Geographic Distribution and Taxonomy of the Chipmunks of Wyoming

by John A. White

Remarks.—E. umbrinus is the largest of the species of Eutamias occurring in Wyoming. This species usually occurs in the Canadian and Hudsonian life-zones in the mountains of northwestern, southwestern, and south-central Wyoming.

[ Eutamias umbrinus umbrinus (J. A. Allen) ]

Tamias umbrinus J. A. Allen, Bull. Amer. Mus. Nat. Hist. 3:96, June, 1890.

Eutamias umbrinus, Miller and Rehn, Proc. Boston Soc. Nat. Hist., 30:45, December 27, 1901.

Type.—Male, adult, skull and skin, No. 186463 (NM); from Blacks Fork, about 9,500 ft., Uinta Mountains, Summit County, Utah; obtained on September 19, 1888, by Vernon Bailey; original No. 228.

Diagnosis.—Size medium; over-all tone of upper parts dark and shadowy; skull smallest of this species in Wyoming.

Description.—Color pattern: Crown Pale Smoke Gray; facial stripes Fuscous Black or Snuff-Brown; ears Fuscous Black; posterior margin of ear and postauricular patch grayish white; median dorsal dark stripe black with Sayal Brown along margins; lateral pair of dorsal dark stripes Fuscous Black mixed with Sayal Brown, or entirely Sayal Brown; outermost pair of dorsal dark stripes Sayal Brown mixed with Fuscous Black or lacking; sides Sayal Brown mixed with Cinnamon; rump and thighs Sayal Brown mixed with Smoke Gray; antipalmar and antiplantar surfaces of feet Cinnamon-Buff; underside of tail Ochraceous-Tawny or Sayal Brown, with Fuscous Black around margin and Pinkish Buff around outermost edge; underparts creamy white with dark gray underfur. Skull: Smooth and rounded; braincase inflated; zygomata strong. Baculum: Broadened at base; shaft tapers rapidly to tip.

Comparisons.—From E. u. fremonti, the subspecies from the north in the mountains of northwestern Wyoming, E. u. umbrinus differs in: Over-all tone of upper parts darker; sides lighter; skull smaller. From E. u. montanus, the subspecies from the Medicine Bow Range of south-central Wyoming, E. u. umbrinus differs in: Over-all tone of upper parts darker; sides darker; skull smaller.

Remarks.—This subspecies occurs only in the foothills of the Uinta Mountains in the southern part of Uinta County. These "foothills" are well-timbered and at an altitude of 7,000 feet and higher.

Specimens examined.—Total number, 23.