Their fossil records date back to the early Oligocene era in North America. There are currently two living species in the genus Microdipodops, M. megacephalus and M. pallidus. Kangaroo mice can survive for a long period of time without drinking water. They can obtain sufficient moisture from their food while it is metabolized, and from drops of dew. They have specially designed kidneys, which can efficiently concentrate urine and avoid loss of water. Some individuals have been reported to have survived without water for 7 months.
O'Farrell and Blaustein (1974), Nowak (1991), Grizmek (1990).
Perception Channels: tactile ; chemical
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
Used in laboratory researches for water conservation, renal physiology, and irradiation. http://netvet.wustl.edu/org/AWIC/misc/uncomsp.htm
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).
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 )
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
Average lifespan
Status: captivity: 5.4 years.
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).
Other Physical Features: endothermic ; bilateral symmetry
Average mass: 13.4 g.
Average basal metabolic rate: 0.168 W.
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).
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
Average number of offspring: 4.
The dark kangaroo mouse (Microdipodops megacephalus) is a species of rodent in the family Heteromyidae.[2] It is found in California, Idaho, Nevada, Oregon and Utah in the United States.[1][3]
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 Australian kangaroos.[4][5][6][1] It belongs to the order Rodentia and Family Heteromyidae.[4][5][6][1][7][8][9] Its head is large in comparison to its body size due to enlarged auditory bullae.[7] It has a relatively short neck[7] large ears, prominent eyes, a long snout, long whiskers and a fat, haired tail.[4][5]
The coat of dark kangaroo mouse is long, silky, and soft with its back being brownish to greyish black while its belly having a greyish or whitish hue.[7] 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.[5][7][9] The tails are thickest before entering winter hibernation and thin in the spring, when they come out of hibernation and assume normal activity.[4][9] This is unique among North American small mammals.[5]
There is no sexual dimorphism shown in dark kangaroo mice except for zymomatic breadth. Length of hind foot, cranial measurement, and mandibular length vary little while weight is highly variable in the population.[8] The total length ranges from 138 to 177 millimetres (5.43 to 6.97 in) with an average of 160 millimetres (6.30 in), length of tail: 68 to 103 millimetres (2.68 to 4.06 in), hind foot length: 23 to 27 millimetres (0.91 to 1.06 in), weight of adults ranges from 10 to 16.9 grams (0.35 to 0.60 oz) with an average of 13.1 grams (0.46 oz).[4][6]
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).[6][1] They prefer to live in loose sand and gravels (found in the Upper Sonoran life zone).[5][6]
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.[1]
Their main predators are owls, foxes, badgers and snakes.[1][7]
Dark kangaroo mice mostly eat small seeds (granivores), which are carried back to their burrows in their cheek pouches.[4][5][6][1][7] 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.[6][7]
Kangaroo mice do not drink water actively, instead, utilize water from their food source. They also have adaptation mechanisms to further conserve water: being active at night (lower temperature so lose less water), concentrating their urine, and producing dry feces.[4]
Dark kangaroo mice are mostly bipedal which move around by hopping on their two hind legs.[4][6][7] Using bipedalism is suggested to be a result of foraging behaviors and using it as a locomotion mode only serves as a side function.[6] They also have been seen to be moving on all 4 limbs when moving in contained spaces such as a cage.[6]
These kangaroo mice are nocturnal animal with peak of activity in the first 2 hours after sunset.[6] Their activity is only observed from March through October while they go into hibernation during winter months.[6] 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.[6]
The dark kangaroo mouse (Microdipodops megacephalus) is a species of rodent in the family Heteromyidae. It is found in California, Idaho, Nevada, Oregon and Utah in the United States.
