RODENTS: Prairie Dogs
Prevention and Control Methods
Wire mesh fences can be installed but they are
usually not practical or cost-effective. Visual
barriers of suspended burlap, windrowed pine trees,
or snow fence may be effective.
- Cultural Methods
Modify grazing practices on mixed and mid-grass
rangelands to exclude or inhibit prairie dogs.
Cultivate, irrigate, and establish tall crops to
discourage prairie dog use.
No methods are effective.
None are registered
Aluminum phosphide. Gas cartridges.
Box traps. Snares. Conibear® No. 110 (body-gripping)
traps or equivalent.
Shooting with .22 rimfire or larger rifles.Day
shooting and spotlighting are effective where legal.
- Other Methods
Several home remedies have been used but most are
unsafe and are not cost-effective.
Prairie dogs (Fig. 1) are
stocky burrowing rodents that live in colonies called
“towns.” French explorers called them “little dogs”
because of the barking noise they make. Their legs are
short and muscular, adapted for digging. The tail and
other extremities are short. Their hair is rather coarse
with little underfur, and is sandy brown to cinnamon in
color with grizzled black and buff-colored tips. The
belly is light cream to white.
Five species of prairie
dogs are found in North America: the black-tailed (Cynomys
ludovicianus), Mexican (C. mexicanus), white-tailed (C.
leucurus), Gunnison’s (C. gunnisoni), and Utah prairie
dog (C. parvidens). The most abundant and widely
distributed of these is the black-tailed prairie dog,
which is named for its black-tipped tail. Adult
black-tailed prairie dogs weigh 2 to 3 pounds (0.9 to
1.4 kg) and are 14 to 17 inches (36 to 43 cm) long. The
Mexican prairie dog also has a black-tipped tail, but is
smaller than its northern relative. White-tailed, Gunni-son’s,
and Utah prairie dogs all have white-tipped tails.
White-tailed prairie dogs are usually smaller than
black-tailed prairie dogs, weighing between 1 1/2 and 2
1/2 pounds (0.7 to 1.1 kg). The Gunnison’s prairie dog
is the smallest of the five species.
Prairie dogs occupied up
to 700 million acres of western grasslands in the early
1900s. The largest prairie dog colony on record, in
Texas, measured nearly 25,000 square miles (65,000 km2)
and contained an estimated 400 million prairie dogs.
Since 1900, prairie dog populations have been reduced by
as much as 98% in some areas and eliminated in others.
This reduction is largely the result of cultivation of
prairie soils and prairie dog control programs
implemented in the early and mid-1900s. Population
increases have been observed in the 1970s and 1980s,
possibly due to the increased restrictions on and
reduced use of toxicants.
Today, about 2 million
acres of prairie dog colonies remain in North America.
The black-tailed prairie
dog lives in densely populated colonies (20 to 35 per
acre [48 to 84/ha]) scattered across the Great Plains
from northern Mexico to southern Canada (Fig 2).
Occasionally they are found in the Rocky Mountain
foothills, but rarely at elevations over 8,000 feet
(2,438 m). The Mexican prairie dog occurs only in Mexico
and is an endangered species. White-tailed prairie dogs
live in sparsely populated colonies in arid regions up
to 10,000 feet (3,048 m). The Gunnison’s prairie dog
inhabits open grassy and brushy areas up to 12,000 feet
(3,658 m). Utah prairie dogs are a threatened species,
limited to central Utah.
All species of prairie dogs are found in
grassland or short shrubland habitats. They prefer open
areas of low vegetation. They often establish colonies
near intermittent streams, water impoundments, homestead
sites, and windmills. They do not tolerate tall
vegetation well and avoid brush and timbered areas. In
tall, mid- and mixed-grass rangelands, prairie dogs have
a difficult time establishing a colony unless large
grazing animals (bison or livestock) have closely grazed
vegetation. Once established, prairie dogs can maintain
their habitat on mid-and mixed-grass rangelands. In
shortgrass prairies, where moisture is limited, prairie
dogs can invade and maintain acceptable habitat without
Prairie dogs are active
above ground only during the day and spend most of their
time foraging. In the spring and summer, individuals
consume up to 2 pounds (0.9 kg) of green grasses and
forbs (broad-leafed, nonwoody plants) per week. Grasses
are the preferred food, making up 62% to 95% of their
diet. Common foods include western wheatgrass, blue
grama, buffalo grass, sand dropseed, and sedges. Forbs
such as scarlet globe mallow, prickly pear, kochia,
peppergrass, and wooly plantain are common in prairie
dog diets and become more important in the fall, as
green grass becomes scarce. Prairie dogs also eat
flowers, seeds, shoots, roots, and insects when
General Biology, Reproduction, and Behavior
Prairie dogs are social
animals that live in towns of up to 1,000 acres (400 ha)
or more. Larger towns are often divided into wards by
barriers such as ridges, lines of trees, and roads.
Within a ward, each family or “coterie” of prairie dogs
occupies a territory of about 1 acre (0.4 ha). A coterie
usually consists of an adult male, one to four adult
females, and any of their offspring less than 2 years
old. Members of a coterie maintain unity through a
variety of calls, postures, displays, grooming, and
other forms of physical contact.
Black-tailed prairie dog
towns typically have 30 to 50 burrow entrances per acre,
while Gunnison’s and white-tailed prairie dog towns
contain less than 20 per acre. Most burrow entrances
lead to a tunnel that is 3 to 6 feet (1 to 2 m) deep and
about 15 feet (5 m) long. Prairie dogs construct crater-
and dome-shaped mounds up to 2 feet (0.6 m) high and 10
feet (3 m) in diameter. The mounds serve as lookout
stations. They also prevent water from entering the
tunnels and may enhance ventilation of the tunnels.
Prairie dogs are most
active during the day. In the summer, during the hottest
part of the day, they go below ground where it is much
cooler. Black-tailed prairie dogs are active all year,
but may stay underground for several days during severe
winter weather. The white-tailed, Gunnison’s, and Utah
prairie dogs hibernate from October through February.
Black-tailed prairie dogs
reach sexual maturity after their second winter and
breed only once per year. They can breed as early as
January and as late as March, depending on latitude. The
other four species of prairie dogs reach sexual maturity
after their first winter and breed in March. The
gestation period is about 34 days and litter sizes range
from 1 to 6 pups. The young are born hairless, blind,
and helpless. They remain underground for the first 6
weeks of their lives. The pups emerge from their dens
during May or June and are weaned shortly thereafter. By
the end of fall, they are nearly full grown. Survival of
prairie dog pups is high and adults may live from 5 to 8
Even with their sentries
and underground lifestyle, predation is still a major
cause of mortality for prairie dogs. Badgers, weasels,
and black-footed ferrets are efficient predators.
Coyotes, bobcats, foxes, hawks, and eagles also kill
prairie dogs. Prairie rattlesnakes and bull snakes may
take young, but rarely take adult prairie dogs.
Accidents, starvation, weather, parasites, and diseases
also reduce prairie dog populations, but human
activities have had the greatest impact.
Prairie dog colonies
attract a wide variety of wildlife. One study identified
more than 140 species of wildlife associated with
prairie dog towns. Vacant prairie dog burrows serve as
homes for cottontail rabbits, small rodents, reptiles,
insects, and other arthropods. Many birds, such as
meadowlarks and grasshopper sparrows, appear in greater
numbers on prairie dog towns than in surrounding
prairie. The burrowing owl is one of several uncommon or
rare species that frequent prairie dog towns. Others
include the golden eagle, prairie falcon, ferruginous
hawk, mountain plover, swift fox, and endangered
black-footed ferret (see Appendix A of this chapter).
and Damage Identification
studies have produced inconsistent results regarding the
impacts of prairie dogs on livestock production. The
impacts are difficult to determine and depend on several
factors, such as the site conditions, weather, current
and historic plant communities, number of prairie dogs,
size and age of prairie dog towns, and the intensity of
site use by livestock and other grazers. Prairie dogs
feed on many of the same grasses and forbs that
livestock feed on. Annual dietary overlap ranges from
64% to 90%. Prairie dogs often begin feeding on pastures
and rangeland earlier in spring than cattle do and clip
plants closer to the ground. Up to 10% of the
aboveground vegetation may be destroyed due to their
burrowing and mound-building activities. Overall,
prairie dogs may remove 18% to 90% of the available
forage through their activities.
The species composition of
pastures occupied by prairie dogs may change
dramatically. Prairie dog activities encourage
shortgrass species, perennials, forbs, and species that
are resistant to grazing. Annual plants are selected
against because they are usually clipped before they can
produce seed. Several of the succeeding plant species
are less palatable to livestock than the grasses they
Other studies, however,
indicate that prairie dogs may have little or no
significant effect on livestock production. One research
project in Oklahoma revealed that there were no
differences in annual weight gains between steers using
pastures inhabited by prairie dogs and steers in
pastures without prairie dogs. Reduced forage
availability in prairie dog towns may be partially
compensated for by the increased palatability and crude
protein of plants that are stimulated by grazing. In
addition, prairie dogs sometimes clip and/or eat plants
that are toxic to livestock. Bison, elk, and pronghorns
appear to prefer feeding in prairie dog colonies over
Prairie dog burrows
increase soil erosion and are a potential threat to
livestock, machinery, and horses with riders. Damage may
also occur to ditch banks, impoundments, field trails,
Prairie dogs are
susceptible to several diseases, including plague, a
severe infectious disease caused by the bacterium
Yersinia pestis. Plague, which is often fatal to humans
and prairie dogs, is most often transmitted by the bite
of an infected flea. Although plague has been reported
throughout the western United States, it is uncommon.
Symptoms in humans include swollen and tender lymph
nodes, chills, and fever. The disease is curable if
diagnosed and treated in its early stages. It is
important that the public be aware of the disease and
avoid close contact with prairie dogs and other rodents.
Public health is a primary concern regarding prairie dog
colonies that are in close proximity to residential
areas and school yards.
Rattlesnakes and black
widow spiders also occur in prairie dog towns, but can
be avoided. Rattlesnakes often rest in prairie dog
burrows during the day and move through towns at night
in search of food. Black widow spiders are most often
found in abandoned prairie dog holes where they form
webs and raise their young. Bites from these animals are
rare, but are a threat to human health.
white-tailed, and Gunni-son’s prairie dogs are typically
classified as unprotected or nuisance animals, allowing
for their control without license or permit. Most states
require purchase of a small game license to shoot
prairie dogs. If the shooter is acting as an agent for
the landowner to reduce prairie dog numbers, a license
may not be required. The Utah and Mexican prairie dogs
are classified as threatened and endangered species,
respectively. Contact your local wildlife agency for
The black-footed ferret is
an endangered species that lives almost exclusively in
prairie dog towns, and all active prairie dog colonies
are potential black-footed ferret habitat. It is a
violation of federal law to willfully kill a
black-footed ferret or poison prairie dog towns where
ferrets are present. Federal agencies must assess their
own activities to determine if they “may affect”
endangered species. Some pesticides registered for
prairie dog control require private applicators to
conduct ferret surveys before toxicants can be applied.
Detailed information on identifying black-footed ferrets
and their sign is included in Appendix A of this
chapter. To learn more about federal and state
guidelines regarding prairie dog control, black-footed
ferret surveys, and block clearance procedures, contact
personnel from your local Cooperative Extension,
USDA-APHIS-ADC, US Fish and Wildlife Service, or state
wildlife agency office.
Prevention and Control Methods
Exclusion of prairie dogs is rarely practical, although
they may be discouraged by tight-mesh, heavy-gauge,
galvanized wire, 5 feet (1.5 m) wide with 2 feet (60 cm)
buried in the ground and 3 feet (90 cm) remaining
aboveground. A slanting overhang at the top increases
the effectiveness of the fence.
Prairie dogs graze and closely clip vegetation to
provide a clear view of their surroundings and improve
their ability to detect predators. Fences, hay bales,
and other objects can be used to block prairie dogs’
view and thus reduce suitability of the habitat.
Franklin and Garrett (1989) used a burlap fence to
reduce prairie dog activity over a two-month period.
Windrows of pine trees also reduced prairie dog
activity. Unfortunately, the utility of visual barriers
is limited because of high construction and maintenance
costs. Tensar snow fences (2 feet [60 cm] tall) are less
costly, at about $0.60 per foot ($1.97/m) for materials.
Unfortunately, they were inconsistent in reducing
reinvasion rates of prairie dog towns in Nebraska (Hygnstrom
and Virchow, unpub. data).
Proper range management can be used to control prairie
dogs. Use stocking rates that maintain sufficient stand
density and height to reduce recolonization of
previously controlled prairie dog towns or reduce
occupation of new areas. The following general
recommendations were developed with the assistance of
extension range management specialists and research
Overgrazed pastures are favorable for prairie dog town
establishment or expansion. If present, prairie dogs
should be included in stocking rate calculations. At a
conservative population density of 25 prairie dogs per
acre (60/ha) and dietary overlap of 75%, it takes 6
acres (2.4 ha) of prairie dogs to equal 1 Animal Unit
Month (AUM) (the amount of forage that one cow and calf
ingest per month during summer [about 900 pounds; 485
Grazing. Rest pastures for a period of time
during the growing season to increase grass height and
maintain desired grass species. Instead of season-long
continuous grazing, use short duration or rapid rotation
grazing systems, or even total deferment during the
growing season. Livestock can be excluded from vacant
prairie dog towns with temporary fencing to help
vegetation regain vigor and productivity. Mid- to
tallgrass species should be encouraged where they are a
part of the natural vegetation. In semiarid and
shortgrass prairie zones, grazing strategies may have
little effect on prairie dog town expansion or
Prairie dogs often establish towns in areas where
livestock congregate, such as at watering sites or old
homesteads. Move watering facilities and place salt and
minerals on areas that are underutilized by livestock to
distribute livestock grazing pressure more evenly.
Prescribed burns in spring may enhance regrowth of
desirable grass species.
Prairie dog numbers can be reduced by plowing or disking
towns and leaving the land fallow for 1 to 2 years,
where soil erosion is not a problem. Establish tall
grain crops after the second year to further discourage
prairie dogs. Burrows can be leveled and filled with a
tractor-mounted blade to help slow reinvasion. Flood
irrigation may discourage prairie dogs.
not a practical means of control.
Safety Precautions. Use pesticides safely
and comply with all label recommendations. Only use
products that are registered for prairie dog control by
the Environmental Protection Agency. Some pesticides
registered for prairie dog control require that private
applicators conduct ferret surveys before toxicants can
be applied. Detailed information on identifying
black-footed ferrets and their sign is included in
Appendix A of this chapter. Seek assistance from your
local extension agent or from the USDA-APHIS-ADC if
The only toxic baits currently registered and legal for
use to control prairie dogs are 2% zinc phosphide-treated
grain bait and pellet formulations. Zinc phosphide baits
are effective and relatively safe regarding livestock
and other wildlife in prairie dog towns, if used
properly. These baits are available through national
suppliers, USDA-APHIS-ADC, and local retail
Toxic baits are most
effective when prairie dogs are active and when there is
no green forage available. Therefore, it is best to
apply baits in late summer and fall. Zinc phosphide
baits can only be applied from July 1 through January
Prairie dog burrows must be prebaited before applying
toxic bait. Prebaiting will accustom prairie dogs to
eating grain and will make the toxic bait considerably
more effective when it is applied. Use clean rolled oats
as a prebait if you are using 2% zinc phosphide-treated
rolled oats. Drop a heaping teaspoon (4 g) of untreated
rolled oats on the bare soil at the edge of each prairie
dog mound or in an adjacent feeding area. The prebait
should scatter, forming about a 6-inch (15-cm) circle
(Fig. 3). Do not place the prebait in piles or inside
burrows, on top of mounds, among prairie dog droppings,
or in vegetation far from the mound.
Apply toxic bait only
after the prebait has been readily eaten, which usually
takes 1 to 2 days. If the prebait is not accepted
immediately, wait until it is eaten readily before
applying the toxic bait. More than one application of
prebait may be necessary if rain or snow falls on the
prebait. Prohibit shooting and other disturbance of the
colony at least 6 weeks prior to and during treatment.
Prebait and toxic bait can
be applied by hand on foot, but mechanical bait
dispensers attached to all-terrain vehicles are more
convenient and cost-ef-fective for towns greater than 20
acres (8 ha). Motorcycles and horses can also be used to
apply prebait and toxic bait.
Apply about 1 heaping teaspoon (4 g) of grain bait per
burrow in the same way that the prebait was applied.
About 1/3 pound of prebait and 1/3 pound of zinc
phosphide bait are needed per acre (0.37 kg/ha). Excess
bait that is not eaten by prairie dogs can be a hazard
to nontarget wildlife or livestock. It is best to remove
livestock, especially horses, sheep, or goats, from the
pasture before toxic bait is applied; however, removal
is not required. Apply toxic bait early in the day for
best results and restrict any human disturbance for 3
days following treatment. Always wear rubber gloves when
handling zinc phosphide-treated baits. Follow all label
directions and observe warnings regarding bait storage
Apply prebait and bait
during periods of settled weather, when vegetation is
dry and dormant. Avoid baiting on wet, cold, or windy
days. Bait acceptance is usually best after August 1st
or when prairie dogs are observed feeding on native
seeds and grains. Do not apply zinc phosphide to a
prairie dog town more than once per year. If desired,
survivors can be removed by fumigation or shooting.
Treatment with toxic baits, followed by a fumigant
cleanup, is most cost-effective for areas of more than 5
acres (2 ha).
evaluation. Inspect treated prairie dog towns 2
to 3 days after treatment. Remove and burn or bury any
dead prairie dogs that are aboveground to protect any
other animals from indirect poisoning. Success rates of
75% to 85% can usually be obtained with zinc phosphide
if it is applied correctly.
To evaluate the success of
a treatment, mark and plug 100 burrows 3 days prior to
treatment. Count the reopened burrows 24 hours later.
Replug the same 100 burrows 3 days after treatment and
again count the reopened burrows 24 hours later. Divide
the number of reopened burrows (posttreatment) by the
number of reopened burrows (pretreatment) to determine
the survival rate. Abandoned burrows are usually filled
with spider webs, vegetation, and debris. Active burrows
are clean and surrounded by tracks, diggings, and fresh
droppings at the entrances.
Zinc phosphide is a
Restricted Use Pesticide, available for sale to and use
by certified pesticide applicators or their designates.
Contact your county extension office for information on
acquiring EPA certification. Treatment of a prairie dog
town with zinc phosphide-treated baits cost about $10
per acre ($25/ha) (includes materials and labor).
including aluminum phosphide tablets and gas cartridges,
can provide satisfactory control of prairie dogs in some
situations. We do not recommend fumigation as the
primary means of control for large numbers of prairie
dogs because it is costly, time-consuming, and usually
more hazardous to desirable wildlife species than toxic
baits. Fumigants cost about 5 to 10 times more per acre
(ha) to apply than toxic baits. Therefore, fumigation is
usually used during spring as a follow-up to toxic bait
treatment. Success rates of 85% to 95% can usually be
obtained if fumigants are applied correctly.
For best results, apply
fumigants in spring when soil moisture is high and soil
temperature is greater than 60o F (15o C). Fumigation
failures are most frequent in dry, porous soils. Spring
applications are better than fall applications because
all young prairie dogs are still in their natal burrows.
Do not use fumigants in
burrows where nontarget species are thought to be
present. Black-footed ferrets, burrowing owls, swift
fox, cottontail rabbits, and several other species of
wildlife occasionally inhabit prairie dog burrows and
would likely be killed by fumigation. Be aware of sign
and avoid fumigating burrows that are occupied by
nontarget wildlife. Some manufacturers’ labels now
require private applicators to conduct black-footed
ferret surveys before application. Detailed information
on identifying black-footed ferrets and their sign is
included in Appendix A of this chapter. Burrows used by
burrowing owls often have feathers, pellets, and
whitewash nearby. Natal burrows are often lined with
finely shredded cow manure. Migratory burrowing owls
usually arrive in the central Great Plains in late April
and leave in early October. Fumigate before late April
to minimize the threat to burrowing owls.
Aluminum phosphide is a Restricted Use Pesticide,
registered as a fumigant for the control of burrowing
rodents. The tablets react with moisture in prairie dog
burrows, and release toxic phosphine gas (PH3). Use a
4-foot (1.2-m) section of 2-inch (5-cm) PVC pipe to
improve placement of the tablets. Insert the pipe into a
burrow and roll the tablets down the pipe. Place
crumpled newspaper and/or a slice of sod in the burrow
to prevent loose soil from smothering the tablets and
tightly pack the burrow entrance with soil. To increase
efficiency, work in pairs, one person dispensing and one
Always wear cotton gloves
while handling aluminum phosphide. Aim containers away
from the face when opening and work into the wind to
avoid inhaling phosphine gas from the container and the
treated area. Aluminum phosphide should be stored in a
well-ventilated area, never inside a vehicle or occupied
building. Aluminum phosphide is classified as a
flammable solid. Check with your local department of
transportation for regulations regarding transportation
of hazardous materials.
Aluminum phosphide can be
purchased by certified pesticide applicators through
national suppliers (see Supplies and Materials) or local
retail distributors. It typically provides an 85% to 95%
reduction in prairie dog populations when applied
correctly and costs about $25 per acre ($63/ha) to
apply. It is typically more cost-effec-tive to use than
gas cartridges because of the reduced handling time.
Gas cartridges have been used for many years to control
prairie dogs. When ignited, they burn and produce carbon
monoxide, carbon dioxide, and other gases. To prepare a
gas cartridge for use, insert a nail or small
screwdriver in the end at marked points and stir the
contents before inserting and lighting the fuse. Hold
the cartridge away from you until it starts burning,
then place it deep in a burrow. Burrows should be
plugged immediately in the same way as with aluminum
phosphide. Be careful when using gas cartridges because
they can cause severe burns. Do not use them near
flammable materials or inside buildings. Gas cartridges
are a General Use Pesticide, available through
USDA-APHIS-ADC. They provide up to 95% control when
applied correctly and cost about $35 per acre ($88/ha)
Cage traps can
be used to capture individual animals, but the process
is typically too expensive and time consuming to be
employed for prairie dog control. Best results are
obtained by trapping in early spring after snowmelt and
before pasture green up. Bait traps with oats flavored
with corn oil or anise oil.
It may be difficult to
find release sites for prairie dogs. Releasing prairie
dogs into an established colony will increase stress on
resident and released prairie dogs.
Body-gripping traps, such
as the Conibear® No. 110, are effective when placed in
burrow entrances. No. 1 Gregerson snares can be used to
remove a few prairie dogs, but the snares are usually
rendered useless after each catch. Prairie dogs also can
be snared by hand, using twine or monofilament line.
These traps and snares may be effective for 1- to 5-acre
(0.4- to 2-ha) colonies where time is not a
very selective and not hazardous to nontarget wildlife.
It is most effective in spring because it can disrupt
prairie dog breeding. Continuous shooting can remove 65%
of the population during the year, but it usually is not
practical or cost-effective. Prairie dogs often become
wary and gun-shy after extended periods of shooting.
They can be conditioned to loud noises by installing a
propane cannon or old, mis-timed gasoline engine in the
town for 3 to 4 days before shooting.
Long range, flat
trajectory rifles are the most efficient for shooting
prairie dogs. Rifles of .22 caliber or slightly larger
are most commonly used. Bipods and portable shooting
benches, telescopic sights, and spotting scopes are also
useful equipment for efficient shooting. Contact a local
extension office or state wildlife agency for lists of
shooters and receptive landowners.
variety of home remedies have been tried in desperate
attempts to control prairie dogs. Engine exhaust, dry
ice, butane, propane, gasoline, anhydrous ammonia,
insecticides, nonregistered rodenticides, water, and
dilute cement are all unregistered for prairie dog
control. None have proven to be as cost-effective or
successful as registered rodenticides, and most are
hazardous to applicators and/or nontarget species. In
addition, those methods that have been observed by the
authors (exhaust, propane, ammonia, nonregistered
rodenticides, and water) were substantially more
expensive than registered and recommended methods.
A modified street sweeper
vacuum has recently been used to suck prairie dogs out
of their burrows. Inventor Gay Balfour of Cortez,
Colorado, reports that the “Sucker Upper” can typically
clear a range of 5 to 20 acres (2 to 8 ha) per day at a
cost of $1,000 per day, not including travel expenses.
This device, unfortunately, has not been independently
tested. Although relatively expensive, this method may
provide a nonlethal approach to dealing with prairie
dogs where conventional methods are not appropriate or
acceptable. The prairie dogs can either be euthanized
with carbon dioxide gas or relocated if a suitable site
can be found.
Integrated Pest Management
pest management approach dictates the timely use of a
variety of cost-effective management options to reduce
prairie dog damage to a tolerable level. We recommend
the application of toxic bait in the fall, followed by
the application of aluminum phosphide in the spring. If
possible, defer grazing on the treated area during the
next growing season to allow grasses and other
vegetation to recover. A computer program was produced
by Cox and Hygnstrom in 1993 to determine cost-effective
options and economic returns of prairie dog control (see
For Additional Information).
Economics of Damage and Control
Prairie dogs play an
important role in the prairie ecosystem by creating
islands of unique habitat that increase plant and animal
diversity. Prairie dogs are a source of food for several
predators and their burrows provide homes for several
species, including the endangered black-footed ferret.
Burrowing mixes soil types and incorporates organic
matter, both of which may benefit soil. It also
increases soil aeration and decreases compaction.
Prairie dogs provide recreational opportunities for
nature observers, photographers, and shooters. The
presence of large, healthy prairie dog towns, however,
is not always compatible with agriculture and other
human land-use interests.
Prairie dogs feed on many
of the same grasses and forbs that livestock do. Annual
dietary overlap has been estimated from 64% to 90%. One
cow and calf ingest about 900 pounds (485 kg) of forage
per month during the summer (1 AUM). One prairie dog
eats about 8 pounds (17.6 kg) of forage per month during
the summer. At a conservative population density of 25
prairie dogs per acre (60/ha) and dietary overlap of
75%, it takes 6 acres (2.4/ha) of prairie dogs to equal
1 AUM. Small, rather widely dispersed colonies occupying
20 acres (8 ha) or less are tolerated by many landowners
because of the sport hunting and aesthetic opportunities
they provide. Colonies that grow larger than 20 acres (8
ha) often exceed tolerance levels because of lost AUMs,
taxes, and increasing control costs.
The South Dakota
Department of Agriculture (1981) reported that 730,000
acres (292,000 ha) were inhabited by prairie dogs in
1980, with a loss of $9,570,000 in production. The South
Dakota livestock grazing industry similarly estimated
losses of up to $10.29 per acre ($25.43/ha) on pasture
and rangeland inhabited by prairie dogs and $30.00 per
acre ($74.10/ha) for occupied hay land. Prairie dogs
inhabited about 73,000 acres (29,200 ha) in Nebraska in
1987, with a loss estimated at $200,000. A reported 1/2
to 1 million acres (200,000 to 400,000 ha) are occupied
in Colorado. A committee of the National Academy of
Sciences (1970) concluded that “the numerous eradication
campaigns against prairie dogs and other small mammals
were formerly justified because of safety for human
health and conflicts with livestock for forage.”
On the other hand, Collins
et al. (1984) found it was not economically feasible to
treat prairie dogs on shortgrass rangeland with zinc
phosphide in South Dakota because the annual control
costs exceeded the value of forage gained. Seventeen
acres (6.8 ha) would have to be treated to gain 1 AUM.
Uresk (1985) reported that South Dakota prairie dog
towns treated with zinc phosphide yielded no increase in
production after 4 years. The cost-effectiveness of
prairie dog control depends greatly on the age, density,
and size ofthe prairie dog colony; soil and grassland
type; rainfall; and control method employed.
We acknowledge M. J.
Boddicker and F. R. Henderson, who authored the “Prairie
Dogs” and “Black-footed Ferrets” chapters, respectively,
in the 1983 edition of Prevention and Control of
Figure 1 by Emily Oseas
Figure 2 by Dave Thornhill,
University of Nebraska.
Figure 3 by Renee Lanik,
University of Nebraska.
For Additional Information
Agnew, W., D. W. Uresk, and R. M. Hansen. 1986. Flora
and fauna associated with prairie dog colonies and
adjacent ungrazed mixed-grass prairie in western South
Dakota. J. Range. Manage. 39:135-139.
Bonham, C.D., and A.
Lerwick. 1976. Vegetation changes induced by prairie
dogs on shortgrass range. J. Range Manage. 29:217-220.
Cable, K. A., and R. M.
Timm. 1988. Efficacy of deferred grazing in reducing
prairie dog reinfestation rates. Proc. Great Plains
Wildl. Damage Control Workshop 8:46-49.
Cincotta, R. P., D. W.
Uresk, and R. M. Hansen. 1987. Demography of
black-tailed prairie dog populations reoccupying sites
treated with rodenticide. Great Basin Nat. 47:339-343.
Clark, T. W. 1986.
Annotated prairie dog bibliography 1973 to 1985. Montana
Bureau Land Manage. Tech. Bull. No. 1. Helena. 32 pp.
Clark, T. W., T. M.
Campbell, III, M. H. Schroeder, and L. Richardson. 1983.
Handbook of methods for locating black-footed ferrets.
Wyoming Bureau Land Manage. Tech. Bull. No. 1. Cheyenne.
Vertebrate Pests: Problems and Control. Natl. Acad. of
Science. Washington, DC. 153 pp.
Collins, A. R., J. P.
Workman, and D. W. Uresk. 1984. An economic analysis of
black-tailed prairie dog (Cynomys ludovicianus) control.
J. Range Manage. 37:358-361.
Cox, M. K., and S. E.
Hygnstrom. 1991. Prairie dog control: a computer model
for prairie dog management on rangelands. Proc. Great
Plains Wildl. Damage Control Workshop 10:68-69.
Dobbs, T. L. 1984.
Economic losses due to prairie dogs in South Dakota.
South Dakota Dep. Agric. Div. Agric. Regs. Inspect.
Pierre. 15 pp.
Fagerstone, K. A. 1982. A
review of prairie dog diet and its variability among
animals and colonies. Proc. Great Plains Wildl. Damage
Control Workshop 5:178-184.
Franklin, W. L., and M. G.
Garrett. 1989. Nonlethal control of prairie dog colony
expansion with visual barriers. Wildl. Soc. Bull.
Foster-McDonald, N. S.,
and S. E. Hygnstrom. 1990. Prairie dogs and their
ecosystem. Univ. Nebraska. Dep. For., Fish. Wildl.
Lincoln. 8 pp.
Hansen, R. M., and I.
Gold. 1977. Blacktail prairie dogs, desert cottontails
and cattle trophic relations on shortgrass range. J.
Range Manage. 30:210-214.
Hygnstrom, S. E., and P.
M. McDonald. 1989. Efficacy of three formulations of
zinc phosphide for black-tailed prairie dog control.
Proc. Great Plains Wildl. Damage Control Workshop 9:181.
Hygnstrom, S. E., and D.
R. Virchow. 1988. Prairie dogs and their control. Univ.
Nebraska-Coop. Ext. NebGuide No. C80-519. Lincoln. 4 pp.
Knowls, C. J. 1986.
Population recovery of black tailed prairie dogs
following control with zinc phosphide. J. Range Manage.
Koford, C. B. 1958.
Prairie dogs, whitefaces and blue grama. Wildl. Mono.
Merriam, C. H. 1902. The
prairie dog of the Great Plains. Pages 257-270 in
Yearbook of the USDA. US Govt. Print. Office.
O’Meilia, M. E., F. L.
Knopf, and J. C. Lewis. 1982. Some consequences of
competition between prairie dogs and beef cattle. J.
Range Manage. 35:580-585.
Schenbeck, G. L. 1981.
Management of black-tailed prairie dogs on the National
Grasslands. Proc. Great Plains Wildl. Damage Control
Sharps, J. C., and D. W.
Uresk. 1990. Ecological review of black-tailed prairie
dogs and associated species in western South Dakota.
Great Basin Nat. 50:339-345.
Snell, C. P., and B. D.
Hlavachick. 1980. Control of prairie dogs -the easy way.
South Dakota Department of
Agriculture. 1981. Vertebrate rodent economic loss,
South Dakota 1980. US Dep. Agric. Stat. Rep. Serv. Sioux
Falls. 4 pp.
Uresk, D. W. 1985. Effects
of controlling black-tailed prairie dogs on plant
production. J. Range Manage. 38:466-468.
Uresk, D. W. 1987.
Relation of black-tailed prairie dogs and control
programs to vegetation, livestock, and wildlife. Pages
312-322 in J. L. Caperinera, ed. Integrated pest
management on rangeland: a shortgrass prairie
perspective. Westview Press. Boulder, Colorado.
Uresk, D. W., J. G.
MacCracken, and A. J. Bjugstad. 1982. Prairie dog
density and cattle grazing relationships. Great Plains
Wildl. Damage Control Workshop. 5:199-201.
Whicker, A. D., and J. K.
Detling. 1988. Ecological consequences of prairie dog
disturbances. BioSci. 38:778-785.
Cox, M. K., and S. E.
Hygnstrom. 1993. Prairie dog control: An educational
guide, population model, and cost-benefit analysis for
prairie dog control. Available from 105 ACB IANR-CCS,
University of Nebraska, Lincoln, NE 68583-0918.
The black-footed ferret (Mustela
nigripes, Fig. 4) is the most rare and endangered mammal
in North America. Black-footed ferrets establish their
dens in prairie dog burrows and feed almost exclusively
on prairie dogs. The reduction in prairie dog numbers in
the last 100 years and the isolation and disappearance
of many large towns has led to the decline of the ferret
population. Large and healthy prairie dog towns are
needed to ensure that black-footed ferrets survive in
Black-footed ferrets are
members of the weasel family and are the only ferret
native to North America. The most obvious distinguishing
feature is the striking black mask across the face. The
feet, legs, and tip of the tail are also black. The
remaining coat is pale yellow-brown, becoming lighter on
the under parts of the body and nearly white on the
forehead, muzzle, and throat. The top of the head and
middle of the back are a darker brown. Ferrets have
short legs, long, well-developed claws on the front
paws, large pointed ears, and relatively large eyes.
Ferrets are similar in
size and weight to wild mink. Adult male ferrets are 21
to 23 inches (53.3 to 58.4 cm) long and weigh 2 to 2 1/2
pounds (0.9 to 1.2 kg). Females are slightly smaller.
The native black-footed
ferret may be confused with the domestic European fitch
ferret, long-tailed weasel, bridled weasel, or wild mink
(Fig. 5). The domestic fitch ferret has longer and
darker pelage on the back, yellowish underfur, and an
entirely black tail. The bridled weasel is a variant of
the been released in north-central Wyoming. For the past
10 years, biologists have intensively searched for and
investigated hundreds of reports of black-footed
ferrets, but no new populations have been found. In
addition, a public reward of $5,000 to $10,000 was
available during the 1980s for sightings of black-footed
ferrets, but none were confirmed. Current efforts are
being made to identify black-footed ferret habitat and
potential reproduction sites. Captive breeding
populations are held at Wheatland, Wyoming, at the
Wyoming Game and Fish Depart-ment’s Sybille Conservation
and Education Center, and at zoos in Omaha, Nebraska;
Washington, DC; Louisville, Kentucky; Colorado Springs,
Colorado; Phoenix, Arizona; and Toronto, Ontario.
Black-footed ferrets rely
on prairie dogs for both food and shelter. Therefore,
all active prairie dog colonies are considered potential
black-footed ferret habitat. Resident ferrets have only
been found in prairie dog towns. Transient and
dispersing ferrets may cross areas that are not occupied
by prairie dogs.
General Biology, Reproduction, and Behavior
Normally 4 young ferrets
are born per litter in May and June. The mother alone
cares for the young and directs their activities until
they disperse in mid-September. The young are first
observed aboveground during daylight hours in July.
From June to mid-July, the
ferret family remains in the same general area of the
prairie dog town. Around the middle of July, after the
young are active aboveground at night, the family
extends its area of activity. By the middle of July the
young ferrets are weaned at nearly one-half adult size.
By early August, the
mother ferret separates the young and places them in
different burrows. At this time some longtail weasel. It
occurs in southwest Kansas, parts of Oklahoma, Texas,
and New Mexico. The bridled weasel has a mask or dark
markings on its face, but is smaller than a black-footed
ferret. It does not have black feet, and it has a tail
that is longer in relation to its total body length.
Mink are about the same size as black-footed ferrets but
are dark brown and occasionally have white markings on
The original range of the
black-footed ferret included most of the Great Plains
area. Its current range within the Great Plains is
unknown, although it is assumed to be greatly reduced
from the original range. Currently the only known wild
ferret population is an experimental population that has
of the young occasionally hunt at night by themselves.
By mid-August, they can be seen during daylight hours,
peering out of their burrow, playing near the entrance,
and sometimes following the adult female.
By late August or early
September, when the young are as large as the adult, the
ferret family starts to disperse and is no longer seen
as a closely knit group. The young ferrets are solitary
during the late fall, winter, and early spring. In
December, ferrets become active just after sunset and
are active at least until midnight.
The black-footed ferret is
classified as an endangered species and receives full
protection under the Federal Endangered Species Act of
1973 (PL 93-205). The act, as amended, requires federal
agencies to ensure that any action authorized, funded,
or carried out by them is not likely to jeopardize the
continued existence of a threatened or endangered
species or their habitat. Regulations implementing
Section 7 of the act require that federal agencies
determine if any actions they propose “may affect” any
threatened or endangered species. If it is determined
that a proposed action “may affect,” then the agency is
required to request formal Section 7 consultation with
the US Fish and Wildlife Service. Section 9 of the act
prohibits any person (including the federal government)
from the “taking” of a listed species. The term take
means to harass, harm, pursue, hunt, shoot, wound, kill,
capture, or collect, or to attempt to engage in any such
conduct. Habitat destruction constitutes the taking of a
black-footed ferret searches have been developed by the
US Fish and Wildlife Service (Blackfooted Ferret Survey
Guidelines for Compliance with the Endangered Species
Act, 1989). Federal agencies are required by the US Fish
and Wildlife Service to conduct black-footed ferret
surveys if their proposed actions may affect ferrets or
their habitat. Although encouraged to do so, private
landowners and applicators are not required by law to
conduct surveys unless their activities are associated
with federal programs or if they are specifically
directed by pesticide labels. Compliance with or
disregard for black-footed ferret survey guidelines does
not, of itself, show compliance with or violation of the
Endangered Species Act or any derived regulations.
Guidelines for Black-footed Ferret Surveys
Any actions that kill
prairie dogs or alter their habitat could prove
detrimental to ferrets occupying affected prairie dog
towns. The US Fish and Wildlife Service guidelines
should assist agencies or their authorized
representatives in designing surveys to “clear” prairie
dog towns prior to initiation of construction projects,
prairie dog control projects, or other actions that
affect prairie dogs. If these guidelines are followed by
individuals conducting black-footed ferret surveys,
agency personnel can be reasonably confident in results
that indicate black-footed ferrets are not occupying a
proposed project area.
Survey Areas. Until the time that wildlife
agencies are able to identify reintroduction areas and
to classify other areas as being free of ferrets,
surveys for black-footed ferrets will usually be
recommended. During this interim period the following
approach is recommended to determine where surveys are
A black-tailed prairie dog
town or complex of less than 80 acres (32 ha) having no
neighboring prairie dog towns may be developed or
treated without a ferret survey. A neighboring prairie
dog town is defined as one less than 4.3 miles (7 km)
from the nearest edge of the town being affected by a
Black-tailed prairie dog
towns or complexes greater than 80 acres (32 ha) but
less than 1,000 acres (400 ha) may be cleared after a
survey for black-footed ferrets has been completed,
provided that no ferrets or ferret sign have been found.
A white-tailed prairie dog
town or complex of less than 200 acres (81 ha) having no
neighboring prairie dog towns may be cleared without a
ferret survey. White-tailed prairie dog towns or
complexes greater than 200 acres (81 ha) but less than
1,000 acres (400 ha), may be cleared after completion of
a survey for black-footed ferrets, provided that no
ferrets or their sign were found during the survey.
Contact the US Fish and
Wildlife Service before any federally funded or
permitted activities are conducted on black-tailed or
white-tailed prairie dog towns or complexes greater than
1,000 acres, to determine the status of the area for
future black-footed ferret reintroductions.
Defining a Prairie Dog
purpose of this document a prairie dog town is defined
as a group of prairie dog holes in which the density
meets or exceeds 20 burrows per hectare (8
burrows/acre). Prairie dog holes need not be active to
be counted but they should be recognizable and intact;
that is, not caved in or filled with debris. A prairie
dog complex consists of two or more neighboring prairie
dog towns, each less than 4.3 miles (7 km) from the
Timing of Surveys
The US Fish
and WIldlife Service recommends that surveys for
black-footed ferrets be conducted as close to the
initiation of a project construction date as possible
but not more than 1 year before the start of a proposed
action. This is recommended to minimize the chance that
a ferret might move into an area during the period
between completion of a survey and the start of a
Construction projects (buildings, facilities, surface
coal mines, transmission lines, major roadways, large
pipelines, impoundments) that permanently alter prairie
dog towns should be surveyed. Projects of a temporary
nature and those that involve only minor disturbances
(fences, some power lines, underground cables) may be
exempted from surveys when project activities are
proposed on small prairie dog towns or complexes of less
than 1,000 acres (400 ha), do not impact those areas
where ferret sightings have been frequently reported, or
occur on areas where no confirmed sightings have been
made in the last 10 years.
The US Fish and Wildlife
Service recommends that before any action involving the
use of a toxicant in or near a prairie dog town begins,
a survey for ferrets should be conducted. If toxicants
or fumigants are to be used, and the town proposed for
treatment is in a complex of less than 1,000 acres (400
ha), the town should be surveyed using the nocturnal
survey technique 30 days or less before treatment.
Prairie dog towns or complexes greater than 1,000 acres
(400 ha) should not be poisoned without first contacting
your local US Fish and Wildlife Service office.
— Daylight surveys for ferrets are recommended if
surveys are conducted between December 1 and March 31.
This type of survey is used to locate signs left by
ferrets. During winter months, ferret scats, prairie dog
skulls, and diggings are more abundant because prairie
dogs are less active and less likely to disturb or
destroy ferret sign. When there is snow cover, both
ferret tracks and fresh diggings are more obvious and
Daylight searches for
ferret sign should meet the following criteria to
fulfill the minimum standards of these guidelines:
Three searches must be
made on each town. Conduct each search when fresh
snow has been present for at least 24 hours and
after 10 or more days have passed between each
Vehicles driven at
less than 5 miles per hour (8.3 km/hr) may be used
to search for tracks or ferret diggings, but
complete visual inspections of each part of the town
being surveyed is required (that is, visually
If ferret sign is
observed, photograph the sign and make drawings and
measurements of diggings before contacting the US
Fish and Wildlife Service and state wildlife agency.
Method 2 —
Nighttime surveys involve the use of spotlighting
techniques for locating ferrets. This survey method is
designed to locate ferrets when the maximum population
and the longest periods of ferret activity are expected
Minimum standards should
be followed as recommended below:
between July 1 and October 31.
the prairie dog town using spotlights. Begin surveys
at dusk and continue until dawn on each of at least
3 consecutive nights. Divide large prairie dog
colonies into tracts of 320 acres (130 ha) and
search each tract systematically throughout 3
consecutive nights. Rough uneven terrain and tall
dense vegetation may require smaller tracts to
result in effective coverage of a town.
Begin observations on
each prairie dog town or tract at a different
starting point on each successive night to maximize
the chance of overlapping nighttime activity periods
A survey crew should
consist of one vehicle and two observers equipped
with two 200,000 to 300,000 candlepower (lumen)
spotlights. In terrain not suitable for vehicles, a
crew should consist of two individuals working on
foot with battery-powered 200,000 to 300,000
candlepower (lumen) spotlights. To estimate the
number of crew nights for a survey, divide the total
area of prairie dog town to be surveyed by 320 acres
(130 km) and multiply by 3. One or both of the
observers in each survey crew should be a biologist
trained in ferret search techniques.
Additional information on
data collection, reporting, and training workshops are
included in Black-footed Ferret Survey Guidelines for
Compliance with the Endangered Species Act, 1989,
available from the US Fish and Wildlife Service.
Black-footed Ferret Sign
To determine if
black-footed ferrets are living in a given area, some
sign must be found or a ferret observed. Evidence such
as tracks, diggings, or droppings is uncommon, even
where ferrets occur. They are secretive, nocturnal, and
inactive for long periods of time, and therefore are
very seldom seen by people.
Prairie dogs compact the
soil around their burrows, making it difficult to find
ferret tracks. Most ferret tracks are observed when snow
covers the ground. The average distance between each
“twin print” track in the normal bounding gait is 12 to
16 inches (30.5 to 40.6 cm) (Fig. 6). The track of a
ferret is very similar to that of a mink or weasel. In
Wyoming, ferrets are most active between December and
early March, sometimes covering up to 5 miles (8 km) per
night. Scent marks, scrapes, and scratches in the snow
may be noticeable. Ferret droppings are rarely found
above ground. They are long and thin, taper on both
ends, and consist almost entirely of prairie dog hair
Ferrets sometimes form
“trenches” or “ramps” when they excavate prairie dog
burrows. Prairie dogs occasionally plug the entrances to
their burrow systems with soil. When excavating such a
plug in a burrow, the ferret backs out with the soil
held against its chest with its front paws. It generally
comes out of the burrow in the same path each time. This
usually occurs when snow covers the ground. After
repeated trips, a ramp from 3 to 5 inches (7.6 to 12.7
cm) wide and from 1 to 9 feet (0.3 to 2.7m) long is
formed (Fig. 7). Badgers, foxes, and weasels
occasionally form similar ramps.
Prairie dogs generally
deposit excavated soil around the burrow entrance to
form a mound, building it higher by adding soil from
outside the mound. The movement of soil toward the mound
is in the opposite direction of that done by a ferret.
Ferrets sometimes dig in
fresh snow. These "snow trenches are narrow trough-like
depressions in the snow that extend away from prairie
dog burrow entrances. Snow trenches are relatively rare
compared to trenches in the soil.
If you observe a
black-footed ferret or identify ferret sign while
conducting surveys, notify your local US Fish Wildlife
Service or state wildlife representative within 24
Figures 4 and 5 by Emily
Figure 6 courtesy of
Thomas M. Campbell III, Biota Research and Consulting
Figure 7 courtesy of Walt
For Additional Information
Biggins, P.E., and R.A.
Crete. 1989. Black-footed ferret recovery. Proc. Great
Plains Wildl. Damage Control Workshop 9:59-63.
Clark, T.W., T.M.
Campbell, III, M.H. Schroeder, and L. Richardson. 1984.
Handbook of methods for location of black-footed
ferrets. Wyoming BLM Wildl. Tech. Bull. No. 1. US Bureau
Land Manage., in coop. with Wyoming Game Fish Comm.
Cheyenne. 47 pp.
Hall, E.R. 1981. The
mammals of North America. John Wiley and Sons, New York.
Hillman, C.N. 1968. Field
observations of black-footed ferrets in South Dakota.
Trans. North Am. Wildl. Nat. Resour. Conf. 33:346-349.
Hillman, C.N. 1974. Status
of the black-footed ferret. Pages 75-81 in Proc. symp.
endangered and threatened species of North America. Wild
Canid Survival Res. Center. St. Louis, Missouri.
Hillman, C.N., and T.W.
Clark. 1980. Mustela nigripes. Mammal. Species 126:1-3.
Hillman, C.N., and R.L.
Linder. 1973. The black-footed ferret. Pages 10-23 in R.
L. Linder and C. N. Hillman, eds. Proc. black-footed
ferret and prairie dog workshop. South Dakota State
Sheets, R.C., R.L. Linder,
and R.B. Dahlgren. 1972. Food habits of two litters of
black-footed ferrets in South Dakota. Am. Midl. Nat.
US Fish and Wildlife
Service. 1988. Black-footed ferret recovery plan. US
Fish Wildl. Serv., Denver, Colorado. 154 pp.
US Fish and Wildlife
Service. 1989. Black-footed ferret survey guidelines for
compliance with the endangered species act. US Fish
Wildl. Serv. Denver, Colorado, 15 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