Dipodomys stephensi
Creators: name: Don E. Wilson
name: Thomas E. Lacher, Jr
name: Russell A. Mittermeier
Publisher: name: Lynx Edicions
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Rodentia
Heteromyidae
Dipodomys
Dipodomys stephensi

description: 64.
Stephens’s Kangaroo Rat
Dipodomys stephensi
French: Rat-kangourou de Stephens / German: Stephens-Kangururatte / Spanish: Rata canguro de Stephens
Other common names: Bonsall Relict Kangaroo Rat
Taxonomy. Perodipus stephens: Merriam, 1907,
San Jacinto Valley [= a little W of Winchester, toward Menifee], Riverside Co., California, USA.
Based on molecular sequence analyses, D. stephensi 1s a member of the heermanni species group, along with D. heermanni, D. gravipes, D. panamintinus, D. microps, and D. ingens. Monotypic.
Distribution. SW USA (restricted distribution in the San Jacinto Valley and adjacent lowlands, and a disjunct population near Warner Springs in SW California).
Descriptive notes. Head-body 115-120 mm, tail 164-180 mm, ear mean 14 mm, hindfoot mean 42 mm; weight 45-73 g. Stephens’s Kangaroo Rat is a medium-sized kangaroo rat, with five toes on hindfeet (including small claw on side of hindfoot), relatively large auditory bullae, and wide face. Upper parts are dusky cinnamon buff; tail is 145% of head-body length and is bicolored, with dull brownish-black crest and tuft. Chromosomal complement has 2n = 70 and FN = 86. Stephens’s Kangaroo Ratis most similar to the allopatric Heermann’s Kangaroo Rat (D. heermanni) and Panamint Kangaroo Rat (D. panamintinus), and it has a broader face than the sympatric,five-toed Dulzura Kangaroo Rat (D. simulans).
Habitat. Open, sparsely vegetated annual grasslands in Coastal Sage and light chaparral communities at elevations of 55-1250 m in the San Jacinto Valley interior to ranges along the Pacific coast of southern California. Stephens’s Kangaroo Rat occurs in gravelly to sandy soils. Burrows are often found clustered in complexes (discrete patches with burrow entrances less than 1 m apart). Tunnels or aboveground runways often connect neighboring burrow entrances. Burrows are usually 21-23 cm in depth (maximum of 45 cm). Stephens’s Kangaroo Rat also uses abandoned burrow networks of Botta’s Pocket Gopher (Thomomys bottae) and the California Ground Squirrel (Otospermophilus beecheyi). Species of rodents co-occurring with Stephens’s Kangaroo Rat include the North American Deermouse (Peromyscus maniculatus), the Agile Kangaroo Rat (D. agilis), the Dulzura Kangaroo Rat, the San Diego Pocket Mouse (Chaetodipus fallax), Bryant's Woodrat (Neotoma bryanti), Botta’s Pocket Gopher, and the California Ground Squirrel. Common barn owls (7yto alba) and northern long-eared owls (Asio otus) are important predators, along with snakes, small carnivores, and feral dogs.
Food and Feeding. There is no information available for this species.
Breeding. Breeding of Stephens’s Kangaroo Rat occurs from late spring to mid-summer. In years with greater than average rainfall, females may produce two litters, and females born early in the year may mature and produce their first litters by the end of summer. Average litter sizes are 2-3 young (range 2-4).
Activity patterns. Stephens’s Kangaroo Rats might spend only c.1 hour outside oftheir burrows each night.
Movements, Home range and Social organization. Stephens’s Kangaroo Ratis solitary; however,as suggested by clumping of burrows and connecting tunnels and runways, 26% of individuals sampled shared at least one burrow entrance with another individual during a three-year study. Most (93%) entrance sharing was between two individuals. The most common pair was adults of mixed sexes, but sharing was unrelated to reproductive condition or breeding season, suggesting male-female cohabitation is not limited to periods of breeding activity. Other pairs involved one adult and one juvenile, irrespective of sex. This pattern is similar to that observed in Heermann’s Kangaroo Rat, although not as common as natal philopatry documented for the Banner-tailed Kangaroo Rat (D. spectabilis) and possibly Nelson’s Kangaroo Rat (D. nelsoni). Furthermore, the study relied on observation of sharing of burrow entrances, and shared burrow entrances may not necessarily indicate shared nesting chambers or food resources. Densities of Stephens’s Kangaroo Rats average 20-36 ind/ha but can vary monthly from 7 ind/ha to 57 ind/ha. Population peaks follow reproductive seasons in late spring and early summer, and changes in density are closely tied to seasonal precipitation.
Status and Conservation. Classified as Endangered on The IUCN Red List. Because of agricultural and urban development, remaining populations of Stephens’s Kangaroo Rats (mostly in western Riverside County) are fragmented and isolated. Total adult population size is unknown but exceeds 10,000. As of the late 1980s, there were 79 known extant populations; in 1997, the US Fish and Wildlife Service mapped a dozen “significant populations.” Most existing populations occupy relatively small areas of less than optimalsize for maximum viability.
Bibliography. Alexander & Riddle (2005), Best (1993a, 1999j), Bleich (1977), Brock & Kelt (2004a, 2004b), Eisenberg (1963, 1993), Hall (1981), Ingles (1954), Jones (1993), Linzey & NatureServe (Williams & Hammerson) (2008b), Patton & Rogers (1993), USFWS (1997), Williams et al. (1993).
description: Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Heteromyidae, pp. 170-233 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on pages 231-232, DOI: 10.5281/zenodo.6611160