Although there are many similarities between kangaroo rats (Dipodops) and kangaroo mice (Microdipodops), these are mainly a product of convergent evolution. Microdipodops pallidus is classified with other pocket mice because of dental and skull morphology (Woods, 1990).
Perception Channels: tactile ; chemical
Woods (1990) describes Microdipodops pallidus as common, and the IUCN rates the species as a whole as "Lower risk/least concern". However, they rate the subspecies M. pallidus restrictus (the Soda Spring Valley pale kangaroo mouse) as vulnerable, because it is only known from one location.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
Microdipodops pallidus are primarily granivorous. They use their incisors for husking seeds, and carry seeds to their burrows in fur-lined cheek pouches (Dayan and Simberloff, 1994). During summer these mice will also eat insects (Woods, 1990). The tail of M. pallidus stores fat for use during dormant periods (Nowak, 1999). One of the most remarkable aspects of the diet of M. pallidus and some other heteromyid species, is that they can survive for extended periods, even lifetimes, without consuming water. It is believed that their extremely efficient kidneys (Woods, 1990) and their ability to derive sufficient water from food (Nowak, 1999) are responsible for this unique adaptation to an arid environment.
Animal Foods: insects; terrestrial non-insect arthropods
Plant Foods: seeds, grains, and nuts
Foraging Behavior: stores or caches food
Primary Diet: herbivore (Granivore )
Microdipodops pallidus are found in Western Nevada and a portion of bordering California.(Nowak, 1999).
Biogeographic Regions: nearctic (Native )
Kangaroo mice usually excavate their simple burrows near shrubs. The burrows of M. pallidus are far more simple than those of their sister species M. megacephalus (Nowak, 1999). These mice live in arid environments along sand dunes, gravelly soil, and lowlands. Microdipodops pallidus have been found at elevations ranging from 1100 - 2500 meters. They may occur sympatrically with as many as six other species of heteromyid rodents (Woods, 1990).
Range elevation: 1100 to 2500 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: desert or dune ; savanna or grassland
The lifespan of M. pallidus is approximately 5.5 years.
The pale, whitish-cream dorsal pelage earns Microdipodops pallidus their name. The white coloration continues to the underside of the animal. This characteristic is used to differentiate between M. pallidus and their sister species, the darker Microdipodops megacephalus. The fur is silky and long, and the tail is neither crested nor penciled (Nowak, 1999). Much of the body is shaped to aid in its hopping locomotion; M. pallidus has long hind legs, shortened forelegs, and uses its tail for balance. The proportionately large hind feet of M. pallidus improve movement through sandy habitats by being fringed at the sides with stiff hairs. These hairs, also found on the undersurface of the hind feet, act to increase the surface area of the foot (Nowak, 1999). The kidneys of kangaroo mice are very efficient, and fat is stored in their tails (Woods, 1990).
The skull of Microdipodops pallidus is quite large in relation to body size. This is because of their extremely inflated auditory bullae, which extend onto the upper portion of the skull (Nowak, 1999; Woods, 1990). This inflation is greater than in any other member of the Heteromyidae (Nowak, 1999). Molars of kangaroo mice do not regrow, and the dental formula is 1/1, 0/0, 1/1, 3/3 = 20.
Body Length: 6.6 - 7.7 cm
Tail Length: 6.4 - 10.3 cm
Range mass: 10 to 17 g.
Other Physical Features: endothermic ; bilateral symmetry
The large interal ear structures of this species sugget that it has very keen hearing, and uses this to detect predators. The pale color of these mice may also help it blend in with its background environment. Natural predators of pale kangaroo mice include rattlesnakes, predatory birds (mainly owls), weasels, and coyotes (Woods, 1990).
Known Predators:
Anti-predator Adaptations: cryptic
Information about the reproduction of M. pallidus is limited. This may be due in part to the limited amount of reproductive behaviors observed while these animals are in human care (Woods, 1990). Neither the time of weaning nor that of sexual maturity is known (Woods, 1990). Kangaroo mice are believed to be polyestrous, and in the wild pregnancies have been recorded between March and September (Nowak, 1997). The average weight of young at birth is about 1 gram, and litter size ranges from 2-7 young.
Range number of offspring: 2 to 7.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
The pale kangaroo mouse or Soda Spring Valley kangaroo mouse (Microdipodops pallidus) is a species of rodent in the family Heteromyidae. It is endemic to California and Nevada in the United States.[1]
Named for its pale-furred back and long hind limbs and feet, the pale kangaroo mouse is a large-headed rodent with fur-lined external cheek pouche. This species is bipedal, meaning that it generally moves around on its strong hind legs, hopping much like a kangaroo.[2]
The pallid kangaroo mouse, also called the pale kangaroo mouse, is one of two recognized species of kangaroo mouse, and is considered to be one of the most uncommon species of nocturnal desert dwelling rodent.[3] The coloration of the pallid kangaroo mouse is a pale cinnamon color on the dorsal side with the ventral being covered by a pale whitish colored hair coat.[4] The total length of the species ranges in size from 150 to 173 millimetres (5.9 to 6.8 in), with a tail length alone of 74 to 99 millimetres (2.9 to 3.9 in). The hind foot measures in length from 25 to 27 millimetres (0.98 to 1.06 in), and the weight range is between 10.3 and 16.8 grams (0.36 and 0.59 oz).[4]
While both the dark and the pallid kangaroo mouse species are desert dwelling, each species have unique habitat associations within the Great Desert Basin in North America where they are found. The pallid kangaroo mouse is found in central Nevada and a limited range in the eastern desert region of California.[5] The pallid kangaroo mouse is a sand obligate species and has been known to be an indicator of the health of the sand habitats of the Great Basin Desert.[5] Kangaroo mice are considered specialists in ecology, with regards to surviving within extreme desert environments. This allows scientists to assess the health of the ecosystem by studying in which locations the mice are located and which they avoid.[5]
The pallid kangaroo mouse has a diet that is grain based and have been known to supplement their diet with insects where they derive most of their water needs, as they are not known to consume free water.[4]
The desert is an extreme environment with unpredictable food resources. The pallid kangaroo mouse has developed some behavioral adaptations as a way of utilizing food in this environment.[6] Pale kangaroo mice will collect seeds and then cache them in specific locations. They are known to have multiple caches so as to prevent any competing species from stealing their entire food source.[6] In addition to their caching behaviors, kangaroo mice have other behavioral adaptation as a nocturnal desert dwelling species. One study followed the behavior of the kangaroo mice to avoid moonlight.[7] While the reasons behind this behavior are not fully known, it is thought that it is to avoid predation, by risk of moonlight exposure.[7]
The pale kangaroo mouse or Soda Spring Valley kangaroo mouse (Microdipodops pallidus) is a species of rodent in the family Heteromyidae. It is endemic to California and Nevada in the United States.
