960. Record of an albino pine vole. Journal viduals are not captured in proportion to their occur­ of Mammalogy 41: 129. rence in the population. Viereck, L.A., and E. L. Little, Jr. 2007. Alaska trees and shrubs. Second edition. University of Alaska Press, Fair­ Acknowledgments banks, Alaska. 359 pages. M. Rabe assured adequate funding for the project Warren, E. R. 1929. An albino field mouse. Journal of Mammalogy 10: 82. through the State Wildlife Grants program, adminis­ tered by the Alaska Department of Fish and Game, Received 26 October 2007 Wildlife Conservation Division, Nongame Program. Accepted 8 March 20 l 0