Thirteen-lined ground squirrel

The thirteen-lined ground squirrel (Ictidomys tridecemlineatus), also known as the striped gopher, leopard ground squirrel, squinney, (formerly known as the leopard-spermophile in the age of Audubon), is a ground squirrel that is widely distributed over grasslands and prairies of North America.

Thirteen-lined ground squirrel
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Sciuridae
Genus: Ictidomys
Species:
I. tridecemlineatus
Binomial name
Ictidomys tridecemlineatus
(Mitchill, 1821)
Synonyms

Spermophilus tridecemlineatus

Description
The animal is well camouflaged and frequently stands to keep watch.

It is brownish, with 13 alternating brown and whitish longitudinal lines (sometimes partially broken into spots) on its back and sides, creating rows of whitish spots within dark lines.

Biological statistics
Length 6¾–11⅝ inches (170–297 mm)
Tail 2⅜–5¼ inches (60–132 mm)
Head 1–1⅝ inches (27–41 mm)
Weight 3⅞–9½ oz (110–270 g)

Taxonomy

This species has usually been placed in the genus Spermophilus with about 40 other species. As this large genus is paraphyletic to prairie dogs, marmots, and antelope squirrels, Kristofer Helgen and colleagues have split it into eight genera, placing the thirteen-lined ground squirrel in Ictidomys with two other species.[2]

Behavior

The thirteen-lined ground squirrel is strictly diurnal and is especially active on warm days. A solitary or only somewhat colonial hibernator, it often occurs in aggregations in suitable habitats.

In late summer, it puts on a heavy layer of fat and stores some food in its burrow. It enters its nest in October (some adults retire much earlier), rolls into a stiff ball, and decreases its respiration from between 100 and 200 breaths per minute to one breath about every five minutes. It emerges in March or early April.

The burrow may be 15 to 20 feet (4.6 to 6.1 metres) long, with several side passages. Most of the burrow is within one to two feet (about half a meter) of the surface, with only the hibernation nest in a special deeper section. Shorter burrows are dug as hiding places. This ground squirrel's home range is two to three acres (0.8 to 1.2 ha).

Late in life, naturalist John James Audubon made a final expedition to the western plains in search of four-footed mammals. These striped ground squirrels would be tempting prey for many birds, especially hawks and owls. After the squirrels had left, burrowing owls might take over their underground dens.

Its primary diet includes grass and weed seeds, caterpillars, grasshoppers, and crickets, but it may also eat mice and shrews; it will viciously attack and consume cicadas if able to catch them. This squirrel sometimes damages gardens by digging burrows and eating vegetables, but also devours weed seeds and harmful insects.

It is well known for standing upright to survey its domain, diving down into its burrow when it senses danger, then sometimes poking out its nose and giving a bird-like trill. The "trill" is an alarm call that is most often used by females to warn nearby relatives.[3] It has a maximum running speed of 8 mph (13 km/h) and reverses direction if chased.

See also

References
  1. Linzey, A. V. & Hammerson, G. (2008). "Spermophilus tridecemlineatus". IUCN Red List of Threatened Species. 2008. Retrieved 8 January 2009.
  2. Helgen, Kristofer M.; Cole, F. Russel; Helgen, Lauren E. & Wilson, Don E (2009). "Generic Revision in the Holarctic Ground Squirrel Genus Spermophilus" (PDF). Journal of Mammalogy. 90 (2): 270–305. doi:10.1644/07-MAMM-A-309.1. Archived from the original (PDF) on 22 October 2011.
  3. Schwagmeyer, P. L. (1980). "Alarm Calling Behavior of the Thirteen-Lined Ground Squirrel, Spermophilus tridecemlineatus". Behavioral Ecology and Sociobiology. 7 (3).
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