Stephens' kangaroo rat (Dipodomys stephensi)

Stephens' kangaroo rat fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Stephens' kangaroo rat description

Stephens’ kangaroo rat (Dipodomys stephensi) is a small nocturnal mammal ⁽³⁾ which gains its common name from its kangaroo-like hopping movements. This characteristic hopping is aided by the kangaroo rat’s long, powerful hind legs, with the long tail balancing it while it moves and holding it upright while standing ⁽⁴⁾. Kangaroo rats are known to jump up to two metres when travelling quickly ⁽⁴⁾. The forelegs are relatively small in comparison with the hind legs ^{(2) (3) (5)}.

The upperparts of all kangaroo rat species are pale yellow to dark brown. This contrasts with the underparts, which are usually white. A prominent, oil-secreting gland is present between the shoulders. In most species of kangaroo rat there is a white band running across the thigh to the base of the tail ⁽⁴⁾.

Stephen’s kangaroo rat has a bicoloured tail, which is crested and darkly striped, with narrow white stripes running horizontally along its surface ^{(2) (3) (5)}. All kangaroo rat’s tails are much longer than the head and body and are usually lighter above than below, with a tuft of longer hair on the tip ⁽⁴⁾.

Kangaroo rats generally do not vocalise, although they are known to occasionally make drumming noises with their feet ⁽⁴⁾. 

Size

Total length: 27.7 - 30 cm ⁽²⁾

Tail length: 16.4 - 18 cm ⁽²⁾

Weight

c. 67 g ⁽²⁾

Stephens' kangaroo rat biology

Stephens’ kangaroo rat is thought to give birth to one litter per year containing between one and six young. Up to three litters may be usually produced under favourable conditions, but during droughts no young may be born ^{(1) (3) (4)}. The young are born in late spring or early summer, or sometimes even later ^{(1) (2) (3)}, and are weaned after 18 to 22 days ⁽⁴⁾. Young females are occasionally known to reproduce by the end of their first summer ^{(1) (3)}.

The diet of Stephens’ kangaroo rat is mainly composed of forb seeds ⁽³⁾, with insects and herbaceous vegetation also likely to be taken ⁽¹⁾. Kangaroo rats transport both food and nesting materials in pouches on the inside of the cheeks, and this material is then retrieved using the forefeet. Water is obtained through the kangaroo rat’s diet, although the water requirements of most Dipodomys species are very low due to their highly efficient kidneys ⁽⁴⁾. Kangaroo rats use sand and dust bathing to clean and groom the fur ^{(3) (4)}.

Stephens’ kangaroo rat is nocturnal and lives a mainly subterranean lifestyle, only appearing above ground for around one hour per night ^{(2) (3)}. Burrows may be constructed by the rat itself or it may utilise the old burrows of pocket gophers (Geomyidae species) or California ground squirrels (Otospermophilus beecheyi) ⁽¹⁾. The burrows of Stephens’ kangaroo rat are usually around 45 centimetres deep ⁽³⁾. Very little is known of the social behaviour of this solitary species ⁽³⁾, although it is known that most kangaroo rats are highly territorial, with only a single individual occupying a burrow ⁽⁴⁾.

Predators of Stephens’ kangaroo rat include barn owls (Tyto alba), long-eared owls (Asio otus) ⁽²⁾, foxes, coyotes and feral and domestic cats ⁽³⁾. 

Stephens' kangaroo rat range

Stephens’ kangaroo rat is known from southern California in the United States, where it is found in the San Jacinto Valley, south-western San Bernardino County and northern San Diego ^{(1) (2) (3) (4) (6)}. 

Stephens' kangaroo rat habitat

Stephens’ kangaroo rat is found in open grassland habitats where the sparse vegetation is mainly composed of shrubs, sagebrush, grasses and forbs ^{(1) (2) (3) (6) (7)}. The terrain is usually slightly sloped or flat, with well-drained, loose soil which is at least 50 centimetres deep ^{(1) (3)}. ). It is also known to colonise abandoned agricultural areas and other disturbed habitats ^{(1) (2)}.

Stephen’s kangaroo rat is found at elevations between 55 and 1,250 metres ⁽¹⁾. 

Stephens' kangaroo rat status

Stephens' kangaroo rat is classified as Endangered (EN) on the IUCN Red List ⁽¹⁾.

Stephens' kangaroo rat threats

Much of the habitat of Stephens’ kangaroo rat has been lost due to urbanisation and agriculture, and remaining areas of suitable habitat are severely fragmented ^{(1) (2) (3) (5) (7)}. Within the fragments, its populations are threatened by loss of genetic diversity and unequal sex ratios, which leave populations vulnerable to local extinctions. Urbanisation has also resulted in unnaturally high levels of predation from feral and domestic cats, putting further strain on population numbers ^{(1) (3)}.

Stephens’ kangaroo rat requires open areas with native forb vegetation to survive, so invasion of its habitat by non-native vegetation poses an additional threat to this species ^{(1) (3)}.

The remaining habitat of Stephens’ kangaroo rat may have insufficient protection to prevent any future human development from occurring ⁽³⁾. With a large majority of the range of this species being located on private land, it is thought that some landowners may have destroyed populations before any laws protecting it could be introduced ^{(1) (3)}. Off-road vehicle use is also a major threat to Stephens’ kangaroo rat and its habitat ^{(1) (3)}. 

Stephens' kangaroo rat conservation

Complete protection of Stephens’ kangaroo rat and its habitat must be granted by the California Fish and Game Commission to ensure its future survival ⁽²⁾. Some land has been purchased by Riverside County in California to create reserves ⁽¹⁾, and dispersal corridors have been established to link separate habitat areas ^{(3) (6)}. Large habitats at higher altitudes should be protected to provide refuge during times of drought and to support larger, more genetically diverse populations ⁽¹⁾.

Some populations of Stephens’ kangaroo rat already exist within protected areas such as San Jacinto Wildlife Area and Sycamore Canyon park ⁽¹⁾, although more suitable habitats need to be identified and offered the same protection ⁽³⁾. More studies also need to be done into aspects of the biology of Stephens’ kangaroo rat, such as its reproduction, feeding habits and dispersal, which may provide the necessary information to correctly protect this species ^{(1) (6)}. For the long-term survival of Stephens’ kangaroo rat, management and monitoring programs must be implemented within its habitat ⁽⁶⁾.

Find out more

Find out more about North American rodent conservation:

• Hafner, D.J., Yensen, E. and Kirkland Jr, G.L. (1998) North American Rodents: Status Survey and Conservation Action Plan. IUCN/SSC Rodent Specialist Group, IUCN, Gland, Switzerland and Cambridge, UK. Available at: 
  http://data.iucn.org/dbtw-wpd/edocs/1998-039.pdf
• Bleich, V.C. (1977) Dipodomys stephensi. Mammalian Species, 73: 1-3. Available at:
  http://www.science.smith.edu/msi/pdf/i0076-3519-073-01-0001.pdf

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Glossary

Feral

Previously domesticated animals that have returned to a wild state.

Forb

Any herbaceous (non-woody) flowering plant that is not a grass.

Genetic diversity (genetic variation)

The variety of genes within a particular species, population or breed causing differences in morphology, physiology and behaviour.

Genus

A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.

Gland

An organ that makes and secretes substances used by the body.

Herb

A small, non-woody, seed bearing plant in which all the aerial parts die back at the end of each growing season.

Nocturnal

Active at night.

Subterranean

Living underground, in caves or groundwater.

Territorial

Describes an animal, a pair of animals or a group that occupies and defends an area.

References

1.  IUCN Red List (April, 2012)
   http://www.iucnredlist.org/
2. Bleich, V.C. (1977) Dipodomys stephensi. Mammalian Species, 73: 1-3. Available at:
   http://www.science.smith.edu/msi/pdf/i0076-3519-073-01-0001.pdf
3. Burke, R.L. et al. (1991) Conservation of the Stephens’ kangaroo rat (Dipodomys stephensi): Planning for persistence. Bulletin of the Southern California Academy of Science, 90(1): 10-40.
4. Nowak, R.M. (1999) Walker's Mammals of the World. Johns Hopkins University Press, Baltimore, Maryland.
5. Bowers, N., Bowers, R. and Kaufman, K. (2007) Kaufman Field Guide to Mammals of North America. Houghton Mifflin Harcourt, New York.
6. Hafner, D.J., Yensen, E. and Kirkland Jr, G.L. (1998) North American Rodents: Status Survey and Conservation Action Plan. IUCN/SSC Rodent Specialist Group, IUCN, Gland, Switzerland and Cambridge, UK. Available at: 
   http://data.iucn.org/dbtw-wpd/edocs/1998-039.pdf
7. Brock, R.E. and Kelt, D.A. (2003) Keystone effects of the endangered Stephens’ kangaroo rat (Dipodomys stephensi). Biological Conservation, 116: 131-139.