This file was created by scanning the printed publication.
Errors identified by the software have been corrected;
however, some errors may remain.
Habitat Use by Gunnison's
Prairie Dogs1
C. N. Slob~dchikoff,~
Anthony R~binson,~
and Clark Schaack4
Prairie dogs often have been considered "weedy" species that thrive in
disturbed habitats. However, uncertainty remains about the impact of
prairie dogs on their habitat, and
about their economic imvact as competi tors of domesticated'herbivores.
Some studies of primarily blacktailed prairie dogs (Cynornys ludovicianus) show that they have a negative effect on their habitat, while
other studies show a positive effect.
Negative effects include decreased
forb and grass cover in prairie dog
towns (Knowles 1982, Archer et al.
19841, higher silicon concentrations
in gasses found in areas grazed by
prairie dogs (Brizuela et al. 19841,
and removal of plant biomass that
could be utilized by cattle (CrackerBedford 1976, Hansen and Gold
1977, Crocker-Bedford and Spillett
1981). Positive effects include increased plant species diversity in
prairie dog towns (Lerwick 1974,
Boddicker and Lerwick 1976, Gold
1976, Severe 1977, Beckstead and
'Paper presented at symposium, Management of Amphibians, Reptiles, and
Small Mammals in North America. [Flagstaff AZ, July 1 9-2 1, / 988.)
'C.N. Slobodchikoff is Professor of Biology, Northern Arizona University,Flagstaff,
AZ86011.
JAnthonyRobinson is a graduate student in the Department of Biology, Northern
Arizona University,Flagstaft AZ 860 1 1.
4ClarkSchaack is Assistant Scientist, Department of Botany, University of Wisconsin,
Madison, WI 53706.
Abstract.-Gunnison's prairie dogs (Cynornys gunnisoni) are social, colonial mammals found in Colorado, New Mexico, and Arizona, Colony location
depends to a great extent on the distribution and
abundance of plants used as food. Colonies with
the highest densities of prairie dogs occur in habitats
where there is a high abundance of native species
of plants. From a management standpoint, prairie
dog populations can be conserved by maintaining
habitats that offer such resources.
Schitoskey 1980, Fagerstone 1981,
Archer et al. 1984); greater production of forbs and grasses (Uresk and
Bjugstad 1980, Agnew 1983); and better quality food and growing conditions inside prairie dog towns
(Hassien 1976, Beckstead and Schitoskey 1980, Fagerstone 1981, Coppock et al. 1980,1983a, 1983b, Detling and Painter 1983). Prairie dog
colonies have also been shown to
provide habitat for many different
species of vertebrates other than
prairie dogs (Campbell and Clark
1981, O'Meilia et al. 1982, Agnew
1983, Clark et al. 1982).
The economic effects of prairie
dogs are also currently unclear. Although they are considered pests
(Uresk 1985), a series of studies has
shown that controlling or eradicating
prairie dogs has little effect on increasing the amount of food available
for cattle (Cracker-Bedford 1976,
Klatt and Hein 1978, Collins et al.
1984, Uresk 19851, and experimental
studies of competition between prairie dogs and steers failed to show
that the prairie dogs had any significant negative impact on the weight of
the steers (O'Meilia et al. 1982).
Prairie dogs have been characterized as being oriented to disturbed
sites that are overgrazed by cattle or
buffalo (Osborn and Allan 1949). The
relationship between prairie dog occurrence and overgrazing, however,
is a correlational one: prairie dogs
can be found at sites that are overgrazed by large herbivores, but this
does not necessarily imply that the
prairie dogs specialize in colonizing
sites that are overgrazed. Overgrazing might be occurring subsequent to colonization. For example,
bison are attracted to prairie dog
towns as grazing sites, because the
vegetation associated with such
towns may be more digestible,and
have a higher nitrogen content than
the vegetation at sites not colonized
by prairie dogs (Coppock et al.
1983a, 1983b).
Disturbance of a habitat can be
provided by the activities of the prairie dogs themselves. By digging extensive burrow systems (King 1984),
prairie dogs disturb soil, promoting
the growth of disturbance-oriented
vegetation and increasing plant diversity (Gold 1976; Hansen and Gold
1977). Because prairie dogs have a
system of vigilance that depends on
being able to see terrestrialpredators
from some distance away (Slobodchikoff and Coast 19801, they clip
shrubs and other tall vegetation that
impede visual detection. This in turn
alters the habitat into one that has
predominantly short grasses and annual forbs, rather than the taller
grasses and shrubs that are more
characteristic of climax communities
(Koford 1958).
The goal of this paper is to evaluate habitat use by Gunnison's prairie
dogs (Cynornys gunnisoni), and to
consider this habitat use in the context of managing existing populations of this species. Many previous
ecological studies of prairie dogs
have focused on the blacktailed prairie dogs (Cynornys ludovicianus)
found in the midwestern states. Gunnison's prairie dogs offer a better
opportunity to evaluate habitat requirements, because this species is
associated with habitats that have
been modified less by man than habitats where blacktailed prairie dogs
are currently found.
In an attempt to establish some
common habitat conditions that are
preferred by Gunnison's prairie
dogs, we have examined the following factors at several prairie dog
sites: (1) burrow density as an indicator of prairie dog population density;
and (2) plant diversity, evenness,
cover, and proportions of native and
introduced species.
Study Areas
Seven colonies in the vicinity of Flagstaff, Arizona, were investigated.
These were: (1)Humane Society
(HS), within the city limits at an elevation of 2250 m, in a meadow surrounded by Ponderosa pine (Pinus
ponderosa) trees on three sides and a
heavily-utilized dirt road on the remaining side; (2) Denny's (D), also
within the city limits at an elevation
of 2250 m, in a small meadow encircled by a traffic loop that serves as
an approach to the 1-17 freeway; (3)
Snow Bowl (SB), 10 km north of Flagstaff in an old-field pasture at an elevation of 2400 m; (4) Upper Michelbach (UM), on a privately owned
ranch 20 km north of Flagstaff at an
elevation of 2650 m; (5) Lower Michelbach (LM), also at 2650 m and located within 1 km east of UM; (6) Potato Lake (PL), in an alpine meadow
surrounded by forested slopes, 25
km northeast of Flagstaff at an elevation of 2850 m; and (7) Bismark Lake
(BL), another alpine meadow 20 km
northeast of Flagstaff at 2900 m.
Grazing pressure on these sites
varied. The most heavily grazed site
was Upper Michelbach, with grazing
levels of 0.8 ha per AUM. The Humane Society site was heavily grazed
(1.2 ha per AUM) until 1978, after
which there was no grazing. Both
Lower Michelbach and Snow Bowl
had the same level of grazing (6 ha
per AUM). The Potato Lake and Bismark Lake sites had relatively light
levels of grazing (12 ha per AUM at
PL; 14 ha per AUM at BL). The
Denny's site was not grazed at all in
the last 20 years (all grazing information from J. Mundell, pers. comm.).
Methods
To estimate relative densities of prairie dog populations, we sampled
burrow densities at six of the sites
(HS, SB, UM, LM, PL, and BL). Burrows were estimated by laying out
twelve 50 m transects, and counting
all the burrows that were within 0.5
m of each side of the transect line.
Based on the counts of burrows per
transect, mean numbers of burrows /
0.005 ha (mean number of burrows
per 50 m-sq) were calculated for each
colony. Because of the small size of
the colony at BL, only six transects
were used there. Although this
method did not provide a total number of burrows per site (a number
constantly changing depending on
prairie dog construction activity), it
did provide a measure that allowed
comparison of the six sites.
As an estimate of habitat composition, vegetation at five sites (HS, SB,
D, PL, and BL) was sampled from
May-October, 1986-87. All plant species found at each site were identified to species and classified as native non-weedy, native-weedy, or
introduced-weedy. Reference specimens for each species from each site
have been deposited in the Herbarium at Northern Arizona University.
For estimates of plant diversity
and percent cover, we sampled
plants every month along transects at
two sites (HS and SB) from May-October, 1986 and 1987. Each site had
six 100 m parallel transects spaced 20
m apart. Presence or absence of
plants by species were recorded every 2 m along each transect.
Similarity indices (SI) were calculated for plant species composition
between sites, as follows:
Number of Species Common
to Both Site A and B
Total Number of Species in
Site A + Site B
This is an index that allows comparisons of sites based on the percentage
of species common to the two.
Prairie dog densities were determined at two sites, HS and SB, by
actual counts of all the animals at
each site. The prairie dogs were
trapped weekly in squirrel-sized
Tomahawk live traps and marked
with hair dye. Movements of marked
prairie dogs were observed and plotted with respect to a 100 x 120 m grid
of stakes set up 10 m apart. Territories were determined behaviorally,
on the basis of aggressive behaviors
such as chases between interterritory
members, and cooperative behaviors
such as greet-kisses between intraterritory members. At these two sites,
HS and SB, the number of burrows in
each territory was counted.
All statistical analyses were done
on a Honeywell Sigma 6 mainframe
computer, using SPSS statistical
packages (Nie et al. 1975). Analyses
included regression, correlation,
analysis of variance, and least significant difference. Additionally, ecological indices were calculated: evenness, percent cover, Simpson's dominance, Shannon-Weaver diversity,
and H max (Poole 1974).
Results
Plant Species Composition
Similarity indices show that some
sites were quite dissimilar from other
sites (table 1). The HS and D sites
were most similar (63.7 percent similarity), and SB was fairly similar to
the HS site (54.1 percent similarity)
and to the D site (44.1 percent similarity). The HS, D, and SB sites were
quite dissimilar from the other two
sites, PL and BL,and the two latter
sites had a low level of similarity
(23.4 percent) to each other.
The five sites differed in plant species composition based on the proportion of native-nonweedy, nativeweedy, and introduced-weedy plant
species (fig. 1).The PL site had the
greatest proportion of native-nonweedy species (93.1 percent), and the
D site had the lowest (27.2 percent).
Conversely, the PL site had no (0
percent) na tive-weedy species, while
the D site had the highest proportion
(45.7 percent) of native-weedy species. The BL site has the greatest proportion (33.3 percent) of introducedweedy species found at any site.
Prairie Dog Burrow Density
NNWI
NNWI
NNWI
NNWI
NNW I
SITES
Figure 1.-Composition of plant species at five Gunnison's prairie dog colonies near Ragstaff, Arizona. Percentages shown are for Native-nonweedy species (N), Native-weedy species (NW), and Introduced-weedy species (I). Sites are: HS = Humane Socieiy; SB = Snow
Bowl; BL = Bismark Lake; PL = Potato Lake; D = Denny's.
The mean numbers of burrows per
0.005 ha found at sites HS, SB, UM,
LM, PL, and BL are shown in table 2.
The highest burrow density was at
UM, and the lowest density was at
BL. These differences between sites
were significant (LSD = 1.62, P =
0.05). The two sites from the Michelbach colonies (UM and LM) had significantly different burrow densities,
even though these two sites were
within 1 km of one another.
Burrow density was positively
correlated with prairie dog density at
both sites (HS and SB) where prairie
dog densities were determined and
all burrows were counted. Burrow
density significantly correlated with
prairie dog density at r = 0.665, accounting for 44.2 percent of the variance (F = 10.32, df = 1,13, P < 0.01).
For a pooled 15 territories at the
two sites, the mean burrow density
was 13.73 burrows per territory (s =
8.31, and the mean number of prairie
dogs per territory was 6.4 (s = 6.7).
Consequently, on the average, there
were twice as many burrows as prairie dogs per territory.
Burrow Density, Evenness, Plant
Cover, and Plant Species Diversity
Plant cover and plant species diversity were negatively correlated with
burrow density. Multiple regression
analysis with burrow density as the
dependent variable and plant evenness, percent cover, Simpson's dominance, Shannon-Weaver diversity,
and H max as independent variables
was significant (F = 5.25, df = 5,7, P
< 0.051, accounting for 88.8 percent of
the total variance in burrow density.
Of these, evenness (F = 7.471, percent
cover (F = 10.371, and ShannonWeaver diversity (F = 7.39) were significant to the regression. Evenness
had an r = -0.416, percent cover had
an r = -0.349, and Shannon-Weaver
diversity had an r = -0.427.
Burrow Density, Native Species,
and Introduced Species
Burrow density was negatively correlated with the number of introduced-weedy plant species (F =
18.14, df = 1,10, P < 0.01). Regression
analysis showed that burrow density
was correlated with introducedweedy plant species at r = -0.673, accounting for 45.3 percent of the variance in burrow density.
Burrow density was not significantly correlated with either nativenonweedy species or native-weedy
species when each of these was considered as an independent variable.
However, when these two were combined into a single variable, native
species, this produced a highly significant positive correlation of r =
0.803 (F = 18.14, df = 1, 10, p < 0.01),
accounting for 64.5 percent of the
variance in burrow density.
Burrow Density, Plant Species, and
Levels of Grazing
Burrow density was significantly correlated with the level of grazing (r =
0.903, F = 17.8, df = 1,4, P < 0.05).
The more a site was grazed, the
higher was the burrow density. Regression analysis showed that grazing levels were not significantly correlated with either the number of introduced species or the number of
native nonweedy species at a site.
Grazing was significantly correlated
with the number of native weedy
species (r = 0.975, F = 37.9, df = 1,2, P
< 0.05), and weakly correlated with
the total number of plant species (r =
0.947, F = 17.4, df = 1,2, P = 0.06).
Multiple regression with burrow
density as the dependent variable
and native species, introduced species, and grazing level as independent variables showed that native species (number of native weedy and
native nonweedy species combined)
explained 97.9 percent of the variance in burrow density, while grazing level explained an additional 1.8
percent and introduced species explained 0.2 percent.
Discussion
Our results show that Gunnison's
prairie dogs thrive at sites with native-nonweedy and native-weedy
species of plants. Gunnison's prairie
dogs apparently do not prefer sites
that have a high proportion of introduced-weedy species. This is not surprising when one considers the dietary requirements of these animals.
Shalaway and Slobodchikoff (1988)
found that the diet of Gunnison's
prairie dogs at three sites in the Flagstaff area consisted primarily of native plants: native-weedy and nativenonweedy species made up 60-80
percent of the animals' food. Introduced-weedy species made up a relatively low proportion of the diet of
Gunnison's prairie dogs in that
study.
Contrary to the findings of studies
with blacktailed prairie dogs (Lerwick 1974, Boddicker and Lerwick
1976, Gold 1976, Hansen and Gold
1977, Beckstead and Schitoskey 1980,
Archer et al. 19841, Gunnison's prairie dogs did not increase plant species diversity, but instead decreased
it. This effect can be produced by the
clipping action of prairie dogs on
plants that tend to grow tall and obscure the animals' view of terrestrial
predators. Such clipping action can
lower the competitive ability of
shrubs and other tall plants, eventually eliminating them from prairie
dog towns. Many of these species are
introduced weedy plants. A similar
effect was described by Clements
and Clements (1940) with Gunnison's
prairie dogs.
The effects of Gunnison's prairie
dogs on plant cover were consistent
with those found by other studies
(Knowles 1982, Archer et al. 1984). In
each case, prairie dogs decreased
plant cover. This is to be expected,
since all species of prairie dogs graze
on vegetation and can eat up some
24-90 percent of the primary production of a site (Osborn and Allan 1949,
Hansen and Gold 1977, CrockerBedford and Spillett 1981).To the
extent that blacktailed prairie dogs
and cattle have a dietary overlap of
76 percent (Kelso 1939), prairie dogs
have been construed as competitors
of large herbivores such as cattle.
However, because prairie dogs feed
very selectively on plants, 80 percent
of the biomass they ingest may come
from plant parts not utilized by cattle
(Cracker-Bed ford 1976).Also, any
potential competitive effect might be
minimized by the relatively small
size of most extant prairie dog colonies (King 1955; Koford 1958; Smith
1955), and the beneficial effects that
large herbivores may obtain from
plants that grow in prairie dog colonies (Coppock et al. 1983a).
The positive correlation between
grazing level and density of prairie
dog burrows suggests that prairie
dogs are found more in habitats that
are highly grazed. However, merely
addressing prairie dog management
in terms of possible competition with
cattle misses a much more fundamental issue: that of the prairie dog's
place in a natural ecosystem. While
our study has found a positive correlation between prairie dog densities
and grazing, the presence of these
animals at ungrazed sites indicates
that they can establish themselves in
ungrazed areas that have the right
configuration of habitat characteristics.
A much more important point
than grazing is the strong link between the presence of prairie dogs
and the success of native species of
plants. Introduced weeds are not favored in prairie dog colonies, even
though the soil is disturbed through
the burrowing actions of these animals. Rather than being "weedy"
pests who come into overgrazed
lands, prairie dogs might actually
have the function of repairing overgrazed land, and driving the plant
community toward a more natural
one.
The mechanism for how prairie
dogs might drive the ecosystem toward more native plant species is
still unclear. We have found that
Gunnison's prairie dogs decrease
both species diversity and plant
cover. The decrease in species diversity apparently comes from a decrease in the component represented
by the introduced weedy plant species, and not from the native plant
species. The decrease in plant cover
comes from herbivory on the plants
growing in the colonies. Some native
plant species produce more flowering stalks and more seeds when they
are grazed by herbivores (Paige and
Whitham 1987). Experimental evidence for black-tailed prairie dogs
shows that both forbs and grasses
increased in plots that contained both
prairie dogs and cows (Uresk and
Bjugstad 1980).In the arid conditions
of the Southwest, native plants might
be better adapted to climatic conditions than introduced weedy species,
and might respond to herbivory by
increasing their numerical abundance. The rela tionship that we
found between levels of grazing and
prairie dog burrow densities may be
the result of herbivory stimulating
the growth of plants necessary to the
diet of Gunnison's prairie dogs.
Our results suggest that Gunnison's prairie dogs must be conserved
by maintaining habitats with a large
component of native vegetation.
Gunnison's prairie dogs are a natural
part of native ecosystems, and have
evolved alongside large herbivores
such as elk, deer, and buffalo, all of
which feed to some extent on native
species of grasses and forbs. Native
plant species have evolved to compensate for these effects of herbivory,
and possibly for this reason prairie
dogs might have a beneficial function
of restoring rangeland that has been
damaged by grazing; this is a management question that must be addressed experimentally in the future.
In addition to the positive association
between prairie dogs and native
plant species, prairie dog towns are
habitat sites that are integral to the
existence of large numbers of other
vertebrates and invertebrates, and
eradication of prairie dogs can have
detrimental consequences to natural
ecosystems. Experimental and economic evidence currently indicates
that eradication of prairie dogs is neither economically feasible nor particularly beneficial to cattle. We suggest that prairie dogs should be
looked at in a more positive role that
reflects their impact on the maintenance of natural ecosystems.
Acknowledgments
We thank Jim Benedix, Ed Creef, Cheryl Fischer, Kitty Gehring, Gene
Hickman, and Steve Travis for assistance in data collection and summarization. We also thank Judith Kiriazis for her helpful and insightful
comments on this manuscript.
Literature Cited
Agnew, W. 1983. Flora and fauna associated with prairie dog ecosys-
tems. M. S. Thesis, Colorado State
University, Fort Collins, 47 p.
Archer, S. R., I. D. Lebreton, M. G.
Garrett, and J. K. Detling. 1984.
Structural changes in a mixedgrass prairie dog community as a
function of prairie dog colonization history. Bulletin Ecological
Society of America 65:162.
Beckstead, M. and F. Schitoskey, Jr.
1980. Assimilation efficiency of the
black-tailed prairie dog. Proceedings South Dakota Academy of
Science 59:184-194.
Boddicker, M. J. and A. Lenvick.
1976. Vegetation changes induced
by prairie dogs on shortgrass
range. Journal of Range Management 29:221-225.
Brizuela, M. A., J. K. Detling, and M.
S. Cid. 1984. Seasonal silicon content of grasses from sites receiving
different grazing pressure by
grassland herbivores. Bulletin Ecological Soc. of Amer. 65:161-162.
Campbell, T. M., 111, and T. W. Clark.
1981. Colony characteristics and
vertebrate associates of whitetailed and black-tailed prairie
dogs in Wyoming. American Midland Naturalist 105:269-275.
Clark, T. W., T. M. Campbell, 111, D.
C. Socha, and D. E. Casey. 1982.
Prairie dog colony attributes and
associated vertebrate species.
Great Basin Naturalist 42:572-582.
Clements, F. E. and E. S. Clements.
1940. The biotic significance of disturbance. Climate, Climax, and
Conservation: Carnegie Institute
of Washington Yearbook Wl74175.
Collins, A. R., J. P. Workman, and D.
W. Uresk. 1984. An economic
analysis of black-tailed prairie dog
(Cynomys ludovicianus)control.
Journal of Range Management
37:358-361.
Coppock, D. L., J. K. Detling, and M.
I. Dyer. 1980. Interactions among
bison, prairie dogs and vegetation
in Wind Cave National Park. Final
Report to National Park Service,
Wind Cave National Park, Hot
Springs, South Dakota. 177 p.
Coppock, D. L., J. K. Detling, J. E.
Ellis, and M. I. Dyer. 1983a. Plantherbivore interactions in a North
American mixed-grass prairie. I.
Effects of black-tailed prairie dogs
on interseasonal aboveground
plant biomass and nutrient dynamics and plant species diversity. Oecologia 56:l-9.
Coppock, D. L., J. E. Ellis, J. K. Detling, and M. I. Dyer. 1983b. Plantherbivore interactions in a North
American mixed-grass prairie. 11.
Responses of bison to modification
of vegetation by prairie dogs.
Oecologia 56:10-15.
Crocker-Bedford, D. C. 1976. Food
interactions between Utah prairie
dogs and cattle. M. S. Thesis. Utah
State University, Logan. 131 p.
Crocker-Bedford, D. C. and J. J.
Spillett. 1977. Home ranges of
Utah prairie dogs. Journal of
Mammalogy 585724573.
Detling, J. K. and E. L. Painter. 1983.
Defoliation responses of western
wheatgrass populations with diverse histories of prairie dog grazing. Oecologia 57:65-71.
Fagerstone, K. A. 1981. A review of
prairie dog diet and its variability
among animals and colonies. p.
178-184. In R. M. Timm and R. J.
Johnson, eds. Proceedings Fifth
Great Plains Wildlife Damage
Control Workshop. Institute of
Agriculture and Natural Resources, University of Nebraska,
Lincoln.
Gold, I. K. 1976. Effects of blacktail
prairie dog mounds on shortgrass
vegetation. MS Thesis, Colorado
State University, Fort Collins,
Colorado.
Hansen, R. M. and I. K. Gold. 1977.
Blacktail prairie dogs, desert cottontails and cattle trophic relations
on shortgrass range. Journal of
Wildlife Management 30:210-214.
Hassien, F. 1976. A search for blackfooted ferrets in the Oklahoma
panhandle and adjacent area and
an ecological study of black-tailed
prairie dogs in Texas County,
Oklahoma. M. S. Thesis, Okla-
homa State University, Stillwater.
11.1 p.
Kelso, L. H. 1939. Food habits of
prairie dogs. USDA Circular
Number 529.
King, J. A. 1955. Social behavior, social organization, and population
dynamics in a black-tailed prairie
dog town in the Black Hills of
South Dakota. Contributions of
the Laboratory of Vertebrate Biology, University of Michigan 621123.
King J. A. 1984. Historical ventilations on a prairie dog town. p.
447-456. In J. 0. Murie and G. R.
Michener, eds. The biology of
ground-dwelling squirrels. University of Nebraska Press, Lincoln,
Nebraska.
Klatt, L. E. and D. Hein. 1978. Vegetative differences among active
and abandoned towns of blacktailed prairie dogs (Cynornys ludovicianus). Journal of Rangeland
Management 31:315-317.
Koford, C. B. 1958. Prairie dogs,
whitefaces, and blue grama. Wildlife Monographs 3:l-78.
Knowles, C. J. 1982. Habitat affinity,
populations, and control of -blacktailed prairie dogs on the Charles
M. Russell National Wildlife Refuge. Ph. D. Dissertation, University of Montana, Missoula. 171 p.
Lerwick, A. C. 1974. The effects of
the black-tailed prairie dog on
vegetative composition and their
diet in relation to cattle. M.S. Thesis, Colorado State University,
Fort Collins. 106 p.
Nie, N. H., C. H. Hull, J. G. Jenkins,
K. Steinbrenner, and D. H. Bent.
1975. SPSS: Statistical package for
the social sciences. ed. 2, McGrawHill, New York.
O'Meilia, M. E. 1980. Competition
between prairie dogs and beef
cattle for range forage. M.S. Thesis, Oklahoma State University,
Stillwater. 32 p.
Osborn, B. and P. F. Allan. 1949.
Vegetation of an abandoned prairie dog town in tallgrass prairie.
Ecology 30:322-332.
Paige, K. N. and T. G. Whitham.
1987. Overcompensation in response to mammalian herbivory:
the advantage of being eaten.
American Naturalist 129:407-416.
Poole, R. W. 1974. An introduction to
quantitative ecology. McGrawHill, N. Y. 532 p.
Severe, D. S. 1977. Revegetation of
black-tailed prairie dog mounds
on shortgrass prairie in Colorado.
M.S. Thesis, Colorado State University, Fort Collins. 92 p.
Shalaway, 9. and C. N. Slobodchikoff. 1988. Seasonal change in
the diet of the Gunnison's prairie
dog. Journal of Mammalogy, in
press.
Slobodchikoff, C. N. and R. Coast.
1980. Dialects in the alarm calls of
prairie dogs. Behavioral Ecology
and Sociobiology 249-53.
Smith, R. E. 1955. Natural history of
the prairie dog in Kansas. University of Kansas Museum Natural
History and State Biological Survey Publication, Number 16.
Uresk, D. W. 1985. Effects of controlling black-tailed prairie dogs on
plant production. Journal of
Rangeland Management 38:466468.
Uresk, D. W. and A. J. Bjugstad.
1980. Prairie dogs as ecosystem
regulators on the Northern High
Plains. p. 91-94. In C. L. Kucera,
ed. Proceedings 7th North America Prairie Conference. Southwestern Missouri State University,
Springfield.