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Melanistic Gray Squirrel, Sciurus carolinensis, Observed in the Piedmont Region of North Georgia
Gary W. Barrett and Terry L. Barrett

Southeastern Naturalist, Volume 10, Issue 1 (2011): 189–190

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Melanistic Gray Squirrel, Sciurus carolinensis, Observed in the Piedmont Region of North Georgia Gary W. Barrett1,* and Terry L. Barrett1 Abstract - A melanistic morph of Sciurus carolinensis Gmelin (Eastern Gray Squirrel or Gray Squirrel) was observed on 17 and 27 September 2008 in the Georgia Piedmont, Athens-Clarke County, GA. This is a rare observation because we have found no reports of Gray Squirrel melanism located south of Virginia in the southeastern United States. Melanism in Sciurus carolinensis Gmelin has long been of interest to biologists and ecologists. For example, Nelson (1918:445) described and illustrated the black phase (morph) of the Gray Squirrel in National Geographic Magazine. He noted that litters are found to contain black young in some parts of America, but no additional information was provided. Shorten (1945) reported on variation found in melanistic Gray Squirrels, such as melanistic individuals with brown under parts, or with hairs on the back tipped with brown. Although the range of S. carolinensis covers the deciduous forest biome of the eastern United States from Nova Scotia to Florida, west to southwestern Saskatchewan, a large portion of North Dakota, and eastern Nebraska, Kansas, Oklahoma, and Texas (Whitaker and Hamilton 1998), melanistic individuals are only common in the northern part of its range, where they are frequently described as black above and pale brown below. Melanism in the Gray Squirrel is found primarily in urban populations and near the northern limit of the species range. Steele and Koprowski (2001) report that melanistic Gray Squirrels are common in southern Ontario, Canada. Thorington and Ferrell (2006) note that black morphs are common in the Washington, DC area and as far south as Prince William County, VA. Gustafson and VanDruff (1990) describe behavior of black morphs of S. carolinensis found primarily in urban populations, such as Syracuse, NY. They note that among exurban populations (i.e., in districts outside a city), the black morph is abundant only in Canada and in Northern Michigan. In summary, distribution of S. carolinensis color morphs has perplexed biologists for decades (Banfield 1974, Creed and Sharp 1958, Schorger 1949). On 17 September 2008, we observed an adult melanistic S. carolinensis at the edge of a hardwood forest located in Athens-Clarke County, GA (33°57'19"N, 83°22'59"W). The melanistic Gray Squirrel returned to the same site on 27 September 2008, but was not observed again, although 10 to 15 Gray Squirrels come daily to a ground-feeding station at this site. This is the first report of a melanistic Gray Squirrel in the Georgia Piedmont. The individual that we observed had a completely black dorsal area, white hairs around its nostrils, and a few gray hairs on its ventral under parts. The forest site of observation is located on private property and dominated by Quercus velutina Lam. (Black Oak), Q. falcata Michx. (Southern Red Oak), Q. alba L. (White Oak), Fagus granifolia Ehrh. (American Beech), Liquididambar styraciflua L. (Sweet Gum), and Liriodendron tulipifera L. (Tuliptree). The existence of melanistic individuals in wild Gray Squirrel populations is seldom well explained. Introduction of one or more melanistic squirrels is a possible explanation regarding our observation. We have no evidence, however, that introduction of melanistic Gray Squirrels has occurred in the Georgia Piedmont. 1Eugene P. Odum School of Ecology, University of Georgia, Athens, GA 30602. *Corresponding author - gbarrett@uga.edu. Notes of the Southeastern Nat u ral ist, Issue 10/1, 2011 189 190 Southeastern Naturalist Vol. 10, No. 1 From an evolutionary perspective, winter temperatures of extreme cold (-10°C) in the northern United States and southern Ontario, Canada provide the melanistic Gray Squirrel with an energetic advantage, while in summer there is no advantage or disadvantage (Ducharme et al. 1989, Innes and Lavigne 1979). We doubt that black morphs have any advantage in the southeastern United States. It has been suggested that melanistic Sciurus niger Gmelin (Fox Squirrel) in the southeastern United States are related to historical frequency of forest fires (Kiltie 1989, 1992). The area of our observation has not been burned for decades. Because none of these possible explanations seems plausible, we suggest that our observed black morph occurred naturally within an abundant wild population of Gray Squirrels observed to inhabit this forest area. Natural or non-selective appearances of melanism in Gray Squirrels may have a genetic explanation. Recently, McRobie et al. (2009) sequenced the MCIR gene for 3 coat-color phenotypes in the Gray Squirrel, and found that a 24 base-pair deletion in MCIR is associated with melanism. Coat color is due to varying distributions of eumelanin and phaeomelanin production. They discovered that MCIR plays a central role in regulating eumelamin and phaeomelan production, a finding possibly related to the melanistic coat color in the Gray Squirrel that we observed. They do not rule out, however, that other genes may contribute to melanism in the Gray Squirrel as well. In Great Britain, the melanistic squirrel population is increasing in both size and geographic range (Thomas and Pankhurst 2005). It will be interesting to see if other melanisic Gray Squirrels are observed in the Georgia Piedmont in future years. Acknowledgments. We thank Steven W. Seagle and two anonymous reviewers for their comments on the manuscript. Literature Cited Banfield, A.W.F. 1974. The Mammals of Canada. University of Toronto Press, Toronto, ON, Canada. 438 pp. Creed, W.A., and W.M. Sharpe. 1958. Melanistic squirrels in Cameron County, PA. Journal of Mammalogy 39:532–537. Ducharme, M.R., J. Larochelle, and D. Richard. 1989. Thermogenic capacity in gray and black morphs of the Gray Squirrel, Sciurus carolinensis. Physiological Zoology 62:1273–1292. Gustafson, E.J., and L.W. VanDruff. 1990. Behavior of black and gray morphs of Sciurus carolinensis in an urban environment. American Midland Naturalist 123:186–192. Innes, S., and D.M. Lavigne. 1979. Comparative energetics of coat colour polymorphs in the Eastern Gray Squirrel, Sciurus carolinensis. Canadian Journal of Zoology 57:585–592. Kiltie, R.A. 1989. Wildfire and the evolution of dorsal melanism in Fox Squirrels. Journal of Mammalogy 70:726–739. Kiltie, R.A. 1992. Camouflage comparisons among Fox Squirrels from the Mississippi River Delta. Journal of Mammalogy 73:906–913. McRobie, H., A. Thomas, and J. Kelly. 2009. The genetic basis of melanism in the Gray Squirrel (Sciurus carolinensis). Journal of Heredity 100:709–714. Nelson, E.W. 1918. Smaller mammals of North America. National Geographic Magazine 33:391–493. Schorger, A.W. 1949. Squirrels in early Wisconsin. Transactions of the Wisconsin Academy of Science, Arts, and Letters 39:195–247. Shorten, M. 1945. Inheritance of melanism in Gray Squirrels. Nature 156:46–47. Steele, M.A., and J.L. Koprowski. 2001. North American Tree Squirrels. Smithsonian Institution Books, Washington, DC. 201 pp. Thomas, A.P.M., and S.J. Pankhurst. 2005. The black squirrels of Cambridgeshire. Nature in Cambridgeshire 46:61. Thorington, Jr., R.W., and K. Ferrell. 2006. Squirrels: The Animal Answer Guide. Johns Hopkins University Press, Baltimore, MD. 183 pp. Whitaker, Jr., J.O., and W.J. Hamilton, Jr. 1998. Mammals of the Eastern United States. Cornell University Press, Ithaca, NY. 583 pp.