Like other jerboas, ive-toed pygmy jerboas have a keen sense of hearing, smell, and vision. The greatly inflated auditory bullae allow five-toed pygmy jerboas to sense vibrations produced by low frequency sounds, as well as aid in their sensitive hearing. As is true for most rodents, this species likely communicates largely using olfactory cues.
Communication Channels: tactile ; chemical
Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical
Five-toed pygmy jerboas are widely regarded as vulnerable and rare. They are especially rare in China. The causes of the decline being observed in five-toed pygmy jerboa populations ranges from habitat destruction to predation and interspecific competition. Climatic changes in their usually dry desert habitats are causing increased moisture levels, which in turn lead to rapid plant growth. This eliminates some of the rocky desert habitat that these jerboas require. Human expansion is also degrading this limited habitat type. Increased predation is seriously decimating jerboa populations in Kazakhstan. Interspecific competition with other rodents for food and habitat is also taking its toll in the Russian populations.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: data deficient
Cardiocranius paradoxus has no known negative economic importance for humans.
Five-toed pygmy jerboas have no known positive economic importance for humans aside from their role as members of healthy, desert ecosystems.
The largest role that Cardiocranius paradoxus plays in the ecosystem is as prey for the animals that prey upon it. They are also important predators on seeds in the ecosystems they inhabit.
These small rodents are strictly herbivorous. The diet of Cardiocranius paradoxus mainly consists of seeds and leaves of the grasses and low-growing vegetation found in its habitat. This species is also known to eat the occasional flower. Five-toed pygmy jerboas eat only the juiciest parts of the leaves, although it has been observed that they will also nibble on dead grass. Seeds are collected from the plants themselves, as well as from the ground.
Plant Foods: leaves; seeds, grains, and nuts; flowers
Primary Diet: herbivore (Folivore , Granivore )
Five-toed pygmy jerboas, Cardiocranius paradoxus, are found only in a few areas in Asia. In Russia they are found in the Ubsu-Nur Depression of the Tuva Autonomous Region in the extreme south-central part of the country. In Kazakhstan, their range is restricted to a small area north of Lake Balkhash, where the species was first discovered. They are also found throughout western and southern Mongolia, as well as in the Nan Shan Mountains of northern China.
Biogeographic Regions: palearctic (Native )
Five-toed pygmy jerboas are especially adapted to rocky deserts. These animals prefer to have dunes or outcroppings with ample vegetative cover within their home ranges. The protective shrubbery offers a safe place under which to burrow.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: desert or dune
The lifespan of Cardiocranius paradoxus is currently not known and further data are needed on the subject. A close relative, Jaculus jaculus, is known to live for up to 4 years in the wild and up to 6 years in captivity.
Cardiocranius paradoxus generally reaches a body length of 50 to 75 mm, with the tail extending a further 70 to 78 mm. These small jerboas are grayish buff with white underbellies. The tail is thinly haired and is light brown above and white below. Although rather slim at the base, the tail quickly thickens before coming to a tapering point. At the end of the tail is a tuft of hair.
In most jerboas, the three metatarsals near the center of each hind foot fuse to form a cannon bone, thus there are a total of three toes on each hind foot. Instead, C. paradoxus has five individual toes. The two outside toes (digits 1 and 5) are rather small in comparison to the three central toes, but they are present nonetheless and give this species its common name. The hind foot exhibits a patch of bristly hairs on the sole, which help five-toed pygmy jerboas to obtain better traction on loose sand.
The skull of these small jerboas is heart-shaped, which explains the origin of the generic name, Cardiocranius. Although the external ears are extremely small, the auditory bullae are greatly inflated, allowing C. paradoxus to hear quite well and sense low frequency vibrations. Five-toed pygmy jerboas have large upper incisors that are grooved on the front surface.
Range length: 50 to 75 mm.
Sexual Dimorphism: sexes alike
Other Physical Features: endothermic ; bilateral symmetry
Predators of Cardiocranius paradoxus include common foxes (Vulpes vulpes), Corsac foxes (V. corsac), Eversmann's polecats (Mustella eversmanni), long-eared hedgehogs (Erinaceus auritus), short-eared owls (Asio flammeus), and little owls (Athene noctua). When faced with a predator, these pygmy jerboas hop rapidly (and in a zig-zag manner) for the cover of a shrub or burrow.
Known Predators:
Anti-predator Adaptations: cryptic
To date, nothing has been published concerning the mating system of five-toed pygmy jerboas. Their close relatives, four-toed jerboas (Allactaga tetradactyla), might give some hints as to the mating system for this species. During the breeding months, a male A. tetradactyla will playfully chase a female until she briefly stops and allows him to copulate with her.
Individuals in reproductive condition have been discovered in Kazakhstan in the month of July, but little else is known about the reproductive behavior of this species. This is most likely due to the fact that Cardiocranius paradoxus is a rare species, living in isolated areas, and difficult to study. A close relative that might offer insight is Allactaga tetradactyla. In the case of A. tetradactyla, the breeding season is quite long, with a peak during the summer months. Over the course of the year, these jerboas give birth to three litters of 3 to 5 young per litter. The gestation period for A. tetradactyla is 25 to 42 days and the young reach sexual maturity just after one year of age.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Female five-toed pygmy jerboas have eight teats, as do most jerboas, and nurse their young as all mammals do. Other than this, little is known about the parental investment of Cardiocranius paradoxus. In a close relative, Allacta elater, parental investment consists of the mother caring for her young for several months, protecting and teaching them until they are old enough to fend for themselves.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female); pre-independence (Protecting: Female)
The five-toed pygmy jerboa (Cardiocranius paradoxus) is a species of rodent in the family Dipodidae. It is monotypic within the genus Cardiocranius. It is found in China, Kazakhstan, and Mongolia.
Its natural habitat is temperate desert. This species is not well known and its population and conservation status are unresolved.
Cardiocranius paradoxus has adapted to its desert environment by burrowing underground to prevent overheating and promote survival. They use their burrows for food storage and shelter, and, in cold winters, they hibernate in burrows to conserve energy. Burrowing accounts for the five-toed pygmy jerboa's tendency to be nocturnal, as they prefer to forage for food during the night when conditions are less severe.[2]
The five-toed pygmy jerboa (Cardiocranius paradoxus) is a species of rodent in the family Dipodidae. It is monotypic within the genus Cardiocranius. It is found in China, Kazakhstan, and Mongolia.
Its natural habitat is temperate desert. This species is not well known and its population and conservation status are unresolved.
Cardiocranius paradoxus has adapted to its desert environment by burrowing underground to prevent overheating and promote survival. They use their burrows for food storage and shelter, and, in cold winters, they hibernate in burrows to conserve energy. Burrowing accounts for the five-toed pygmy jerboa's tendency to be nocturnal, as they prefer to forage for food during the night when conditions are less severe.
