Dipodomys simulans Merriam 1904

60.

Dulzura Kangaroo Rat

Dipodomys simulans

French: Rat-kangourou de Dulzura / German: Baja-California-Kangururatte / Spanish: Rata canguro de Dulzura

Other common names: Cabezon Kangaroo Rat, San Borja Kangaroo Rat, Santa Catarina Kangaroo Rat

Taxonomy. Dipodomys simulans Merriam, 1904,

Dulzura, San Diego Co., California, USA.

Based on molecular sequence analyses, D. simulansis a member of the agilis species group, along with D. agilis and D. venustus. Dipodomys simulans, formerly considered conspecific with D. agilis, was found to differ karyotypically (different diploid numbers), allozymically, morphologically (external, cranial, and bacular characters), and ecologically, and the two species are probably sympatric in Cajon Pass, separating the San Gabriel and San Bernardino mountains. Other likely former sites of sympatry have probably been engulfed by urban development. Two subspecies recognized.

Subspecies and Distribution. D.s.simulansMerriam,1904—SWUSAandNWMexico(coastalbasinsofSWCalifor-niaandslopesofSierraJuarezandSierraSanPedroMartir,Pacificcoastalplains,andValledelosCiriosofBajaCalifornia).

D. s. peninsularis Merriam, 1907 — NW Mexico (from Vizcaino Desert of S Baja California to Magdalena Plains of Baja California Sur).

Descriptive notes. Head—body 111-121 mm, tail 160-181 mm, ear mean 15 mm, hindfoot mean 42 mm; weight 55-70 g. Male Dulzura Kangaroo Rats are slightly larger than females. This is a medium-sized kangaroo rat with five toes on hindfeet (including small claw on side of hindfoot) and moderately long ears. Upper parts are pale grayish brown to dark reddish brown; tail is bicolored, with dull brownish-black crest and tuft. Chromosomal complement has 2n = 60 and FN = 116. The Dulzura Kangaroo Rat is most similar to the Agile Kangaroo Rat (D. agilis), which is larger, has larger ears, and has a broader face. It has a narrower face, smaller hindfeet, and larger ears than the sympatric San Quintin Kangaroo Rat (D. gravipes), and is smaller with a narrower face than the sympatric Stephens’s Kangaroo Rat (D. stephensi).

Habitat. Gravely or sandy soils of slopes, washes, and open chaparral of the Pacific coast of southern California, northern Baja California, and down into the Peninsular Desert of the Baja California peninsula, from sea level to elevations of ¢.2250 m. The Dulzura Kangaroo Rat occupies coastal chaparral and grassland communities from the Los Angeles Basin and San Jacinto Mountains of southern California through mountains and plains of northern Baja California to the Magdalena Plains of Baja California Sur. In some areas,it is restricted to coarse sand in dry washes, where it burrows within and into the edges of the washes. Typical burrows have three openings, seven side branches at an average depth of 32 cm, and two food caches. The most complex burrows are in northern areas, with the lowest temperatures and most precipitation, and where smaller individuals occur. This may be related to relative difficulty of digging in drier, harder soils in the south and availability of more vegetation in the north, requiring more storage for food. Burrow openings are often plugged during the day. Species of rodents co-occurring with the Dulzura Kangaroo Rat include the California Ground Squirrel (Otospermophilus beecheyi), Botta’s Pocket Gopher (Thomomys bottae), the California Pocket Mouse (Chaetodipus californicus), Merriam’s Kangaroo Rat (D. merriami), Stephens’s Kangaroo Rat, the Dusky-footed Woodrat (Neotoma fuscipes), and the California Deermouse (Peromyscus californicus). Coyotes (Canis latrans) excavate burrow systems and are major predators, along with western rattlesnakes (Crotalus viridis), great horned owls (Bubo virginianus), Bobcats (Lynx rufus), Kit foxes (Vulpes macrotis), and Northern Gray Foxes (Urocyon cinereoargenteus).

Food and Feeding. There is no information for this species.

Breeding. Breeding season of the Dulzura Kangaroo Rat occurs during any month of the year, but peaks occur in winter and spring. Average littersizes are 2-3 young (range 1-4).

Activity patterns. There is no specific information for this species, but Dulzura Kangaroo Rats are known to be excellent swimmers.

Movements, Home range and Social organization. There is no information available for this species.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Alexander & Riddle (2005), Best (1999h), Best et al. (1986), Ceballos & Oliva (2005), Eisenberg (1963, 1993), Hall (1981), Ingles (1954), Jones (1993), Linzey, Timm, Alvarez-Castafieda, Castro-Arellano & Lacher (2008c), Patton & Rogers (1993), Sullivan & Best (1997), Williams et al. (1993).