Dipodomys microps (Merriam, 1904)
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https://doi.org/ 10.5281/zenodo.6611160 |
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https://doi.org/10.5281/zenodo.6612101 |
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persistent identifier |
https://treatment.plazi.org/id/3C3D87A6-876A-B133-1E9D-5102F876FE49 |
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Carolina |
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Dipodomys microps |
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62. View Plate 11: Heteromyidae
Chisel-toothed Kangaroo Rat
French: Rat-kangourou du Grand Bassin / German: Meil 3elzahn-Kangururatte / Spanish: Rata canguro de dientes de cincel
Other common names: Great Basin Kangaroo Rat, Houserock Chisel-toothed Kangaroo Rat, House Rock Valley Kangaroo Rat, Inyo Pocket Rat, Small-faced Kangaroo Rat
Taxonomy. Perodipus microps Merriam, 1904 ,
Lone Pine, Owens Valley, Inyo Co., California, USA.
Based on molecular sequence analyses, D. microps 1s a member of the heermanni species group, along with D. heermanni , D. gravipes , D. ingens , D. panamintinus , and D. stephensi . Genetic relatedness based on biochemical analyses indicated little variation among populations. Of seven populations for which chromosomal complement has been described (representing five subspecies), all had 2n = 60 and six had FN = 116. The lone exception was one of the disjunct populations from Joshua Tree National Park in the western Mojave Desert of south-eastern California that had FN = 90 but shared 83% ofits alleles with a population 32 km away with FN = 116. Dipodomys microps (with five toes on hindfeet) is sympatric or marginally sympatric with three other five-toed kangaroo rats ( D. ordii , D. agilis , and D. panamintinus ) and with two four-toed kangaroo rats ( D. merriami and D. desert:). Thirteen subspecies recognized.
Subspecies and Distribution.
D. m. microps Merriam, 1904 — SW USA (Owens River drainage of W Mojave Desert, S California).
D. m. alfredi Goldman, 1937 — W USA (Gunnison I, Great Salt Lake, Utah).
D. m. aquilonius Willett, 1935 — W USA (lower elevations of the Great Basin Desert of NE California and NW Nevada).
D. m. bonneuvillei Goldman, 1937 — W USA (Great Basin Desert of NE Nevada and NW Utah, corresponding closely with the former outline of Pleistocene Lake Bonneville).
D. m. celsus Goldman, 1924 — SW USA (possibly disjunct distribution in Virgin River Valley of SW Utah and adjacent NW Arizona).
D. m. centralis Hall & Dale, 1939 — W USA (Great Basin Desert of C & E Nevada).
D. m. idahoensis Hall & Dale, 1939 — W USA (restricted to the Snake River Valley, SW Idaho).
D. m. leucotis Goldman, 1931 — SW USA (restricted distribution between the Vermilion Cliffs and the brink of Marble Canyon of the Colorado River in N Arizona).
D. m. levipes Merriam, 1904 — SW USA (restricted to Panamint Valley, S California).
D. m. occidentalis Hall & Dale, 1939 — SW USA (Great Basin Desert in W & S Nevada and disjunct, restricted populations in the W Mojave Desert, SE California).
D. m. preblei Goldman, 1921 — W USA (Great Basin Desert of SE Oregon and NW Nevada).
D. m. russeolus Goldman, 1939 — W USA (Dolphin I, Great Salt Lake, Utah).
D. m. subtenuis Goldman, 1939 -W USA (Badger, Carrington, and Stansbury Is, Great Salt Lake, and S on the mainland to Cedar Valley, NC Utah). View Figure
Descriptive notes. Head—-body 110-120 mm, tail 135-175 mm, ear 13 mm, hindfoot 42 mm; weight 40-70 g. Male Chisel-toothed Kangaroo Rats are slightly larger than females. Tail is ¢.135% of head-body length. This is a medium-sized kangaroo rat, with five toes on hindfeet (including small claw on side of hindfoot), narrow skull, and lowerincisors that are flattened (chisel-like) on anterior faces. Upper parts are somewhat dark with a gunmetal hue;tail is bicolored, with prominent dark stripes and dull brownish-black crest and tuft. Chromosomal complement has 2n = 60 and FN = 90 or 116. The Chisel-toothed Kangaroo Rat is smaller than the Agile Kangaroo Rat ( D. agilis ) and the Panamint Kangaroo Rat ( D. panamintinus ), and it has chisel-shaped rather than awl-shaped lower incisors, which also distinguishes it from similarly sized Ord’s Kangaroo Rat (D. ordi), which also has wider face.
Habitat. Wide variety of desert plant communities in Great Basin and Mojave deserts. The Chisel-toothed Kangaroo Rat is most abundant in two plant associations: desert valleys dominated by shadscale or saltbush ( Atriplex confertifolia, Amaranthaceae ) and upland desert areas with a deciduous blackbush ( Coleogyne ramosissima, Rosaceae ) component. It is least abundant in areas dominated by creosote bush ( Larrea tridentata, Zygophyllaceae ), brome ( Bromus rubens, Poaceae ), wheatgrass ( Agropyron , Poaceae ), mountain mahogany ( Cercocarpus ledifolius, Rosaceae ), juniper ( Juniperus , Cupressaceae ), and sagebrush ( Artemisia tridentata, Asteraceae ) or where there is an understory or perennial grasses. It occurs on rocky slopes and gravelly floors of low deserts. Where the Chisel-toothed Kangaroo Rat coexists with other kangaroo rats,it is more common than Ord’s Kangaroo Rat where soil is gravelly rather than sandy or loose clay, and it is usually more abundant than Merriam’s Kangaroo Rat. Merriam’s Kangaroo Rat replaces the Chisel-toothed Kangaroo Rat in areas of low shrub cover and at elevations above 1200 m in southern Nevada . Merriam’s Kangaroo Rat ( D. merriami ), the Northern Grasshopper Mouse (Onychomys leucogaster), and the Long-tailed Pocket Mouse ( Chaetodipus formosus ) were trapped at burrow entrances of the Chisel-toothed Kangaroo Rat when seed caches in burrows were large. Burrows average 20-40 cm in depth, with 2-3 surface openings and 2-18 side tunnels, and sometimes form low mounds. Seeds and leaves are cached in burrows. The Chisel-toothed Kangaroo Rat has a discontinuous distribution of apparently relictual populations in San Bernardino and Riverside counties, California , including the isolated population in Joshua Tree National Park. An unusually high-elevation capture at 3200 m occurred in the Inyo-White Mountains of California .
Food and Feeding. Unlike other kangaroo rats, the Chisel-toothed Kangaroo Rat is behaviorally and morphologically adapted for feeding on leaves of shadscale and other desert plants, including spiny hop sage ( Grayia spinosa, Amaranthaceae ), greasewood ( Sarcobatus , Sarcobataceae ), peppergrass ( Lepidium , Brassicaceae ), and clover (7rifolium, Fabaceae ). Shadscale leaves are the predominant item found in cheek pouches. Seeds and seed heads are also gathered, and insects and fungal spores are eaten. Diet of the Chisel-toothed Kangaroo Rat has a high proportion of leaves to seeds in northern and central parts ofits distribution and a high proportion of seeds to leaves along the southern part ofits distribution when leaves are not available. Captive Chiseltoothed Kangaroo Rats from a shadscale-dominated habitat were unable to survive on a diet of air-dried seeds without water or succulent plant material, although most individuals from a habitat without shadscale survived on air-dried seeds alone. Urine concentrating ability is low for the genus. Leaves of shadscale are high in electrolytes (salts), which are concentrated on leaf surfaces. The Chisel-toothed Kangaroo Rat uses its uniquely shaped lower incisors to scrape off salty outer layers before eating the interior, which has only 3% of sodium concentration of discarded shavings and a high starch and water content. This unique feeding behavioris not present in adults from areas where shadscale does not occur, but it can be induced in some captive individuals when exposed to the plant. Coprophagy (ingestion of feces) allows a Chisel-toothed Kangaroo Rat to assimilate 90% ofits natural diet. Reingested feces have more water, lower ash, and higher nitrogen content than non-reingested feces. A Chisel-toothed Kangaroo Rat spends most ofits foraging time collecting succulent leaves of shrubs, first by standing on its hindlegs and then quickly and easily climbing to uppermost twigs, where most leaves are harvested. After a minute or two collecting mostly small sprigs ofleaves,it returnsto its burrow with cheek pouches stuffed with leaves.
Breeding. The Chisel-toothed Kangaroo Rat is able to reproduce when climatic factors prevent reproduction of granivorous species dependent on annual herbs. Breeding season occurs in February-March, with litters a month later. Average littersizes are 2-3 young (range 1-4). Females usually produce a single litter each year, but they are able to produce more than one in very productive years.
Activity patterns. Most (86%) nocturnal activities outside of burrows of Chisel-toothed Kangaroo Rats occur within circular areas of 0-22 ha and include sand bathing, social interactions, foraging, and caching. Underground, the Chisel-toothed Kangaroo Rat is active every day throughout the year. Nightly activity totals less than two hours, soon after sunset, and only 10-15 minutes are spent climbing in shrubs and collecting leaves. Maximum speed of released individuals was 21 km/h. The Chisel-toothed Kangaroo Rat swims voluntarily.
Movements, Home range and Social organization. Densities of Chisel-toothed Kangaroo Rats of 8-34 ind/ha occur a variety of habitats in western Utah, where they make up 22-81% of the nocturnal small mammal community. Densities in Nevada were lower (1-7 ind/ha). The Chisel-toothed Kangaroo Rat is most abundant in spring and early summer, and unlike most species of kangaroo rats, post-reproductive abundance is not strongly correlated with presence of winter annuals.
Status and Conservation. Classified as Least Concern on The IUCN Red Last.
Bibliography. Alexander & Riddle (2005), Best (1993a), Csuti (1979), Eisenberg (1963, 1993), Hafner et al. (2007), Hall (1946, 1981), Hayssen (1991, 1999), Ingles (1954), Jones (1993), Linzey & NatureServe (Hammer son) (2008e), Patton & Rogers (1993), Williams et al. (1993).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
