Sigmodon hispidus

Hispid Cotton Rat
(*Sigmodon hispidus*)
Hispid Cotton Rat (Sigmodon hispidus)
Range
Taxonomic classification
Order:	Rodentia
Suborder:	Supramyomorpha
Infraorder:	Myomorphi
Superfamily:	Muroidea
Family:	Cricetidae
Subfamily:	Sigmodontinae
Tribe:	Sigmodontini
Genus:	Sigmodon
Binomial details
	Sigmodon hispidus Say & Ord, 1825
Other resources
	Full taxonomic details at MDD

The Hispid Cotton Rat (Sigmodon hispidus) is a cotton rat of medium size. This species is found in grasslands, and it is generally more abundant in areas where grasses are tall and dense.

Description

From Hoffmeister (1986): "A Sigmodon of medium size; hind foot usually less than 32 mm; tail usually less than 110 mm; pelage similar to that in S. arizonae; skull medium to large size; distance between parietal and squamosal crests less than 3.2 mm; length of squamosal crest usually less than 7.0 mm; occipital "shield" angled dorsally; anterior spine on infraorbital plate blunt and broad; presphenoid narrow; palatine foramina rounded posteriorly; antero-venral border of foramen magnum rounded."

From Best & Hunt (2020): "A medium-sized rat with a dorsum that is grayish-brown to dark brown to blackish and that is interspersed with paler hairs giving a grizzled appearance. Ventral pelage is usually grayish. Eyes are dark, and ears are dark and partially hidden in pelage. The tail is shorter than the length of head and body combined, indistinctly bicolored, scaly, and sparsely haired."

From Armstrong et al. (2010): "Hispid cotton rats have harsh, dark-colored pelage. Dorsal color is blackish brown interspersed with yellowish to buffy hairs. The underparts are paler in color, tending toward gray. The tail is sparsely haired, revealing the scales underneath. Length of the tail is less than that of the head and body. The ears are small but well haired."

Museum specimens

According to the American Society of Mammalogists' Mammal Diversity Database, the type specimen for this species is lost.

NEON01IGB. Sigmodon hispidus. Adult female. The Jones Center At Ichauway, Baker County, Georgia. Collected 14 August 2018.
NEON01IGB. Sigmodon hispidus. Adult female. The Jones Center At Ichauway, Baker County, Georgia. Collected 14 August 2018.
NEON01IGB. Sigmodon hispidus. Adult female. The Jones Center At Ichauway, Baker County, Georgia. Collected 14 August 2018.

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
Alabama	Best & Dusi (2014)	233 (135–300) (n=40)	97 (82–114) (n=40)	30 (26–35) (n=40)	18 (15–21) (n=18)	95.9 (70.8–145.0) (n=16)
Arizona (southeastern)	Hoffmeister (1986)	males: 225–266 (n=5); females:228–269 (n=5)	males: 102–109 (n=5); females: 88–119 (n=5)	males: 29–32 (n=5); females: 27–30 (n=5)	males: 17–20 (n=5); females: 18–20 (n=5)
Arizona (vicinity of Yuma)	Hoffmeister (1986)	males: 226–311(n=14); females: 210–319 (n=8)	males: 99–132 (n=14); females: 94–130 (n=8)	males: 31–34 (n=14); females: 29–32 (n=8)	males: 18–20 (n=14); females: 17–21 (n=8)
California	Jameson & Peeters (2004)	224–365	81–166	28–41	16–24	100–225
Carolinas, Virginia, Maryland	Webster et al. (1985)	230–320	80–140			112–245
Colorado	Armstrong et al. (2010)	224–265	81–166	28–35	16–24	100–225
Texas	Schmidly & Bradley (2016)	270	110	31		80–150
Virginia	Linzey (1998)	225–325	80–135			112–225

Skull

From Armstrong et al. (2010): "Molars are rooted and high-crowned. Their occlusal surface has large, flattened cusps (sometimes described as "lozenge-shaped") arranged in a sigma-shaped pattern (hence the generic name). The skull is long, narrow, and stout with well-developed supraorbital (temporal) ridges. The infraorbital foramen is prominent, and the infraorbital plate of the zygomatic arch has a pronounced, blunt, spinelike, anterior projection."

NEON01IG9. Sigmodon hispidus. Adult male. The Jones Center At Ichauway, Baker County, Georgia. Collected 15 August 2018. Dorsal view of the skull.
NEON01IG9. Sigmodon hispidus. Adult male. The Jones Center At Ichauway, Baker County, Georgia. Collected 15 August 2018. Ventral view of the skull.
NEON01IG9. Sigmodon hispidus. Adult male. The Jones Center At Ichauway, Baker County, Georgia. Collected 15 August 2018. Lateral view of the skull.
NEON01IG9. Sigmodon hispidus. Adult male. The Jones Center At Ichauway, Baker County, Georgia. Collected 15 August 2018. Dorsal view of the mandible.
NEON01IG9. Sigmodon hispidus. Adult male. The Jones Center At Ichauway, Baker County, Georgia. Collected 15 August 2018. Lateral view of the left mandible.
NEON01IG9. Sigmodon hispidus. Adult male. The Jones Center At Ichauway, Baker County, Georgia. Collected 15 August 2018. Upper molars.
NEON01IG9. Sigmodon hispidus. Adult male. The Jones Center At Ichauway, Baker County, Georgia. Collected 15 August 2018. Lower molars.

Footprint

NEON09TVO. Sigmodon hispidus. Front left footprint.
NEON09TVO. Sigmodon hispidus. Hind right footprint.

Taxonomic notes

From Rose (2025): " Since 1970, several taxa, originally considered as subspecies of S. hispidus, have been elevated to species level. Sigmodon hispidus no longer includes S. arizonae and S. mascotensis (Zimmerman 1970); S. inopinatus and S. peruanua (Voss 1992); S. zanjonensis (Carleton and Musser 2005); and S. hirsutus and S. toltecus (Peppers and Bradley 2000). Currently there is support for the subspecific status of S. h. eremicus (Bradley et al. 2012). Contemporary references list Sigmodon hispidus as monotypic (Patton 2017; Burgin et al. 2020) and it is evident that additional information is needed to determine the status of subspecies."

Similar species

Comparison with Sigmodon arizonae

From Rose (2025): "Sigmodon hispidus and S. arizonae (Arizona Cotton Rat) share many features, which in turn separate them from others in the genus, including broad (0.75 mm) scales in the nearly naked tail, a relatively long and narrow skull, long and broad basioccipital, and shallow palatal pits (Hall 1981). The 2 species differ by length of hind foot (32.5 mm or less in S. hispidus vs. 34 or more mm in S. arizonae) and also by chromosome number (n = 52 vs. 22, respectively—Blood 1990)."

Hispid Cotton Rat (Sigmodon hispidus) observed by Bob Oswald in Gainesville, Florida. Sigmodon hispidus and Sigmodon arizonae are similar in appearance but their ranges are mostly non-overlapping.
Arizona Cotton Rat (Sigmodon arizonae) photographed by Gordon Karre in Gilbert, Arizona.

Comparison with Sigmodon fulviventer

From Hoffmeister (1986): "S. hispidus differs from S. fulviventer as follows: underparts silvery or grayish rather than buffy or fulvous; tail bicolored, lighter below than above; tops of hind feet silvery or grayish rather than buffy; hind feet and ears averaging longer; preoptic foramen usually absent; nasals usually truncate or notched rather than tapered posteriorly."

Hispid Cotton Rat (Sigmodon hispidus) observed by Bob Oswald in Gainesville, Florida.
Tawny-bellied Cotton Rat (Sigmodon fulviventer) observed by Ricardo Arredondo T. in Coeneo, Michoacán, México.

Comparison with Sigmodon ochrognathus

From Hoffmeister (1986): "S. hispidus differs from S. ochrognathus as follows: no orangeish or ochraceous nose ring and eye ring but color in these areas nearly same as that of sides and back; hind foot longer, usually 29 mm or more, but may be slightly smaller in some females; ears and tail longer; skull larger, especially for comparable ages and sexes; posterior border of interparietal without a median notch formed by supraoccipital; base of baculum gradually curved and broad."

Hispid Cotton Rat (Sigmodon hispidus) observed by Bob Oswald in Gainesville, Florida.
Yellow-nosed Cotton Rat (Sigmodon ochrognathus) observed by Randy Babb. Sigmodon ochrognathus has a conspicuous "yellow" nose.

References

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

Best, T.L., & Hunt, J.L., 2020. Mammals of the southeastern United States. University Alabama Press.

Blood BR. 1990. Taxonomy and distribution of Sigmodon in California. Bulletin of the California Academy of Sciences 89(2):86–93.

Bradley RD, Lark JB, Pfau RS, Pepper LL, Henson DD, Stallings AO, Hoany CN, Van Den Bussche R. 2012. Genetic and conservation status of a relictual population of the hispid cotton rat (Sigmodon hispidus eremicus). Southwestern Naturalist 57(3):231–239. https://doi.org/10.1894/0038-4909-57.3.231

Burgin CJ, Wilson DE, Mittermeier RA, Rylands AB, Lacher TE, Sechrist W. 2020. Illustrated checklist of mammals of the world. Vol. 1, Monotremata to Rodentia. Barcelona (Spain): Lynx Edicions.

Ceballos G, editor. 2014. Mammals of Mexico. Baltimore (MD, USA): Johns Hopkins University Press.

Hall ER. 1981. The mammals of North America. 2 vols. John Wiley and Sons, New York.

Hoffmeister DF. 1986. Mammals of Arizona. Tucson (AZ, USA): University of Arizona Press.

Jameson EW, Peeters HJ. 2004. Mammals of California (No. 66). Berkeley (CA, USA): University of California Press.

Linzey DW. 1998. The mammals of Virginia. McDonald & Woodward Publishing.

Patton JL. 2017. Sigmodon hispidus Say & Ord, 1825. In: Wilson DE, Mittermeier RA, Lacher TE, editors. Handbook of mammals of the world, 7. Rodents II. Barcelona (Spain): Lynx Edicions; p.121–125.

Peppers LL, Bradley RD. 2000. Cryptic species in Sigmodon hispidus: evidence from DNA sequences. Journal of Mammalogy 81(2):332–343. https://doi. org/10.1644/1545-1542(2000)081<0332:CSISHE>2.0.CO;2

Rose RK. 2025. Sigmodon hispidus (Rodentia: Cricetidae). Mammalian Species 57(1041):1-26. https://doi.org/10.1093/mspecies/seae007

Say T, Ord G. 1825. Description of a new species of Mammalia, whereon a genus is proposed to be founded. Journal of the Academy of Natural Sciences of Philadelphia 4:352-356.

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

Voss RS. 1992. A revision of the South American species of Sigmodon (Mammalia: Muridae) with notes on their natural history and biogeography. American Museum Novitates 3050:1–56. http:// hdl.handle.net/2246/5014

Webster WD, Parnell JF, Biggs WC. 1985. Mammals of the Carolinas, Virginia, and Maryland. Chapel Hill (NC, USA): University of North Carolina Press.

Zimmerman EG. 1970. Karyology, systematics, and chromosomal evolution in the rodent genus, Sigmodon. Publications of the Museum, Michigan State University, Biology Series 4(9):385–454.