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Brief Summary

    Gerbil: Brief Summary
    provided by wikipedia
    For other uses, see Gerbil (disambiguation).

     src= A young gerbil sitting by the food bowl to eat  src= A mother gerbil sitting with four young gerbils

    A gerbil is a small mammal of the subfamily Gerbillinae in the order Rodentia. Once known as desert rats, the gerbil subfamily includes about 110 species of African, Indian, and Asian rodents, including sand rats and jirds, all of which are adapted to arid habitats. Most are primarily active during the day, making them diurnal (but some species, including the common household pet, exhibit crepuscular behavior), and almost all are omnivorous. Gerbils are related to mice and rats; they all belong to the family Muridae.

    One Mongolian species, Meriones unguiculatus, also known as the clawed jird, is a gentle and hardy animal that has become a popular small house pet. It was first brought from China to Paris in the 19th century. It was brought to the United States much later, in 1954, by Dr. Victor Schwentker for use in research. Notably, it is illegal to keep gerbils as pets in California and New Zealand.

    The gerbil got its name as a diminutive form of "jerboa", an unrelated group of rodents occupying a similar ecological niche. Gerbils are typically between 6 and 12 inches (150 and 300 mm) long, including the tail, which makes up about 1/2 of their total length. One species, the great gerbil, Rhombomys opimus, originally native to Turkmenistan, can grow to more than 16 inches (410 mm). The average adult gerbil weighs about 2.5 ounces (71 g).

Comprehensive Description

Distribution

    Distribution
    provided by Animal Diversity Web

    Gerbillines are Old World rodents. They are distributed throughout Africa and the Middle East, through central Asia including much of India, to eastern Mongolia.

    Biogeographic Regions: palearctic (Native ); oriental (Native ); ethiopian (Native )

Morphology

    Morphology
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    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.

    Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

    Sexual Dimorphism: sexes alike; male larger

Habitat

    Habitat
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    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.

    Habitat Regions: temperate ; tropical

    Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral ; forest ; scrub forest ; mountains

    Other Habitat Features: agricultural

Trophic Strategy

    Trophic Strategy
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    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.

    Foraging Behavior: stores or caches food

    Primary Diet: carnivore (Eats terrestrial vertebrates, Eats eggs, Insectivore ); herbivore (Folivore , Frugivore , Granivore ); omnivore

Associations

    Associations
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    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.

    Ecosystem Impact: disperses seeds; pollinates

    Commensal/Parasitic Species:

    • Xenopsylla debilis
    • Xenopsylla humilis
    • Xenopsylla difficilis
    Associations
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    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.

    Known Predators:

    • snakes (Serpentes)
    • owls (Strigiformes)
    • mammalian carnivores (Carnivora)

    Anti-predator Adaptations: cryptic

Behavior

    Behavior
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    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.

    Communication Channels: acoustic ; chemical

    Other Communication Modes: pheromones ; scent marks ; vibrations

    Perception Channels: visual ; tactile ; acoustic ; chemical

Life Expectancy

    Life Expectancy
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    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.

Reproduction

    Reproduction
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    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.

    Mating System: polygynandrous (promiscuous)

    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.

    Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous ; delayed implantation ; post-partum estrous

    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.

    Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Male, Female)

Conservation Status

    Conservation Status
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    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.

Benefits

    Benefits
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    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.

    Negative Impacts: injures humans (carries human disease); crop pest

    Benefits
    provided by Animal Diversity Web

    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.

    Positive Impacts: pet trade ; body parts are source of valuable material; research and education