Dark Kangaroo Mouse
These kangaroo mice are found in the Great Basin region of western United States, including Oregon, Utah, California, and Nevada. 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.
Dark kangaroo mouse
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 under parts, 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 tassel; 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.
Reproduction
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.
Behavior
Microdipodops megacephalus are primarily bipedal, using large and powerful hind legs for locomotion. The small forelegs are scarcely used in moving. The tail, if used at all, functions as a balancing device. Upright posture is also used in defending territory and in fleeing from danger. During nest defense, kangaroo mice make high pitched squeals. These kangaroo mice sleep on their backs with their forelimbs stretched over their heads and the hind limbs tucked on the belly. They are nocturnal and extremely sensitive to light. When exposed to a light, they seek shelter under the darkest spot available.
Peak activity occurs in the first two hours after sunset. Moonlight and temperature are additional factors affecting the activity of the kangaroo mice. Activity reaches its peak under partly cloudy skies, and ceases during rain. Activity is only observed from March to October, suggesting the kangaroo mice may hibernate. Kangaroo mice are solitary animals and are aggressive toward one another. Cannibalism has been recorded when two individuals were kept together. Other laboratory studies showed that adults avoid one another or stay together for only one or two nights. Kangaroo mice can be easily kept in captivity.
Food Habits
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. In captivity they should be offered a complete diet of rodent lab blocks, and rat or mouse mix, with bits of fruit or veggies regularly. Cheerios or wheat bread are great treats, in small quantities. Do NOT feed chocolate, fried foods, salted foods, candy or junk food! They may enjoy crickets and mealworms if they are captive bred, never feed wild insects as they may carry parasites. Vitamins, like Nutri-Cal are a good addition to their diet, and added calcium during nursing and growth due to demands on their systems at those times, but take care not to overdo it. Water bottles should be used to proved constant, clean water. Ceramic or stoneware food dishes work well for keeping seeds or fresh foods off the floor, and a wire mesh hopper that allows them to eat the lab blocks through without extra waste.
