RODENTS: Kangaroo Rats
Fig. 1. The Ord’s kangaroo
rat, Dipodomys ordi
There are 23 species of
kangaroo rats (genus Dipodomys) in North America.
Fourteen species occur in the lower 48 states. The Ord’s
kangaroo rat (D. ordi, Fig. 1) occurs in 17 US states,
Canada, and Mexico. Other widespread species include the
Merriam kangaroo rat (D. merriami), bannertail kangaroo
rat (D. spectabilis), desert kangaroo rat (D. deserti),
and Great Basin kangaroo rat (D. microps). Kangaroo rats
are distinctive rodents with small forelegs; long,
powerful hind legs; long, tufted tails; and a pair of
external, fur-lined cheek pouches similar to those of
pocket gophers. They vary from pale cinnamon buff to a
dark gray on the back with pure white underparts and
dark markings on the face and tail. The largest, the
giant kangaroo rat (D. ingens), has a head and body
about 6 inches (15 cm) long with a tail about 8 inches
(20 cm) long. The bannertail kangaroo rat is
approximately the same size, but has a white-tipped
tail. The other common species of kangaroo rats are
smaller. The Ord’s kangaroo rat has a head and body
about 4 inches (10 cm) long and a tail about 7 inches
(18 cm) long.
Kangaroo rats inhabit semiarid and arid
regions throughout most of the western and plains
states. The Ord’s kangaroo rat is the most common and
widespread of the kangaroo rats (Fig. 2). Several other
species are located in Mexico, California, and the
southwestern United States. They generally are not found
in irrigated pastures or crops, but may be found
adjacent to these areas on native rangelands, especially
on sandy or soft soils. They also invade croplands under
minimum tillage in these areas, particularly areas under
Kangaroo rats are primarily seed eaters, but
occasionally they will eat the vegetative parts of
plants. At certain times of the year they may eat
insects. They have a strong hoarding habit and will
gather large numbers of seeds in their cheek pouches and
take them to their burrows for storage. This caching
activity can cause significant impact on rangeland and
cropland. They remove seeds from a large area, thus
preventing germination of plants, particularly grasses,
in succeeding years. Since these rodents do not
hibernate, the seed caches are a source of food during
severe winter storms or unusually hot summer weather.
Kangaroo rats are quite sensitive to extremes in
temperature and during inclement weather may remain
underground for several days.
General Biology, Reproduction, and Behavior
Kangaroo rats breed from
February to October in southern desert states. The
breeding period is shorter in the northern states. The
gestation period is approximately 30 days. Reproductive
rates vary according to species, food availability, and
density of rodent populations. Females have 1 to 3
litters of 1 to 6 young per year. The young are born
hairless and blind in a fur-lined nest within the tunnel
system. Usually, the young remain in the nest and tunnel
for nearly a month before appearing aboveground.
Only a few females will
breed after a prolonged drought when food is in short
supply. Most females will bear young when food is
abundant, and some young females born early in the
season will also produce litters before the season ends.
All kangaroo rats build
tunnels in sandy or soft soil. The tunnel system is
fairly intricate, and consists of several sleeping,
living, and food storage chambers. The extensive
burrowing results in a fair amount of soil being brought
up and mounded on the ground surface. These mounds can
be mistaken for prairie dog mounds, particularly when
observed on aerial photographs. They may vary in size
but can be as large as 15 feet (4.5 m) across and up to
2 feet (60 cm) high.
Kangaroo rats are
completely nocturnal and often plug their burrow
entrances with soil during the day to maintain a more
constant temperature and relative humidity. They are
often seen on roads at night, hopping in front of
headlights in areas where they occur.
Kangaroo rats often occur
in aggregations or colonies, but there appears to be
little if any social organization among them. Burrows
are spaced to allow for adequate food sources within
normal travel distances. Spacing of mounds will vary
according to abundance of food, but well-defined travel
lanes have been observed between neighboring mounds.
When kangaroo rats are
locally abundant, their mounds, burrow openings, and
trails in vegetation and sand are conspicuous features
of the terrain. Both the number of burrows and
individuals per acre (ha) can vary greatly depending on
locality and time of year. There are usually many more
burrow openings than there are rats. Each active burrow
system, however, will contain at least one adult rat.
There could be as many as 35 rats per acre (14/ha) in
farmlands. In rangelands, 10 to 12 rats per acre (4 to
5/ha) is more likely. Kangaroo rats do not have large
home ranges; their radius of activity is commonly 200 to
300 feet (60 to 90 m), rarely exceeding 600 feet (183
m). They may move nearly a mile (1.6 km) to establish a
new home range.
Damage and Damage Identification
rats were considered to be of relatively minor economic
importance. They have come into direct conflict with
human interests, however, with large-scale development
of sandy soil areas for sprinkler-irrigated corn and
alfalfa production. A primary conflict develops at
planting time when kangaroo rats dig up newly planted
seeds and clip off new sprouts at their base. Damage is
more severe when population densities are high. Smaller
populations apparently are able to subsist on waste
grain and damage is not as apparent. Since kangaroo rats
are primarily seed eaters, they find irrigated fields
and pastures a veritable oasis and feed extensively on
waste grain after harvest.
Kangaroo rats have foiled
attempts to restore overused rangelands. Their habit of
collecting and caching large numbers of grass seeds
restricts the natural reseeding process. In semiarid
rangelands, activities of kangaroo rats can prevent an
area from making any appreciable recovery even though
the area received complete rest from livestock grazing
for 5 years or more. Reducing livestock grazing is not
enough. As long as kangaroo rats remain in an area, they
will restrict the reestablishment of desirable forages,
particularly native grasses.
Most kangaroo rats are
considered nongame animals and are not protected by
state game laws. Certain local subspecies may be
protected by regulations regarding threatened and
endangered species. Consult local authorities to
determine their legal status before applying controls.
Five kangaroo rat species currently are listed as
endangered by the US Fish and Wildlife Service. They are
found mostly in California and include the Fresno
kangaroo rat (D. nitratoides exilis), giant kangaroo rat
(D. ingens), Morro Bay kangaroo rat (D. heermanni
morroensis), Stephens’ kangaroo rat (D. stephensi
including D. cascus), and Tipton kangaroo rat (D.
nitratoides nitratoides). Persons working in California,
southern Oregon, south central Nevada, and western
Arizona should have expertise in identifying these
species, their mounds, and the ranges in which they
Damage Prevention and Control
Exclusion is most often accomplished by the
construction of rat-proof fences and gates around the
area to be protected. Most kangaroo rats can be excluded
by 1/2-inch (1.3-cm) mesh hardware cloth, 30 to 36
inches (75 to 90 cm) high. The bottom 6 inches (15 cm)
should be turned outward and buried at least 12 inches
(30 cm) in the ground. Exclusion may be practical for
small areas of high-value crops, such as gardens, but is
impractical and too expensive for larger acreages.
Alfalfa, corn, sorghum, and other grains are the
most likely crops to be damaged by kangaroo rats. When
possible, planting should be done in early spring before
kangaroo rats become active to prevent loss of seeds.
Less palatable crops should be planted along field edges
that are near areas infested with kangaroo rats.
High kangaroo rat numbers
most often occur on rangelands that have been subjected
to overuse by livestock. Kangaroo rats usually are not
abundant where rangelands have a good grass cover, since
many of the forbs that provide seeds for food are not
abundant in dense stands of grass. Thus, changes in
grazing practices accompanied by control programs may be
necessary for substantial, long-term relief.
There are no registered repellents for kangaroo
Zinc Phosphide. At present, 2% zinc phosphide bait
is federally registered for the control of the
bannertail, Merriam, and Ord’s kangaroo rats in
rangeland vegetation and noncrop areas. Some states may
also have Special Local Needs 24(c) registrations for
zinc phosphide baits to control kangaroo rats.
Zinc phosphide pelleted
rodent bait was tested on kangaroo rats in New Mexico
(Howard and Bodenchuk 1984). Levels of control were much
lower than those for 0.5% strychnine oats, but higher
than for 0.16% strychnine oats. Zinc phosphide applied
in June produced the highest percentage of control. Zinc
phosphide is advantageous because it is thought to
present little or no hazard of secondary poisoning to
small canids and a low hazard to other nontarget
Carefully read and follow
all label instructions. Zinc phosphide is a Restricted
Use Pesticide for retail sale to and use by certified
applicators or persons under their direct supervision,
and only for those uses covered by the applicator’s
There are no fumigants registered specifically for
kangaroo rats. Aluminum phosphide and gas cartridges are
currently registered for “burrowing rodents such as
woodchucks, prairie dogs, gophers, and ground
Live Traps. Trapping with box-type (wire
cage) traps can be successful in a small area when a
small number of kangaroo rats are causing problems.
These traps can be baited successfully with various
grains, oatmeal, oatmeal and peanut butter, and other
baits. One problem is the disposal of kangaroo rats
after they have been trapped. They usually die from
exposure if they remain in the trap for over 6 hours. If
the rats are released, they should be taken to an area
more than 1 mile (1.6 km) from the problem site. The
release site should provide suitable habitat and be
acceptable to everyone involved. Do not release kangaroo
rats in areas where landowners do not want them.
Trapping with snap traps is probably the most efficient
and humane method for kangaroo rats. Mouse traps will
suffice for smaller animals, but Victor® “museum
specials” or rat traps are needed for larger kangaroo
rats, particularly the bannertail. Successful baits
include whole kernel corn, peanut butter and oatmeal,
and oatmeal paste, which are placed on the trigger
mechanism. Place traps near, but not inside, the burrow
entrances or along runways between mounds. Check traps
each day to remove dead kangaroo rats. Reset tripped
traps and replace baits that may have been removed by
ants or other insects. Do not use whole kernel corn when
large numbers of seed-eating songbirds are in the area.
If kangaroo rats from only
one or two mounds are causing the problems, and water is
available, they may be flushed from their burrows and
either killed or allowed to go elsewhere. Collapse the
mounds after the kangaroo rats have been driven out.
This not only levels the surface but also allows you to
detect burrow reinvasion by other kangarooa rats. Use
caution when flushing burrows with water or trapping
kangaroo rats. The burrow entrances are sometimes used
by rattlesnakes seeking to escape heat and direct
sunlight during hot days. Even on warm days,
rattlesnakes may be found near mounds since kangaroo
rats are a source of food for them.
Economics of Damage and Control
Wood (1969) found that
Ord’s kangaroo rats eat about 1,300 pounds (585 kg) of
air-dried plant material per section per year in south
central New Mexico based on average (medium) densities.
He also reported an additional 336 pounds (151 kg) of
air-dried plant material per section per year consumed
by bannertail kangaroo rats in the same area under
average (medium) population densities. These data were
for arid rangelands and could be higher if the
populations of either species were denser. This forage
loss (3 Animal Unit Months [AUMs]) is currently valued
at $6 to $12 per section in New Mexico.
Bannertail kangaroo rats
stored 2.9 tons (2.6 mt) of plant material per section
per year in their burrows. Furthermore, production of
grasses on rangelands in excellent condition were
reduced by 10.6% (or 12 AUMs) by denuding of areas in
the vicinity of kangaroo rat mounds. These estimates do
not include the loss of regeneration of desirable
grasses due to seed consumption.
In areas that are being
farmed for production of pasture or commercial crops,
densities of kangaroo rats could become much higher than
those reported by Wood (1969). These higher densities,
coupled with higher crop values, could conceivably
produce losses greater than $100 per acre ($250/ha).
The cost of controlling
kangaroo rats can be quite high if labor-intensive
methods are employed. Of course, the cost per mound will
be higher when controlling a few mounds rather than
larger numbers. Trapping is the most costly method;
toxicants the least costly. The cost of the traps varies
greatly, depending on the size, number, and kind of
traps used. Live traps cost more than snap traps. The
cost of toxic baits is relatively low on a per-mound
basis. Labor costs are reduced when large areas are
treated with toxic grain baits using a four-wheel,
Information on specific
control techniques and limitations can be obtained from
your local extension agent or extension wildlife
specialist. In addition, personnel from state wildlife
agencies or USDA-APHIS-ADC can provide information on
control measures available in your area.
Figure 1 by Emily Oseas
Figure 2 adapted by the
author from Burt and Grossenheider (1976).
Burt, W. H., and R. P.
Grossenheider. 1976. A field guide to the mammals, 3d
ed. Houghton Mifflin Co., Boston, 289 pp.
Eisenbert, J. F. 1963. The
behavior of heteromyid rodents. Univ. California Publ.
Zool. 69:1-100. P>
Howard, V. W., Jr., and M.
J. Bodenchuk. 1984. Control of kangaroo rats with poison
baits. New Mexico State Univ. Range Improv. Task Force.
Res. Rep. 16.
Wood, J. E. 1965. Response
of rodent populations to controls. J. Wildl. Manage.
Wood, J. E. 1969. Rodent
populations and their impact on desert rangelands. New
Mexico Agric. Exper. Stn. Bull. 555. 17 pp.
Scott E. Hygnstrom, Robert
M. Timm, Gary E. Larson
PREVENTION AND CONTROL OF
WILDLIFE DAMAGE — 1994
Division Institute of Agriculture and Natural Resources
University of Nebraska - Lincoln
United States Department
of Agriculture Animal and Plant Health Inspection
Service Animal Damage Control
Great Plains Agricultural
Council Wildlife Committee