Dipodomys heermanni, Le Conte, 1853
|
publication ID |
https://doi.org/ 10.5281/zenodo.6611160 |
|
DOI |
https://doi.org/10.5281/zenodo.6608128 |
|
persistent identifier |
https://treatment.plazi.org/id/3C3D87A6-8768-B13D-1BE6-5DCBFCE4F930 |
|
treatment provided by |
Carolina |
|
scientific name |
Dipodomys heermanni |
| status |
|
65. View Plate 11: Heteromyidae
Heermann'’s Kangaroo Rat
Dipodomys heermanni View in CoL
French: Rat-kangourou de Heermann / German: Heermann-Kédngururatte / Spanish: Rata canguro de Heermann
Other common names: Morro Bay Kangaroo Rat (morroensis), Tulare Kangaroo Rat (tularensis)
Taxonomy. Dipodomys heermanni Le Conte, 1853 View in CoL ,
“Sierra Nevada,” California, USA. Restricted by J. Grinnell in 1922, to “Calaveras River,” Calaveras Co., California .
Based on molecular sequence analyses, D. heermanniis a member of the heermanni species group, along with D. gravipes , D. panamintinus , D. microps , D. ingens , and D. stephens . Nine subspecies recognized.
Subspecies and Distribution.
D.h.heermanniLeConte,1853—WUSA(NESanJoaquinValley,CCalifornia).
D.h.arenaeBoulware,1943—WUSA(CoastRangesofSanLuisObispoandSantaBarbaracounties,SWCalifornia).
D.h.berkeleyensisGrinnell,1919—WUSA(hillsandvalleysEofSanFranciscoBay,WCCalifornia).
D.h.dixon:Grinnell,1919—WUSA(EmarginoftheSanJoaquinValley,CCali-fornia).
D.h.goldman:Merriam,1904—WUSA(PacificcoastandslopeoftheCoastRang-es,SWCalifornia).
D.h.jolonensisGrinnell,1919—WUSA(SalinasValleyalongthePacificcoast,SWCalifornia).
D.h.morroensisMerriam,1907—WUSA(restricteddistributionalongMorroBay,SWCalifornia),butmaybeextinct.
D. h. tularensis Merriam, 1904 — W USA (floor of San Joaquin Valley to foothills of the Tehachapi and Temblor ranges, SC California ). View Figure
Descriptive notes. Head-body 90-113 mm,tail 160-200 mm, ear mean 15 mm, hindfoot mean 43 mm; weight 70-80 g. Male Heermann’s Kangaroo Rats are slightly larger than females. Tail is 147% of head-body length. Thisis a medium-to-large-sized kangaroo rat, with five toes on hindfeet (including small claw on side of hindfoot) and broad skull. Upper parts are dark tawny-olive (morroensis) to ocherous buff (albino specimens are known); tail is bicolored, with dusky to blackish and slight or sparsely haired crest. White flank stripes across lateral thighs—typical of kangaroo rats—are lacking in 5% of arenae and 75% of morroensis. Chromosomal complement has 2n = 64 and FN = 90- 94. Heermann’s Kangaroo Ratis similar in size and appearance to nearby populations of the Agile Kangaroo Rat ( D. agilis ) and the Narrow-faced Kangaroo Rat ( D. venustus ), but it has smaller ears, lighter color, less heavily crested tail, and broader face. There is no known physical characteristic that distinguishes all Heermann’s Kangaroo Rats from Panamint Kangaroo Rats ( D. panamintinus ), but no areas of sympatry are known. Compared with the sympatric San Joaquin Kangaroo Rat ( D. nitratoides ), Heermann’s Kangaroo Rat is much larger (twice the body weight) and has five rather than four toes on hindfeet. Compared with the sympatric Giant Kangaroo Rat ( D. ingens ), Heermann’s Kangaroo Rat is much smaller, with shorter hindfeet and relatively longertail.
Habitat. Wide variety of habitats from foothills of Sierra Nevada and Tehachapi Range to Coast Range and Pacific coast of California , ranging from ridge tops where soil is shallow and well drained and vegetation is scanty to sandy valley floors or coastal plains. Typical habitat of Heermann’s Kangaroo Rate is dry, grassy plains and gravelly ground on hillsides with sparse chaparral. Surrounding vegetation ranges from blue oak ( Quercus douglasii, Fabaceae ), digger pine ( Pinus sabiniana, Pinaceae ), and interior live oak ( Quercus wislizeni) association at upper elevations to coastal chaparral and scrub at lower elevations. In all cases, only open patches with low vegetation and well-drained soils are occupied. Main entrances to burrows of Heermann’s Kangaroo Rats are usually under bushes or boulders. Complexity of burrow systems varies with soil type. In areas of hard-packed soils, burrows are relatively shallow and less complex, unless they are the frequently used abandoned burrows of ground squirrels (Otospermophilus and Ammospermophilus). In deeper, fine soils, burrows are correspondingly deeper and more complex. In fine, sandy soils along the coast, burrows are shallow and simple. Species of rodents co-occurring with Heermann’s Kangaroo Rat include Nelson's Antelope Squirrel (Ammospermophilus nelsoni ), the Giant Kangaroo Rat, the San Joaquin Kangaroo Rat, the Southern Grasshopper Mouse (Onychomys torridus), the California Pocket Mouse ( Chaetodipus californicus ), the San Joaquin Pocket Mouse ( Perognathus inornatus ), the Brush Deermouse (Peromyscus boylii), the Western Harvest Mouse (Reithrodontomys megalotis), and the California Ground Squirrel (Otospermophilus beecheyr). Densities of Heermann’s Kangaroo Rat are highest when that of syntopic rodents is low, and vice versa. Common predators include western rattlesnakes (Crotalus vindis), gopher snakes (Pituophis melanoleucus), barn owls (1yto alba), great horned owl (Bubo virginianus), Coyotes (Canis latrans), Gray Fox (Urocyon cinereoargenteus), Kit Fox (Vulpes macrotis), Long-tailed Weasels (Mustelafrenata), Striped Skunks (Mephitis mephitis), and domestic cats (Felis catus).
Food and Feeding. Apparently, Heermann’s Kangaroo Rat does not store large amounts of food in burrow larders (compared with some other species of kangaroo rats); instead, food is stored in small pockets in walls of tunnels or at blind ends. Diet includes seeds of a wide variety of grasses and forbs. Pine nuts and insects are also eaten; moths, beetles, and grasshoppers are captured at night and may be a considerable part of the diet, at least seasonally. Unlike other kangaroo rats, Heermann’s Kangaroo Rat is not able to exist solely on metabolic water and apparently gets sufficient water from dew or moisture in its food (succulent vegetation and insects). Captive individuals had a strong aversion to water but skimmed their paws over the water surface and licked water from their paws. Green vegetation is a large part of the diet, particularly in winter and spring. Most seeds are returned to the burrow, but succulent vegetation is eaten outside of the burrow.
Breeding. Heermann’s Kangaroo Rat has a mating system typical of most kangaroo rats: a promiscuous or polygynous pattern in which males and females are asocial and aggressively territorial, and males have greater home ranges and mobility, particularly during breeding season. Body weight is only slightly higher for males or about equal between sexes. Number and timing of litters are tied to environmental conditions; there may be no reproduction in years of food stress. Consequently, populations often comprise mostly adults; although during peak density, many individuals are juveniles. Timing of reproduction appears to be cued, at least in part, by substances ingested along with new plant growth, so that litters arrive during highest seed abundance. Breeding occurs is February—October, with peak activity in April and a decrease after July. Average litter sizes for three areas were 2-6 (range 2-3), 3-3 (3-4), and 3-8 (2-5). Females are polyestrous, with estrous cycles (18-20 days) somewhat longer than most other species of kangaroo rats. Gestation is 30-32 days, and young are altricial, with birth weights of 3-4 g. Young are weaned in 17-25 days and may be reproductively active at c.2 months of age. Youngest trapped specimens were estimated to be 5-6 weeks old.
Activity patterns. Heermann’s Kangaroo Rat is primarily nocturnal and is active yearround. Most foraging is done in the early part of the night, along surface runways that are often made and used by syntopic ground squirrels, or along roads,firebreaks, and othertrails. Most individuals have two peaks of activity: an early peak of c¢.40 minutes followed by c.4 hours in the burrow and then a second peak ofvariable duration. Rain and fog tend to keep them in their burrows.
Movements, Home range and Social organization. Social system of Heermann’s Kangaroo Rat likely conformsto the typical pattern among most kangaroo rats, but there is some evidence of delayed dispersal of offspring and possible natal philopatry, although not likely to the degree observed in the Banner-tailed Kangaroo Rat ( D. spectabilis ). Dispersal of Heermann’s Kangaroo Rat does not show male-biased pattern typical of many mammals. Instead, less than 84% of young kangaroo rats dispersed less than 100 m from natal home ranges, with little difference between sexes, and most juveniles took up residence in unoccupied areas, most often within the home range of adult females.
Status and Conservation. Classified as Least Concern on The IUCN Red List. The subspecies morroensis, restricted to old, stabilized sand dunes in 15 ha on the south side of Morro Bay,is listed as Endangered by the US Fish and Wildlife Service. Populations of morroensis declined significantly from the 1950s to the 1980s due to a loss of suitable habitat through development and lack of natural disturbance by fire, which resulted in growth ofless suitable, local vegetation. The subspecies has not been observed in the wild since 1986, the last individual in captivity died in 1993, and it was considered possibly extinct in 1999. It may persist in pockets of suitable habitat including large private properties in which it formerly existed.
Bibliography. Alexander & Riddle (2005), Best (1993a), Eisenberg (1963, 1993), Grinnell (1922), Hafner et al. (2007), Hall (1981), Ingles (1954), Jones (1993), Kelt (1988a, 1999b), Linzey & NatureServe (Hammerson) (2008d), Patton & Rogers (1993), USFWS (2011b), 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.
