(DRAFT) - Taxonomy
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
TAXONOMY
NAME - RAT, GIANT KANGAROO
OTHER COMMON NAMES - RAT and GIANT KANGAROO
ELEMENT CODE -
CATEGORY - Mammals
PHYLUM AND SUBPHYLUM - CHORDATA,
CLASS AND SUBCLASS - MAMMALIA,
ORDER AND SUBORDER - RODENTIA,
FAMILY AND SUBFAMILY - HETEROMYIDAE,
GENUS AND SUBGENUS - DIPODOMYS,
SPECIES AND SSP - INGENS,
SCIENTIFIC NAME - DIPODOMYS INGENS
AUTHORITY -
TAXONOMY REFERENCES -
COMMENTS ON TAXONOMY -
Giant Kangaroo Rat
Dipodomys ingens (Merrium, 1904)
KINGDOM: Animal GROUP: Mammal
PHYLUM: Chordata CLASS: Mammalia
ORDER: Rodentia FAMILY: Heteromyidae
Dipodomys ingens is among the largest kangaroo rats (01), having
the greatest average weight (reported range of average weights of
various age and sex samples are from about 109 to 157 g; 02) and a
length of head and body greater than 130 mm (usually more than 135 mm;
mean of 8 adults = 144; 03). The proportions of body and limbs are
typical of kangaroo rats in general. The hind limbs are large
relative to the size of the forelimbs, the neck is short, the head is
large and flattened, and the eyes and ear pinnae are placed
dorso-laterally. The tail is longer than the head and body,
conspicuously thickened, and has a dorsal crest of long hairs
distally, terminating in a large tuft of hairs. The claws on both the
fore and hind feet are long and stout. Large, fur-lined cheek pouches
open on the front of the face, on each side of the mouth. The pouches
extend as deep pockets of skin along the sides of the head (02).
The coloration of D. ingens does not differ notably from that
Taxonomy - 1 (DRAFT) - Taxonomy
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
of other species of kangaroo rats. The dusky-colored nose and
vibrissae patches are separated, not forming a continuous dark mark.
The cheeks are whitish and the eyelids are completely blackish. The
lateral white stripes along the tail are only slightly narrower than
the dorsal and ventral dark stripes. The tail tuft is dark in
appearance due to a mix of light and dark hairs. The lateral surfaces
of the body are pure white to the bases of the hairs. The
buff-colored hairs of the sides and dorsum are mixed with fewer,
scattered blackish and dusky hairs. The flanks have a darker
appearance due to a greater number of dusky hairs. Juvenile giant
kangaroo rats are paler and grayer than adults, whose general body
color is "warm buff" (02,03).
External measurements in mm (means of 15 males and 7 females,
respectively, from Grinnell [05]; followed by ranges of measurements
[04]) are as follows: total length, 332.9, 334.4 (311 to 348); length
of tail, 181.2, 185.7 (157 to 198); length of hind foot, 50, 50 (46
to 55); weight 131 to 180 g. Grinnell (03) estimated the crown
length of ear to be 13 mm. Length of ear from notch averaged 17.0 mm
(16.0 to 18.5) for 13 males and 16.7 (15.0 to 18.0) for five females
(05).
There is no controversy about the identification or taxonomy of
the giant kangaroo rat. Dipodomys ingens was first described as
Perodipus ingens by Merriam (01). The genus name Perodipus was used
for several years to include all of the kangaroo rats with five toes
on the hind feet. Grinnell (06), in 1921, relegated Perodipus to a
synonym of Dipodomys. This taxonomy has been sustained in the latest
systematic review of the family Heteromyidae (07).
The type locality for Dipodomys ingens is Painted Rock,
20 [= 12] mi SE Simmler, Carrizo Plain, San Luis Obispo Co.,
California. The type specimen is in the United States National Museum
of Natural History in Washington, D.C. Other specimens are found in
several museums; the collections in the Museum of Vertebrate Zoology,
Univ. of California, Berkeley and the U.S. National Museum are the
largest. Williams (08,09) provided lists of museum specimens.
Taxonomy - 2 (DRAFT) - Status
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
STATUS
Coded Status
E: Federal Endangered
Pest
COMMENTS ON STATUS -
U.S. STATUSES AND LAWS:
The giant kangaroo rat (Dipodomys ingens) has been designated an
Endangered species pursuant to the Endangered Species Act of 1973
(50 CFR 17.11; P.L. 93-205, 87 Stat. 884; 16 U.S.C. 1531-1540),
as amended. The species has this status wherever found including the
States of California.
This species is protected by the Lacey Act
(P.L. 97-79, as amended; 16 U.S.C. 3371 et seq.) which makes it
unlawful to import, export, transport, sell, receive, acquire, or
purchase any wild animal (alive or dead including parts, products,
eggs, or offspring):
(1) in interstate or foreign commerce if taken, possessed,
transported or sold in violation of any State law or
regulation, or foreign law; or
(2) if taken or possessed in violation of any U.S. law,
treaty, or regulation or in violation of Indian tribal law.
It is also unlawful to possess any wild animal (alive or dead
including parts, products, eggs, and offspring) within the U.S.
territorial or special maritime jurisdiction (as defined in
18 U.S.C. 7) that is taken, possessed, transported, or sold in
violation of any State law or regulation, foreign law, or Indian
tribal law.
RESPONSIBLE FEDERAL AGENCIES:
USFWS -Responsible for the management/recovery, listing, and
law enforcement/protection of this species.
BLM -Responsible for the law enforcement/protection of this
species with applicable State and Federal laws on
public land under their control (43 CFR 4140). Also
responsible for management/recovery on Bureau of Land
Management lands.
All Federal agencies have responsibility to ensure that any
action authorized, funded, or carried out by that agency is not likely
to jeopardize the continued existence of the species or result in the
destruction or adverse modification of Critical Habitat (50 CFR 402),
and to utilize their authorities to carry out programs for the
conservation of the species.
STATE STATUSES AND LAWS:
Status - 1 (DRAFT) - Status
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
STATE: California
DESIGNATED STATUS: Endangered
ADMINISTRATIVE AGENCY: Calif. Dept. of Fish and Game
STATE STATUTE: Calif. Endangered Species Act, Fish and Game Code
Chapter 1.5, Art. 1, Sect. 2050
INTERNATIONAL STATUSES, TREATIES, AND AGREEMENTS:
None.
ECONOMIC STATUSES:
It is considered a pest because it is thought to compete with
livestock for forage. However, there are no data substantiating
economic loss by this species. In contrast, biologist have shown that
activities of giant kangaroo rats promote an increase in plant
productivity. Probably the overall impact of this species is to
enhance production of livestock forage.
82/12/30:47 FR 58454/58460 - Category-2 listing
85/08/13:50 FR 32585/32587 - Proposed listing
85/11/26:50 FR 48617/48618 - Notice of extension on comment period
87/01/05:52 FR 00283/00288 - Final rule - listed as Endangered
Status - 2 HABITAT ASSOCIATIONS
HABITAT - TERRESTRIAL
TERRESTRIAL
LAND USE -
Herbaceous Rangeland
Shrub and Brush Rangeland
Mixed Rangeland
COMMENTS ON HABITAT ASSOCIATIONS -
The habitat of D. ingens (giant kangaroo rat) consists
primarily of gently sloping piedmont plains, largely devoid of shrub
cover (05,08,10). Giant kangaroo rats were most numerous in desert
and arid grassland communities with about 16 cm or less of annual
precipitation and sandy loam soils free from flooding in winter.
The largest extant colonies were located on flat and gently
sloping terrain of less than 5`; however, a few marginal areas with up
to 15` slopes support small colonies (08,09). There is no information
on aspect. Nearly all populations examined by Grinnell (05) and Shaw
(10) were located on sandy loam soils, and both researchers considered
that giant kangaroo rats were limited to shrubless areas with such
soils. An inventory of extant colonies, however, found giant kangaroo
rats living on soils of widely varying textures, from fine sands to
conglomerates of mixed pebbles and clay (08). Bolster (16) found tiny
colonies of giant kangaroo rats living on soils of loams, silty clay,
and shale [probably meaning disintegrating pieces of shale mixed with
soil particles]. Williams (08) found that nearly all extant colonies
were located in average to marginal conditions, based upon comparisons
with descriptions of habitat and densities of expansive colonies
described by Grinnell (05) and Shaw (10). Williams (08) noted that
presence or absence of shrubs in areas inhabited by D. ingens appeared
to be related to the texture of soils, and that some colonies and
individual burrows of giant kangaroo rats were found in areas
supporting considerable numbers of shrubs. Soils must be friable when
damp, have sufficient silt and clay so that tunnels do no collapse
when soils dry, and be at least 30 to 45 cm in depth.
Grinnell (05) noted that by February rain water had penetrated
the soil only to a depth of 220 to 230 mm, leaving most of the burrows
relatively dry. He considered that the scanty rainfall and "peculiar"
consistency of the fine sandy loam soils inhabited by D. ingens might
be factors in determining the distribution of this species, in that
the water did not normally penetrate to a depth as great as the
shallow burrows.
Common plants in areas with colonies of giant kangaroo rats
include: red-stemmed filaree (Erodium cicutarium), peppergrass
(Lepidium nitidum), fiddleneck (Amsinkia douglasiana), brome grass
(Bromus rubens; 10); malpais blue grass (Poa scabrella), snakeweed
(Gutierrezia californica), and green ephedra
(Ephedra viridis; Hawbecker, 11, 12); desert saltbush
(Atriplex polycarpa), golden bush (Haplopappus acrideneus), and
Arabian grass (Schismus arabicus; 08, 14).
Habitat Associations - 1 (DRAFT) - Food Habits
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
FOOD HABITS
TROPHIC LEVEL -
HERBIVORE
LIFESTAGE FOOD FOOD PART
General Poaceae
General
General Forb Leaves/Stems
General Forb Flowers/Fruit/Seed
General Deciduous Shrubs-Flowers/Fruit/Seed
General Evergreen Shrubs-Flowers/Fruit/Seed
General Arthropods
Food Habits - 1 (DRAFT) - Environment Associations
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
G Terrestrial Features: Burrows
Environment Associations - 1 (DRAFT) - Life History
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
LIFE HISTORY
FOOD HABITS:
Giant kangaroo rats are primarily granivorous, but also eat green
plants. Usually in April and May they cut the ripening heads of
grasses and forbs and cure them in small surface pits located on the
precinct (10). Surface pits examined by Shaw (10) were uniform in
diameter and depth (about 2.5 cm), placed vertically in firm soil, and
filled with seed pods. After placing seeds and seed heads in pits,
the animal covered them with a layer of loose, dry dirt. Sets of
pits associated with a single precinct covered 0.8, 2.6, 3.2, 5.1,
6.1, and 7.3 m2; the 5.1 m2 cache consisted of 875 separate pits.
Numbers of pits out of 875 containing each type of seed head or pod,
were: Lepidium nitidum 873, Oenothera sp. 179, Erodium sp. 169,
Gnaphalium sp. 5, Plantago sp. 4, Atriplex sp. 4, and Bromus rubens 1
(10). Shaw (10) surmised that pits were filled with the contents of
the cheek pouches after a single trip to harvest seeds, and that
before being moved underground the seeds were sun-dried to prevent
molding. A similar behavior in some populations of D. ingens involves
making large stacks of separated seed heads on the surfaces of
precincts (09,11). The material is cured, then stored underground.
Stacks Hawbecker (11) measured averaged about 10 x 10 x 61 cm,
although one measured 1.2 x 1.8 m and was 10 cm deep; each stack
appeared to belong to one giant kangaroo rat.
In one den, 24 large, underground caches of seeds were found;
12 were apparently old, filled mostly with sand and empty seed pods,
and 12 others were newer, consisting primarily of seeds of filaree and
pepper grass. Measurements (averages) of the newer caches were:
depth 14 cm; length, width, and height 26, 14, and 10 cm,
respectively. In another den, 9 caches were located, each containing
from 1.1 to 9.1 liters of seeds (10).
Grinnell (05) examined three nursing females who had their cheek
pouches "literally crammed with green stuff," and speculated that
green foliage of annual grasses and forbs might be an important part
of the diet during lactation (probably from about January through
April or May). Other individuals, including a young female and adult
males were captured with foliage and fruits of pepper grass and
foliage of filaree in their cheek pouches.
In captivity, giant kangaroo rats have been maintained for
periods of from 2 weeks to more than 2 years on a diet of air-dried
seeds, consisting primarily of millet, oat, and sunflower,
occasionally supplemented with green plants. Of the green plants,
captives preferred forbs to annual grasses, and usually ignored the
blades of perennial grasses (14). Shaw (10) found a live hymenopteran
insect in the cheek pouch of a giant kangaroo rat. Eisenberg (17)
kept a giant kangaroo rat in captivity on a diet that included seeds,
lettuce, and mealworm larvae (Tenebrio sp.).
HOME RANGE/TERRITORY:
Grinnell (05) first suggested that giant kangaroo rats were
territorial, based on the regular spacing of precincts and single
occupancy of burrows. Individual precincts studied by Grinnell were
never found to contain more than one adult. Shaw (10) excavated five
Life History - 1 (DRAFT) - Life History
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
burrows in which he had previously placed canisters of cyanide; one of
these was occupied by a male-female pair of adults; others in which
animals were found were occupied by single adults. By measuring
overlap between home ranges of individual animals, Braun (18) showed
that individuals exhibited strict intrasexual avoidance, with moderate
levels of intersexual contact. Although each individual had a
distinct home burrow, animals frequently entered burrows at some
distance from their home burrows during nightly periods of activity.
Braun (18) reported that home range sizes for D. ingens ranged from
60 to 350 m2 (mean 239.3 m2). She found no significant differences in
size of home range between sexes.
Although independent observations and time-weighted measures gave
slightly different centers of activity, both showed centers close to
the home burrow, indicating that the area around the burrow (precinct)
was the most intensely-used location in the home range (18)
PERIODICITY:
Giant kangaroo rats are active year around, although they may
stay underground for several days at a time during inclement weather
and in late fall and winter. They are usually strictly nocturnal, but
occasionally are observed and trapped during the day (14). Activity
patterns were monitored by Braun (18) by placing collars equipped with
blinking light-emitting diodes on giant kangaroo rats. The rats
emerged from their burrows soon after sunset and were active for
1.8 ! 0.2 h (time of first emergence to time of last disappearance).
There was no second period of activity before dawn. Animals were seen
above ground only for an average of 15.2 ! 5.8 min/night. Time spent
above ground ("foraging bouts") lasted 80.7 ! 6.9 s; animals performed
3.5 ! 0.09 bouts/h. Giant kangaroo rats spent most of their time
above ground in the vicinity of their home burrows; on average,
individuals used 2.2 ! 0.35 grid squares (5 x 5 m) per bout, with a
maximum distance travelled of 47.1 m by one individual during a single
bout. During bouts, animals moved slowly, spending an average of
47.5 ! 3.8 s in each 5 x 5 m grid square. Activity patterns appeared
to be unaffected by distance from the home burrow, snow, rain, wind,
moonlight, or season (18).
MIGRATION PATTERNS:
Giant kangaroo rats do not migrate.
COVER/SHELTER REQUIREMENTS:
Giant kangaroo rats typically inhabit shrubless terrain vegetated
with a scant cover of annual grasses and forbs (08,09). Presumably,
they do not require vegetative cover. They den in ground burrows
which they or their predecessors have dug. The surfaces of typical
burrow systems (precincts) of giant kangaroo rats are roughly
circular, show little or no mounding above surrounding terrain, and
range from 2.4 to 7.7 m in diameter (n = 30; 08). Other studies found
that the diameter of precincts varied from 1.8 to 3.6 m (05) and from
about 3 to 6.7 m (10). Colonies examined by both Grinnell (05) and
Shaw (10) were in prime habitat and were continuously distributed over
hundreds to thousands of hectares, whereas colonies studied by
Williams (08) were smaller and less dense, being located in poorer
Life History - 2 (DRAFT) - Life History
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
habitats.
Precincts have one to five separate burrow openings with three
being typical (05,08). Although plugged burrows can be found at all
times of the year, most burrows entrances lack visible plugs of earth
(08,14). Burrow openings are of two general types: a vertical shaft
with a circular opening with no apron of dirt near the mouth and no
well-worn trail leading from the mouth; and larger, more
horizontally-opening burrows that are usually wider than high, and
with a well-worn path leading from the mouth. Typically, a precinct
has two slanting tunnels and one vertical shaft opening to the surface
(08).
Excavations of burrows were described by Eisenberg (17), Grinnell
(05), Shaw (10), and Tappe (19). Grinnell (05) discovered that three
excavated burrows were dichotomous, with no reconnecting tunnels.
Tunnels were constructed in a single layer. Tappe (19), however, dug
out a burrow that had a three-layer arrangement of tunnels.
Measurements based on excavated precincts were: internal tunnel
diameter, 50 to 75 mm, with occasional enlargements up to 150 mm;
average tunnel depth, 263 mm with greatest depth of 463 mm; greatest
tunnel length, 3 m; and total lengths of three systems, including side
branches, 9.1, 7.3, and 8.2 m (05). Both Grinnell (05) and Shaw (10)
noted that soil excavated from precincts of giant kangaroo rats had
numerous seed hulls and other plant debris mixed in, suggesting that
tunnels had been worked and reworked, perhaps over several decades.
REPRODUCTIVE SITE REQUIREMENTS:
No information is available on species requirements or place of
courtship and breeding. Young are probably born in a nest in the
ground burrow, and remain there for the first several weeks of life.
Only one nest has been found in excavated burrows (05); it was located
330 mm below the surface, and consisted of sheep's wool and fine,
shredded grass stems, and 0.5 liter of seed hulls.
REPRODUCTIVE CHARACTERISTICS:
No information is available on courtship or breeding of giant
kangaroo rats, but Eisenberg (17) gave a general description of
breeding behavior of captive kangaroo rats, based primarily upon
observations of Dipodomys nitratoides. There are probably no lasting
male/female pair bonds formed. Females may breed with more than one
male during estrus.
Scant information has been recorded on reproduction of giant
kangaroo rats. Grinnell (05) suggested that the reproductive season
extended from January to May, based on capture of seven juveniles on
19 and 20 February, the largest of which weighed 103.5 g, and on other
substantiating evidence from captured giant kangaroo rats. During
October 1987, the testes of males had begun to enlarge, suggesting
that mating might start in late November or December (14). Grinnell
(05) captured three pregnant females during February and one on 18
May. Another pregnant female was taken on 16 February (14). During
excavation of a burrow system on 3 March, Shaw (10) discovered a
lactating female and four half-grown young.
Based on weights of animals captured during July and August 1987
all young had attained nearly adult proportions; young animals could
Life History - 3 (DRAFT) - Life History
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
not be separated reliably from adults on the basis of weight (14).
This suggests that at least on the Elkhorn Plain during 1987, birth of
young probably had ceased by late April or early May.
A sample of six female giant kangaroo rats (05,10,14) averaged
4.7 embryos. The finding of a pregnant female in mid-May (05)
suggests that females could have two litters during the breeding
season, or that some females born early in the season might breed
during their first year of life.
Gestation is probably about 32 days, based on other species of
Dipodomys (20).
PARENTAL CARE:
There is no specific information on parental care by giant
kangaroo rats. Presumably the general pattern exhibited by other
species of kangaroo rats will hold for D. ingens. Eisenberg (17)
described parental care and growth and development for kangaroo rats
in general, based mostly on studies of D. nitratoides. Tappe (19)
described some aspects of growth and development in D. heermanni, the
species that is probably most closely related to D. ingens.
Young are altricial and live in a nest in a ground burrow where
they are nursed and cared for exclusively by the female. They are
probably about 3- to 4-weeks old when they are first found on the
surface, and may not be out of the burrow and foraging for themselves
until about 6-weeks old (17). Weaning occurred at 21 to 24 days in
captive D. nitratoides (20). It is possible that sexual maturity of
young born early in the season is reached within about 90 days, based
on D. nitratoides (20), but there is no data specific to giant
kangaroo rats. Dispersal probably occurs between about mid July and
mid August (14).
POPULATION BIOLOGY:
Little data are available on demographic features of D. ingens.
Although availability of food, predation, disease, competition for
space, and other factors probably contribute to environmental
resistance limiting giant kangaroo rat populations, their importance
has not been measured.
Known predators of giant kangaroo rats include: barn owls (Tyto
alba), great horned owls (Bubo virginianus), coyotes (Canis latrans),
kit foxes (Vulpes macrotis), and badgers (Taxidea taxus; 05,11,21,22).
Hawbecker (11) also observed a weasel (Mustela frenata) being chased
from a burrow system of either D. ingens or A. nelsoni. Other common,
nocturnal predators seen within giant kangaroo rat colonies include
rattlesnakes (Crotalus viridis), gopher snakes (Pituophis
melanoleucus), king snakes (Lampropeltis getulus), and other snakes
(14).
One giant kangaroo rat, captured as an adult in October, was kept
in captivity for a period of 2 years and 4 months (14). Of 31 animals
marked on a 1-ha grid by Braun (18) during summer 1981, 10 (35.7%)
were recaptured in spring 1982.
There is no other information on survival of giant kangaroo rats
in the wild or other aspects of population structure.
Estimates of density, based on counts of precincts in
high-quality habitat (05), ranged from 40 to 69 per ha (mean = 52).
Life History - 4 (DRAFT) - Life History
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
Braun (18), employing both trapping and counts of burrows, estimated a
density of 25 adults per ha for her study site on the Carrizo Plain.
This colony was typical of the larger colonies still extant in that
area. Williams (08) counted precincts on 1-ha plots in the four
largest remaining colonies of giant kangaroo rats in Kern and San Luis
Obispo counties, recording a mean of 32 per ha (range 18 to 49,
n = 12); approximately 30% of the precincts were unoccupied,
resulting in a mean estimate of density of 22 per ha during September.
Other colonies of giant kangaroo rats were smaller and less dense.
The largest was estimated as covering about 125 ha, but most consisted
of from 2 to 10 precincts, each isolated by several hundred meters or
more from other colonies (08).
Based on the Schnabel method for estimating populations by
repeated mark-recapture, Williams and Tordoff (14) estimated densities
of giant kangaroo rats on the Elkhorn Plain on two 1-ha grids to be
45 ! 3 and 41 ! 3, respectively, during the last week of July 1987.
This was thought to be at or near the peak numbers during the annual
cycle, and probably included at least some individuals that had not
yet dispersed from their natal precinct. Because giant kangaroo rats
are relatively sedentary, the effective sampling area of traps on the
grids was probably not much larger than 1 ha. These densities are
relatively high, but are probably similar to good-quality habitat
investigated by Grinnell (05).
Objectives for population density under management have not been
developed. Optimum densities in good habitat, such as found on parts
of the Elkhorn Plain, are probably lower than densities measured there
recently (14). Currently, this area is suffering from decades of
severe overgrazing, threatening the livelihood of the entire biotic
community. A reduction or elimination of grazing may cause a decrease
in density of giant kangaroo rats, but probably would be beneficial to
the entire community and to the long-term survival of D. ingens (14).
Foot drumming is an important aspect of territorial behavior in
banner-tailed kangaroo rats (23) and is probably also the case with
giant kangaroo rats. Individuals respond differently to drumming of
neighbors, strangers, and recordings of their own drumming, indicating
that individual patterns are recognizable. Shaw (10) related an
incident whereby he discovered drumming in giant kangaroo rats. He
was preparing to excavate a precinct, the burrow entrances of which
were plugged, when he heard repeated, muffled drumming, apparently
produced by beating the fur-padded hind feet upon the ground in the
depth of the burrow. Shaw described how that "in the summer when
their granaries are full, the animals may be induced to reply to one's
beating with the hand upon the ground above them." Foot drumming was
heard regularly in colonies of giant kangaroo rats on the Elkhorn
Plain during July and August (23). The intensity of drumming was high
and was interpreted as signifying intense territoriality at the time
of probable dispersal.
SPECIES INTERRELATIONSHIPS:
Giant kangaroo rats are a principal prey species for the
Endangered San Joaquin kit fox (Vulpes macrotis mutica). Kit foxes
are numerous everywhere substantial colonies of D. ingens are found.
Giant kangaroo rats also are probably important prey for American
Life History - 5 (DRAFT) - Life History
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
badgers (Taxidea taxus), long-tailed weasels (Mustela frenata), and
other small predators. The burrows of giant kangaroo rats are used by
the Endangered blunt-nosed leopard lizard (Gambelia silus) and the
State Threatened San Joaquin antelope squirrel (Ammospermophilus
nelsoni; 14).
The actions by giant kangaroo rats of harvesting seed heads,
digging and caching seeds in pits, clearing the central precinct of
dense herbaceous growth, and burrowing and remodeling burrows provide
important beneficial impacts on the community. The digging and
burrowing lightens and aerates the soil, allows water to infiltrate
the soil more readily, and promotes a dense growth of herbaceous
grasses and forbs two or more times greater than in surrounding areas
(11,25). Seed caching probably helps disperse and plant seeds. The
clearing of vegetation on the precinct provides bare areas required by
blunt-nosed leopard lizards. The burrows dug by giant kangaroo rats
provide refuges and den sites for blunt-nosed leopard lizards,
antelope squirrels, and a variety of other animals (14).
OTHER LIFE HISTORY DESCRIPTORS:
In areas inhabited by giant kangaroo rats, they are typically the
most numerous small mammal. In areas of extensive colonies, they are
often the only nocturnal small mammal, sharing their terrain only with
the diurnal San Joaquin antelope squirrel. Giant kangaroo rats
apparently exclude other species of small mammals from their colonies
(05,12,14), although it is not known if this is by competitive
exclusion or overt aggression.
Life History - 6 (DRAFT) - Management Practices
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Suppressing wildfire
Beneficial Prescribed/controlled burning of habitat
Beneficial Controlling/Restricting Off-Road Vehicles
Beneficial Controlling/Restricting Road Maintainance Actions
Beneficial Maintaining undisturbed/undeveloped areas
Beneficial Land Acquisition
Beneficial Controlling/Restricting Pesticide Use
Beneficial Controlling/Restricting Agricultural Practice
Beneficial Controlling/Removing Nonnative Vegetation
Beneficial Controlling/Removing Native Vegetation
Beneficial Controlling/Removing Domestic Animals
Adverse Low Gene Pool
Existing Low Gene Pool
Adverse Predation
Existing Predation
Adverse Oil Spills
Existing Oil Spills
Adverse Gas/Oil Development
Existing Gas/Oil Development
Adverse Recreational development
Existing Recreational development
Adverse Highway/Railroads
Existing Highway/Railroads
Adverse Transmission Lines/Towers
Existing Transmission Lines/Towers
Adverse Predator control
Existing Predator control
Adverse
Existing
COMMENTS ON MANAGEMENT PRACTICES -
Numbers of giant kangaroo rats have diminished dramatically in
recent years. Grinnell (05), Shaw (10), and Hawbecker (11,12)
described colonies spread over thousands of acres of continuous
habitat. The decline in populations of giant kangaroo rats has been
primarily due to loss of habitat. Up until the late 1960's and early
1970's, little land within their geographic range was cultivated or
otherwise developed. With the completion of the canals of the massive
State Water Project and the San Luis unit of the Central Valley
Project, irrigation water became available to the west side of the
Tulare Basin, the principal habitat of giant kangaroo rats (08,09).
Between about 1970 and 1979, virtually all land on the floor of the
Tulare Basin was converted to irrigated agriculture, restricting
occurrence of most species of the San Joaquin saltbush community,
including D. ingens.
Williams (08,09) investigated the population status of D. ingens.
Outlines of major, historical distribution areas encompassed an
estimated 755,844 ha. Extant colonies located between 1979 and 1987
Management Practices - 1 (DRAFT) - Management Practices
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
occupied approximately 11,145 ha about 1.47 percent of their historic
range. Several of the smaller colonies declined or disappeared after
being inventoried in 1979 and 1980. Five areas totaling about 4406 ha
supported population densities approaching conditions described as
typical up to the 1960's, but with densities averaging less than
one-half of those reported for high-quality habitat. The Elkhorn
Plain contained the largest and densest populations of the remaining
areas.
Use of rodenticide-treated grain to control ground squirrels and
kangaroo rats probably has contributed to the decline of giant
kangaroo rats in some areas, as rodent control on central California
rangelands has been a common practice during all of this century (13).
Degradation of desert and steppe rangelands by overgrazing might
also be a factor in the historic decline of giant kangaroo rats, but
there is no evidence to support this hypothesis. Giant kangaroo rats
can survive in areas that have been grazed to a point where virtually
no plant material remains (05,10,14). It is not known, however, if
they could survive indefinitely if those grazing intensities were
sustained for several successive years.
Oil developments in the Elk Hills Region of Kern County have
destroyed habitat for giant kangaroo rats, and oil spills associated
with petroleum extraction has killed some giant kangaroo rats (15).
The greatest future threats to giant kangaroo rats throughout
their remaining range are habitat loss through development for
agriculture and other purposes and high intensity grazing by cattle
and sheep. If levels characteristic of current grazing intensity on
the Carrizo and Elkhorn plains and the Panoche Region are sustained,
the desert communities will ultimately be destroyed and the soils lost
(09,14). Some ranchers with grazing operations within the range of
giant kangaroo rats have expressed dislike for kangaroo rats and
antelope squirrels, and believed that they competed with cattle for
food (08). Because anticoagulant-type rodenticides are available
without restriction and their use on private lands is unregulated, the
potential for poisoning giant kangaroo rats is significant.
UNAPPROVED PLAN:
Development of a recovery plan for the giant kangaroo rat has not been
initiated and no target date for initiation has been set.
Actions required for recovery fall into five categories:
1) reducing and controlling the level of livestock grazing in areas
inhabited by giant kangaroo rats; 2) securing habitat for the species,
which could be some combination of preventing cultivation in inhabited
areas and controlling or restricting oil extraction other developments
that would destroy or alter habitat, and acquiring land vulnerable to
agricultural and other developments; 3) prohibiting off-road vehicle
travel and recreation in areas inhabited by giant kangaroo rats;
4) restricting the purchase and use of anticoagulant-type rodenticides
by the public; 5) developing basic life history, demographic and
genetic data bases and determining effects of current land use
practices on giant kangaroo rats, including livestock grazing and fire
(03).
Management Practices - 2 (DRAFT) - Management Practices
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
Legislation or regulations are needed that require listing of
giant kangaroo rats and other vulnerable Endangered and Threatened
Species on labels of non-restricted rodenticides, prohibiting
application of the products within the ranges of listed species
without prior review by administrating agencies.
No recovery activities have been initiated for the giant
kangaroo rat.
Recovery potential for giant kangaroo rats is high because
Endangered Species listing was accomplished while some substantial
populations were still extant. Preservation of habitat and reduction
or elimination of grazing are the actions needed most to secure
populations. Once this is accomplished and basic demographic and
genetic data are gathered and effects of livestock grazing, fire, and
other potential habitat-management techniques are determined and
instituted, upgrading to Threatened status should follow rapidly.
Delisting might follow after a period of additional data gathering and
monitoring.
Management Practices - 3 (DRAFT) - References
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
References
***** REFERENCES FOR ALL NARRATIVES EXCEPT N-OCCURRENCE *****
01 Merriam, C. H. 1904. New and little known kangaroo rats of the
genus Perodipus. Proc. Biol. Soc. Washington, 17:139-146.
02 Williams, D. F., and K. S. Kilburn. In press. Dipodomys ingens.
Mammal. Species.
03 Grinnell, J. 1922. A geographical study of the kangaroo rats of
California. Univ. Calif. Publ. Zool., 24:1-124.
04 Hall, E. R. 1981. The mammals of North America. Second ed. John
Wiley and Sons, New York, 1:1-600 + 90.
05 Grinnell, J. 1932. Habitat relations of the giant kangaroo rat.
J. Mamm., 13:305-320.
06 Grinnell, J. 1921. Revised list of the species in the genus
Dipodomys. J. Mamm., 2:94-97.
07 Williams, D. F., and H. H. Genoways. In press. Taxonomy. In,
Biology of the family Heteromyidae. Amer. Soc. Mammalogists, Spec.
Publ. 10.
08 Williams, D. F. 1981. Distribution and population status of the
San Joaquin antelope squirrel and giant kangaroo rat. Calif. Dept.
Fish and Game, Nongame Wildl. Invest., Final Report, E-W-4,
IV-10.1 48 pp.
09 Williams, D.F. In press. Geographic distribution and population
status of the giant kangaroo rat, Dipodomys ingens (Rodentia,
Heteromyidae). In, Proceedings of the Conference on Endangered and
Sensitive Species of the San Joaquin Valley, California (D.F.
Williams, ed.).
10 Shaw, W. T. 1934. The ability of the giant kangaroo rat as a
harvester and storer of seeds. J. Mamm., 15:275-286.
11 Hawbecker, A. C. 1944. The giant kangaroo rat and sheep forage.
J. Wildl. Mgmt., 8:161-165.
12 Hawbecker, A. C. 1951. Small mammal relationships in an ephedra
community. J. Mamm., 32:50-60.
13 Grinnell, J., and J. S. Dixon. 1918. Natural history of the
ground squirrels of California. Bull. Calif. State Comm. Hort.,
7:597-708.
14 Williams, D. F., and W. Tordoff III. 1987. Operations and
maintenance schedule, Elkhorn Plain Ecological Reserve, San Luis
Obispo California. Calif. Dept. Fish and Game, Nongame-Heritage
Prog., Sacramento, Draft report. 60 pp.
15 Unpublished correspondence with U.S. Fish and Wildlife Service,
Endangered Species Office, Sacramento California, and Daniel F.
Williams.
16 Bolster, B. 1981. The occurrence and distribution of the giant
kangaroo rat (Dipodomys ingens) on Bureau of Land Management land
in the Panoche Hills and Tumey Hills, California. Office Study,
U.S. BLM, Hollister Resource Area, Hollister, CA. 14 pp.
17 Eisenberg, J. F. 1963. The behavior of heteromyid rodents. Univ.
Calif. Publ. Zool., 69:1-100.
18 Braun, S. E. 1985. Home range and activity patterns of the giant
kangaroo rat, Dipodomys ingens. J. Mamm., 66:1-12.
19 Tappe, D. T. 1941. Natural history of the Tulare kangaroo rat.
References - 1 (DRAFT) - References
Species RAT, GIANT KANGAROO
Species Id ESIS051013
Date 14 MAR 96
J. Mamm., 22:117-148.
20 Eisenberg, J. F., and D. E. Isaac. 1963. The reproduction of
heteromyid rodents in captivity. J. Mamm., 44:61-67.
21 Hawbecker, A. C. 1943. Food of the San Joaquin kit fox. J.
Mamm., 24:499.
22 Hawbecker, A. C. 1945. Food habits of the barn owl. Condor,
47:161-166.
23 Randall, J. A. 1984. Territorial defense and advertisement by
footdrumming in bannertail kangaroo rats (Dipodomys spectabilis) at
high and low population density. Behav. Ecol. Sociobiol, 16:11-20.
24 Williams, D. F. 1987. Unpubl. observations on foot drumming by
giant kangaroo rats on Elkhorn Plain Ecological Reserve.
25 Williams, D. F. 1985. Plant productivity in a desert ecosystem
dominated by giant kangaroo rats. Final Rep., Memorandum of
Understanding, California Dept. Fish and Game, Sacramento, 10 pp.
***** REFERENCES FOR N-OCCURRENCE NARRATIVE ONLY *****
01 Hall, E. R. 1981. The mammals of North America. Second ed. John
Wiley and Sons, New York, 1:1-600 + 90.
02 Grinnell, J. 1932. Habitat relations of the giant kangaroo rat.
J. Mamm., 13:305-320.
03 Williams, D. F. 1981. Distribution and population status of the
San Joaquin antelope squirrel and giant kangaroo rat. Calif. Dept.
of Fish and Game, Nongame Wildl. Invest., Final Report, E-W-4,
IV-10.1, 48 pp.
04 Williams, D. F. 1987. Distribution records for the giant kangaroo
rat Dipodomys ingens. Unpublished list of historic and current
records of occurrence of the giant kangaroo rat.
05 U.S. Fish and Wildlife Service. 1988. Unpublished maps depicting
locality records of giant kangaroo rats. Portland, OR 97232.
06 Williams, D.F. In press. Geographic distribution and population
status of the giant kangaroo rat, Dipodomys ingens (Rodentia,
Heteromyidae). In, Proceedings of the Conference on Endangered
and Sensitive Species of the San Joaquin Valley, California (D.F.
Williams, ed.).
07 Braun, S. 1982. Letter to D. F. Williams in which suspected
localities for giant kangaroo rats are listed.
08 Williams, D. F. Unpublished field notes from 1979 and 1985.
Inspections of Antelope Plain and Sunflower Valley, Kern and
Kings Counties, where evidence of unoccupied precincts of giant
kangaroo rats were found, but no extant colonies were located.
09 Glotzbach, S. F., and H. C. Heller. 1975. CNS regulation of
metabolic rate in the kangaroo rat Dipodomys ingens. Amer. J.
Physiol., 228:1880-1886.
10 Hawbecker, A. C. 1945. Food habits of the barn owl. Condor,
47:161-166.
11 O'Farrell, T. P., et al. 1987. Distribution of the endangered
giant kangaroo rat, Dipodomys ingens, on the Naval Petroleum
Reserves, Kern County, California. EG&G Energy Measurement,
Santa Barbara, Calif., EGG 10282-2173. 30 pp.
References - 2