Ictidomys tridecemlineatus

Thirteen-lined Ground Squirrel
(*Ictidomys tridecemlineatus*)
Thirteen-lined Ground Squirrel (Ictidomys tridecemlineatus)
Range
Taxonomic classification
Order:	Rodentia
Suborder:	Sciuromorpha
Family:	Sciuridae
Subfamily:	Xerinae
Tribe:	Marmotini
Genus:	Ictidomys
Binomial details
	Ictidomys tridecemlineatus (Mitchill, 1821)
Other resources
	Full taxonomic details at MDD

The Thirteen-lined Ground Squirrel (Ictidomys tridecemlineatus) inhabitats grasslands, meadows, and shrublands with short vegetation and dry, sandy soil.

Description

From Schmidly and Bradley (2016): "A small ground squirrel with usually 13 alternating dark and light stripes, the dark ones containing a series of squarish or buffy spots, the light stripes occasionally broken into spots; dark dorsal stripes dark brown or black in color, the light stripes usually continuous and buffy white; underside of tail russet at base, shading to orange buff toward tip; lower sides cinnamon buff; belly pinkish buff; chin white; ears small."

Museum specimens

Holotype: USNM 209255. Ictidomys tridecemlineatus monticola. Adult male. Marsh Lake (also called Big Lake), White Mountains, Apache County, Arizona. Collected 15 June 1915.
Holotype: USNM 119025. Ictidomys tridecemlineatus hollisteri. Adult female. Elk Valley, Mescalero Indian Reservation, Sacramento Mountains, Otero County, New Mexico. Collected 11 September 1902.
NEON092X1. Ictidomys tridecemlineatus tridecemlineatus. Adult female. Chase Lake National Wildlife Refuge, Stutsman County, North Dakota. Collected 26 July 2023.
NEON092X1. Ictidomys tridecemlineatus tridecemlineatus. Adult female. Chase Lake National Wildlife Refuge, Stutsman County, North Dakota. Collected 26 July 2023.
NEON092X1. Ictidomys tridecemlineatus tridecemlineatus. Adult female. Chase Lake National Wildlife Refuge, Stutsman County, North Dakota. Collected 26 July 2023.

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 (Apache Co.)	Hoffmeister (1986)	215–228 (n=6)	70–84 (n=6)	29–31.5 (n=6)
Colorado	Armstrong et al. (2010)	170–297	60–132	27–41		100–250
Minnesota	Hazard (1982)	258–297	75–102	34–39	8–10	151.0–204.8
Nebraska	Johnsgard (2020)	220–287	82–103			83–185
North Dakota	Seabloom et al. (2020)	282	93	37	9	post-emergent males: 140–200; immergent males: 250; post-partum females: 160; immergent females: 250
Texas	Schmidly & Bradley (2016)	285	105	40		males: 154 (up to 212); females: 160 (up to 220)

Skull

Holotype: USNM 209255. Ictidomys tridecemlineatus monticola. Adult male. Marsh Lake (also called Big Lake), White Mountains, Apache County, Arizona. Collected 15 June 1915. Dorsal view of the skull.
Holotype: USNM 209255. Ictidomys tridecemlineatus monticola. Adult male. Marsh Lake (also called Big Lake), White Mountains, Apache County, Arizona. Collected 15 June 1915. Ventral view of the skull.
Holotype: USNM 209255. Ictidomys tridecemlineatus monticola. Adult male. Marsh Lake (also called Big Lake), White Mountains, Apache County, Arizona. Collected 15 June 1915. Lateral view of the skull.
Holotype: USNM 209255. Ictidomys tridecemlineatus monticola. Adult male. Marsh Lake (also called Big Lake), White Mountains, Apache County, Arizona. Collected 15 June 1915. Dorsal view of the mandible.
Holotype: USNM 209255. Ictidomys tridecemlineatus monticola. Adult male. Marsh Lake (also called Big Lake), White Mountains, Apache County, Arizona. Collected 15 June 1915. Lateral view of the left mandible.

Similar species

Comparison with Ictidomys parvidens

From Stangl Jr. et al. (2012): "the two are superficially distinctive. The thirteen-lined ground squirrel is the smaller sciurid, seldom weighing in excess of 150 g. The dark dorsal pelage is marked by rows of white spots against a dark dorsum, with the spots of alternate rows confluent to form solid stripes. The Rio Grande ground squirrel is a larger and rangier animal that can exceed 300 g, and sports both a proportionally longer tail and series of distinct spots arranged in rows against a comparatively pale tan-to-gray dorsum."

Thompson (2013) provided "strong evidence for contemporary hybridization between I. parvidens and I. tridecemlineatus in southeastern New Mexico and western Texas."

Thirteen-lined Ground Squirrel (Ictidomys tridecemlineatus) photographed by Zoë Unruh in Saskatchewan, Canada. A small ground squirrel with a relatively short tail that lacks fluff, ears short and rounded, and a dorsum usually with 13 alternating dark and light stripes. The dark stripes contain a series of squarish or buffy spots.
Rio Grande Ground Squirrel (Ictidomys parvidens) photographed by Alex Lamoreaux in Starr County, Texas. A small ground squirrel with a long and moderately bushy tail, ears short and rounded, and upperparts with rows of conspicuous white spots.
Distribution of the Rio Grande Ground Squirrel (Ictidomys parvidens) and the Thirteen-lined Ground Squirrel (Ictidomys tridecemlineatus) and presumed area of sympatry. Circles represent the locations where individuals were morphologically or genetically identified as either species or as hybrids by Thompson et al. (2013).

References

Armstrong DM, Fitzgerald JP, Meaney CA. 2010. Mammals of Colorado, Second Edition. Denver (CO, USA): University Press of Colorado.

Hazard EB. 1982. The mammals of Minnesota. Minneapolis (MN, USA): University of Minnesota Press.

Johnsgard PA. 2020. Wildlife of Nebraska: a natural history. Lincoln (NE, USA): University of Nebraska Press.

Mitchill, S.L. 1821. Description of two mammiferous animals of North America. New York Medical Repository (n.s.)6:248-250.

Schmidly DJ, Bradley RD. 2016. The mammals of Texas. Austin (TX, USA): University of Texas Press.

Seabloom R, Hoganson JW, Jensen WF. 2020. The mammals of North Dakota. Fargo (ND, USA): North Dakota State University Press.

Thompson C. 2013. Implications of hybridization between the Rio Grande ground squirrel (Ictidomys parvidens) and the thirteen-lined ground squirrel (I. tridecemlineatus). [dissertation]. [Lubbock (TX, USA)]: Texas Tech University.