Heermann's kangaroo rat does not need to drink much water to survive. Instead, it produces most of the water it needs by metabolic breakdown of food products. It addition, it reduces water loss by way of a very efficient kidney system, and by it's nocturnal activity (which results in less water lost to evaporation) (Nowak 1991).
Perception Channels: tactile ; chemical
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
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.
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).
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 Co. 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 )
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
Average lifespan
Status: captivity: 8.3 years.
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.
Other Physical Features: endothermic ; bilateral symmetry
Average basal metabolic rate: 0.408 W.
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).
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
Average birth mass: 3.91 g.
Average gestation period: 31 days.
Average number of offspring: 3.1.
Heermann's kangaroo rat (Dipodomys heermanni) is a species of rodent in the family Heteromyidae.[2] Their long smooth pelage resembles typical kangaroo rats, with their dorsal side showing a mixed range of olive, black and orange colors.[3] There are 9 distinguished sub-species of Dipodomys heermanni: D.h. arenae, D.h. berkeleyensis, D.h. dixoni, D.h. goldmani, D.h. heermanni, D.h. jolonensis, D.h.morroensis, D.h. swarthi, and D.h. tularensis.[4] The dental formula of Dipodomys heermanni is 1.0.1.31.0.1.3 × 2 = 20.[5]
It is considered "broad-faced", unlike many other species of kangaroo rats, which are considered to be "narrow-faced". It has five toes on each hind foot, and this small characteristic is important in distinguishing it from similar species such as Dipodomys californicus and Dipodomys nitratoides. Additionally it is smaller than Dipodomys ingens, Dipodomys venustus, and Dipodomys elephantinus.[3]
Heermann's kangaroo rat averages a total length of 250–313 mm (9.8–12.3 in), with their tail measuring 160–200 mm (6.3–7.9 in), their hind foot measuring 38–46 mm (1.5–1.8 in), and their ear measuring 10–17 mm (0.39–0.67 in).[3] Additionally when looking at all standard external measurements it has been found they demonstrate significant sexual dimorphism.[5]
Dipodomys heermanni is endemic to California in the United States.[1] The range is limited as well, extending north to south from Lake Tahoe to Point Conception in Santa Barbara County, and east to west from the Sierra Nevada mountain range to the Pacific Ocean.[5] They can be found in a range of habitats, however they do not surpass the altitude of 910 m (3,000 ft).[6] Even with this small home range, the Heermann's kangaroo rat is listed as a species of least concern according to the IUCN. According to USFWS the sub-species D.h. morroensis is listed as endangered.[7]
With all the interconnected surface runways within a community composed of individual Heermann's kangaroo rats, it is incredibly difficult to narrow down individual home ranges.[8] Because of this difficulty in distinguishing home ranges, the estimated values fluctuate greatly.[8] In one study, more than half of all recaptured rats were found within 30.5 meters (100 ft) of their first capture.[8] Home ranges can be very different from each other and can consist of differing levels of vegetation. Most common areas are on coastal plains or ridges with shallow soil.[5][8]
Population densities experience many ups and downs and have been shown to range between 2–30 kangaroo rats per hectare (1–12 per acre). There seems to be no way of predicting whether or not emigration has anything to do with these large fluctuations in population density. Typically, it is only the larger rats that take part in emigration, and females have been shown to exhibit this behavior more often than males.[5][8]
Heermann's kangaroo rats are burrowing animals, and they manipulate the tunnels already made by other burrowing animals to make their own, such as tunnels made by ground squirrels (Spermophilus). The extent of the burrowing behavior depends on the type of soil present: in areas with fine deep soil their tunnels average 10.7 m (35 ft) long and up to 51 cm (20 in) beneath the surface, whereas in shallow rocky soils the average length is 3.3 m (11 ft) and they do not extend deeper than 19.4 cm (7.6 in).[5][8] Additionally they have one to four escape routes besides the main entrance.[9]
Heermann's kangaroo rats are granivores, and seeds provide a significant nutritional value to their diet. They are also herbivores, especially during seasons of winter and spring. Additionally, in the wild they have been documented capturing insects at night such as moths, beetles, and grasshoppers. Most of the plant material near the burrows in their home ranges are utilized. They achieve necessary water consumption from seeds and dew from the plant material in their diet, and will only drink from a puddle or direct water source if water intake isn't achieved for several weeks. If the dry food matter increases and humidity is decreased, the mean daily activity of the rats drastically declines.[5][8][10][9]
They do have some predators such as rattlesnakes, gopher snakes, owls, various raptors, coyotes, foxes, weasels, skunks and house cats. However, predation does not seem to have a noticeable impact on population densities.[5]
The Heermann's kangaroo rat does not hibernate, instead it remains more or less active during the year depending on time of day.[5] It lives in a burrow for the majority of the day (up to 23 hours/day) and typically only comes out at night. Rain, fog and a bright full moon will usually prevent them from coming out of their burrow.[9]
They live a solitary life, however, experiments have shown that sociality does alter the rat's behaviors and that the rat does indeed have some ability to form generalized sociality. Sociality is measured by willingness to participate in social interactions. Kangaroo rats exhibit their willingness to interact with each other with a characteristic foot drumming, where increased foot drumming was associated with unwillingness to socialize and the absence of foot drumming was associated with willingness to socialize.[5][8][11] High rates of interspecies competition has been observed; however, intraspecies competition between Heermann's kangaroo rats has not been directly observed.[12]
They have been observed dust-bathing after foraging. This behavior consists of them lying on their bellies with they hind limbs extended or alternating keeping either their fore or hind limbs straight. It is thought to help withdraw oil and moisture, thus keeping their fur dry and sleek.[9]
Traveling is mostly done in a bipedal position with occasional hops that generally reach distances about 15 cm (6 in). When moving slowly they are usually in a plantigrade position. On the other hand, when they are moving more quickly they can become saltatorial and can even become ricochetal. When running rapidly their hops can range from 61 to 76 cm (24 to 30 in), and their tail aids in providing counterbalance.[9]
Heermann's kangaroo rat has a wide window in which it primarily breeds, ranging from February to October. Its highest breeding activity is in April, and this decreases in July.[8]
Heermann's kangaroo rat rarely show increased levels of sexual behavior. Copulation is rather quick, and typically only lasts a couple seconds. If the animals are caged, the rats show no increase in sexual behavior. Females rats will even show aggression if her genitalia are swollen and enlarged. During labor, the female rat will assist the delivery of the young with her front paws. The female Heermann's kangaroo rats also fondle her babies after birth with fondling, smelling, and licking.[5][9]
The young are born bright pink, wrinkled, hairless (except for colorless vibrissae), poikilothermic, and with their eyes closed. Within 22 hours of birth, hair is already developing and beginning to obtain adult pigmentation, beginning at the head and eventually reaching the feet by day 7. Before day 9 it is not possible to differentiate sexes because external genitalia appear the same. Weaning is completed around day 25, and young begin hunting and scavenging independently by 4 weeks.[8][9]
Heermann's kangaroo rat (Dipodomys heermanni) is a species of rodent in the family Heteromyidae. Their long smooth pelage resembles typical kangaroo rats, with their dorsal side showing a mixed range of olive, black and orange colors. There are 9 distinguished sub-species of Dipodomys heermanni: D.h. arenae, D.h. berkeleyensis, D.h. dixoni, D.h. goldmani, D.h. heermanni, D.h. jolonensis, D.h.morroensis, D.h. swarthi, and D.h. tularensis. The dental formula of Dipodomys heermanni is 1.0.1.31.0.1.3 × 2 = 20.
It is considered "broad-faced", unlike many other species of kangaroo rats, which are considered to be "narrow-faced". It has five toes on each hind foot, and this small characteristic is important in distinguishing it from similar species such as Dipodomys californicus and Dipodomys nitratoides. Additionally it is smaller than Dipodomys ingens, Dipodomys venustus, and Dipodomys elephantinus.
Heermann's kangaroo rat averages a total length of 250–313 mm (9.8–12.3 in), with their tail measuring 160–200 mm (6.3–7.9 in), their hind foot measuring 38–46 mm (1.5–1.8 in), and their ear measuring 10–17 mm (0.39–0.67 in). Additionally when looking at all standard external measurements it has been found they demonstrate significant sexual dimorphism.
