Dipodomys spectabilis (Merriam, 1890)
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publication ID |
https://doi.org/ 10.5281/zenodo.6611160 |
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DOI |
https://doi.org/10.5281/zenodo.10845508 |
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persistent identifier |
https://treatment.plazi.org/id/3C3D87A6-8751-B10A-1B31-5C12FAF9F5FD |
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treatment provided by |
Carolina |
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scientific name |
Dipodomys spectabilis |
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48. View Plate 11: Heteromyidae
Banner-tailed Kangaroo Rat
Dipodomys spectabilis View in CoL
French: Rat-kangourou porte-étendard / German: Fahnenschwanz-Kangururatte / Spanish: Rata canguro de cola de bandera
Other common names: Bannertail Kangaroo Rat
Taxonomy. Perodipus spectabilis Merriam, 1890 ,
Dos Cabezos [= Dos Cabezas]|, Cochise Co., Arizona, USA.
Based on molecular sequence analyses, D. spectabilis is a member of the spectabilis species group; it was previously considered conspecific with the other member of the species group, D. nelsoni . Dipodomys nelsoni is sandwiched between three subspecies of D. spectabilis (nominate spectabilis and zygomaticus on the north, cratodon on the south), and investigators disagree on whether three specimens from near La Resolana in northern Durango (just south of the northern near-contact) represent sympatry, past sympatry with limited introgression, or current secondary intergradation between the two species. Molecular sequences including specimens from near La Resolana and throughout distributions of both species showed no evidence of intergradation. Prior to 1960, D. nelsoni was restricted to the east side and D. spectabilis was restricted to the west side of the Rio Conchos and its tributary to the south, the Rio Florido, but in 1960 and 1961, D. nelsoni was found west of the Rio Florido and potentially in contact with the D. spectabilis . To the south, D. spectabilis has been found within 20 km of D. nelsoni . Six subspecies recognized.
Subspecies and Distribution.
D.s.baileyiGoldman,1923—SWUSA(NewMexico,andWTexas);formerlyinNEArizonawherenowextirpated.
D.s.intermediusNader,1965—NWMexico(restricteddistributionintheSonoranDes-ertofCSonora).
D.s.perblandusGoldman,1933—SWUSAandNWMexico(SonoranDesertofSCArizonaandNCSonora).
D. s. zygomaticus Goldman, 1923 — N Mexico (restricted distribution in the Chihuahuan Desert of SC Chihuahua and possibly NC Durango). View Figure
Descriptive notes. Head—body 130-141 mm, tail 180-208 mm, ear mean 16 mm, hindfoot 40-46 mm; weight 98-132 g. Male Banner-tailed Kangaroo Ratsare slightly larger than females. This is one of the largest-sized kangaroo rats, with four toes on hindfeet. Upperparts are yellowish brown; tail is bicolored, with large and conspicuous white tuft bordered by band of black hairs. Chromosomal complement has 2n = 72 and FN = 70-94. The Banner-tailed Kangaroo Rat and Nelson’s Kangaroo Rat ( D. nelsoni ) can be distinguished in the north by plotting maxillary breadth against total skull length (Nelson’s Kangaroo Ratis smaller in both dimensions), and in the south, by multivariate statistics (predominately greatest skull length, maxillary breadth, and length of maxillary tooth row), again with Nelson’s Kangaroo Rat being smaller in most dimensions.
Habitat. Open, mostly flat desert grasslands with scattered shrubs in the Sonoran and Chihuahuan regional deserts. These grasslands are a mixture of native grasses ( Poaceae ) such as threeawn ( Aristida ), blue grama ( Bouteloua ), tobosa ( Hilaria ), dropseed ( Sporobolus ), and muhly ( Muhlenbergia ), and scattered shrubs in the legume family that vary from mesquite ( Prosopis ) and catclaw ( Acacia , both Fabaceae ) in Arizona, Sonora, and central Mexico, to mesquite, snakeweed ( Gutierrezia , Asteraceae ), and cacti ( Opuntia , Cactaceae ) in New Mexico and Chihuahua, to creosote bush ( Larrea , Zygophyllaceae ) and thickets of shinnery oak ( Quercus havardii, Fabaceae ) in Texas. Experimentalfield studies involving habitat manipulation indicated a negative effect of woody vegetation and a positive effect of increased open spaces on numbers of Banner-tailed Kangaroo Rats. In April 1999, a specimen of the southern disjunct subspecies (cratodon) was collected along the San Luis Potosi-Zacatecas border in a severalhectare field that was virtually devoid of vegetation but had many active mounds. The Banner-tailed Kangaroo Rat occurs in a variety of soil types, including firm, gravelly, or rocky soil; loamy soil; stony mesas; hard-limy ridges; hard-pan soils; loose sand; and sandy loam. Burrows are conspicuous in open, flat grasslands; they form low , rounded, nearly circular moundsas large as 10 m in diameter and 40 cm high, depending on the soil and location of the mound. The mound is constructed by cleaning out, repairing, and modifying tunnels. Most mounds are located in open spaces, but many are built under the protection of shrubs. Areas subjected to flooding are avoided. Although total plant cover is generally less on mounds, they support more annual plants than surrounding areas. Well-traveled runways radiate out from up to a dozen large openings (10-15 cm in diameter), some extending 30-50 m to neighboring burrows. Mounds average ten storage chambers each, most caches being located either near 30 cm in depth or more than 50 cm below the surface, close to the mound’s center on the north or north-west side. Typically, one tunnel goes below the others, and it generally leads to the nest chamber. Mounds represent a substantial investment in energy and require at least several months to construct; at a site with 287 existing mounds, one new mound appeared in three years, and at another site with 105 mounds, six new mounds appeared in two years. Mounds that are not maintained constantly collapse. Although mounds may appear to be in use, they may not be occupied; 39-95% are occupied. In New Mexico, there were 2:6 mounds/ha, and 79 of the 121 mounds (65%) were active. Mean distance was 43-7 m between occupied mounds and 36-3 m between all mounds; all mounds were uniformly spaced, whether occupied or not. About 0-5 m within an open-mouth burrow, daily range of temperature is less than 5°C. Although mean maximum temperature of the soil surface may reach 65°C, deep in the tunnel, the temperature is a nearly static 27°C. Burrow humidity generally is near saturation, and carbon-dioxide concentration is always higher than outside of the burrow. The Banner-tailed Kangaroo Rat is subordinate to pocket gophers ( Geomyidae ) and normally is subordinate to the smaller Merriam’s Kangaroo Rat ( D. merriami ), except during autumn harvesting season, when the smaller species is excluded from home ranges of the larger species. A grasshopper mouse (Onychomys) was observed evicting a Banner-tailed Kangaroo Rat from its mound. The Banner-tailed Kangaroo Rat occasionally lives in abandoned burrows of prairie dogs (Cynomys) or Ord’s Kangaroo Rat ( D. ordii ), and the Southern Plains Woodrat (Neotoma micropus) may coexist in the same mound when suitable den sites or materials are absent. A variety of invertebrates (e.g. grasshoppers, wingless locusts, cave crickets, cockroaches, scorpions, spiders, and centipedes) and other vertebrates (toads, snakes, geckos, and other species of lizards) inhabit large mounds of the Banner-tailed Kangaroo Rat, which also provide nesting sites for burrowing owls (Athene cunicularia).
Food and Feeding. The Banner-tailed Kangaroo Rat often will carry entire seed heads in its cheek pouches, such as those from sand dropseed ( Sporobolus cryptandrus, Poaceae ), a perennial bunchgrass. An individual harvests uniform 3-cm lengths of mature seeds still enclosed in leaf sheaths, carries them to the burrow cache, and later husks sheaths of seeds. A full sheath goes in one side of the mouth and empty leavesfall out the other, while seeds fill cheek pouches before being eaten. The most commonly eaten seeds are those of grasses, but seeds of forbs and shrubs are also harvested, along with green and succulent parts of plants, dried grass, and insects. The Banner-tailed Kangaroo Rat climbs Mormon tea ( Ephedra , Ephedraceae ) to harvest flowers and also eats cactus pods ( Opuntia , Cactaceae ) and yucca flowers ( Yucca , Asparagaceae ). Massive amounts of seeds may be stored: 1018 kg/km? of stored food were found in 21 excavated dens. The Banner-tailed Kangaroo Rat prefersslightly moldy seeds to moldy seeds, dry seeds, and non-moldy, wet seeds—apparently taking advantage of beneficial effects of molds while avoiding liabilities. Seeds are actively moved around in burrows to increase mold growth on sterile seeds and inhibit further growth on sufficiently moldy seeds. Analyses revealed at least 23 species of fungi in caches of Banner-tailed Kangaroo Rats.
Breeding. Breeding season of northern populations of Banner-tailed Kangaroo Rats occurs in January—September, with a peak in April; southern populations breed in December—August, with peaks in December,June, and July. There are 1-3 litters/year; average litter sizes are 2-3 young (range 2—4). Banner-tailed Kangaroo Rats are polyestrous, with short estrous cycles (5-13 days). Gestation lasts for 22-27 days, and young are altricial with birth weights of 7-8 g. Young are weaned in 20-25 days and may be reproductively active at c.2 months of age. Male and female Banner-tailed Kangaroo Rats exhibit natal philopatry, in which young stay with their mothers for 3-7 months, and 39% of surviving offspring remain within natal home ranges through reproductive maturity. Offspring frequently take over natal burrows, or settle in nearby burrow systems. During delayed dispersal, mothers share burrows with as many as five offspring, and juvenile females from earlier litters occasionally reproduce in these circumstances. Although the Banner-tailed Kangaroo Rat is solitary most of the time,it is not unusual to find two or more individuals sharing a mound during reproductive season. Juveniles that acquire the large, complex burrow system and food caches are more likely to survive to reproductive age than individuals that successfully disperse but do not acquire parental resources. Frequency of burrow abandonment by adult femalesis independent of maternal age, and survival of abandoning mothers does not differ from that of non-abandoning females.
Activity patterns. The Banner-tailed Kangaroo Rat does not hibernate or estivate, but it will remain in its burrows when weatheris rainy or cold. Maximum activity is c.20 minutes after sunset, declining throughout the night, and an individual is outside of its burrow nearly one-half of the night. Nevertheless, less than 22% of the nighttime hours is spent more than 6 m from the burrow, although they average 68 m/foraging trip and total 350 m/night of foraging travels. The Banner-tailed Kangaroo Rat avoids moonlit nights; activity is three times higher when the moon is down, except when drought conditions require more nighttime foraging or even daylight foraging. Experiments indicate that Banner-tailed Kangaroo Rats are excellent swimmers.
Movements, Home range and Social organization. The Banner-tailed Kangaroo Rat generally is solitary, and both sexes defend non-overlapping home ranges, except during the breeding season when young remain with their mothers for up to ¢.7 months. Home ranges average 0-4-0-7 ha, but most activity is restricted to 160 m of a burrow. Olfactory communication is likely most important through direct contact or atsites of sand bathing. There is evidence that Banner-tailed Kangaroo Rats can discriminate among species, and individuals are attracted to sand-bathing sites of conspecifics, although reproductive condition of females does not appear to be communicated through sand bathing. They can distinguish between familiar and unfamiliar conspecifics, and sand bathing appears to function in territorial scent-marking behavior. Density has been estimated at 4-9 ind/ha, but populations often show extreme oscillations: one population exhibited a fourfold change in density over eight years, and another declined by 80% and eventually was extirpated following a catastrophic tropical storm.
Status and Conservation. Classified as Near Threatened on The [UCN Red List. Major threats to the Banner-tailed Kangaroo Rat are degradation of grasslands and loss of habitat.
Bibliography. Alexander & Riddle (2005), Anderson (1972), Best (1988a, 1993a, 1999i), Best et al. (1988), Ceballos & Oliva (2005), Eisenberg (1963, 1993), Hafner et al. (2007), Hall (1981), Jones (1993), Linzey, Timm, Alvarez-Castaneda, Frey & Lacher (2008), Patton & Rogers (1993), Waser & Ayers (2003), Williams et al. (1993).
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