Microdipodops pallidus
pale kangaroo mouse

Microdipodops pallidus are found in Western Nevada and a portion of bordering California.(Nowak, 1999).

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). ()

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 ()

The lifespan of M. pallidus is approximately 5.5 years.

Pale kangaroo mice are nocturnal. They are believed to be solitary and are usually aggressive towards conspecifics. Researchers are not sure if this species hibernates, however these mice have been observed to enter short dormant periods in response to temperature and food reductions. ()

Microdipodops pallidus are often compared to another heteromyid group, the kangaroo rats in the genus Dipodops. Both Microdipodops and Dipodops are commonly called "kangaroo" because their jumping movement is saltatory, as in kangaroos (Norwak, 1997). Kangaroo mice are exclusively bipedal, their tail serves as a balance, and they are believed to use their forelegs to aid in turning. ()

Home Range

Male pale kangaroo mice have territories of about 6600 square meters. Female territories tend to be smaller, around 4,000 square meters. ()

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. ()

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). ()

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. ()

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). ()