Heermann's kangaroo rat, Dipodomys heermanni, is found exclusively in the state of California. The northern boundary of the species can be defined by a line connecting Suisun Bay to Lake Tahoe. The range extends south for roughly 500 kilometers to Point Conception in Santa Barbara Dipodomys heermanni occurs widely throughout the central portion of the state, and extends westward to the coast at some points. While found in a variety of habitats, Heermann's kangaroo rat is limited to elevations of 3000 feet and below (Williams et al 1993).

Biogeographic Regions: nearctic (Native )

endemic to a single state or province

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (20,000-200,000 square km (about 8000-80,000 square miles)) West-central California, north to Suisun Bay and the American River, southward through the San Joaquin Valley below about 3,000 feet, and extending through the interior valleys and mountains to the coast at morro Bay and from Point Sal to Point Conception in Santa Barbara County (Grinnell 1922, Hall 1981, Kelt 1988, Williams et al. 1993).

Heermann's kangaroo rat ranges in size from 250 to 313 mm in length, with the tail averaging 180 mm in length. It has a long tufted tail, long hind feet/limbs, short forefeet, dorsal color varying from tawny brown to buff, and a white stripe running along the upper thigh. The hip stripe is conspicuously absent in the subspecies D. h. morroensis. Dipodomys heermanni has 5 toes on the hind foot, and is a member of the "broad-faced" kangaroo rat group. The combination of five toes and broad face distinguish D. heermanni from all other sympatric species of kangaroo rats (except the significantly larger D. ingens) (Brylski 1993, Kelt 1988).

Heermann's kangaroo rat is sexually dimorphic in both external and cranial measurements, with males larger in all cases. The rat has a total of 20 teeth, with the dental formula I=1/1, C=0/0, P=1/1, M=3/3. Dipodomys heermanni has a secretory gland located between the shoulders which is thought to play a part in scent communication or pelage maintenance. The gland does not show seasonal dimorphism in D. heermanni. Variation in tail and body color, among other characters, helps to differentiate the nine recognized subspecies (Best 1993, Brylski 1993).

Range mass: 60 to 90 g.

Average basal metabolic rate: 0.408 W.

Length: 34 cm

Weight: 94 grams

• Terrestrial

Heermann's kangaroo rat is found in a great diversity of habitats. Some of the subspecies prefer the plains of the central California coast, some inhabit sandy valley bottoms, and some are more likely to be found on hilly knolls with shallow soils. These habitats extend from the foothills of the Sierra Nevada to the interior and coastal valleys (Kelt 1988).

Terrestrial Biomes: savanna or grassland ; chaparral

Comments: Primarily inhabits dry, gravelly valley grasslands, open chaparral. May also occur in open foothill woodlands. Lower and Upper Sonoran life zones. Prefers sparsely vegetated areas with loosely textured soil. When inactive, occupies underground burrow. Young are born in a nest in an underground burrow. May dig burrow from shelter of ground squirrel burrow.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Heermann's kangaroo rat feeds on a variety of plant species. Grasses are eaten as the kangaroo rat forages on the ground surface, while seeds are stored in the cheek pouches and taken home to the burrow for storage and later consumption. Dipodomys heermanni feeds on different plants as seasons change. In spring, Erodium species are the prominent source of food. In the dry season, Bromus mollis is taken most frequently, while Eromocarpus is the favored food in fall. With the onset of winter, Erodium becomes the primary food source once again. The kangaroo rat will also feed on insects such as moths, beetles, and grasshoppers (Kelt 1988).

Comments: Diet is mainly seeds; also eats green vegetation, especially in winter and spring. Also feeds seasonally on small amounts of insect material. Obtains food from ground surface or cuts standing seed heads or green vegetation.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 300

Population density varies widely with habitat. In San Luis Obispo County, density estimates varied from 42/ha in best habitat to 5/ha in marginal habitat. In one area in the same county, individual foraging range was estimated at 30-122 m across.

Comments: Generally emerges soon after dark. Rain and fog, and sometimes moonlight, may inhibit activity.

In San Luis Obispo County, little or no activity occurred in January and February; activity increased in early summer, declined in mid-summer, with possible fall resurgence.

Average lifespan

Status: captivity: 8.3 years.

Heermann's kangaroo rat breeds from February to October. Breeding peaks in April. The gestation period lasts 31 days, with litters of up to 6 pups being produced. Average litter size has been reported to range from 2.6 to 3.7. The newborn kangaroo rat is mostly hairless, and the eyes and outer ears are closed. The cheek pouches at this stage are simple folds. By day 3, the young rat is able to crawl and begins to grow dorsal and cranial hairs. It has skin pigmentation that matches adult pelage patterns. By day 9, the sex of the rat can be determined by checking for swellings in the genital area (swellings are present in males, absent in females). By day 14 the kangaroo rat pup can stand, and achieves bipedality by day 20. The weaning process begins in the third week and is completed by day 25. Sexual maturity is achieved at some point past the third week; in congenerics of D. heermanni, maturity was achieved at times ranging from day 32 to day 56. Foraging begins at 4 weeks, adult weight is reached at 2.5-4 months, and the molt to adult pelage is complete by the fifth month (Eisenberg 1993, Kelt 1988, Nowak 1991).

Average birth mass: 3.91 g.

Average gestation period: 31 days.

Average number of offspring: 3.1.

Breeds mainly from February through October; breeding peaks in April, declines after July. Gestation lasts 30-32 days. Litter size is 2-5; may produce multiple litters annually. Young appear above ground at 4-6 weeks. Females breed during their first year.

The subspecies D. h. berkeleyensis is listed as Vulnerable by the IUCN. The IUCN also lists the subspecies D. h. morroensis (the Morro Bay kangaroo rat) as being Critically Endangered. The Morro Bay rat is also classified as endangered by both the federal government and by the state of California. CITES does not list Heerman's kangaroo rat. Human settlement and the resulting habitat fragmentation in the Morro Bay rat's home range has severely decreased this population (CITES 1999, Kelt 1988, WCMC 1999).

US Federal List: endangered

CITES: no special status

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N4 - Apparently Secure

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Occurs in west-central California; many occurrences; trend is poorly known.

The kangaroo rat seems to destroy much vegetation that it does not eat (Kelt 1988).

Heerman's kangaroo rat has been used in research projects, and is a valuable lab species. It might also has some value as a pet, but has not been commercially exploited in the pet trade.

Comments: Dipodomys heermanni formerly included D. californicus, which Hall (1981) regarded as a subspecies of D. heermanni. Based on chromosomal and biochemical differences, Patton et al. (1976) and Patton (in Wilson and Reeder 1993, 2005) regarded D. heermanni and D. californicus as distinct species, as did Williams et al. (1993).