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Salpingotus pallidus, the pale pygmy jerboa, is endemic to Kazakhstan, where it occupies two distinctly isolated desert habitats. The first is the Northern Aral Sea where it is found in the Aral Karakums, and the Great and Small Barsuki regions. They are also found in the southern Lake Balkhash area where they occur in scattered, widely distributed populations.
Biogeographic Regions: palearctic (Native )
Pale pygmy jerboas are small rodents, with an average body length of 55 mm. They have large heads, almost as large as their bodies. They have relatively large eyes and a broad snout in comparison to the size of the head. The tail is long, being almost twice the length of the body and averaging 104.8 mm. The end of the tail is sparsely covered with white hairs in all females and in some males. The tails of males have a black end brush that is 2.5 to 3 times longer than those of the females. This is their only known sexually dimorphic trait. Fur coloration is characterized by light grey or beige fur. They have a broad dorsal stripe that starts as a light yellow grey color but gets darker as it extends down the back. Fur on the muzzle, neck, belly, legs, and feet is white. Pale pygmy jerboas, and other three-toed pygmy jerboas are distinguished by the three toes on their hind feet. Their hind legs and tails are long to help them jump. The length of the hind foot averages 22.7 mm, almost half the length of the body, while both the front feet and limbs are much shorter as they are not used when walking or running. Males can be distinguished with penile morphology, characterized by the coverage of small spines of uniform height. Other differences include thickness of the incisors, the distance between the angular and coronoid processes in the mandible, and the width of the ascending branch of the mandible.
Range mass: 7.6 to 12.5 g.
Average mass: 9.8 g.
Range length: 53 to 61 mm.
Average length: 55 mm.
Other Physical Features: endothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: ornamentation
Pale pygmy jerboas inhabit northern sandy semi-deserts with sparse sod-forming grasses. Specific habitats vary regionally. In the Aral Karakums, they are found in areas with dense wormwood-cereal vegetation where the sand forms small hills or mounds. Tn the Great Barsuki area they are found on level ridges characterized by areas of clumped but dense vegetation that grows between 40 and 50 cm high. This vegetation is composed of sand wormwood (Artemesia arenaria), goat’s wheat (Atraphazis spinosa), Siberian couch grass (Agropyron sibiricum), gray wormwood (Artemisia glance), feather grass (Stipa joannis), and euphorbia (Euphorbia seguieriana). In the southern Lake Balkhash area they are found in a wider variety of sand types. These include ridged or mounded sand areas and depressions between small hillocks or ridges. The vegetation in these areas is composed mainly of wormwood but also includes sand sedge (Carez physodes) and old-world winter fat (Eurotia ceratoides).
The southern Lake Balkash area is located at about 350 m above sea level and the Aral Karakums is at about 55 to 118 m about sea level.
Range elevation: 55 to 350 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: desert or dune
The pale pygmy jerboa diet is almost entirely made up of insects and seeds. In the spring insects make up about 60% of their diet, in summer months seeds comprise 70% of the diet. Commonly eaten seeds are Carex physodes, Eremopyron oreintale, and Menocus linifolius. Pale pygmy jerboas also eat the dead bodies of lizards, birds, and other small rodents when they find them. Vegetation and bulbs comprise about 1 to 2% of their diet.
Animal Foods: birds; mammals; reptiles; insects
Plant Foods: leaves; roots and tubers; seeds, grains, and nuts
Primary Diet: omnivore
Pale pygmy jerboas have multiple ecosystem roles, as do most animals. They effect their ecosystem primarily through diet and burrowing patterns. They are predators of small insects and seeds of Carex physodes, Eremopyron oreintale, and Menocus linifolius, in addition to other species. They also eat carrion occasionally. They also impact their ecosystem by competing with other, sympatric rodents, such as gray hamsters (Cricetulus migratorius), northern three-toed jerboas (Dipus sagitta), and midday gerbils (Meriones meridianus). Their burrowing activities may also impact vegetation communities. The effects of parasites and disease have not been studied in this particular species, but in Salpingotus crassicauda parasite loads were not substantial.
Ecosystem Impact: biodegradation ; soil aeration
No predators of pale pygmy jerboas are reported. It is worth noting that the length of the foot matures more quickly than the body in juvenile pygmy jerboas, allowing them to rapidly acquire the ability to jump and run well. This could be the result of the need to forage at a younger age, an anti-predator adaptation, or both. Moreover, when pale pygmy jerboas are threatened, they will hide under bushes or bury themselves under the sand. Their nocturnal habits and cryptic coloration also help to protect them from predators.
Anti-predator Adaptations: cryptic
Pale pygmy jerboas respond strongly to vocalizations and are believed to use sound as a primary method for communication. They have well-developed ears and large eyes, which is a trait common in nocturnal animals. They are likely to have good vision in low light and use their vision and sense of smell and touch to navigate and find food.
Communication Channels: acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
Pale pygmy jerboas have a maximum lifespan of 2.5 years in the wild. In captivity they live slightly longer, with a maximum lifespan of 3 years. Cause of death has not been well studied but predation rates and parasite loads are low, so it is likely that they die of disease or old age.
Status: wild: 2.5 (high) years.
Status: captivity: 3 (high) years.
Status: wild: 2.5 (high) hours.
Status: captivity: 3 (high) years.
Pale pygmy jerboas are solitary. When kept in captivity with conspecifics, pale pygmy jerboas will bite or kill each other. Their mating behavior is most likely polygynandrous or promiscuous.
Pale pygmy jerboas react better to sound than to scent, although there is currently no information on how these animals locate their mates.
Mating System: polygynandrous (promiscuous)
Female pale pygmy jerboas dig brood burrows that are much more complex than a typical burrow, but are found at the base of ridges or under shrubs, which helps prevent tunnel collapse. Brood burrows consist of about 4 different exists, multiple blind alleys, additional chambers, and one brood chamber with bedding. Mating begins in late April and continues through early May. Births occur in the beginning of July, suggesting a gestation period of 30 to 35 days. A second brood may occur in early August. Average litter size varies with location, consisting of 2 to 4 pups in the northern Aral Sea (average 2.8), while in the southern Lake Balkhash area the average litter contains 4 to 5 pups (average 4.1). The birth weight of pups fluctuates from 0.71 to 0.95 g and body length is approximately 37% the length of adults. Pups grow quickly after birth. In the first two days fur appears on the back and by 13 days fur appears on the rest of the body. At 15 days old the pups have both upper and lower teeth and their body size reaches approximately 68% of that of an adult, with the foot length developing more rapidly and reaching 85% of its adult length. By 30 days the young begin leaving the burrow to forage on their own, although they will continue to nurse for several more days. The young complete their growth before hibernating for winter and do not reach sexual maturity until the next breeding season, in late April.
Breeding interval: Breeding occurs one to two times from early July to late August.
Breeding season: Breeding occurs from late April through early May.
Range number of offspring: 2 to 5.
Range gestation period: 30 to 35 days.
Average weaning age: 30 days.
Average time to independence: 35 days.
Range age at sexual or reproductive maturity (female): 10 to 11 months.
Range age at sexual or reproductive maturity (male): 10 to 11 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Male pygmy jerboas invest very little in their offspring. They find and mate with females in the spring, which is the extent of their contribution, as females raise their offspring by themselves. For female pygmy jerboas, this includes building a burrow and then nursing their offspring for a little over a month at which time the pups gradually begin to leave the burrow to forage on their own.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
Pale pygmy jerboas are considered data deficient by the IUCN because little is known about their population trends. Population sizes are small, fluctuate yearly, and populations are fragmented. They are considered rare in some parts of their range. More research is needed on population status to assess their conservation risk.
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
Pale pygmy jerboas have no negative impact on humans.
Salpingotus pallidus and related jerboas provide no known benefits for humans.