23-532: Rhabdomys dilectus Rhabdomys pumilio Rhabdomys is a largely Southern African genus of muroid rodents slightly larger than house mice . They are known variously as striped or four-striped mice or rats . Traditionally the genus has been seen as a single species, Rhabdomys pumilio , though modern evidence on the basis of karyotype and mtDNA analysis suggests that it comprises two or more species and subspecies. Dorsally Rhabdomys species display four characteristic black longitudinal stripes on
46-721: A "Roman nose" . Head+body length is about 105mm, and the same for the tail. A large male might have a mass of 55 grams. Ignoring distinctions between species, Rhabdomys as a genus is widespread and abundant in the Southern African subregion. A few areas apparently do not support a population, but for the most part they occur rather patchily all the way from the southernmost Western Cape to northern Namibia and parts of Botswana , Mozambique , and Zimbabwe . It also has been recorded from parts of Angola , Zambia , Malawi , Tanzania , Kenya , Uganda and southern Congo . Unlike most small rodents, Rhabdomys species exhibit
69-626: A diurnal , bimodal activity pattern, with activity concentrated around crepuscular periods in mornings and evenings, and reduced during the midday period. The omnivorous diet, the ability to survive without water provided that the food has a minimum water content of 15%, and its extreme plasticity in habitat preference are likely reasons for its wide (if discontinuous; Brooks, 1982) distribution throughout Southern Africa. Rhabdomys are fairly omnivorous and will eat some kinds of insects opportunistically, but their main foods are seeds and other vegetable matter such as certain forbs . They will also eat
92-402: A fairly typical smallish murid, rather larger than house mice. Head+body length is between 90 and 135 mm, the length of the tail between 80 and 135 mm, the length of the foot between 17 and 33 mm, the length of the ears between 10.0 and 20 mm and the weight up to 68 g. The back is dark reddish-brown and displays characteristic black longitudinal stripes. The stripes inspired
115-638: A flexible social organisation and mating system that appears to be shaped primarily by resource (particularly food and cover) availability and, secondarily, by population density . In arid habitats (e.g. Namib ; Kalahari; succulent karoo Rhabdomys can be described as a territorial, group-living, solitary forager that displays biparental care. In mesic, grassland habitats (e.g. Kwa-Zulu Natal Midlands ; Pretoria Highveld ; Zimbabwe grassland; and semi-succulent thorny scrub (e.g. Eastern Cape ) animals are solitary, with females rearing their litters on their own, and both sexes maintain territories that overlap
138-633: A paler background. Dorsally Rhabdomys species display four black longitudinal stripes on a paler background, and accordingly authors sometimes describe it as having seven stripes. In any event Rhabdomys species as a group are unmistakable because no similarly sized Southern African rodents are similarly marked. Their stripes inspired the generic name, which is derived from the Greek rhabdos meaning rod; hence Rhabdomys , meaning something like "barred mouse". Physically they are fairly typical smallish Murids , rather larger than house mice , and with more of
161-652: A suite of (open and free) data and tools named the Global Human Settlement Layer (GHSL) to improve the science for policy support to the European Commission Directorate Generals and Services and as support to the United Nations system. Several of the most densely populated territories in the world are city-states , microstates and urban dependencies . In fact, 95% of the world's population
184-452: Is a key geographical term. Population density is population divided by total land area , sometimes including seas and oceans, as appropriate. Low densities may cause an extinction vortex and further reduce fertility. This is called the Allee effect after the scientist who identified it. Examples of the causes of reduced fertility in low population densities are: Population density is
207-445: Is concentrated on just 10% of the world's land. These territories have a relatively small area and a high urbanization level, with an economically specialized city population drawing also on rural resources outside the area, illustrating the difference between high population density and overpopulation . Deserts have very limited potential for growing crops as there is not enough rain to support them. Thus, their population density
230-455: Is found throughout southern Africa . Rhabdomys dilectus lives in the wetter mountain savannas up to 2,300 meters above sea level. It often invades cultivated fields. In urban areas it may enter houses. Population density Population density (in agriculture : standing stock or plant density ) is a measurement of population per unit land area. It is mostly applied to humans , but sometimes to other living organisms too. It
253-773: Is generally low. However, some cities in the Middle East, such as Dubai , have been increasing in population and infrastructure growth at a fast pace. Cities with high population densities are, by some, considered to be overpopulated, though this will depend on factors like quality of housing and infrastructure and access to resources. Very densely populated cities are mostly in Asia (particularly Southeast Asia ); Africa's Lagos , Kinshasa , and Cairo ; South America's Bogotá , Lima , and São Paulo ; and Mexico City and Saint Petersburg also fall into this category. City population and especially area are, however, heavily dependent on
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#1732793445670276-401: The mesic four-striped grass rat , is a species of rodent in the family Muridae . Traditionally the genus Rhabdomys has been seen as a single species, Rhabdomys pumilio , though modern evidence on the basis of karyotype and mtDNA analysis suggests that it comprises a second species, Rhabdomys dilectus . R. dilectus is divided in the following subspecies. Rhabdomys dilectus is
299-493: The analysis of mitochondrial DNA , as well as evidence of divergent behavioural repertoires among populations (e.g. courtship behaviours). It has initially been suggested that R. pumilio be reclassified as two species: R. pumilio (the social form that occurs in xeric habitats; 2n = 48) and R. dilectus (the solitary form, found in mesic areas, that comprises two subspecies R. d. dilectus , 2n = 46, and R. d. chakae , 2n = 48). More recent mtDNA and nuclear DNA analyses support
322-538: The caracal, serval, wildcat and black-footed cat, jackal, and several species of mongoose. They also are major food items for several species of birds of prey. Even owls take advantage when they catch the mice in crepuscular activity. Rhabdomys is a seasonal breeder and reproductively active from spring to autumn. After a gestation period of 22–23 days, free-living females give birth to approximately five pups; captive females have slightly larger litters (e.g. 7.2 ±1.8). Pups begin to consume solid food at ten days, leave
345-547: The definition of "urban area" used: densities are almost invariably higher for the center only than when suburban settlements and intervening rural areas are included, as in the agglomeration or metropolitan area (the latter sometimes including neighboring cities). In comparison, based on a world population of 8 billion, the world's inhabitants, if conceptualized as a loose crowd occupying just under 1 m (10 sq ft) per person (cf. Jacobs Method ), would occupy an area of 8,000 square kilometres (3,100 sq mi)
368-663: The existence of at least four distinct species, "R. pumilio" confined to the south western coastal parts of South Africa, "R intermedius" confined mostly to the higher altitudes of the arid western part of South Africa (above the Great Escarpment), "R. bechuanae" confined mostly to the western regions of South Africa and Namibia above the Orange river and "R. dilectus" confined to the mesic east of southern Africa ). [REDACTED] [REDACTED] [REDACTED] [REDACTED] Rhabdomys dilectus Rhabdomys dilectus ,
391-417: The generic name, which is derived from the Greek rhabdos meaning rod, giving Rhabdomys, meaning something like "barred mouse". The ventral sides are lighter. The legs are dark grizzled. The tail is shorter than the head and body. It is a terrestrial species, crepuscular and solitary. It feeds mainly on seeds of wheat and partly on plants, berries and small invertebrates. It is considered a plague by farmers. It
414-478: The more northern regions, and animals from the xeric western areas have a paler coat than do mice from the mesic, eastern regions. In addition, there appear to be population level differences in personality – an animal's characteristic and consistent style of behaviour – and stress-sensitivity, although these differences have yet to be investigated empirically. Two karyotypic forms of Rhabdomys (2n = 28 and 2n = 46) have been detected. Based on this finding and on
437-520: The nest from twelve days, and weaning occurs at around 16 days. Sexual maturity is reached at approximately five to six weeks (range 34 – 90 days). Timing of sexual maturity, as well as dispersal age, depends on environmental factors (e.g. resource availability), social cues (e.g. the presence of older, reproductively active animals), as well as the animal's developmental history (e.g. weight at weaning; sex-ratio of litter). Females have an inter-litter interval of approximately 23–30 days. Rhabdomys has
460-510: The number of people per unit of area, usually transcribed as "per square kilometer" or square mile, and which may include or exclude, for example, areas of water or glaciers. Commonly this is calculated for a county , city , country , another territory or the entire world . The world's population is around 8,000,000,000 and the Earth 's total area (including land and water) is 510,000,000 km (200,000,000 sq mi). Therefore,
483-423: The territories of the opposite, but not the same, sex. However, males from both mesic and xeric populations display parental care in captivity, suggesting a plesiomorphic occurrence in the mesic populations, since the desert-living form represents the ancestral form. There is some regional variation in morphology . Striped mice from the southwestern regions of southern Africa are slightly larger than animals from
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#1732793445670506-435: The underground storage organs of certain small species of geophytes , such as edible Moraeas , which they can locate by smell and dig up. Though they are by no means generally regarded as serious pests, their depredations can be unwelcome to grain farmers and horticulturists when their population happens to be high. Rhabdomys are important prey items for many species of snake, and for small to medium-sized carnivores such as
529-599: The worldwide human population density is approximately 8,000,000,000 ÷ 510,000,000 = 16/km (41/sq mi). However, if only the Earth's land area of 150,000,000 km (58,000,000 sq mi) is taken into account, then human population density is 53/km (140/sq mi). This includes all continental and island land area, including Antarctica . However, if Antarctica is excluded, then population density rises to over 58 per square kilometre (150/sq mi). The European Commission's Joint Research Centre (JRC) has developed
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