Gerbillinae, otherwise known as the gerbils, jirds, and relatives, is a large Old World murid subfamily. This subfamily is one of the most well-defined in Muroidea. Its members have much in common; most being diurnal, saltatorial desert rodents. There are 103 gerbilline species in 16 genera. (Musser and Carleton, 2005)
Gerbillines are Old World rodents. They are distributed throughout Africa and the Middle East, through central Asia including much of India, to eastern Mongolia. (Carleton and Musser, 1984)
Most gerbillines live in dry, open habitats with sparse vegetation, including deserts, sandy plains, mountain slopes, steppes, grasslands, and savannahs. Some species also inhabit moist woodlands, agricultural fields, and mountain valleys. (Carleton and Musser, 1984; Nowak, 1999)
Gerbillines are small to medium-sized rodents. They range in length from 50 to 200 mm, with tails measuring 56 to 245 mm. They weigh between 10 and 227 grams. Gerbillines vary in the amount to which they are sexually dimorphic; even within a species males may be heavier than females in one population and the sexes may be the same size in another population (Sinai et al. 2003). Most gerbillines have well-furred, long tails and are modified for saltatorial locomotion, with long, narrow hind feet. Some species are cursorial. Gerbillines are generally slender animals with long claws. They may have long or short ears. Their pelage is long, thick, and soft or short and harsh. Some have tufted tips on their tails. Fur color varies widely, and may be reddish, mouse gray, yellowish, clay-colored, olive, dark brown, orangish, sandy buff, or pinkish cinnamon on the dorsal surface. The underparts are generally paler shades of gray, cream, or white. Some species have whitish spots on their heads, especially behind the ears.
The gerbilline dental formula is 1/1, 0/0, 0/0, 3/3 = 16, except for the genus Desmodilliscus, which only has two lower molars on each side. The layers of enamel on the incisors are very thin compared to other muroid rodents. The molars are rooted, with lophate, planar, or prismatic enamel patterns. The coronoid process is very small or absent. Gerbillines have 12 thoracic vertebrae and seven lumbar vertebrae. Females have three or four pairs of mammae. The stomach consists of just a single chamber. There are no supraorbital or mandibular branches of the stapedial artery, and instead, the infraorbital artery supplies blood to the orbits. Gerbillines have diploid chromosome numbers between 18 and 74. (Carleton and Musser, 1984; Nowak, 1999; Sinai, et al., 2003)
During mating, copulatory plugs form in the reproductive tracts of females that hinder subsequent matings. The presence of these copulatory plugs suggests a polygynandrous mating system. (Carleton and Musser, 1984)
Some gerbilline species breed year-round, and some breed seasonally. Females of most species are polyestrus and are able to bear multiple litters in a year. Some also experience a postpartum estrus and delayed implantation, such that a new litter begins developing as soon as the first is weaned. Gestation periods, if females are not lactating, last three to four weeks, longer if lactating. Overall, litter sizes range from 1 to 13, although litters of 4 to 7 are much more common. Young gerbils are born completely naked and blind. They begin to grow fur between 8 and 13 days after birth, and are fully furred at 13 to 16 days. Eyes open about two or three weeks after birth. The young can walk quickly and hop about on all fours at about three weeks. At around one month of age, the young are weaned and independent; they reach sexual maturity at 10 to 16 weeks. (Dempster and Perrin, 1989; Nowak, 1999)
Female gerbils brood their young until the young are about 30 days old. When brooding, they stand on all fours with their feet splayed out around the litter. Gerbil mothers are known to move their young to new nests several times for the first couple of days after birth, and also to switch burrows between litters. When they leave the young in the nest to go out foraging, they sometimes cover their brood with grass and sand and block up the nest entrance. Females carry their young by gripping them around the midsection in their mouths. Once the young are able to move around more, mothers grab them by their tails and pull them near, then carry the young back to the nest. They stop retrieving their young when the young are between 17 and 23 days old. Mothers frequently groom their young; licking the neonates' hindquarters to stimulate them to produce urine and feces, which the mothers then consume. Gerbil mothers groom their litters until the young go off on their own; the young of some species begin grooming each other and their mothers 25 days after birth. Males of some species brood and groom their young in the same manner as females. (Dempster and Perrin, 1989; Nowak, 1999)
Most gerbillines do not live longer than three or four months in the wild. In captivity, some gerbillines have been known to live as long as eight years. (Nowak, 1999)
Gerbillines are terrestrial and most are saltatorial. Some species are capable of remarkable leaps of up to 3.5 meters. Other species locomote cursorially on all fours. Those that live in rocky habitats are often good climbers. For the most part, gerbillines are diurnal rodents, but some species are nocturnal, crepuscular, or active both day and night. Gerbillines build burrows, which may be simple structures with just one entrance and nest chamber, or elaborate networks of tunnels with multiple entrances and chambers for nesting, food storage, and excrement. Gerbillines take dust baths to keep their silky coats in good condition.
Some gerbilline species are solitary, aggressive, and territorial, with each individual inhabiting its own burrow. Other species are highly gregarious and form large colonies, with many individuals inhabiting tunnel networks tens of meters long and two or three meters deep. Still others live in small family groups, and each family group defends its own territory. There is much socializing among some gerbillines while they are in the nest. The pups groom one another, chase each other, and play-fight when they are between 18 and 35 days old.
Gerbillines are mainly sedentary, though the young may go through a nomadic period until they are able to establish permanent home ranges, and some species migrate in times of drought. Gerbillines do not hibernate or aestivate, but in some areas they experience long bouts of torpor in the winter and remain in their burrows living off of stored food for months at a time. (Carleton and Musser, 1984; Dempster and Perrin, 1989; Hubbard, 1972; Nowak, 1999)
Gerbillines have large eyes and good vision. They also use auditory, chemical, and tactile cues in perceiving their environment.
Gerbils have a range of vocalizations that they use to communicate with one another. Young gerbils squeak when their mother enters the nest, grunt when they are resting together or climbing on one another, and they also make a clicking noise. Adult gerbils squeak and sometimes produce a high-pitched rattle. They also are known to drum their hind feet on the ground. Gerbillines communicate with one another through chemical means, as well, using pheromones to signal reproductive and social status. Male gerbillines communicate territory ownership by scent-marking with their large ventral sebaceous glands. (Carleton and Musser, 1984; Dempster and Perrin, 1989; Nowak, 1999)
Gerbillines are primarily herbivorous or omnivorous, consuming nuts, seeds, roots, bulbs, fruits, grasses, insects, bird eggs and nestlings, and even others of their own species. Gerbillines store large quantities of plant food in their burrows--sometimes as much as 60 kg. (Nowak, 1999)
Gerbillines are preyed upon by various snakes, owls, and small mammalian carnivores. To discourage predators from entering their burrows, some gerbillines keep the entrances blocked with sand. Others incorporate bolt holes into their burrow systems, into which they can make a hasty retreat if caught out in the open. In addition, gerbillines usually have neutral-colored fur, which no doubt helps them blend in to their sandy or rocky background. (Carleton and Musser, 1984; Nowak, 1999)
Gerbillines are primary and secondary consumers, and they are food for a number of higher-level consumers. They are also pollinators of certain plants (Johnson et al. 2001), and probably have a role in seed dispersal. Gerbillines are parasitized by several flea species, such as Xenopsylla debilis, Xenopsylla humilis, and Xenopsylla difficilis. (Hubbard, 1972; Johnson, et al., 2001)
Gerbillines, especially Meriones unguiculatus, are clean, easy to take care of, and breed readily in captivity. For these reasons, they are used in many laboratories for medical, physiological, and psychological research. They are also popular pets. Other gerbilline species are trapped for their skins. (Nowak, 1999)
Some gerbillines are considered pest animals in their native ranges, because they destroy crops, damage embankments and irrigation systems with their digging, and spread bubonic plague. There is also concern that captive gerbils may escape and establish feral populations, which could outcompete native rodents. (Nowak, 1999)
Currently, 35 gerbilline species are on the IUCN's Red List of Threatened Species. This includes one critically endangered species (Cheng's jirds, Meriones chengi), four endangered species (Arabian jirds, Meriones arimalius, Dahl's jirds, Meriones dahli, Buxton's jirds, Meriones sacramenti, and Zarudny's jirds, Meriones zarudnyi), two vulnerable species (western gerbils, Gerbillus hesperinus, and Allenby's gerbils, Gerbillus andersoni allenbyi), one near threatened species (Hoogstral's gerbils, Gerbillus hoogstraali), one lower risk species (large Aden gerbils, Gerbillus poecilops), and 26 species that lack data. Research efforts are needed to establish the status of those species for which little is known. (IUCN, 2004)
Tanya Dewey (editor), Animal Diversity Web.
Allison Poor (author), University of Michigan-Ann Arbor.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
living in landscapes dominated by human agriculture.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.
uses smells or other chemicals to communicate
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
active at dawn and dusk
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
an animal that mainly eats leaves.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
an animal that mainly eats fruit
an animal that mainly eats seeds
An animal that eats mainly plants or parts of plants.
An animal that eats mainly insects or spiders.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
makes seasonal movements between breeding and wintering grounds
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
generally wanders from place to place, usually within a well-defined range.
an animal that mainly eats all kinds of things, including plants and animals
found in the oriental region of the world. In other words, India and southeast Asia.
the business of buying and selling animals for people to keep in their homes as pets.
chemicals released into air or water that are detected by and responded to by other animals of the same species
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
specialized for leaping or bounding locomotion; jumps or hops.
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
scrub forests develop in areas that experience dry seasons.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
places a food item in a special place to be eaten later. Also called "hoarding"
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
movements of a hard surface that are produced by animals as signals to others
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
breeding takes place throughout the year
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