Mammal Species of the World
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- Original description: Merriam, C.H., 1891. Description of a new genus and species of dwarf kangaroo rat from Nevada, (Microdipodops megacephalus) p. 115. North American Fauna5:115-117.
endemic to a single nation
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: Western United States; southeastern Oregon, northeastern and central-eastern California, Nevada, southwestern Idaho, and west-central Utah.
These kangaroo mice are found in the Great Basin region of western United States, including Oregon, Utah, California, and Nevada. Nowak (1991), O'Farrell and Blaustein (1974).
Biogeographic Regions: nearctic (Native )
Total length measures 140-177 mm, head and body length is 66-77 mm, tail length 68-103 mm, and the hind foot is 23-27 mm long. The head is large in proportion to their body size due to the inflation of the tympanic bullae that extends to the upper portion of the cranium. The neck is fairly short. Upper parts are brownish to grayish black. Compared to the similar looking species, M. pallidus, M. megacephalus have basally plumbeous and white-tipped underparts, and the end of the tail is blackish. The distal half of the tail is darker than the proximal. The tail is not crested nor does it end in a tassle; however, it is thick and stores fat. The fat in the tail is used as a source of energy during dormancy.
The pelage is relatively long, silky, and lax. The hind feet are covered with stiff hairs on the sides, which increases the surface of the fine and soft feet. The undersurface of the hind feet are also well furred. The feet functions similar to a sand shoe in a desert.
Kangaroo mice utilize their forelegs more than kangaroo rats when running.
Compared to those of kangaroo rats, the molars of kangaroo mice do not constantly regrow. The base of the zygomatic arch is not enlarged as it is in kangaroo rats.
Several features, including long hind legs, relatively small forelegs, long vibrissae, and enlarged auditory bullae are probably adaptations to the jumping mode of locomotion.
O'Farrell and Blaustein (1974), Nowak (1991), Grizmek (1990).
Average mass: 13.4 g.
Average basal metabolic rate: 0.168 W.
Length: 18 cm
Weight: 17 grams
Comments: In loose sands and gravel. Found in Shadscale Scrub, Sagebrush Scrub, and Alkali Sink plant communities in the Upper Sonoran life zone. May occur in sand dunes near margins of range. Underground when inactive.
Habitat and Ecology
Seeds are the primary food source. They also eats some insects. They do not appear to utilize free water. They are believed to store food in seed caches within burrow system (O'Farrell and Blaustein, 1974). Activity observed March-October. Peak nocturnal activity occurs in first two hours after sunset. Moonlight and ambient temperature influence activity (O'Farrell and Blaustein, 1974).
Kangaroo mice are found among bushes growing in soils covered with gravel or on sand dunes. The altitude of the habitat is around 1,190-2,455 meters. Burrows are constructed in soft ground with the entrance near a shrub. Burrows have simple, unbranched tunnels, elaborate nests, and a food storage room. A small territory is maintained near the burrow, but an individual's home ranges may overlap with those of several other individuals. Average home range for males is 6,613 square meters and 3,932 for females. O'Farrell and Blaustein (1974), Nowak (1991)
Terrestrial Biomes: desert or dune
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.
Comments: Seeds are the primary food source. Also eats some insects. Does not appear to utilize free water. Believed to store food in seed caches within burrow system (O'Farrell and Blaustein 1974).
These kangaroo mice are normally granivorous, although they feed on insects, particularly during summer when their activity reaches its maximum. The shift in diet may be caused by competition for food with pocket mice. Kangaroo mice store food in seed caches found in their burrows. O'Farrell and Blaustein (1974), Nowak (1991), Grizmek (1990).
Predators include owls, foxes, badgers. In west-central Nevada mean yearly circular home range for males was 6613 sq m; for female, 3932 sq m (O'Farrell and Blaustein 1974).
Life History and Behavior
Comments: Activity observed March-October. Peak nocturnal activity occurs in first 2 hours after sunset. Moonlight and ambient temperature influence activity (O'Farrell and Blaustein 1974).
Status: captivity: 5.4 years.
Lifespan, longevity, and ageing
Possibly polyestrous (Hall 1946); majority of young are born in May and June. Litter size is 2-7 (average 3.9).
Females are polyestrous. Pregnant individuals have been found from March to September. The majority of the young are born in May and June. Litter size ranges from 2 to 7 with an average of 3.9. A study done in west-central Nevada showed that the population consisted of 2:1 sex ratio favoring males. A successful reproduction has yet to be recorded in captivity. Maximum longevity (of an individual trapped in the wild) is five years and five months. O'Farrell and Blaustein (1974), Nowak (1991), Grizmek (1990).
Average number of offspring: 4.
Molecular Biology and Genetics
Barcode data: Microdipodops megacephalus
There is 1 barcode sequence available from BOLD and GenBank. Below is the sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen. Other sequences that do not yet meet barcode criteria may also be available.
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Download FASTA File
Statistics of barcoding coverage: Microdipodops megacephalus
Public Records: 1
Specimens with Barcodes: 2
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N4 - Apparently Secure
NatureServe Conservation Status
Rounded Global Status Rank: G4 - Apparently Secure
IUCN Red List Assessment
Red List Category
Red List Criteria
Although not endangered, their number has decreased due to destruction of habitat by modern agriculture and land development. Predators include the kit fox and snakes; however, humans are the biggest threat.
IUCN Red List of Threatened Species: least concern
Comments: Some Microdipodops populations have declined as a result of introduction of weedy grasses and extreme habitat alteration from cultivation (e.g., irrigation of dry sinks) (Hafner et al. 1998). In addition to these human-related habitat changes, apparently natural shifts in vegetative zones have resulted in the replacement of rodent communities including Microdipodops by those including Dipodomys deserti, and vice versa (J. C. Hafner, pers. obs.). Natural and human-related habitat modifications may have amplified effects on the already fragmented, patchy distribution of Microdipodops (Hafner et al. 1998).
Relevance to Humans and Ecosystems
Dark kangaroo mouse
The dark kangaroo mouse (Microdipodops megacephalus), also known as Owyhee River kangaroo mouse, is named for its dark-furred back, long hind feet, and the way it moves around by hopping on its hind legs like Autralian kangaroos. It belongs to the Order Rodentia and Family Heteromyidae   . Its head is large in comparison to its body size due to enlarged auditory bullae. It has a relatively short neck  large ears, prominent eyes, a long snout, long whiskers and a fat, haired tail.
The coat of dark kangaroo mouse is long, silky, and soft with its back being brownish to greyish black while it belly having a greyish or whitish hue. Its tail is swollen in the middle (fat deposits). The fat deposits vary in size as season changes because it is used as a source of energy during dormancy. The tails are thickest before entering winter hibernation and thin in the spring, when they come out of hibernation and assume normal activity. This is very unique among North American small mammals.
There is no sexual diamorphism shown in dark kangaroo mouse except for zymomatic breadth. Length of hind foot, cranial measurement, and mandibular length vary little while weight is highly variable in the population. The total length ranges from 138-177mm with an average of 160mm, length of tail: 68-103mm, hind foot length: 23-27mm, weight of adults ranges from 10-16.9g with an average of 13.1g.
Distribution and Habitat
The dark kangaroo mouse species is native to the west of United States ( southeastern Oregon, northeastern and central-eastern California, Nevada, the tip of southwestern Idaho, and west-central Utah). They prefer to live in loose sand and gravels (found in the Upper Sonoran life zone).
This species is listed as “Least Concern” on the Red List because it is relatively widespread, although there has been a slight reduction in its population due to loss of habitats caused by modern agriculture.
Dark kangaroo mice mostly eat small seeds (granivores), which are carried back to their underground burrows in their cheek pouches. They also feed on some insects (insectivore) in the summer. This change in diet is suggested to be caused by pocket mice ( longimembris) being at its peak activity and competing for food with the dark kangaroo mice.
These kangaroo mice do not drink water actively, instead utilizing water from their food source. They also have adaption mechanisms to further conserve water: being active at night (lower temperature so loose less water), concentrating their urine, and producing dry feces.
Dark kangaroo mice are mostly bipedal which move around by hopping on their two hind legs. Using bipedalism is suggested to be a result of foraging behaviors and using it as a locomotion mode only serves as a side function. They also have been seen to be moving on all 4 limbs when moving in contained spaces such as a cage.
These kangaroo mice are nocturnal animal with peak of activity in the first 2 hours after sunset. Their activity is only observed from March through October while they go into hibernation during winter months. These animals are also sensitive to moonlight and temperature. Their activities are decreased when the temperature is out of their optimal range and in presence of moonlight.
- Linzey, A.V. & NatureServe (Hammerson, G.) (2008). Microdipodops megacephalus. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 14 January 2009.
- Lance, Stacey L.; Light, Jessica E.; Jones, Kenneth L.; Hagen, Cris; Hafner, John C. (2010). "Isolation and characterization of 17 polymorphic microsatellite loci in the kangaroo mouse, genus Microdipodops (Rodentia: Heteromyidae)". Conservation Genetics Resources 2 (1): 139–141. doi:10.1007/s12686-010-9195-4. ISSN 1877-7252.
- Hafner, John C.; Reddington, Emily; Craig, Matthew T. (2006). "KANGAROO MICE (MICRODIPODOPS MEGACEPHALUS) OF THE MONO BASIN: PHYLOGEOGRAPHY OF A PERIPHERAL ISOLATE". Journal of Mammalogy 87 (6): 1204–1217. doi:10.1644/06-MAMM-A-067R1.1. ISSN 0022-2372.
- "Microdipodops megacephalus". Smithsonian National Museum of Natural History. Retrieved 22 April 2013.
- Boone, Jim. "Dark Kangaroo Mouse (Microdipodops megacephalus)". Bird and Hike. Retrieved 22 April 2013.
- O'Farrel, Michael, and Andrew Blaustein. "Microdipodods megacephalus ." Mammalian Species . 46. (1974): 1-3. Print
- Linzey, A.V. & NatureServe (Hammerson, G.) 2008.Microdipodops megacephalus. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>.
- Kim, Dai-Hong. "Microdipodops megacephalus". Animal Diversity Web. Retrieved 22 April 2013.
- Schitoskey, Frank. "Notes on Morphological Variation in the Dark Kangaroo Mouse ." Southwestern Association of Naturalists. 13.2 (1968): 243-248. Print.
- Harris, John. "Variation in the Caudal Fat Deposit of Microdipodops megacephalus." Journal of Mammalogy. 68.1 (1987): 58-63. Print.
Names and Taxonomy
Comments: Hall's (1981) suggestion that subspecies leucotis may warrant specific status was not supported by Hafner and Hafner (1983).