Livestock and Exotic Weeds in the Intermountain West
Lauren McCain, Richard P. Reading, Ph.D., and Brian J. Miller, Ph.D.
Prairie dogs have declined drastically
since European settlement of the Great Plains because of human persecution and
habitat destruction. Traditionally, prairie dogs have been viewed as competitors
for forage with livestock. Today, an emerging scientific view of prairie dogs
as "keystone" species indicates a need to alter attitudes toward and
management of these important grassland animals.
Lauren McCain is president of the Southern Plains
Land Trust, which works for conservation of native shortgrass prairie, and is
a doctoral candidate in policy sciences at the University of Colorado.
Richard P. Reading is director of conservation
biology at the Denver Zoological Foundation and associate research professor
at the University of Denver. He received a Ph.D. degree in wildlife ecology
from Yale University.
Brian J. Miller is a conservation biologist
at the Denver Zoological Foundation. He received his Ph.D. degree from the University
of Wyoming, where he studied the ecology of black-footed ferrets.
Prairie dog (Cynomys sp.) decline began soon after
Europeans began settling the Great Plains in the mid-nineteenth century. The
twentieth century began with an estimated 41 million hectares of black-tailed
prairie dog (C. ludovicianus) colonies spread across the western grasslands
and grassland deserts of North America. By 1960, that number had been reduced
to about 600,000 hectares--a decline of 98.5 percent in sixty years.
|Black-tailed prairie dog.|
This trend continues. In 1995, approximately 540,000 hectares
of black-tailed prairie dogs remained in the United States, but by 1998 that
number had dropped to 280,000-320,000 hectares. This is a loss of 41-49 percent
in three years and an overall decline of over 99 percent since 1900. Similarly,
the area occupied by black-tailed prairie dogs in Mexico declined nearly 80
percent between 1988 and 1996. The other species of prairie dogs have experienced
similar declines. That prairie dog populations have been decimated throughout
the western grasslands is undisputed among scientists.
Despite the dramatic decline of all five prairie dog species
over the last century, it is only very recently that prairie dog management
policy has taken into account any aim other than extermination, largely through
poisoning. The Utah prairie dog (C. parvidens) did receive early protection
in 1973 as an endangered species under the Endangered Species Act, but in 1983
the U.S. Fish and Wildlife Service downgraded its status to threatened, and
over the past few years the species has experienced severe declines. As few
as 1,500 remain today. The Fish and Wildlife Service listed the Mexican prairie
dog (C. mexicanus) as endangered in 1991 and began considering the black-tailed
prairie dog as threatened in March 1999. The white-tailed (C. leucurus)
and Gunnison's (C. gunnisoni) prairie dogs may also warrant listing.
The loss of prairie dogs can be attributed to the activities
of one species--humans. People have caused tremendous damage to the prairie
dog ecosystem. Prairie dogs once existed in a matrix of colonies and off-colony
habitat that shifted in space and time across the landscape of western grasslands
of North America. As European settlers began colonizing the region in the late
1800s, they began converting prairies to farmland. Farther west, ranchers noted
that prairie dogs ate grass, and in the early 1900s ranchers began poisoning
prairie dogs in an attempt to provide more forage for livestock. A few visionaries,
such as naturalist Ernest Thompson Seton, predicted catastrophic outcomes from
the massive prairie dog poisoning campaigns, but such voices went largely unheeded.
In addition, at the turn of the century, people accidentally introduced plague
(Yersinia pestis) to San Francisco. With no natural immunity to this
new disease, prairie dogs began dying in large numbers as plague spread across
Today, real estate developers destroy prairie dog colonies
and replace them with houses, businesses, and parking lots as western cities
swell. Still, ranching and other agricultural interests--the major industries
overlapping prairie dog habitat--continue to have the greatest influence on
both prairie dog ecosystems and policy, on both private and public lands. Thus,
as a result of poisoning and other forms of persecution, plague, and habitat
destruction, the landscape matrix of prairie dogs has been destroyed. Today
we are left with only small, isolated fragments of a once-vast system.
The loss of prairie dogs is also linked to the decline
of several other species. The most prominent example is the black-footed ferret
(Mustela nigripes), one of the most endangered mammals in North America.
Ferrets depend on prairie dogs for about 90 percent of their diet and require
prairie dog burrows for shelter and rearing young. In addition, the swift fox
(Vulpes velox), a predator closely associated with prairie dogs, was
recognized as warranting listing in 1995. The ferret and fox join the ferruginous
hawk (Buteo regalis), the mountain plover (Charadrius montanus),
and the burrowing owl (Speotyto cunicularia) as species that have all
experienced severe declines and that are all closely tied to the prairie dog.
Should prairie dogs reach a nonviable population level, a wave of secondary
extinctions would likely follow.
A range of federal and state government policies run counter
to long-term viability of prairie dogs. Poisoning still occurs throughout the
increasingly fragmented range of prairie dogs on both public and private land.
Government agencies at all levels permit and often encourage prairie dog shooting
on public lands. The federal land management agencies administering public lands--the
Bureau of Land Management (BLM), the U.S. Forest Service, the Fish and Wildlife
Service, and the National Park Service--have all conducted poisoning to control
Although in 1999 the Forest Service issued a moratorium
on poisoning black-tailed prairie dogs, agency policy mandated limiting prairie
dog acreage on the national grasslands and national forests to 1 percent or
less. On BLM lands, poisoning can occur at the discretion of the U.S. Department
of Agriculture Animal and Plant Health Inspection Service Wildlife Services
(formerly known as Animal Damage Control) without the knowledge of BLM administrators.
Federal bureaucracies, including the National Park Service, carry out so-called
"good neighbor" policies, whereby prairie dogs are poisoned to provide
a buffer to adjacent private landholders. Prairie dog shooting is permitted
on most national grasslands and BLM lands.
Most states within prairie dog range designate prairie dogs as pest species, and some try simultaneously to manage them as wildlife. Colorado, Kansas, Montana, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, and Wyoming all have laws that mandate the poisoning of prairie dogs. Only Colorado restricts shooting; yet that restriction--which sets a daily bag limit of five animals--applies only to contest shoots.
The Cowboy Myth
To understand our continued persecution of prairie dogs
since European settlement of North America, we must examine the origin and elements
of anti-prairie dog sentiment. The dominant attitude held by traditional power
holders in the policy process--ranchers--is that of intolerance, even hatred,
of these animals. This attitude persists despite substantial and growing evidence
of the importance of prairie dogs to the ecosystems they inhabit and the relatively
small impact they impose on ranching operations.
Ranchers argue that prairie dogs compete with cattle for
forage, injure livestock that step in their burrows, pose a public health threat,
and cause environmental damage. They further suggest that prairie dogs are abundant--even
suffering from overpopulation--and deserve no legal protection. We can view
these deeply entrenched beliefs as an outgrowth of a larger myth, "the
cowboy myth," that governs the human relationship to the land and treatment
of the environment.
A myth is rooted in fundamental assumptions, regardless
of their truth, that are believed by a community to the extent that they no
longer appear to be myths. Myths are supported by powerful symbols. Myths help
people understand and relate to a world far too complicated to understand in
its entirety, they promote solidarity, and they are utilized by power holders
who manipulate key symbols to explain and justify their use of power.
Generally, rancher attitudes about prairie dogs and other
wildlife can be understood as an outgrowth of the cowboy myth that espouses
human dominion over other living beings--the philosophy that guided European
settlement of the West. This myth is deeply rooted in Christian ethics, as well
as in liberal political and economic philosophy. According to the myth, nonhuman
animals are either commodified or controlled to minimize interference with human
Black-tailed prairie dog pup.
With some exceptions, members of the ranching community
tend to view many wildlife species as potential economic threats and have little
to no tolerance for potential loss due to depredation (for example, coyotes,
Canis latrans, and gray wolves, C. lupus); the risk of disease
transmission from wild to domestic animals (e.g., bison, Bison bison,
and bighorn sheep, Ovis canadensis); or competition for forage (e.g.,
elk, Cervus canadensis, and prairie dogs)--this, despite the high affinity
of ranchers for open space and some types of wildlife, especially nonthreatening
species at low densities, such as modest numbers of deer and grouse.
Proponents of the cowboy myth, especially western ranchers
and agency personnel, generally reject data demonstrating that fears about prairie
dogs are exaggerated. In the 1970s, scientists began quantifying the impact
of prairie dogs on livestock operations. Studies found that cattle averaged
no significant changes in body weight when grazed on prairie dog towns. In addition,
the annual cost of maintaining control of prairie dogs through poisoning exceeds
the annual value in forage gained. Most research finds that total vegetative
cover decreases after prairie dogs abandon the land. Furthermore, one extensive
review of the literature revealed that although plant biomass in patches created
by prairie dogs was lower, it was of higher nutritive value than plant biomass
on uncolonized prairie. In other words, the loss in forage quantity was almost
fully compensated by a large increase in forage quality.
In addition, public health data indicate that plague poses
a more significant danger to prairie dogs than it does to humans. The incidence
of plague in humans is negligible. For example, the Colorado Department of Public
Health and Environment has documented forty-three cases of plague between 1957
and 1998; only five of those cases were linked to prairie dogs.
The Keystone Role of the Prairie Dog
Despite ranchers' claims that prairie dogs cause environmental
damage, a growing body of data suggests just the opposite: that prairie dogs
are keystone species. As we use the concept, keystone species are those that
enrich ecosystem function uniquely and significantly through their activities
and whose impact is larger than predicted by their numerical abundance. Evidence
is mounting that prairie dogs fulfill these requirements.
The changes induced by prairie dogs lead to the creation
of a unique ecological system referred to as the prairie dog ecosystem. Over
200 vertebrate species have been observed on prairie dog colonies. Some of these
species appear to depend on prairie dog colonies for their survival, and many
appear to benefit, at least seasonally or opportunistically.
Prairie dogs and the other animals inhabiting their colonies
represent a rich prey patch for a large number of predators, including prairie
rattlesnakes (Crotalus viridis), golden eagles (Aquila chrysaetos),
great horned owls (Bubo virginianus), long-tailed weasels (Mustela
frenata), bobcats (Lynx rufus), and coyotes. Some predators, such
as black-footed ferrets, are dependent on prairie dogs specifically. Other species,
such as badgers (Taxidae taxus), swift foxes, and ferruginous hawks,
have been shown to derive substantial benefits from the presence of prairie
dogs as prey and eat other prey species in prairie dog colonies as well.
The benefits from prairie dogs extend well beyond simply
providing food for predators. Since prairie dogs excavate more burrows than
they regularly utilize, they create homes for many animals, such as cottontails
(Sylvilagus spp.), burrowing owls, and several species of reptiles and
amphibians. These species and more also use the burrows as refugia from predators
or temperature extremes. As a result, researchers have found that desert cottontails
(S. audonbonii), thirteen-lined ground squirrels (Spermophilis tridecemlineatus),
and northern grasshopper mice (Onychomys leucogaster) exist in higher
numbers on prairie dog colonies than in surrounding grasslands. Similarly, studies
in Mexico found higher rodent species richness, density, and diversity and higher
avian species richness on prairie dog colonies compared with surrounding grasslands
in Chihuahua, Mexico. Most of the work to date has focused on birds and mammals,
with considerably less on reptiles and amphibians. Similarly, little is known
about prairie invertebrates, yet the burrows in a prairie dog colony should
offer habitat advantages to invertebrates as well.
Prairie dogs also have a large effect on vegetation structure,
productivity, nutrient cycling, and ecosystem processes. The activities of prairie
dogs, especially their grazing and clipping of tall vegetation, result in changes
in plant composition. In general, the vegetation on prairie dog colonies is
characterized by lower biomass (smaller quantity), a greater preponderance of
annual forbs (broad-leaved, nonwoody plants such as wildflowers) and short grasses
than tall grasses and shrubs, and higher nitrogen content than plants from surrounding
areas. Prairie dogs negatively impact some plant species, reducing the prevalence
and controlling the spread of taller grasses and several shrubs, such as mesquite
(Prosopis spp.), sagebrush (Artemesia spp.), and Ephedra trifurca.
Ironically, prairie dogs are poisoned for livestock interests, but these shrubs
preempt grass from cattle, and mesquite makes roundups more difficult.
Prairie dog burrowing activities modify ecosystem processes
such as water, mineral, and nutrient cycling. Prairie dogs turn over approximately
225 kilograms of soil per burrow system, which translates to several tons of
soil per hectare. By mixing in nutrient-rich urine and manure, prairie dog digging
can change soil composition, chemistry, and microclimate, facilitate below-ground
herbivory, increase porosity of soil to permit deeper penetration of precipitation,
and increase the incorporation of organic materials into the soil. As a result,
prairie dog colonies support higher numbers of nematodes and higher levels of
soil nitrogen. All of these processes contribute to above-ground plants with
a higher nutritional content, higher digestibility, and a greater live-plant
to dead-plant ratio, creating favorable feeding habitat for other herbivores.
Indeed, pronghorn (Antilocapra americana) and bison preferentially graze
on prairie dog colonies. Scientific models predict that bison can gain weight
faster by grazing on a prairie dog colony than on grasslands without prairie
Prairie dog researchers have concluded that collectively
these functions are large, not wholly duplicated by other species (either in
form or extent), and that the loss of prairie dogs would lead to "substantial
erosion of biological diversity and landscape heterogeneity across the prairie."
The prairie dog therefore fulfills the definition of keystone.
Toward an Integrated Preservation Strategy
Reversing the trend of prairie dog decline demands urgent
attention. Without changes in prairie dog management, all five species will
face extinction. We must now work to reduce prairie dog mortality, recover dwindling
populations, and protect habitat across the range of these species. Yet, policy
changes to achieve these biological goals are unlikely without addressing the
social and political processes that now govern prairie dog management. This
task will be one of the most formidable challenges to prairie dog preservation.
Initiating effective policy reform means exposing and countering the myths that
engender the negative attitudes and values so ingrained in the western agrarian
community and among the land and wildlife managers responsible for prairie dogs.
Instilling more tolerant attitudes toward prairie dogs may be the key to recovery
and long-term viability of their ecosystem. By overturning or altering dominant
myths that hold prairie dogs as pests, we can begin developing a new set of
myths conducive to sustaining the prairie dog ecosystem.
Shifting policy toward prairie dog preservation will first
require enforcing already-existing relevant laws, terminating policies aimed
at reducing prairie dog numbers, and developing a more effective legal framework
directed toward protecting the prairie dog ecosystem. Currently, three of the
five species of prairie dogs enjoy no federal legal protection and only limited
protection in a few states.
Despite the mixed success to date, federal and state legal protection for all species is crucial. But laws must be adequately implemented and enforced to achieve their intended effect. Policy does not end once laws and regulations are promulgated. Implementation is equally, if not more, important. For example, properly enforcing prairie dog protection measures means devoting resources toward detecting and stopping illegal poisoning. Unauthorized poisoning has contributed to the decline of Mexican, black-tailed, and probably Utah prairie dogs. We must also work to induce public land and wildlife managers to stop poisoning prairie dogs and start initiating proactive preservation programs. This will not be easy, as they are often proponents of continuing poisoning programs.
Along with legal measures, government agencies should
initiate other actions to help reduce prairie dog mortality, recover populations,
and protect prairie dog habitat. Agencies should support research focused on
preventing outbreaks of plague and reducing mortality rates from plague infestations
on prairie dog colonies. Public lands within prairie dog range, such as national
grasslands, wildlife refuges, and BLM land, should permit expansion of prairie
dog colonies. A somewhat radical proposal, but one that is gaining support among
certain members of the public, entails the eventual replacement of livestock
with native ungulates, especially bison, on public lands.
Another step toward prairie dog and prairie dog ecosystem
preservation entails reconceptualizing and managing prairie dogs as keystone
species. Keystone species conservation can be a sound basis for conserving entire
natural areas efficiently and effectively, because the keystone helps regulate
the entire system. Thus, effectively managing prairie dogs as keystone species
would aid efforts to switch from a single species strategy to an ecosystem approach.
Focusing on prairie dog preservation makes not only biological
sense but economic sense as well. Protecting prairie dogs and prairie dog habitat
is a cost-effective means of protecting other species dependent on prairie dogs
or otherwise associated with the prairie dog ecosystem. The black-footed ferret
recovery program illustrates this point. The U.S. government is spending millions
of dollars on black-footed ferret captive breeding and reintroduction. The Fish
and Wildlife Service alone spent $1.5 million in 1991. Ensuring an adequate
number of prairie dogs by protecting prairie dog complexes remains a condition
of success for black-footed ferret recovery. Therefore, the greatest challenge
facing ferret recovery is the lack of sufficient prairie dog populations to
support even modest populations of ferrets. Some of the resources now supporting
single-species approaches to conservation and protection could be redirected
to prairie dog preservation, as prairie dog habitat preservation equates to
protection for many other species.
The social and political constraints facing the initiation
of a comprehensive prairie dog preservation program are formidable. More integrated,
interdisciplinary approaches are desperately needed. A more comprehensive program
should identify all of the key stakeholder groups and devise separate strategies
for each. In particular, local, state, and federal wildlife, land management,
and agriculture agency personnel have demonstrated little concern for prairie
dog preservation, yet these individuals exert powerful influence on all phases
of the policy process. Broader public relations programs are unlikely to succeed
in the face of opposition by agency personnel, especially local officials.
Similarly, the ranchers likely will resist any outside
proposal that does not simultaneously bolster their own interests. Yet the economic
and social crises of many ranching communities today may be a door to change.
As family ranches become a thing of the past and the once "self-reliant"
and libertarian rancher increasingly looks for government assistance to stay
in business, prairie dogs serve as convenient scapegoats for the deeper, more
complex problems of the livestock community.
On the other hand, in times of stress, such as economic
downturns, communities are often most likely to seek out new ideas and embrace
new myths. Old myths may no longer work to justify traditional practices, including
the control of native wildlife. Thus, some ranchers are indeed seeking out new
ways, even trying to adopt more environmentally conscientious practices. If
such innovators are successful, we may see others open to alternative techniques.
Such a transformation is unlikely to occur among those who have grown up with
the belief that prairie dogs are pests; however, younger generations may indeed
reach out to new ideas. And if ranchers as a group are to be persuaded to adopt
more tolerant attitudes toward prairie dogs, the best chance is for individuals
among them to initiate and promote the change.
Outside the ranching industry, it will be up to prairie
dog supporters--preservationists, wildlife biologists, and policymakers working
with prairie dog-friendly ranchers--to promote symbols that will help forge
more tolerant attitudes toward prairie wildlife. The symbols most likely to
resonate with the ranching community are symbols that already hold meaning within
this group. Preserving prairie dog habitat also means maintaining open space,
practicing land stewardship, and retaining a sense of wildness to the western
plains--all ideas that are already embraced by the traditional ranching community.
Beyond confronting the major myths that have helped reduce
the prairie dog ecosystem from a once-rich network of biodiversity to a fragmented
patchwork, American grasslands and the prairie dog ecosystems they include need
a national public relations campaign. Unlike wolves and whales, prairie dogs
do not muster the great charisma that the large mammals and predators enjoy.
Moreover, grasslands as wild places lack resonance in the public's consciousness.
Yet the Great Plains were once teeming with wildlife, rivaling the Serengeti
Plains of Africa. Along with the roving herds of bison, America's grasslands
were also rife with wolves, elk, pronghorn, and grizzly bears. We must work
to promote this image of the western plains as a place for wild nature, not
References available in printed version of article.