BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Dipodomys ordii | Ord's Kangaroo Rat 



TIMING OF MAJOR LIFE HISTORY EVENTS : 
Ord's kangaroo rats are nocturnal.  They spend the day in deep burrows
[41].  Males are usually more abundant and active than females.  Ord's
kangaroo rat activity increases under cloud cover, particularly in
winter [11].  Ord's kangaroo rats are active year-round in Texas, but
further north they are seldom seen aboveground in cold weather [41].

Breeding Seasons:  Ord's kangaroo rat breeding season varies with
subspecies and area.  There are usually one or two peak breeding seasons
per year, and in many areas some breeding activity occurs year-round
[11,36].  The size of ovaries is significantly positively correlated
with temperature [11].  The average length of the breeding period is 6.8
months.  In Texas males are fertile all year, with peak reproductive
activity occurring between August and March.  Higher reproductive rates
are associated with increased precipitation and food supply and
decreased population density.  In a favorable growing season most
females bred at least twice a year; but when population density
increased females did not breed until November even though growing
conditions and food supplies were favorable [25].  In Arizona the lowest
proportion of males in breeding condition (about 60 percent of the male
population) occurred in January and September-October.  The lowest
number of females in breeding condition occurred in November, but there
were at least a few females breeding at that time [5].  In Oklahoma
there are two peaks in breeding activity:  August-September and December
through March [14].  In many areas the onset of breeding activity
follows a period of rainfall the previous month [11].

Gestation and Litter Size:  Gestation lasts 28 to 32 days.  There are
usually one to six embryos.  In captivity the maximum litter size was
six young [11].

Productivity and Longevity:  The maximum number of litters produced per
year by a captive female was five, the maximum number of litters per
lifetime was nine, and the maximum number of young per female's lifetime
was 38.  The longest-lived Ord's kangaroo rat in captivity was 7 years 5
months [11].  Brown and Zeng [6] calculated an annual death rate of 0.35
for all age classes.


PREFERRED HABITAT : 
Ord's kangaroo rats occur mainly in semiarid, open habitats.  In Nevada
they were trapped in desert scrub and gravelly soil, flat pebble desert,
and washes [8].  In Utah Ord's kangaroo rats have an affinity for open
shrublands and grasslands on sandy soils [11].  In southeastern Idaho
big sagebrush/crested wheatgrass (Agropyron cristatum) range, most Ord's
kangaroo rat captures occurred on disturbed sites (areas of sparse
cover:  Russian-thistle (Salsola kali), cheatgrass (Bromus tectorum),
and green rabbitbrush (Chrysothamnus viscidiflorus), followed by
disturbed areas seeded to crested wheatgrass, then undisturbed big
sagebrush [17].  In western South Dakota Ord's kangaroo rats are
associated with black-tailed prairie dog (Cynomys ludovicianus) towns
[34].  In Wyoming Ord's kangaroo rats are abundant in sand dune
communities where vegetation is greater than 10 inches (25 cm) tall and
bare soil exceeds 40 percent [11].  In Colorado Ord's kangaroo rats were
primarily captured in open areas with firm soil.  Firm or lightly
compacted soils are needed for burrow construction; highly compacted
soils are too hard to dig into [30].  In areas of desert pavement or
tough clay soils in the Trans-Pecos region of Texas, Ord's kangaroo rats
are confined to pockets of windblown sand and alluvial soils along
arroyos [31].
  
There is strong intraspecific competition and little interspecific
competition among Dipodomys species [32].  In New Mexico, where Ord's
kangaroo rats are sympatric with Merriam's kangaroo rats (Dipodomys
merriamii), Ord's kangaroo rats were mostly captured in grassy
microhabitats, and Merriam's kangaroo rats were captured more often
around creosotebush [32].  Herbicide defoliation of shrubs (for
rangeland improvement) reduced live canopy cover of creosotebush and
resulted in an increase in bush muhly (Muhlenbergia porteri).  After
treatment Ord's kangaroo rat replaced Merriam's kangaroo rat as the
dominant rodent.  It was suggested that this was due to the change in
habitat structure to open grass [42].

Removal experiments to establish single species populations of kangaroo
rats were unsuccessful since many kangaroo rats are transient and
quickly occupy vacated habitats [32].  Only one adult occupies a given
burrow system, except for a brief period during breeding activity.
There is little territoriality above groud except near the burrow
entrance, which is defended [8].
  
Home Range:  In New Mexico Ord's kangaroo rat annual home ranges in
mesquite averaged 3.35 acres (1.36 ha) [11].  In Nevada
sagebrush/grassland Ord's kangaroo rat home ranges were estimated to be
1.53 acres (0.62 ha) by the circular method and 1.06 acres (0.43 ha) by
the principal component method.  Home range movements increased through
spring and again in late fall and early winter.  There was no
significant difference between male and female Ord's kangaroo rat home
ranges; however, female home ranges decreased during reproductive
periods [26].  Recapture data for Ord's kangaroo rats in Arizona
indicate that they do not travel far from the home range; most Ord's
kangaroo rats were recaptured within 165 feet (50 m) of the original
capture site.  Data on the lifetime movements of individuals indicated
that most were recaptured within 330 feet (100 m) of the original
capture site [6].

Population Density:  In sagebrush in the Great Basin, Ord's kangaroo
rats reach an average density of 113 Ord's kangaroo rats per 10 hectares
[38].  In intermountain salt-desert shrublands Ord's kangaroo rat
population density average 28 individuals per 10 hectares in shadscale
communities and 135 individuals per 10 hectares in black greasewood
(Sarcobatus vermiculatus) communities [40].


COVER REQUIREMENTS : 
Even in shrub-dominated communities, heteromyids including Ord's
kangaroo rat tend to concentrate their activity in open areas between
shrubs [44].

Ord's kangaroo rats are poor diggers because of their weak forelegs and
slender claws.  They dig shallow burrows in loose sand in the sides of
natural sand dunes, riverbanks, or road cuts.  There is one central
burrow surrounded by trails to feeding areas [2].  Ord's kangaroo rat
burrows have 3-inch (7.6 cm) diameter openings.  Small mounds are
usually formed outside the entrance to the burrow [41].  The burrow
opening is usually plugged with soil during the day to maintain
temperature and humidity within tolerable levels [11,19].  They scoop
out small, shallow depressions to be used as dusting spots [41].


FOOD HABITS : 
Ord's kangaroo rats are primarily granivorous and herbivorous.  They
consume a variety of foods but most commonly the seeds of grasses and
forbs, green vegetation, and dry vegetation.  They occasionally consume
animal material, mostly arthropods.  In Colorado seeds comprised 74
percent of Ord's kangaroo rat diets, forbs 13 percent, grasses and
sedges 5 percent, arthropods 4 percent, and fungi and mosses 2 percent
[11].

In southeastern Idaho big sagebrush/crested wheatgrass range, Ord's
kangaroo rats consumed (in order of proportion) pollen, arthropods,
plant parts (Asteraceae) and crested wheatgrass seeds [17].  A study of
Ord's kangaroo rat foods in Texas found that the primary foods consumed
included seeds of sand paspalum (Paspalum stramineum), honey mesquite,
sand bluestem (Andropogon gerardii var. paucipilus), common ragweed
(Ambrosia artemisiifolia), and rose-ring gaillardia (Gaillardia
pulchella) [1].  In Texas seeds of creosotebush, gramas (Bouteloua spp.)
and dropseeds (Sporobolus spp.)  form the major portion of Ord's
kangaroo rat diets [31].  Seeds of mesquite, Russian-thistle, sunflowers
(Helianthus spp.), and sandbur (Cenchrus spp.) are also major dietary
items [41].

Harvested seeds are transported in cheek pouches to burrows and consumed
or cached there.  Ord's kangaroo rats also cache seed in scattered
shallow holes; this activity sometimes results in seedling emergence.
Ord's kangaroo rats are easily able to retrieve shallowly buried seeds.
A single Ord's kangaroo rat may make tens to hundreds of caches, each
with tens to hundreds of seeds [21].

Kangaroo rats are physiologically adapted to arid environments.  Most
water is obtained from seeds and succulent plants.  They drink water
when it is available but apparently do not require free water [2,22].


PREDATORS : 
In the Great Basin sagebrush, intermountain sagebrush steppe, and
intermountain salt desert shrublands potential predators of Ord's
kangaroo rats include coyotes (Canis latrans), kit fox (Vulpes velox),
bobcats (Lynx rufus), badgers (Taxidea taxus), long-eared owls (Asio
otus), short-eared owls (Asio flammeus), great horned owls (Bubo
virginianus), burrowing owls (Athene cunicularia), hawks (Buteonidae and
Falconidae spp.), rattlesnakes (Crotalus spp.), and gopher snakes
(Pituophis melanoleucus) [38,39,40].  In Idaho the remains of Ord's
kangaroo rats were found in up to 25 percent of prairie falcon (Falco
mexicanus) nests.  The 3-year average frequency of Ord's kangaroo rat
remains in prairie falcon nests was 4 percent [27].


MANAGEMENT CONSIDERATIONS : 
There is some evidence that Ord's kangaroo rats and other Dipodomys
species are a key component in maintaining the grass component of salt
desert plant assemblages in the Great Basin [21].  Seed predation and
soil disturbance are the major influences of Dipodomys species.  They
exhibit a preference for large seeds and their soil disturbance promotes
annuals over perennials.  In southeastern Arizona desert scrub, removal
of the three Dipodomys species including Ord's kangaroo rat resulted in
a shift from shrubland to grassland.  There was an increase in cover of
Lehmann lovegrass (Eragrostis lehmanniana) and threeawn (Aristida
adscensions) and a decrease in cover of needle grama (Bouteloua
aristoides) and six-weeks grama (B. barbata) [5].


REFERENCES : 
NO-ENTRY

Related categories for Wildlife Species: Dipodomys ordii | Ord's Kangaroo Rat