Dark kangaroo mouse
|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.
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