Habitat suitability for the black-tailed prairie dog at Rocky Mountain Arsenal

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Habitat suitability for the black-tailed prairie dog at Rocky Mountain Arsenal
Clippinger, Norman Wright
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ix, 94 leaves : illustrations, maps ; 29 cm


Subjects / Keywords:
Black-tailed prairie dog ( lcsh )
Habitat selection ( lcsh )
Rocky Mountain Arsenal (Colo.) ( lcsh )
bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )


Includes bibliographical references (leaves 69-74).
General Note:
Submitted in partial fulfillment of the requirements for the degree of Master of Arts, Department of Integrative Biology.
Statement of Responsibility:
by Norman Wright Clippinger.

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Source Institution:
|University of Colorado Denver
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Auraria Library
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
17995238 ( OCLC )

Full Text
Norman Wright Clippinger
B.A., University of Colorado at Boulder, 1984
A thesis submitted to the Faculty of the Graduate
School of the University of Colorado in partial
fulfillment of the requirements for the degree of
Master of Arts
Department of Biology, Denver

This Thesis for the Master of Arts Degree by
Norman Wright Clippinger
has been aproved for the
Department of Biology

Clippinger, Norman Wright (M.A., Biology)
Habitat Suitability for the Black-tailed Prairie Dog
at Rocky Mountain Arsenal
Thesis Directed by Dr. Douglas Reagan
A habitat suitability index (HSI) model was developed for the
black-tailed prairie dog (Cynomys ludovicianus) for use in U.S. Fish
and Wildlife Habitat Evaluation Procedures (HEP). The HSI is a
numerical index comparing study area conditions to conditions
considered optimum for the species in question. The variables
describing habitat conditions for prairie dogs were the percentage of
forb cover, percentage of herbaceous cover, slope, height of
vegetation, and soil types or consistancy. Data was collected for
these variables on prairie dog towns at Rocky Mountain Arsenal (RMA)
in Colorado in an attempt to validate the HSI model. The variable
data was used to produce a HSI value for 21 one hectare plots on
RMA. The HSI was compared to population estimates collected by
counting prairie dogs during their peak activity periods on the
hectare plots. An attempt was made to correlate the individual
variable suitability indeces (SI) to prairie dog densities, and also
to correlate HSI values to densities of prairie dogs on each plot.
HSI values correlated significantly (r = 0.45, p 0.04) to
black-tailed prairie dog densities. A modified HSI model (modified
height variable) also correlated significantly (r = 0.54, p = 0.01)
to prairie dog densities. Possible threshold habitat values for
colonial species like prairie dogs were discussed, and suggestions
for improvement of prairie dog habitats on RMA were made as well.

No part of my academic career would have been successfully
completed without the continuing support of my parents, Dallas and
Margaret Clippinger, to whom this work is dedicated.

This work was completed through the sacrifices of many
individuals whose dedication of time and effort were phenomenal. I
wish to thank the field workers who helped with both the prairie dog
counts and vegetation transects; Sharren Sund, Carolyn Fordham, Ron
Beane, Doug Reagan, Kathleen Cushman, Linda Bexley, and Laurel Pye.
For help with the botanical identifications, I thank Emily Hartman
and Laurel Pye. For access to the Arsenal, and partial funding for
this study, I would like to thank Environmental Science and
Engineering and the U.S. Army for their cooperation and support. I
would also like to thank the employees at ESE for their cooperation,
interest, and participation. Bob Chesson was particularly helpful in
my continuing battle with the computer world, and Grace Thomas
produced the maps for this thesis. Carolyn Fordham, Kathleen Cushman,
and Doug Reagan each edited the model and gave helpful insight and
encouragement throughout the life of this project.
Special thanks to the members of my graduate committee,
especially Gerry Audesirk, who greased the academic wheels when they
had ground to a halt. The entire investigation of prairie dogs, their
habitat, and the resulting thesis has evolved over the last two years
through the efforts of Doug Reagan. For his foresight in the need
for this project, and his encouragement and dedication to realize
this study, he has my lasting gratitude.

I. INTRODUCTION ............................................. 1
General Review .......................................... 1
The Black-Tailed Prairie Dog .......................... 1
Habitat Suitability Index Models ...................... 3
Project History and Objectives ...................... 4
Study Site ............................................ 5
Model Development ..................................... 11
HSI Model for the Black-tailed Prairie Dog ............ 13
General........................................... 13
. Food................................................ 13
Water............................................... 18
Cover .............................................. 18
Reproduction and Social Structure .................... 21
Interspersion and Populations ........................ 23
Special Considerations ............................... 23
Model Applicability................................... 27
Model Description: Overview........................... 28
Food Component........................................ 28
Cover Component....................................... 30
Model Relationships................................... 35

Model Testing Goals and Assumptions ............. 38
Plot Locations . .............................. 38
Visual Count Population Estimates .................... 39
Vegetation, Slope, and Soil Characteristics .... 42
Comparison of HSI and Prairie Dog Populations ... 43
IV. RESULTS ............................................... 44
Population Estimates ............................... 44
Habitat Variables..................................... 44
HSI Model Output vs. Population Estimates ......... 44
V. DISCUSSION ............................................... 57
Population Estimates by Visual Counts .................. 57
Prairie Dog Density ................................ 57
RMA Habitat Quality for Prairie Dogs.................. 57
Modification of Variables and Interpretation of HSI . 59
RMA Plot Data and Variable Modifications ............. 59
Problems and Limitations for Test of HSI Model ... 60
Colonial Species, Carrying Capacity, and HSI .. 64
Suggestions for Study and Further Testing of Model . 65
Applications of the HSI Model for
Black-tailed Prairie Dogs ............................ 67
LITERATURE CITED ................................................. 69
APPENDIX ........................................................ 75

1. Suggested techniques for gathering information on
habitat variables.......................................... 37
2. Population estimates and dates of observation on
21 plots on Rocky Mountain Arsenal......................... 45
3. Population means and confidence limits..................... 45
4. Vegetation variables, slope and soil types with
Suitability indices....................................... 46
5. Relative cover of plant species on 21 plots on
Rocky Mountain Arsenal..................................... 48
6. Plot number with the calculated HSI value and
population estimate........................................ 56
7. Population estimate and modified HSI values for
21 plots on Rocky Mountain Arsenal......................... 63

1. The range of the black-tailed prairie dog................... 2
2. Map of Rocky Mountain Arsenal............................... 6
3. Vegetation map of Rocky Mountain Arsenal.................... 8
4. Black-tailed prairie dog colonies on
Rocky Mountain Arsenal...................................... 9
5. Habitat Variables and their relation to
Life Requisites............................................ 29
6. SI Graph for variable 1, percent cover of forbs.......... 31
7. SI Graph for variable 2, percent herbaceous cover. ... 32
8. SI Graph for variable 3, percent slope................... 33
9. SI Graph for variable 4, height of vegetation............ 34
10. SI Graph for variable 5, soil type or composition. ... 36
11. Map of plot locations on Rocky Mountain Arsenal............ 40
12. Habitat Suitability Index versus Population
estimates for 21 plots on Rocky Mountain Arsenal. ... 55
13. Revised SI graph for height of vegetation.................. 61
14. Modified HSI versus Population estimates
for 21 plots on Rocky Mountain Arsenal..................... 62
15. Modified HSI, population estimates, and two
hypothetical curves describing their relationship. .

General Review
The Black-tailed Prairie Dog
The black-tailed prairie dog (Cynomys ludovicianus) is a
large (average 1 kg), social, ground dwelling squirrel inhabiting
short- and mixed-grass prairie in the semi-arid plains of North
America (Hall 1981; see Figure 1). Prairie dogs are strictly diurnal
rodents, and have only cones in their eyes, so that they are almost
blind in dim light or darkness (Lechleitner 1969). They prefer gently
sloped to flat terrain for their characteristic burrows, but avoid
areas without good drainage (King 1984). Black-tailed prairie dogs
thrive on a diet of short grasses, forbs, and other low vegetation.
In the pre-Columbian West, bison (Bison bison) and prairie
dogs interacted to maintain the short grass vegetation which is ideal
for both species (Koford 1958; Coppock et al. 1983a). Migratory bison
moved throughout the west, leaving trampled and grazed areas with
shorter grasses and invading forbs, which are conditions favorable
for the establishment of prairie dog colonies. There is evidence that
black-tails' social and digestive systems evolved on the basis of
this interaction (see Coppock et al. 1983a, 1983b; Hoogland 1981;
Fagerstone et al. 1981). Bison would then return to prairie dog
colonies to graze; prairie dog towns are still preferred grazing

Figure 1
. The range of the black-tailed prairie dog
(Cynornys ludovicianus). From Hall (1959).

sites for bison in those few areas where the two species are allowed
to co-exist (Coppock et al. 1983a).
As man replaced migratory bison with yearly cattle grazing,
prairie dogs expanded and thrived on overgrazed rangeland (Jones et
al. 1985). This led to the impression that prairie dogs were the
cause, rather than a symptom of damaged range. Black-tailed prairie
dogs became the target for mass extermination, with the battle cry of
'Death to the Rodents' (Bell 1921). The destruction of prairie dog
towns and the poisoning of prairie dogs led directly to the demise
and near extinction of a species which depended almost exclusively on
prairie dogs, the black-footed ferret (Mustela niqripes; Clark 1986).
Black-tailed prairie dogs form unique structures in the soil,
and undoubtedly alter the vegetation and diversity of life above the
ground, creating a special plains ecosystem. Many other species of
birds, mammals, and reptiles depend on prairie dog towns for their
underground and aboveground activities (Clark et al. 1982; Coppock et
al. 1983a; Agnew et al. 1986). Since black-tailed prairie dogs form
the basis of a unique ecosystem, it is important to study the life
history and habitat use of this species. A useful tool for such an
investigation is a model describing the habitat requirements and
habitat suitability for this a wide-ranging and important mammal.
Habitat Suitability Index Models
The Habitat Suitability Index (HSI) is a numerical index that
represents the capacity of habitat to support a fish or wildlife
species (U.S. Fish and Wild. Serv. 1981a). The HSI ranges from 0.0
(representing totally unsuitable habitat) to 1.0 (representing
optimum habitat). The HSI model output is assumed to have a direct

linear relationship to the theoretical carrying capacity of habitat.
In overall habitat assessments using Habitat Evaluation Procedures
(HEP), the HSI is used to compute Habitat Units by the formula:
Habitat Units = (HSI) X (Area of available habitat)
Habitat Units are then available for comparison to mitigation sites,
theoretical alternative analysis in environmental impact assessments,
or any other valid use of HEP (U.S. Fish and Wild. Serv. 1981b).
The creation of an HSI model requires a thorough literature
search and compilation of information on the habitat and life history
of a species. This documentation of the HSI model is most important
in defining model variables and their parameters. The collection of
field data on model variables and species' populations completes
verification of a model, and is the highest level of refinement for
HSI models.
Project History and Objectives
HSI modeling for various fish and wildlife species through
the HEP/HSI format has proceeded since 1980. The creation of a black-
tailed prairie dog model sprang from a need for habitat use
information for this species on Rocky Mountain Arsenal (RMA), a U.S.
Army installation just north of Denver. This site has become
contaminated with toxic waste and agents over the 40 or so years of
its operation by the Army and a combination of lease holders. There
are thousands of acres of prairie dog towns on RMA. Any subsequent
clean up plans or land use at RMA may involve some evaluation of the

habitat for black-tailed prairie dogs, since they are the prey base
for a number of other species frequenting RMA, including the
endangered bald eagle (Haliaeetus leucocephalus).
The first objective of this study was to write and formulate
a HSI model for the black-tailed prairie dog, including the
definition of important habitat variables. A second objective was a
test of the HSI model with field data collected on the habitat
variables and prairie dog densities at RMA. The HSI model predictions
of carrying capacity based on the field data were compared to actual
densities of prairie dogs, and an attempt was made to correlate the
HSI to the densities of prairie dogs. Reformulation (if necessary) of
some model variables and refining the model equations based on the
field data was the final objective of this study.
Study Site
Rocky Mountain Arsenal is situated along the northern city
boundary of Denver, Colorado U.S.A, and along the eastern boundary of
Commerce City; it is just north of Stapleton International Airport
(Figure 2). The six most central sections (1,2, 25, 26, 35, 36) of
RMA contain most of the buildings, chemical settling basins, and
areas of human disturbance. Most of the surface area is comprised of
gently rolling hills and plains, with the exception of Rattlesnake
Hill in section 35, which has a sharply sloped knob at the top of a
long slope. Other physical features on RMA include fresh water
reservoirs and ponds in sections 1,2, and 11 (Figure 2). There is
one natural stream, First Creek, which flows through the boundaries
of the reservation. The ditches, depressions, and creeks


Figure 2. Map of Rocky Mountain Arsenal

on RMA often are lined with cottonwood trees and other riparian
RMA is vegetated with predominantly non-native species, and
has large disturbed (plowed) areas planted with a mixture of grasses
dominated by crested wheatgrass (Agropyron cristatum). These plowed
areas range from conrplete cover of crested wheatgrass, to areas
successfully invaded by forbs and other grasses. A general vegetation
map of RMA is presented in Figure 3. There has been little human
disturbance to vegetation types for the past three years, other than
grading and mowing activities limited to the section border roads.
Cattle grazing has not been allowed for at least two decades.
A great number of wildlife species inhabit RMA for at least
part of the year (Appendix A). Year-round residents include mule and
white tailed deer, coyotes, prairie dogs, badgers, skunks, and a host
of other mammals. Many bird, reptile, and species inhabit the
riparian and plains habitats within the boundaries of RMA. Rare
raptors like ferruginous hawks, golden eagles, and bald eagles spend
the winter months there, depending upon the great abundance of prey
at RMA. Hunting or fishing for consumption is not permitted, due to
the threat of toxic contamination in wildlife tissues. Although
poisoning programs were once implemented to control prairie dogs and
other rodents, there has not been any application of rodenticides for
the past three years. There are approximately 4845 acres (12,112 ha)
of prairie dog towns on RMA; with a total acreage of 17,300 acres
(43,260 ha) for RMA, prairie dogs cover about 28% of the property
(Figure 4). Despite all the past perturbations and destruction of
habitat on this site, RMA has become an interesting location for

o y2 1
> i i
mmm water
Figure 3. Vegetation Map of Rocky Mountain Arsenal (from ESE 1987a).

Figure 4. Black-tailed prairie dog colonies on Rocky Mountain
Arsenal. Each square is one square mile (from ESE 1987b).

observing many wildlife species unseen in most of the Front Range of
Colorado, with a concentration and diversity of wildlife rivalling
or surpassing any other on the eastern plains of the state.
The Denver area (including RMA) has generally low humidity,
light precipitation, and abundant sunshine. Climatological data for
the weather station at Stapleton (just south of RMA) reported a mean
annual precipitation of 14.6 inches, with the total for 1986 in at
12.06 inches (National'Climatic Data Center 1986; see Appendix B).
The average maximum and minimum winter temperatures are 43 F and 17
F respectively (in January), while the average summer temperature
maximum and minimum are 86 F and 59 F (in July). The average first
freezing temperature occurs on October 8 (September 30 in 1986), and
the last occurrence in the spring averages to May 3 (April 20 in
1986). Spring is the cloudiest and wettest season, with much of the
precipitation falling as snow in March and early April. Summers are
normally hot and dry, with scattered thunderstorms accounting for
most of the precipitation. Autumn is dry and sunny, while winters
range from warm to very cold temperatures, and there are occasionally
large snowfalls.

Model Development
The technique for constructing HSI models is outlined in
three document releases by the U.S. Fish and Wildlife Service (1980,
1981a, 1981b). Five phases exist for completion of a HSI model:
1) Setting model objectives,
2) Identification of model variables,
3) Structuring the model,
4) Documenting the model, and
5) Verifying the model.
Setting model objectives includes the steps of defining the
acceptable model outputs, the geographic area to which this species'
model should be applied, and the seasons in which the model will be
valid. Identifying model variables begins with a review of the
literature on the species, and a determination of the relation of a
variable (such as height of vegetation, amount and types of cover,
etc...) to the carrying capacity of habitat based on this review.
Structuring the model involves the assignment of Suitability Indices
(SI) to actual habitat values, and the description of relationships
between habitat variables (their influence upon the overall HSI value
through an equation). Finally, the model must be documented as to the
general and specific habitat requirements, including food, water,

reproduction, cover types, and home range requirements. Verification
follows with a review by the author, review by species authorities or
experts, and, as in the case with this model, a test with field data.
The first step and always the most important phase of producing
a HSI model is a complete review of the literature before commencing
the phases outlined above. A deep understanding of each species' life
requisites is required to even begin to assign relevant habitat
variables for a species' survival, and to relate these variables to
an index that can correspond to carrying capacity in that species'
habitat. The prairie dog model was created through a careful search
of Biological Abstracts (by computer for 1971 1984), by the
referencing of several bibliographies (Clark 1971; Hassien 1976), and
diligent library searches.
Due to time constraints, the black-tailed prairie dog model
has not yet been verified by species authorities. This is a process
of review often requiring months for completion, and is necessary for
its eventual acceptance by the U.S. Fish and Wildlife Service.
However, the other steps outlined above were completed before field
testing began. Various drafts were drawn from May 1986 to May 1987,
yielding the document presented below. There are two main sections to
this model; the first presents habitat use information, and the
second presents the actual documentation and mathematical structure
of the model based on the review of habitat use information.

HSI Model for the Black-tailed Prairie Dog
The black-tailed prairie dog is a large (avg. 1 kg), social,
ground dwelling squirrel inhabiting short- and mixed-grass prairie in
the semi-arid plains of midwestern North America (Lechleitner 1969;
Hall 1981; see Fig. 1). Historically, bison (Bison bison) and prairie
dogs interacted to maintain the short grass vegetation which is ideal
for both species (Koford 1958; Coppock et al. 1983a). As man replaced
migratory bison with stationary cattle, prairie dogs have thrived on
overgrazed rangeland (Jones et al. 1985). Black-tailed prairie dogs
will also invade suitable habitat within urban areas (Bissel and
Dillon 1982). These urban locations are often vacant or neglected
parcels of land which appear much like short-grass prairie habitat.
Grass and sedge species are important in the diet of black-
tailed prairie dogs as year round staples and preferred foods in most
prairie locations (Tileston and Lechleitner 1966; Costello 1970;
Summers and Linder 1978; Fagerstone 1979; Uresk 1984). Western
wheatgrass (Agropyron smithii), blue grama (Bouteloua gracilis), and
buffalo grass (Buchloe dactyloides) are reported as among the most
common grasses in prairie dog stomachs (Koford 1958, Tileston and
Lechleitner 1966, Bonham and Lerwick 1976, Summers and Linder 1978,
Fagerstone 1979). Sand dropseed (Sporobolus cryptandrus) was also
reported as a major food item (Hansen and Gold 1977; Uresk 1984),
accounting for up to 60% of the prairie dog diet in September (Bonham
and Lerwick 1976). Sedges (Carex spp.) may be important on some

prairie dog towns, comprising 55-64% of their diet in May (Bonham and
Lerwick 1976; Hansen and Gold 1977; Summers and Linder 1978, Uresk
1984). Other grasses included in prairie dog diets are sixweeks
fescue (Festuca spp. (Kelso 1939, Bonham and Lerwick 1976, Fagerstone
1979), cheatgrass (Bromus spp.; Costello 1970, Fagerstone 1979), and
ring muhly (Muhlenberqia torreii; Smith 1967, Uresk 1984).
Forbs are a common and occasionally dominant portion of
prairie dog diets. Scarlet globemallow (Sphaeralcea coccinea) may
form 20-24% of black-tailed prairie dog diets (Bonham and Lerwick
1976, Fagerstone 1979). Plains prickly pear (Opuntia polyacantha) is
an important seasonal food, with up to 58% of the diet in the winter
(Fagerstone 1979; see below). Peppergrass (Lepidlum densiflorum)
comprises 50% of the June prairie dog diet in some areas (Costello
1970; see also Fagerstone et al. 1977). Wooly plantain (Plantago
purshii) is taken upon occasion (Bonham and Lerwick 1976, Fagerstone
et al. 1977, Summers and Linder 1978), as is prickly lettuce (Lactuca
spp.), goosefoot (Chenopodium spp.), and Kochia (Koford 1958,
Fagerstone et al. 1977). Plants other than those mentioned above may
be locally important food sources for the prairie dogs; the plants
mentioned above are generally the most commonly available on short-
or mixed-grass prairies.
Black-tailed prairie dogs will avoid consuming certain plant
species common on their range. Threeawn (Aristida fendleriana),
horseweed (Conzya ramossissima), buffalo bur (Solanum rostaratum)
and, despite its common name, prairie dog weed (Dyssodia papposa) are
all avoided by prairie dogs (Summers and Linder 1978, Fagerstone
1979). King (1955), Tileston and Lechleitner (1966) and Costello

(1970) reported that prairie dogs clipped down and left laying all
inedible plants, and tall edible plants not needed for food. Koford
(1958) found much the same behavior, but noted that they would
neither clip nor consume snow on the mountain (Euphorbia marginata),
tansy mustard (Sisymbrium altissimum), beeplant (Cleome serrulata),
and plains milkweed (Asclepias pumila).
Black-tailed prairie dogs are often described in the
literature as opportunistic herbivores, while in the same paper an
author will describe the selective diet or preferences of prairie
dogs. A more accurate description of prairie dogs is that they are
'selective opportunists'. They prefer certain phenological stages or
types of vegetation according to their immediate or eventual needs,
and will exploit such vegetation as it occurs in their environment.
Prairie dog diets may be best understood by examining the literature
for known preferences and examples of opportunistic feeding.
Food choices of prairie dogs are greatly influenced by plant
phenology. Prairie dogs prefer grasses and sedges in the spring and
summer, yielding to a growing percentage of forbs in the diet by late
summer and fall (Koford 1958; Bonham and Lerwick 1976; Hansen and
Gold 1977; Fagerstone 1979; Uresk 1984). Black-tails show a marked
preference for growing plants and meristematic tissue (Fagerstone et
al. 1981 ). The prairie dogs' habit of clipping vegetation short leads
to higher nitrogen concentration and higher proportions of succulent
forage (Coppock 1981, Coppock et al. 1983b). Beckstead (cited in
Fagerstone and Williams 1982) proposed that prairie dogs select
growing plants because they contain more protein and less fiber than
mature plants. Grasses in particular are less digestible when mature

in the fall (Bonham and Lerwick 1976). Thus grasses and sedges are
preferred in the spring while their young shoots are still succulent
and prevalent (Koford 1958; Costello 1970; Fagerstone et al. 1981).
Although grasses dominate prairie dog diets in most seasons, forbs
are sought out in every season (Fagerstone et al. 1977). Forbs
generally grow more slowly, and thus remain more palatable than
grasses through more of the year. Assimilation efficiencies of
prairie dogs are up to twice as high on diets that included forbs
than on diets of grass only (Fagerstone et al. 1981). Forbs appear
to be sought out by prairie dogs on nutritional grounds.
Flowers and seeds may be required for their fats, protein,
and other nutrients, and seem to be taken as they become available
from both grasses and forbs (an example of dietary opportunism;
Koford 1958; Smith 1967; Fagerstone 1979). But normally, black-
tailed prairie dogs prefer different parts of plants depending on
the time of year (Fagerstone et al. 1981 ). Spring and summer plant
parts eaten include the early leaves of grasses, early forb shoots,
and the seed heads of grasses as they are developed. In the fall, the
leaves of forbs and seeds of almost any plant in abundance are eaten
(Koford 1958, Smith 1967; Uresk 1984). In the winter, the remaining
leaves on plants, seeds, basal parts of grasses, dry grasses, twigs
of shrubs, and prickly pear stems are consumed (Koford 1958; Smith
1967). Roots are occasionally taken from their burrows and small
circular pits dug among the plains grasses (Tileston and Lechleitner
1966; Smith 1967). The only plant parts available in the winter are
the few standing stems, seeds of any plants, and plains prickly pear.
High proportions of succulent vegetation in most seasons, and of

prickly pear in winter diets of prairie dogs, suggests that they are
in need of water as much as forage (Fagerstone et al. 1981).
Black-tailed prairie dogs, in contrast to white-tailed
prairie dogs (Cynomys leucurus), do not hibernate, and rarely are
torporous (Tileston and Lechleitner 1966; Harlow and Menkins 1986).
Water is not generally available on short-grass prairie, therefore
prairie dogs must obtain it from their vegetation. In the winter
diet, this must be particularly difficult, given the dry state of
winter forage on short grass prairie. Prickly pear retains a high
amount of water in the photosynthetic stems. Unlike most other
animals (including white-tailed prairie dogs), black-tails tolerate
the oxalic acid present in prickly pear and consume this species
(Fagerstone et al. 1981 ). Water may be the major dietary attraction
of prickly pear to wintering black-tails (Fagerstone 1979).
There are important preferences and specificities in prairie
dog diets, but their adaptability to various proportions and kinds of
vegetation should not be underemphasized. Food availability plays
the most important role in determining the overall opportunity of
prairie dogs to make a food choice (Fagerstone 1979). Fagerstone et
al. (1977) performed a study of black-tailed prairie dog food habits
in an area where forbs were reduced in abundance by 2,4-D herbicide.
They found that forbs were reduced from 50% in the prairie dog diet
to 9% of the prairie dog diet, without any apparent effect on the
weight, health, or activities of the prairie dogs. Yet it is also
important to point out that the prairie dogs must have searched out
the smaller coverage of forbs in this area to include 9% forbs in
their diet (Fagerstone et al. 1977). This study is illustrative of

'selective opportunism' in prairie dog diets and food choice.
The black-tailed prairie dog does not require a standing
water source (Young 1944; Tileston and Lechleitner 1966): It is
assumed the life requisite for water is satisfied from the vegetation
they consume.
Black-tailed prairie dogs have long been known to occur in
areas where there has been very low and sparse vegetation (see
Merriam 1902). They will clip down most plants which grow higher than
they can see over or more dense than they can see through (see
above). Black-tails will seldom enter tall and thick vegetation,
particularly if they cannot walk without being constantly brushed by
the vegetation (Koford 1958). Apparently, prairie dogs prefer sites
with high visibility afforded by low vegetation for protection from
predation (King 1955; Hoogland 1981). They may have evolved their
social grouping and extensive warning calls in order to detect
possible predators near their, towns. Overgrazed rangeland has been
known to encourage the growth of prairie dog colonies because of its
low vegetation, among other factors (Bond 1945; Osborn and Allen
1949; King 1955; Koford 1958; Smith 1967; Costello 1970). The
choice of new territories by dispersing individuals is controlled by
the visibility of the site and its proximity to existing colonies
(Cincotta 1985; Knowles 1985). In a study of black-tailed prairie dog
towns surrounded by tall grass prairie, Osborn and Allen (1949)
discovered that prairie dogs will abandon a site or gradually be

eliminated if they and other herbivores cannot keep the vegetation
clipped down. The maximum height of vegetation (in summer) on prairie
dog colonies can average anywhere from 13 cm on short-grass sites
(Koford 1958; Agnew et al. 1986), to 64 cm in grasslands of eastern
New Mexico (Clark et al. 1982). Overall cover of vegetation on
black-tail towns is quite variable, ranging from 25-49% in Montana
(Fagerstone et al. 1977), to a maximum range of 73-91% canopy cover
in western South Dakota (Uresk 1984). In other vegetation studies on
prairie dog colonies, total canopy cover ranged from 41-60% in
western South Dakota (Agnew et al. 1986), from 32-58% in Wind Cave
National Park, S.D. (Krueger 1986), and from 58-70% in northern
Colorado (Klatt and Hein 1978).
The burrows of prairie dogs are one of the most conspicuous
indicators of their presence. Burrows are refuges from the external
environment, a location for breeding and rearing young, and a center
for the social structure of prairie dogs (King 1955). The black-
tailed prairie dog depends on its burrow for protection from
predation, and often will pass its burrow on to its descendants. All
of the above factors lead to substantial advantages for the cost in
time and effort of building and defending a burrow system (King
1984). Their burrows are one of the most important features in the
life of prairie dogs (King 1955).
There are three categories of prairie dog burrow entrances.
The characteristic domed entrance is formed by subsoil brought to the
surface and deposited evenly around the entrance (King 1955; Smith
1967); the dome may reach 1.8 m in diameter and 0.9 m in height (King
1984). A rimmed crater hole is opened from underground, and is

constructed by the prairie dog scraping topsoil and forming a rimmed
entrance with forceful application of its nose (King 1955; Smith
1967). Burrow entrances without structures about them are often
located on slopes of more than 10%, or the structure may have eroded
away (King 1955; Smith 1967).
Burrows lead downward at an incline of 15-20 from domed
craters into complex passages containing waiting chambers just under
the surface, several blind chambers (often containing feces), and
nest chambers lined with dry grass (Sheets et al. 1971). Burrows then
make an abrupt vertical ascent to a rimmed crater entrance, with the
maximum depth ranging from one to four meters. The burrow is about 2
meters deep on average, and extends 13 m in length (Sheets et al.
1971 ). Most burrow systems have only one or two entrances, with a
few long occupied burrows having three entrances (Stromberg 1978).
Complicated and extensive prairie dog burrows are preferred for
habitation by black-footed ferrets (Houston et al. 1986).
The number and depth of burrows depends greatly on the
substrate and length of occupation of an area. Black-tails will
usually build on slopes of less than 10% (Koford 1958; Tileston and
Lechleitner; Dalsted et al. 1981 ). Almost any well drained soil type
other than sandy soils are acceptable for burrows, with silty loam
clay soils the best for tunnel construction (Koford 1958; Sheets et
al. 1971; Lewis et al. 1979; Dalsted et al. 1981).
The density of prairie dog burrow openings varies
substantially. King (1955) found a density of 143 burrow openings /ha
in South Dakota, Smith (1967) found 50 /ha in Kansas, and Clark et
al. (1982) found 33 /ha in New Mexico. No index can be used to

estimate the number of prairie dogs from the number of burrows, since
the burrows are often more permanent or constant in number than the
prairie dogs (King 1955). Burrow density is not a good index of the
suitability of range for prairie dogs either, because they can
reflect past as well as present conditions (Koford 1958).
Reproduction and Social Structure
Black-tailed prairie dogs are social rodents living in
colonies or 'towns' with 5 to thousands of individuals. Their
colonies are divided by topographic features such as a hill or a
stream into 'wards' (King 1955). Communication or interaction between
wards is rare, except through emigration/immigration of individuals
(Hoogland 1981). Wards are in turn subdivided by the basic
polygynous social groups called coteries (King 1955; Hoogland 1979a).
A coterie usually contains one adult male, 3-4 genetically related
adult females, and several yearlings and juveniles of both sexes.
Coterie members defend a territory of about 0.26 ha (Hoogland 1981)
against encroachment by prairie dogs of other coteries. Coterie
members gain fitness through the common defence from predators; the
variety of sharp alarm calls, 'all clear' signals, and other 'barks'
of prairie dogs are an important aspect of the social structure of
this colonial species.
The coterie social structure corresponds to a reproductive
function, since females normally mate with the resident male (Foltz
and Hoogland 1981 ). Normal minimum breeding age for both females and
males is two years, but yearling females may breed if supplies of
food and space are abundant (Koford 1958; Smith 1967; Garrett et al.
1982). Breeding times vary with site location, latitude and specific

geography of the colony. In the northern extent of the prairie dog's
range, breeding occurs from early March to April (King 1955; Koford
1958), while in Kansas, breeding occurs from early February to the
middle of March (Wade 1928; Smith 1967). Gestation lasts from 28-32
days, and the pups are nursed for about seven weeks (King 1955). The
number of litters raised per adult female is less than 1, as there is
high juvenile mortality. Infant and juvenile mortality is as high as
50% among the 3-5 pups born (Garrett et al. 1982). Infanticide by
resident lactating females accounts for up to 51% of juvenile
mortality (Hoogland 1985), but in this curious social system, these
same females will sometimes nurse the pups of their kin as part of a
limited communal breeding strategy (Hoogland 1983b).
Females will often remain in their natal coterie for their
entire lifetimes with their siblings and other female relatives,
while males of breeding age will emigrate to the ward boundaries or
beyond to start new coteries, or will try to usurp the males on
existing territories (Hoogland 1983a). Adult females may emigrate to
unoccupied areas if they did not reproduce in the preceding breeding
season (Cincotta et al. 1987). Adult males leave their breeding
coteries before their daughters mature, either to invade another
coterie, disperse, or may simply perish in an outlying area (Hoogland
1982). There is high mortality among the emigres, since isolated
prairie dogs fall more easily to predation on the borders of coteries
and wards, or on rare occasions when they leave their wards (Hoogland
1981). Male dispersal and mortality is evidently a mechanism to
avoid inbreeding; females are reluctant or unable to mate with close
male relatives (Hoogland 1982). Female dispersal occurs more often

because of a lack of food and prime burrow space. If the life
requisite requirements for food and cover are satisfied, the
reproductive habitat requirements for this species are satisfied.
Interspersion and Populations
Population density is dependent on the availability of food
and opportunities for ward or colony expansion. Most plains
locations support at least 13 prairie dogs per hectare (Koford 1958),
with the minimum density for a sustained population at about 10 /ha
(Lewis et al. 1979). Other densities reported include 32 /ha in
Colorado (Tileston and Lechleitner 1966) and 22 /ha in South Dakota
(King 1955). Food availability is often described as a major control
on population (Koford 1958; Smith 1967), while at the same time the
availability of suitable territories may be the major limit to
prairie dog populations (Hoogland 1979b). Newly established and
expanding towns have a greater proportion of successful pregnancies,
have larger and faster growing litters, have higher adult
survivorship, and twice the population density than old colonies with
stable populations of black-tails (40 /ha vs. 18 /ha; Garrett et al.
Special Considerations
The black-tailed prairie dog was the most numerous and
widespread herbivore in the American western grasslands (Koford
1958). Up to the latter part of the 1800's, this species had an
estimated population of 5 billion (Costello 1970), and a single
colony in Texas spanned 64,750 square kilometers with over 400
million prairie dogs (Merriam 1902). The expeditions of Lewis and

Clark and of Zebulon Pike gave the first written accounts of the
species, and reported a name given the prairie dog by the native
Americans, 'wishtonwish' (apparently from a territorial call of the
prairie dogs; Coues 1895). Since the turn of the century, however,
they have been labeled as destructive and dangerous pests. Early
studies of the diet and habits of prairie dogs concluded that they
competed directly with livestock for forage, and advised that they be
eliminated from any 'usable' range (Merriam 1902; Bell 1921; Kelso
1939). Both the government and cattle ranchers followed that advice,
as towns were destroyed by the plowing, shooting and poisoning of
millions of prairie dogs in the first half of this century. The mass
extermination continued until the banning from public lands of
secondary poisons such as compound 1080 in 1972. Since 1972, it is
believed that prairie dog populations have grown on federal lands;
this has lead to considerable agitation by ranchers to resume
'management' of prairie dog towns on public lands (see USDA Forest
Service 1977). Yet prairie dog populations are probably only 2% or
less of their level a century ago (Coppock et al. 1983b).
The future treatment and proper management of the black-
tailed prairie dog should be tempered by discoveries relating to the
diet and ecology of the species. Competition between prairie dogs and
cattle for forage on rangeland, and the rodents' alleged destructive
influence on range values were (and are) the main reasons given for
eliminating prairie dogs. But when prairie dogs are poisoned out of
overgrazed cattle range, plant productivity on that range does not
inprove (Uresk 1985). On range where both cattle and black-tails
forage, cattle do not show any significant weight losses when

compared to cattle foraging on range without prairie dogs (O'Meilia
et al. 1982). Cattle in fact seem to prefer prairie dog towns for
grazing locations (Knowles 1986). The black-tailed prairie dog habit
of invading overgrazed grasslands and other areas of little
vegetative cover has implicated them as the cause of poor range
conditions. But the presence of prairie dogs is an accurate
indication that the range was already damaged and vegetation reduced
by cattle or other human disturbance (see Knowles 1986). Prairie dogs
unquestionably modify the development of grassland they occupy from
the area that surrounds them, but usually for gains in productivity
or diversity (Koford 1958; Bonham and Lerwick 1976; Coppock et al.
1983a; Agnew et al. 1986). Grass is the main component of prairie dog
diets in most areas, but they will consume vegetation which cattle
will not (Bond 1945; Koford 1958; Smith 1967; Fagerstone 1979).
Prairie dogs tend to maintain short grass communities over time
rather than cause devegetation and erosion (Koford 1958; Smith 1967;
Costello 1970). If the prairie dog were overwhelmingly destructive to
the short grass communities they maintain, it is not likely they
would have flourished for the million or so years in which they
shared the prairie with millions of bison and antelope (Clark 1968).
Prairie dog poisoning efforts by either the government or
private ranchers have been shown to be grossly uneconomical (Collins
et. al. 1984). In ecological terms, the costs of eliminating prairie
dog towns include the elimination of the prairie dog ecosystems.
Prairie dogs are a regulator and representative of their own
ecosystem, unique and set apart from the surrounding grassland
ecosystems by the alteration of soil and vegetation. Prairie dogs

towns are an important reservoir of diversity for plants, birds, and
many carnivores (Clark et al. 1982; Coppock et al. 1983a; Agnew et
al. 1986). Bison preferentially graze on black-tail colonies (Coppock
et al. 1983a). Rattlesnakes, desert cottontails (Sylvilagus
auduboni), and burrowing owls (Athene cunicularia) use the burrows on
prairie dog towns for cover and nesting (Butts and Lewis 1982; Clark
et al. 1982), while other birds such as mountain plovers (Charadrius
montanus) and McCown's Longspur (Calcarius mccownii) utilize prairie
dog town habitat for feeding and cover locations (Clark et al. 1982;
Knowles et al. 1982).
Poisoning of prairie dogs has adversely effected the
predators that feed upon them, including the endangered black-footed
ferret (Clark 1986). Badgers, foxes, coyotes, bobcats, weasels,
rattlesnakes, bald eagles, golden eagles, ferruginous hawks, and
Swainson's hawks are also potential indirect targets of poisoning
programs, both through the consumption of poisoned animals, and loss
of prey (Koford 1958; Clark 1968; Clark et al. 1982; pers. observ.).
The balance of land management or use, and conditions of
specific range sites call for logical decisions to be made based on
facts. Often, poisoning programs are started based on outdated
management policies and prejudicial evidence, or may be halted by
emotional pleas. Prairie dog range in most areas should be allowed to
expand, rather than continue to be plowed and poisoned into
recession. For complete recovery of some grasslands and selected
range, some sites may require the elimination of prairie dogs, with
simultaneous elimination of cattle grazing for years, possibly
decades. But poisoning should be a last resort rather than the

preferred method for prairie dog control. By encouraging predators,
reducing grazing when possible, and by promoting the growth of higher
and more dense cover surrounding prairie dog towns, black-tailed
prairie dog populations may be controlled when necessary in an
ecologically sound manner (Osborn and Allen 1949; Koford 1958;
Cincotta 1985).
Model Applicability: Geographic area
This model has. been developed for application throughout the
range of the black-tailed prairie dog (Figure 1).
Model Applicability: Season.
The model will produce HSI values for year-round habitat of
the species.
Model Applicability: Cover types.
The model was developed to evaluate black-tailed prairie dog
habitat in short-grass prairie and mixed-grass prairie cover types.
Minimum Habitat Area.
Minimum habitat area is defined as the minimum amount of
contiguous habitat that is required before an area will be occupied
by a species. A home range for a social animal such as the black-
tailed prairie dog is hard to delineate, since coterie boundaries
depend much on habitat quality, prairie dog density/social factors,
and the age of a colony. Coterie sizes averaged 0.26 ha + .12 in
South Dakota (Hoogland 1981), and Lewis et al. (1979) suggested that
a fenced area of 0.25 ha is large enough to encourage the
establishment of a small transplanted colony of 3-10 black-tails. Two

individuals at isolated sites rarely survive or establish a new
colony (Hoogland 1981; Knowles 1985). Therefore, in this model any
area smaller than 0.25 ha will be considered as unsuitable habitat.
Verification level
This model has been verified by author review and by data
collected in the field.
Model Description: Overview
All habitat requirements of black-tailed prairie dogs are met
by short-grass and mixed-grass prairie habitats. These two habitat
types may be considered as one for the purposes of habitat
evaluations, since the same variables in this model will apply to
both short- and mixed-grass habitat types.
The relationships between habitat variables and life
requisites of food and cover are presented in Fig. 5. It is important
to note that the percentage of herbaceous cover is assumed to
influence both food and cover values of the habitat.
The following sections identify the variables, define and
justify the suitability levels of each variable, and describe the
assumptions shaping the calculation of a HSI value for the black-
tailed prairie dog.
Food Component.
Black-tails consume herbaceous vegetation in varying amounts
according to the season and the specific composition of the
vegetation. Prairie dogs require at least 5% of their diet in forbs
for nutritional purposes. This percentage may be met by trace amounts
of forbs relative to other vegetation, but it is assumed that habitat

Habitat Variables
Life Requisite
Cover Types
Short-grass Prairie
Mixed-grass Prairie
Figure 5..Relationship of habitat variables, life requisites and cover types in the prairie dog HSI model.

with up to 10% relative cover of forbs is best. The relative
percentage of cover in forbs may approach 100% in areas of prairie
dog habitation, but it is assumed (based on previous studies) that
black-tailed prairie dogs will best fulfill their food requirements
in habitats with at least 20-40% relative cover in grasses and
sedges. The suitability index (SI) value for variable V-|, relative
percent cover of forbs, may be found by comparing the habitat
measurement to Figure 6.
The percentage of herbaceous cover (variable V2) should be at
least 15% for continuous habitation of an area by prairie dogs. The
shape of the SI graph (Figure 7) was determined by observing the
minimum cover of 25% reported on active prairie dog colonies
(Fagerstone et al. 1977), and the maximum cover of 91% (Uresk 1984).
The minimum cover is assumed to meet the year-round food requirements
of black-tailed prairie dogs, while the maximum cover is limited by
the visibility requirements for the species.
Cover Component.
Black-tailed prairie dogs avoid building burrows on slopes of
more than 10%, and do not build at all on slopes over 20%. Thus
variable V3 (in Figure 8) shows a linear decline in SI values from 1
to 0 as slope increases from 10 to 20%. Koford (1958) mentioned that
flat areas might be avoided by prairie dogs, but their occurrence in
such flat terrain indicates that his observations may have been
limited to areas where there is a history of flooding.
The average height of vegetative cover (variable V4; Figure
9) and the slope of an area have the narrowest range of optimum
habitat values of all the variables for black-tails. Contrary to


Figure 6. Suitability Index graph for variable 1, Percent
cover of forbs.

Figure 7. Suitability Index graph for variable 2, percent
herbaceous cover.

Figure 8. Suitability Index graph for variable 3, percent


Figure 9. Suitability Index graph for variable 4, height of

early descriptions of habitat preferences of prairie dogs, prairie
dogs will not likely occur in areas devoid of vegetation. There is a
height below which grasses and forbs will not grow and will expire,
ceasing to be a food source for prairie dogs. The minimum height for
viable vegetative cover is near 5cm for most plains locations. In
most prairie dog towns, the height of vegetative cover averages from
7cm and 13cm up to 64cm (see above). Greater heights of vegetation
might be tolerated on some locations if the overall cover is low;
this would allow for high visibility for prairie dogs.
The soil type in an area (variable V5; Figure 10), along with
the percentage of forbs, has perhaps the widest range of optimum
values of all the variables. Prairie dogs are known to avoid
excessively sandy areas for their burrows. They are most often found
in silty loam clay soils, but will use other substrates which will
support a burrow system.
Model Relationships: Suitability Index (SI)Graphs
For Habitat Variables
The SI graphs are presented in figures 6 to 10. All variables
are numeric, except for Soil Composition (V5 ; Figure 10) which
displays SI values based on a category.
Equation for HSI Determination.
The variables from life requisites for food and cover are
included in the equation below:
( Vt X V2 X V3 X V4 X V5)1/5 = HSI
Application of the Model
This model may be applied by making a number of simple

9*0 Y 0

silty, silty clay soils
silty clay loam
silty loam
clay loam
5 - loam
6 - sandy loam
7 - sandy
Figure 10. Suitability index graph for soil type or

observations on the vegetation and soil of an area. The variable
definitions and suggested field techniques are presented in Table 1.
It is important to emphasize that this model should only be
applied to the black-tailed prairie dog, and not to any of the other
4 species of Cynomys (White-tails; the endangered Utah prairie dog,
C. parvidens; Gunnison's prairie dog, CL_ qunnisoni; and the Mexican
prairie dog, C. mexicanus. White-tails, Utah, and Gunnison's prairie
dogs have loosely social towns of lower density and lesser impact on
vegetation, and are ecologically quite different from the black-
tails' dense, highly social colonies with short vegetation.
The black-tailed prairie dog model could be used in making
management decisions on prairie dogs, and the species which depend on
prairie dogs as a prey base. Possible uses of this model include the
evaluation of current colony sites for habitat suitability, the
evaluation of possibilities for colony expansion, and the suitability
of sites for transplantation or rehabitation by prairie dogs.
Suggested techniques for gathering information on habitat variables.
Variable (definition) Cover
Vi Relative Cover of Forbs SgP,
v2 Herbaceous Cover SgP,
V3 Slope (%) SgP,
v4 Height of Vegetation cn
V5 Soil Texture SgP,
type Suqqested Technique
MxgP Line Intercept; Point Intercept methods.
MxgP As above for Forb cover.
MxgP Clinometer, Topographic Maps
MxgP Graduated Rod (along transects)
MxgP Soil Texture by Feel; Deduction from Soil Maps

Model Testing Goals and Assumptions
The test of the HSI model for black-tailed prairie dogs had
the immediate goals of collecting information on the habitat
variables spelled out in the model for one hectare plots on prairie
dog towns, and the estimation of the density of prairie dogs on those
same plots. It is assumed that there is a relationship between the
density of prairie dogs on a certain site and the carrying capacity
of that site. The carrying capacity of a site theoretically bears a
linear relationship to the HSI (the model output). Therefore, if
there is a correlation of the density of prairie dogs on a site and
the HSI based on the habitat variable values of a site, the model
should gain some amount of validity.
Plot Locations
A map of prairie dog colonies was generated by the
manipulation of black and white aerial photographs taken in October
1986. A transparent rnylar sheet was placed over the 1" : 600' scale
photographs and areas were outlined which showed obvious burrowing by
prairie dogs. The resulting map was then ground truthed along the
major roads on RMA, and by accounts of their distribution from
subsequent field trips by personnel frequenting the Arsenal. Figure 4

is a reduced scale product of these efforts.
One hectare (100m by 100m) plot locations were determined by
random choice of coordinates from a grid superimposed on the prairie
dog colony map. The plot locations from the grid had only the
following restrictions:
1) that they fall within a prairie dog colony, and
2) that they not duplicate a previously chosen set of
An earlier provision in the selection criteria for the plots provided
for a minimum number of plots in certain prairie dog towns, but the
plots eventually chosen fulfilled these requirements without
deviation from the randomly generated coordinates. No plots were
counted in areas of possible toxic contamination. Twenty plots were
eventually chosen off the grid map and located on RMA, while one site
was deliberately staked in an area of high slope on Rattlesnake Hill
(Section 35, plot number 21). A map of prairie dog plot locations is
presented in Figure 11. Each plot was flagged with 1m tall stakes at
each corner, with small 40cm tall stakes at various intervals between
the stakes, marking the borders of the plots.
Visual Count Population Estimates
Visual counting techniques to estimate prairie dog
populations were formulated along the lines of similar studies
completed by Fagerstone (1984) on Richardson's ground squirrels
(Spermophilus richardsonii elegans), and by Fagerstone and Biggins
(1986) on white-tailed prairie dogs (Cynomys leucurus). Visual
population estimates in the studies above were shown to correlate
well with mark-recapture techniques completed in the same physical

Figure 11. Map of plot locations on Rocky Mountain Arsenal (ESE

space. Both of the species above are similar to black-tailed prairie
dogs in their strictly diurnal activity, and their tendency to live
in social colonies. Each of these rodents also show a definite
bimodal activity pattern, with above ground activity generally
limited to a morning and late afternoon or evening period.
Prairie dog colonies on RMA were observed for several days
before commencing the study on plots. From these observations, and
several references (including King 1955; Fagerstone and Biggins
1986), it was determined that the morning activity period would yield
the largest visual count of prairie dogs, and thus the most accurate
visual estimates of population. Occasional counts outside the morning
activity pattern (but not included here) were taken to justify this
Prairie dogs were counted on each plot for three consecutive
mornings for at least 75 minutes. The time period in which these
counts were restricted was from 0700 to 1010 (on one plot, one count
proceeded to 1300). Upon arrival at the plot location, the observer
would assume a counting location from which he or she could observe
the entire hectare, and would then wait a minimum of 15 minutes
before the first count. This procedure allowed the prairie dogs to
resume a normal routine after being disturbed by the initial presence
of the observer. The counting location was either an on-ground site,
on top of a step ladder, or on top of a automobile. Counting of
prairie dogs then proceeded with 10x25 binoculars from one side of a
plot to the other without backtracking for a maximum of five minutes.
Observers then waited a minimum of 15 minutes to the next count,
until 4 counts were recorded for each morning. The number of

juveniles and adults/yearlings were recorded separately in June, but
were recorded and counted together in a lump sum in July, due to the
similarity of juveniles to yearlings by early July. Males are
slightly larger than females, but are always similarly colored in
pelts, so that sex determination without handling is nearly
inpossible. The maximum number of juveniles and adults counted in any
one count over the three days (a total of 12 counts) was the
population estimate for that plot. The mean population (per hectare)
was calculated for the above estimates with a determination of
confidence limits on the population, as described in Zar (1974).
Vegetation, Slope, and Soil Characteristics
Vegetation transects within the prairie dog plots were
determined by randomly choosing a compass azimuth with parameters
which would keep the two parallel 50m transects form running outside
the plots. The transects were completed with 30 paces separating each
line. At each meter on the transect tape, the plant species, litter,
or bare ground was recorded. In addition, every 10m starting at 5m,
the height of the tallest plant within 0.5m of each side of the
transect tape was recorded. The species' relative cover, the mean
height of vegetation, and herbaceous cover was then calculated for
each plot, and the data from all plots summarized.
The maximum slope on each plot was determined with the
clinometer on a Brunton pocket transect. Soil types were determined
for plots with Soil Conservation Service maps for Adams County in
comparison with a map of the plot locations (Figure 11). The
specific soil types were then converted to the designations given by
Hays et al. (1981) for the U.S. Fish and Wildlife Service, in order

to conform to the HSI model.
Comparison of HSI and Prairie Dog Populations
After compilation of the vegetation data with slope and soil
characteristics, the HSI for each plot location was calculated using
the computer program Micro-HSI (Hays and Heasley 1985). The Si's for
each of the five variables are determined by the program, and the
overall HSI calculated based on the data entered. The maximum prairie
dog count on plots and the HSI's calculated for those plots were then
processed through the computer program SYSTAT (1987) for linear
regression/correlation analysis. This is a process similar to the
validation scheme for the pronghorn (Antilocapra americana) by Cook
and Irwin (1985), where the overall HSI and variable Si's are
regressed against the population estimates for an area. A regression
analysis of variable Si's (independent variable) onto populations
(dependent variable) was performed utilizing the microcomputer
program SYSTAT (1987). Any significant accounting for variability in
populations due to Si's was then reported.

Population Estimates
Prairie dog counts proceeded from June 4 to July 18 1987.
Maximum counts for each plot are presented with the dates of
observation in Table 2. The population mean (per hectare) and
confidence limits for the black-tailed prairie dog population on RMA
are found in Table 3.
Habitat Variables
The relative cover of forbs, herbaceous cover, slope, soil type,
and mean height of vegetation (in cm) for each plot are presented
together in Table 4 with the prairie dog population estimates, and
their calculated Si's. Vegetation transect data summaries over all
plots, with species relative cover, are presented in Table 5. Also
included in Table 5 are species observed on plots, but which were not
counted on the transects.
HSI Model Output Vs. Population Estimates
The HSI model output correlated significantly to actual prairie
dog densities (r = 0.45, p < 0.04). HSI values for each plot are
shown graphed against their corresponding population estimate for the

Population estimates and dates of observation on 21 plots.
1 28 6/4 6/6/87
2 10 6/4 6/6/87
3 33 6/4 6/6/87
4 10 6/10 6/12/87
5 10 6/10 6/12/87
6 35 6/10 6/12/87
7 18 6/10 6/12/87
8 7 6/10 6/12/87
9 37 6/16 6/18/87
10 10 6/16 6/18/87
11 14 6/16 6/18/87.
12 26 6/16 6/18/87
13 6 7/16 7/18/87
14 40 7/16 7/18/87
15 9 7/13 7/15/87
16 18 7/13 7/15/87
17 28 7/16 7/18/87
18 12 7/13 7/15/87
19 20 7/13 7/15/87
20 27 7/16 7/18/87
21 0 7/13 7/18/87
At 95% Confidence:
At 90% Confidence:
Means and Confidence Limits.
19.9 prairie dogs per hectare
s = 10.98
s2 = 120.56
SE = 2.455
19.9 +5.1 (+ 25%)
19.9 + 4.2 (+ 20%)

HSI model variable raw values and SI values for 21 plots on Rocky Mountain Arsenal.
Also included are population estimates for each plot.
Plot # Vi % Forbs SI v2 % Cover SI . V3 s Slope SI V4 Height (cm) SI v5 Soil Type (FWS) SI POP
1 2.4 0.54 86 0.51 3 1.0 38.6 0.62 Sandy Loam 0.6 28
2 1.4 0.48 76 1.0 16 0.4 10.8 1 .0 Sandy Loam 0.6 10
3 60.5 1.0 76 1 .0 3 1.0 14.0 1.0 Sandy Loam 0.6 33
4 10.3 1.0 78 1.0 5 1.0 30.5 0.79 Sandy Loam 0.6 10
5 100.0 0.1 58 1.0 3 1.0 11.9 1.0 Sandy Loam 0.6 10
6 0.0 0.4 23 0.8 0 1.0 14.2 1.0 Silty Loam 1.0 35
7 2.0 0.52 59 1.0 3 1.0 31.1 0.77 Sandy Loam 0.6 18
8 17.3 1.0 60 1.0 1 1.0 50.4 0.38 Loam 0.8 7
9 96.0 0.28 53 1 .0 3 1.0 13.1 1.0 Loam 0.8 37
10 7.5 0.85 40 1.0 7 1.0 19.4 1.0. Loam 0.8 10
11 31.5 1 .0 73 1.0 5 1.0 38.3 0,63 Sandy Loam 0.6 14

TABLE 4 (Continued)
HSI model variable raw values and SI values for 21 plots on Rocky Mountain Arsenal.
Also included are population estimates for each plot.
Plot # o\o SI v2 % Cover SI v3 % Slope SI £ ^ (D < Q 4 SI v5 Soil Type (FWS) SI POP
12 31.4 1.0 70 1.0 6 1.0 32.1 0.75 Sandy Loam 0.6 26
13 7.7 0.86 65 1.0 2 1.0 44.1 0.51 Sandy Loam 0.6 6
14 82.6 0.88 63 1.0 2 1.0 18.0 1.0 Sandy Loam 0.6 40
15 100.0 0.1 48 1.0 5 1.0 12.2 1 .0 Loam 0.8 9.
16 100.0 0.1 53 1.0 1 1.0 18.8 1.0 Sandy Loam. 0.6 18
17 17.0 1.0 47 1.0 9 1.0 17.5 1.0 loam 0.8 28
18 83.8 0.83 37 1.0 1 1.0 14.6 1.0 Loam 0.8 12
19 33.3 1.0 45 1.0 2 1.0 27.9 0.84 Loam 0.8 20
20 47.7 1.0 65 1.0 2 1.0 18.4 1.0 Sandy Loam 0.6 27
21 16.1 T.O 55 1.0 20 0.0 27.6 0.84 Gravel/Loam 00 o 0

Plant species cover over all plots, including total cover over RMA.
Species 1 2 Re] 3 .ative p 4 ercent 5 cover c 6 3f Plot 7 (Hits/1 8 00) 9 10 11
Grasses and Sedges: Aaropvron cristatum 48(11)
Aoropyron smithii 22(5) 92(3)
Aristada fendleriana 4.3(1 )
Bouteloua qracilis 99(75)
Bromus tectorum 94(81; 57(43) 85(66) 98(58) 68(40) 3.7(2) 68(50)
Branus iaponicus 26(6)
Buchloe dactyloides
Sporobulus cryptandrus 5.1(4) 15(9)
Stipa comata
Unknown Poaceae (Gramineae) 3.5(3:

TABLE 5 (continued)
Plant species cover over all plots, including total cover over RMA.
Species 12 R 13 elative 14 percer 15 it cover 16 of Plo 17 : (Hits 18 /100) 19 20 21 Relative Cover (All Plots)
Grasses and Sedges: Aqropyron cristatum 16(6) 1.3(17)
Agropyron smithii 52(34) 6 (76)
Aristada fendleriana 7.2(5) 47(22) 3.6(2) 2.4(30)
Bouteloua qracilis 28(13) 9(5) 7 (93)
Bromus tectorum 61 (43) 85(55) 17(11 ) 8.5(4) 64(29) 66(37) 41(519)
Broraus japonicus 0.4(6)
Euchloe dactyloides 3.6(2) 0.1(2)
Sporobulus cryptandrus 3.1(2) 1.2(15)
Stipa comata 4.6(3) 0.2(3)
Unknown Poaceae (Gramineae! 2.2(1 ) 0.3(4)

TABLE 5 (continued)
Plant species cover over all plots, including total cover over RMA.
Species 1 2 I 3 Relative 4 percer 5 it cove] 6 : of Pic 7 Dt (Hits 8 /100) 9 10 11
Forbs and Shrubs: Ambrosia spp. 1.2(1)
Artemesia ludoviciana 2.6(2)
Carduus nutans 5(3) 2.6(2)
Chenopodium spp. 5.2(3)
Convolvulus arvensis 57(43) 65(38) 1.7(1) 94(50) 19(14)
Kochia iranica 2.6(2) 28(16) 5(3) 2( 1 )
Lvgodesmia iuncea
Meliotus officinalis 1.3(1)
Mentzelia nuda 1.3(1)
Opuntia polycantha
Physalis heterophylla 1.4(1) 1.3(1)
Phvsalis virginiana 1.3(1)

TABLE 5 (continued)
Plant species cover over all plots, including total cover over RMA.
Species 12 13 Relati 14 ve perce 15 it cover ~ 16 of Plot 17 (Hits/ 18 00) 19 20 21 Relative Cover (All Plots!
Ambrosia spp. >0.1(1)
Artemesia ludoviciana 2.1(1) 2.2(1 ) 16(9) 0.8( 11)
Carduus nutans ' 0.4(5)
Chenopodium spp. 0.2(3)
Convolvulus arvensis 11 (8) 76(48) 92(44) 65(38) 43(16) 22(10) 24.5(310)
Kochia iranica 3.2(2) 8.3(4) 28(16) 14(5) 3.9(49)
Lygodesmia iuncea 2.7(1 ) >0.1(1)
Meliotus officinalis - >0.1(1)
Mentzelia nuda >0.1(1)
Opuntia polycantha 2.1(1) 1.8(1) 0.1(2)
Physalis heterophylla 1.4(1) ) 0.2(3)
Physalis virginiana >0.1(1)

TABLE 5 (continued)
Plant species cover over all plots, including total cover over RMA.
Species 1 2 I 3 Relative 4 percer 5 it cove 6 r of Pic 7 3t (Hits/ 8 o O 10 11
Forbs and Shrubs (continued): Sisymbrium altissimum 1.7(1) 1.3(1)
Solanum triflorum 1.7(1)
Sphaeralcea coccinea 1.2(1) 1.3(1 ) 8(3) 5.5(4)
Verbascum thapsus 6.7(4)
Verbena bract eata 1.3(1 )
Yucca qlauca 3.8(3)
Compositae (Asteraceae) Cruciferae 48(31)

TABLE 5 (continued)
Plant species cover over all plots, including total cover over RMA.
Species 12 13 Relati 14 ve perc 15 :ent co\ 16 ?er of P 17 lot (Hits 18 5/1 00) 19 20 21 Relative Cover (All Plots)
Farbs and Shrubs (continued): Sisymbrium altissimum 1.4(1) 0.2(3)
Solanum triflorum 2.7(1) 0.1(2)
Sphaeralcea coccinea 8.6(6) 3.2(2) 13(6) 5.4(2) 9(4) 2.3(29)
Verbascum thapsus 0.3(4)
Verbena bracteata >0.1(1 )
Yucca qlauca 8.6(6) - 0.7(9)
Compositae (Asteraceae) Cruciferae 1.4(1) 7.7(5) 2.8(36)
34(18) 16(6) 2.1(24)

21 plots on RMA in Figure 12, and the tabular form of this data is
available in Table 6. The regression line approximation is given for
general information; I do not assume that there is a dependent
relationship between HSI and population densities.
The regression of SI's onto populations on the same plots
yielded no significant accountability for variation in population
size for any of the five variables. This aspect of the investigation
will be discussed in detail with the modification of the HSI model.

Figure 12. Habitat Suitability Index versus Population for 21 plots
on Rocky Mountain Arsenal. Included is the line
approximating the regression relationship
( y = (24.50 HSI) + 0.50 ; r = 0.45, p =0.04).

Plot nuniber with the calculated HSI value and population estimate.
1 28 0.635
2 10 0.650
3 33 0.903
4 10 0.860
.5 10 0.570
6 35 0.796
7 18 0.752
8 7 0.787
9 37 0.741
10 10 0.926
11 14 0.822
12 26 0.853
13 6 0.765
14 40 0.881
15 9 0.603
16 18 0.570
17 28 0.956
18 12 0.921
19 20 0.923
20 27 0.903
21 0 0.0
MEAN HSI = 0.749

Population Estimates by Visual Counts
Prairie Dog Density
Most prairie dog town locations will support at least 13
black-tailed prairie dogs per hectare (Koford 1958), while the
minimum density for a sustained population is about 10 per hectare
(Lewis et al. 1979). Other densities reported in the literature
include 32 prairie dogs per hectare in northern Colorado (Tileston
and Lechleitner 1966), and 22 per hectare in South Dakota (King
1955). Thus the 20 prairie dogs per hectare reported here is on the
lower end of an expected range for the species.
RMA Habitat Quality for Prairie Dogs
Prairie dog population density is dependent on the
availability of food and opportunities for ward or colony expansion.
Nutrition and food supply on the short grass prairie may limit the
population density of prairie dogs (Koford 1958; Smith 1967). The
predominance of cheatgrass and morning glory (Convolvulus arvensis)
on many of the RMA plots (see Table 5). limit the nutritional and
food supply options open to the prairie dogs on those sites. The
limitation on diversity of vegetation on these plots could be a
factor which reduces the carrying capacity of the RMA habitat.

It is also likely that a related factor, the availability
of suitable territories, may be the limiting resource on carrying
capacity for prairie dog populations (Hoogland 1979; 1981; 1985).
Newly established and expanding towns have a greater proportion of
successful pregnancies, larger and faster growing litters, higher
adult survivorship, and twice the population density of old colonies
(more than 5 years old) with stable populations of black-tails (40
per hectare vs. 18 per hectare; Garrett et al. 1982). Although they
have been reduced in the past (over 4 years ago) by periodic
poisoning programs, the prairie dogs and their colonies at RMA seem
to be well established and stable entities. The largest town on RMA
dominates over 1800 acres, and has extended itself up to formidable
vegetation and topographic boundaries; these colonies have limited
room for expansion. The size, extent, and stability of the colonies
at RMA may have led to ray finding a relatively low mean density of
prairie dogs at RMA. ,
Precipitation in the summer months preceding the breeding
season (in late February to March) has been shown to be directly
correlated to litter size in black-tailed prairie dogs (Knowles
1987). Precipitation is a factor which could directly effect the
vegetation, and thus the habitat quality of the RMA plots.
Precipitation then has direct effects on spring juvenile counts, and
indirect effects on succeeding yearly population levels. Knowles
(1987) estimated reductions of 1 to 2 prairie dogs per litter
depending on the severity of summer drought. Since the summer
precipitation in 1986 (3.72 inches from June to September) was below
normal (6.27 inches) (see Appendix B), this factor probably had some

small effect on this year's population estimates.
Modification of Variables and Interpretation of HSI
RMA Plot Data and Variable Modification
The original model for black-tails yielded a significant
correlation. But none of the five model variables' SI values based on
the RMA data correlated significantly to population levels,
suggesting that no one variable was,a dominant factor. The SI
variables considered individually are not expected to predict overall
carrying capacity or address the interaction among variables. Only
when combined to produce the composite HSI value is there a
significant relationship between habitat quality and carrying
There was very little variability in the soil, cover, and
slope Si's over RMA plots. The slope variable (V3) had only two plots
which scored below 1.0 in SI; as was the case with the cover variable
(see Table 4). Twelve of the 21 plots had a sandy loam soil type,
also limiting the variability in the SI values. Thus the lack of
variation in the Si's may be insufficient to show correlation with
single factors, while the combination of these values in the HSI
shows a valid relationship to population densities of prairie dogs.
Some adjustments of the HSI model variables were possible
with the consideration of the data collected on RMA. As predicted,
the populations of black-tailed prairie dogs varied along many
different percentages of herbaceous and forb covers. But the
populations for very low and very high forb cover were outside those
predicted by the SI. These results indicate that the variable for

forb cover (V-j) be examined more closely, both by further data
analysis, and eventual expert review of this HSI model. The
populations across the soil types found on RMA varied greatly, with
few conclusions possible due to the paucity of variability for soil
types on RMA plots. This variable should remain unchanged until more
data are available for prairie dog town soil types. Slope seemed to
effect the population density of black-tailed prairie dogs as
predicted by the Si's as did height of vegetation. Although not
significant, the SI for height of vegetation has a relatively strong
correlation to population sizes (r = 0.35, p = 0.12 for the original
model). And a careful comparison of the SI for height to populations
for those heights on RMA showed that the lower population densities
were at too high a SI value for this variable. I modified the SI
graph as shown in Figure 13. The SI is still at 1.0 up to 20 cm in
height, but the SI descends from this point to 0.1 at 40cm, instead
of at 64 cm.
The modification above yielded a significant correlation
between the new HSI's and populations, but at a higher regression
coefficient and level of significance (r = 0.536, p = 0.01; see
Figure 14 and Table 7). The modified model seems to confirm my
suspicions, based on the literature review, that height of vegetation
has the strongest effect on the habitat suitability of an area.
Problems and Limitations of the Test of this HSI Model
The obvious problem with the field test of this model was the
lack of variable extremes for some of the data, most notably the
cover, slope, and soil variables. It is more difficult to make a
judgement on the validity of individual variables and their

Figure 13. Revised SI graph for height of vegetation (variable V4).

Figure 14. Modified HSI for 21 plots on RMA, and corresponding
populations on those plots. Also included is the line
approximating the regression relationship
( y = (28.17 HSI) 0.88 ; r = 0.54, p = .01 ).

Population estimates and modified HSI values for 21 plots on RMA.
1 28 0.486
2 10 0.650
3 33 0.903
4 10 0.794
5 10 0.570
6 35 0.796
7 18 0.690
8 7 0.568
9 37 0.741
10 10 0.926
11 14 0.638
12 26 0.771
13 6 0.541
14 40 0.881
15 9 0.603
16 18 0.570
17 28 0.956
18 12 0.921
19 20 0.876
20 27 0.903
21 0 0.0
MEAN HSI = 0.706

corresponding SI values based on the RMA plot data alone.
Unfortunately, time pressures and the initial thrust of this study
limited the number of plots which could be sampled. But an increase
in samples may not be in order on this site. The occurrence of silty
and clay soils (at least in prairie dog towns) and steep slopes are
limited on RMA. There are also aspects of prairie dog ecology
influencing their distribution and use of habitat which depend on the
aggregate of a number of variables (as represented by the HSI) to a
threshold of habitat quality.
Colonial Species, Carrying Capacity, and HSI
If we examine the graphs of the original and modified HSI
values versus population (Figures 12 and 14), there is a paucity of
HSI values from 0 (excepting Plot 21) to about 0.5. As I argued
above, this may be due to the lack of sampling in the extreme ranges
of variables such as cover. But since I sampled randomly, and only
within the boundaries of prairie dog towns, the absence of HSI values
in this low range may be due to the colonial nature of black-tailed
prairie dogs, and the need for a threshold of habitat value for
prairie dogs to inhabit an area. As previously stated, prairie dogs
will not continue to survive in isolation or thrive in small groups
(less than 10 per hectare). Thus, an area's vegetation, soil, and
slope characteristics (its habitat value) must be sufficient to
support a minimum of about two coteries or 15 prairie dogs per
hectare, not just one or a few prairie dogs. It then follows
logically that there should be a minimum or threshold value for the
HSI on any site to allow successful colonization or continuation of
prairie dogs in a given area. The data from RMA suggest that this is

indeed the relationship between HSI and populations of prairie dogs.
Certainly, the line describing this relationship in Figures 12 and 14
lacks validity under scrutiny; the relationship between HSI and
population density would appear to be either linear from a threshold
HSI value, or a non linear function from the origin (Figure 15).
Although the data from the RMA plots would be inadequate to test
these hypotheses directly, they would seem to be a logical
conclusions based on my available evidence.
A threshold or minimum HSI may hold for other species as well
as in prairie dogs. Other colonial species, or species which depend
on a minimum density of individuals for reproduction also would
require a minimum value for their habitats for their further
survival in an area. The consideration of colonial species'
requirements appears to be an aspect of HSI modeling which requires
further investigation.
Suggestions for Study and Further Testing of the HSI Model
Further testing of this model should include directed
sampling of sites either near or in prairie dog towns which had, for
example, from 0 to 15% or 80 to 100% herbaceous cover (similar to the
way plot 21 was chosen here). A site with different and more varied
soils and slopes (especially from 10 to 20%), would increase the
breadth of our knowledge concerning these variables and their
relationship to habitat suitability for black-tailed prairie dogs. In
addition, a study which would adequately sample across marginal
habitat values (to yield low HSI's) could be used to test the
hypothesis of a threshold or non-linear relationship between HSI and

Figure 15. Modified HSI, population estimates, and two hypothetical
curves describing their relationship.

density of prairie dogs.
Various methods other than the one used here could be used to
study this HSI model, and other similar models. In particular, remote
sensing of habitat variables and some kind of indexing for population
levels would appear to be of great use for studying the relationship
of HSI and populations on a regional level (see Dalsted et al. 1981).
Application of the HSI Model for Black-tailed Prairie Dogs
The possible applications of this model include the analysis
of uncolonized habitat for colonization by prairie dogs, the
prediction of the success of colonization in previously uncolonized
habitat, and the analysis of present colonies for habitat
suitability. But with an organism which substantially modifies both
the height and composition of vegetation where it lives, how can one
evaluate present colonies, or predict where prairie dogs might invade
based on the height and composition of vegetation in the habitat?
While there is no unopposed answer to this question, what we know of
the past and present behavior of the species suggest an outline of a
response. It seems quite dear that prairie dogs will not begin
colonize new territories in areas with high vegetation. Their common
protection from predators can only be active when there is high
visibility; and surely their frequent and varied calls of alarm and
'all clear' have adaptive value. If we assume that the migration of
bison or wildfires through the old western short-grass prairie left
suitable habitat for prairie dogs, and that prairie dogs depended on
these mechanisms for theirexpansion of colonies, it is not illogical
to assume that a similar mechanism for expansion of colonies is still

depended on, after a million years of adaptive behavior between these
species. It is quite possible, and in fact likely, that black-tailed
prairie dogs await the opportunity of expansion through the modern
mechanisms of overgrazing, plowing or brush fires. The disturbed
areas are then maintained as long as the climactic and topoedaphic
environment holds, and prairie dogs can maintain the conditions
outlined in this model for ideal habitat conditions. Based on the
above argument, this model can both predict the suitability of non-
colonized sites, and presently occupied sites.
An immediate application for this model could be for the
direction of alterations of vegetation on RMA for black-tailed
prairie dog habitat enhancement. Controlled burns and/or plowing on
sites dominated by cheatgrass, morning glory, or thistle, and
subsequent reseeding with native grasses and forbs would greatly
enhance many of the present prairie dog towns on RMA. This model has
proven to be adequate for the prediction of prairie dog density from
habitat variables, and should be a useful tool in habitat assessment
for perhaps the most important high plains herbivore, the black-
tailed prairie dog.

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A. Plant and animal species list for
Rocky Mountain Arsenal ......................... 77
B. Weather Data for Stapleton International Airport
weather station just south of RMA................ 92

Appendix A. Plant and animal species list for Rocky Mountain Arsenal
(Possible and historical species included)
Family Genus Species Common Name Status* Source Document**
Verbenaceae Abronia fragrans Prairie snowball 5
Aceraceae Acer negurtdo Boxelder 5
Aceraceae Acer saccharinum Silver-leaf naple 5
Granineae Agropyron cristatun Crested wheatgrass 5
Granineae Agropyron desertorurn Crested wheatgrass 5
Granineae Agropyron elongatuo Tall wheatgrass 5
Granineae Agropyron intermedium Wheatgrass, interned. 5
Graaineae Agropyron repens Quack grass 5
Granineae Agropyron smithii Western wheatgrass 5
Granineae Agropyron trachycaulum Slender wheatgrass 5
Anaranthaceae Amaranthus albus Tumble pigweed 5
Amaranthaceae Asaranthus arenicola Rope-spike pigweed 5
Anaranthaceae Amaranthus retroflexus Rough pigweed 5
Conpositae Ambrosia psilostachya Western ragweed 5
Coapositae Antennaria rosea Pussy-toes 5
Apocynaceae Apocynum sibiricum Siberian dogbane 5
Papaveraceae Argemone polyanthemos Prickly poppy 5
Granineae Aristida longiseta Red three-awn 5
Compositae Artemisia filifolia Sand sagebrush 5
Conpositae Artemisia frigida Fringed sagebrush S
Conpositae Artemisia ludoviciana Prairie sage 5
Ascleoiadaceae Asclepias incarnata Marsh milkweed C w
Asclepiadaceae Asclepias speciosa Showy milkweed 5
Asparagaceae Asparagus officinalis Asparagus 5
Conpositae Aster commutatus White prairie aster 5
Leguninosae Astragalus lotiflorus Lotus milk-vetch C Cheriopodiaceae Bassia hyssopifolia Bassia 5
Umbel1 iferae Berula erecta Water parsnip 5
Granineae Bouteloua curtipendula Side-oats grama 5
Granineae Bouteloua gracilis Blue grama 5
Granineae Broaus inernis Smooth brome 5
Grasineae Bromus japonicus Japanese brome 5
Granineae Bronus tectorum Cheatgrass 5
Granineae Buchloe dactyloides Buffalo grass 5
Granineae Calaraovilfa longifolia Prairie sand reed 5
Cruciferae Cardaria draba Hoary cress 5
Conpositae Carduus nutans Musk thistle 5
Cyperaceae Carex spp. Sedge 5
Leguninosae Catalpa speciosa Catalpa 5
Ulnaceae Celt is reticulata Hackberry 5
Cheriopodiaceae Ceratoides lanata Winterfat 5
Euphorbiaceae Chamaesyce glyptosperma Corrugate-seed spurge 5
Euphorbiaceae Chamaesyce aissurica Narrow-leave spurge 5
Euphorbiaceae Chamaesyce serpyllifolia Thyme-leaved spurge 5
Chenopodiaceae Chenopodium albun Pigweed 5
Chenopodiaceae Chenopodius leptophylun Narrow-leaf gooseft 5

Appendix A (continued).
Fanily Genus Species Common Name Status* S'( D(
Conpositae Chrysothamnus nauseosus Rabbitbrush 5
Conpositae Cirsiura arvense Canadian thistle 5
Capparidaceae Cleone serrulata Beeweed 5
Convolvulaceae Convolvulus arvensis Horning glory 5
Conpositae Conyza canadensis Horseweed 5
Cactaceae Coryphantha vivipara Ball cactus 5
Euphorbiaceae Croton texensis Croton 5
Boraginaceae Cryptantha fendleri Fendlers cryptantha 5
Cucurbitaceae Cucurbita foetidissina Mild gourd 5
Umbelliferae Cymopterus montanus Biscuit root 5
Leguainosae Dalea aurea Prairie clover 5
Cruciferae Descurainia sophia Tansy mustard 5
6ramineae Distichlis stricta Alkali saltgrass S
Conpositae Dyssodia papposa Fetid marigold 5
Cactaceae Echinocereus viridiflorus Hen and chickens 5
Eleagnaceae Eleagnus angustifolia Russian olive 5
Granineae Elywus canadensis Canadian wild rye 5
Oriagraceae Epilobiun adenocaulon Willow-herb 5
Granineae Eragrostis cilianensis Stinkgrass 5
Polygonaceae Eriogonun annuun Tall eriogonun 5
Coupositae Erigeron divergens Spreading fleabane S
Polygonaceae Eriogonun effusun Bushy eriogonun 5
Coupositae Erigeron punilus Low daisy 5
Geraniaceae Erodiun cicutariun Filaree 5
Cruciferae Erysimum asperuu Western wallflower 5
Euphorbiaceae Euphorbia narginata Sriow-on-t he-nount a i n 5
Conpositae Euthamia graninifolia Bushy goldenrod 5
Convolvulaceae Evolvulus nuttallianus Bindweed 5
Oleaceae Fraxinus pennsylvanica Green ash 5
Onagraceae Gaura coccinea Scarlet gaura 5
Onagraceae Gaura parviflora Tall gaura 5
Leguninosae Gleditsia triacanthos Honey locust 5
Conpositae Gnaphaliun chilense Yellow cudweed 5
Conpositae Grindelia squarrosa Gunweed 5
Conpositae Gutierrezia sarothrae Snakeweed 5
Caryophyllaceae Gypsophila paniculata Babys breath 5
Conpositae Haplopappus spinulosus Spiny goldenweed 5
Conpositae Helianthus annuus Common sunflower 5
Conpositae Helianthus petiolaris Prairie sunflower 5
Conpositae Heterotheca villosa Hairy golden aster 5
Granineae Hordeuu jubatun Foxtail barley 5
Granineae Hordeuu pusilluto Little Barley 5
Polenoniaceae Ipomopsis laxiflora Loose-flowered cilia 5
Convolvulaceae Iponoea leptophylla Bush morning glory 5
Conpositae Iva xanthifolia Tall marsh elder 5
Juncaceae Juncus arcticus Creeping rush 5
Pinaceae Juniperus virginiana Rocky Mt. juniper 5
Chenopodiaceae Kochia scoparia Kochia 5
Conpositae Kuhnia eupatorioides False boneset 5

Appendix A (continued).
Family Genus Species Common Name Status* Source Document**
Compositae Lactuca serriola Prickly lettuce 5
Boraginaceae Lappula redowskii Stickweed 5
Cruciferae Lepidiun perfoliatum Peppergrass 5
Polemoniaceae Leptodactylon pungens Prickly gilia 5
Liliaceae Leucocrinun montanum Sand lily 5
Compositae Liatris punctata Blazing star 5
Boraginaceae Lithospermun irtcisun Narrow-leaf puccoon 5
Leguminosae Lupinus argenteus Lupine 5
Coapositae Lygodesnia juncea Rush skeleton weed 5
Compositae Machaeranthera linearis Aster 5
Coapositae Machaeranthera spp Aster 5
Leguminosae Medicago sativa Alfalfa 5
Leguminosae Melilotus alba White sweet clover 5
Leguminosae Melilotus officinalis Yellow sweet clover 5
Labiatae Mentha arvensis Field mint 5
Loasaeeae Mentzelia nuda Evening star 5
Gramineae Muhlenbergia asperifolia Alkali muhly 5
Granineae Muhlenbergia torreyi Ring muhly 5
Granineae Monroa squarrosa False buffalo grass 5
Cruciferae Nasturtium officinale Nasturtium 5
Coapositae Mothocalais cuspidata False dandelion S
Onagraceae Oenothera albicaulis Evening primrose 5
Onagraceae Oenothera caespitosa Stemless primrose 5
Onagraceae Oenothera coronopifolia Cut-leaf primrose 5
Onagraceae Oenothera nuttallii Nuttall's primrose 5
Onagraceae Oenothera strigosa Evening primrose 5
Cactaceae Opuntia compressa Prickly pear S
Cactaceae Opuntia polycantha Starvation cactus 5
Leguminosae Oxytropis lambertii Colorado loco-weed 5
Nyctaginaceae Oxybaphus nyctagineus Umbrella wort 5
Granineae Panicun capillare Witch grass 5
Vitaceae Parthenocissus inserta Virginia creeper 5
Scrophulariaceae Penstemon albidus White penstemon 5
Scrophulariaceae Penstemon angustifolius Narrow-1 f penstemon 5
Polygonaceae Persicaria pennsylvanica Smartweed C >J
Solanaceae Physalis virginiana Ground cherry 5
Pinaceae Picea pungens Colorado blue spruce 5
Pinaceae Pinus ponderosa Ponderosa pine 5
Pinaceae Pinus sylvestris Scotch pine 5
Plantaginaceae Plantago purshii Wooly plantain 5
Granineae Poa agassizensis Mountain bluegrass 5
Polygonaceae Polygonum aviculare Devil's shoestring 5
Capparidaceae Polanisia dodecandra Clammy weed S
Granineae Polypogon monspeliensis Rabbit foot grass 5
Polygonaceae Polygonum ramossissiusiun Bushy knotweed 5
Galicaceae Populus alba White poplar 5
Salicaceae Populus sargentii Plains cottonwood 5
Portulacaceae Portulaca oleracea Common purslane 5
Rosaceae Prunus americana Wild plum S

Appendix A (continued).
family Genus Species Common Name Status* Source
Rosaceae Prurtus virginiana Choke cherry 5
Pinaceae Pseudotsuga menziesii Douglas fir S
Leguninosae Psoralea tenuiflora Slender scurf-pea 5
Granineae Puccinellia nuttalliana Alkali grass 5
Rosaceae Pyrus malu5 Apple 5
Saxifragaceae Ribes aureura Golden currant 5
Leguminosae Robinia neonexicana New Mexico locust 5
Leguminosae Robinia pseudoacacia Black locust 5
Cruciferae Rorippa sinuata YelloM-cress 5
Polygonaceae Rumex crispus Curly dock 5
Alisoataceae Sagittaria spp Arrowhead 5
Salicaceae Salix amygdaloides Peach-leaved willow 5
Chenopodiaceae Salsola collina Russian thistle 5
Salicaceae Salix exigua Sandbar willow 5
Salicaceae Salix interior Sandbar willow 5
Chenopodiaceae Salsola kali Russian thistle 5
Gramineae Scbedortnardus paniculatus Tumble grass 5
Cyperaceae Scirpus acutus Compact bulrush 5
Cyperaceae Scirpus americanus American bulrush 5
Labiatae Scutellaria galericulata Marsh skullcap 5
Compositae Senecio spartioioes Butterweed 5
Cotopositae . Senecio tridenticulatus 3-toothed butterweed 5
Cruciferae Sisynbriun altissimun Tumble mustard 5
Cruciferae Sisymbriun officirtale Hedge mustard 5
Granirteae Sitartion longifolium Squirrel tail 5
Solanaceae Solanum rostratua Buffalo-bur 5
Solartaceae Solatium triflorum Cut-leaf nightshade 5
Compositae Soncnus uliginosus Sow thistle 5
Malvaceae Sphaeralcea coccinea Copper mallow 5
Granirteae Sporobolus cryptandrus Sand dropseed 5
Compositae Stephanoneria pauciflora Hire lettuc 5
Granirteae Stipa CGmata Needle and thread 5
Caprifoliaceae Synphoricarpos occidental is Snowberry 5
Tamaricaceae Tamarix pentandra Tamarisk 5
Conpositae Taraxacum officinale Dandelion 5
Labiatae Teucriua canadense Germander 5
Conpositae Thelesperma megapotamicum Greenthread 5
Cruciferae Thlaspi arvense Penny-cress 5
Tiliaceae Tilia spp. Basswood j
Conpositae Tragopogon dubius Yellow salsify 5
Commelinaceae Tradescantia occidental is Western spiderwort j
Zygophyllaceae Tribulus terrestris Puncture vine 5
Typhaceae Typha angustifolia Marrow-leaf cattail 5
Typhaceae Typha latifolia Broad-leaf cattail 5
Ulnaceae Ulnus americana American elm 5
Ulnaceae U1B1U5 parvifolia Chinese elm 5
Urticaceae Urtica dioica Stinging nettle 5
Scrophulariaceae Veronica americana American Brooklime 5
Scrophulariaceae Veronica . anagallis Rater Speedwell 5

Appendix A (continued).
Family Genus Species Comson Name Status* Source Document**
Verbenaceae Verbena bracteata Bracted verbena 5
Coopositae Verbesina encelioides Crownbeard 5
Scrophulariaceae Verbascum thapsus Great nullein 5
Leguminosae Vicia villosa Vetch 5
Violaceae Viola nuttallii Nuttalls violet 5
Granineae Vulpia octoflora Six-weeks fescue 5
Liliaceae Yucca glauca Spanish bayonet c J
Granineae Zea nays Corn e j
Liliaceae Zygadenus venenosus Death canus 5
Salnonidae Salmo gairdneri Rainbow Trout I 1.2
Esocidae Esox lucius Northern Pike I 1.2
Catostonidae Catostcnus catostomusi Longnose Sucker 1.2
Catostonidae Catostomus commerscni White Sucker 1.2
Cyprinidae Cyprinus carpio Carp 1.2
Cyprinidae Semotilus atronaculatus Northern Creek Chub 1
Cyprinidae Rhinichthys cattaraceae Longnose dace 1
Cyprinidae Notropis cornutus Common Shiner 1
Cyprinidae Notropis deliciousus Plains Sand Shiner 1
Cyprinidae Notropis dorsalis Bigmouth Shiner 1
Cyprinidae Notropis lutensis Plains Red Shiner 1.2
Cyprinidae Hybrognathus placita Plains minnow 1
Cyprinidae Pimephales pronelas Fathead minnow 1.2
Cyprinidae Carapostoma anonalun Plains stoneroller 1
Aneiuridae Ictalurus punctatus Channel catfish I 1,2
Aaeiuridae Ictalurus nelas Black Bullhead 1,2
Aneiuridae Fundulus kansae Plains killifish 1,2
Aneiuridae Fundulus sciadicus Plains top minnow 1.2
Centrarchidae Micropterus salmoides Large mouth bass s, 1,2
Centrarchidae Leponis cyanellus Green sunfish 1,2
Centrarchidae Lepoais gibbosus Pumpkin seed 1,
Centrarchidae Lepomis nacrochirus Northern bluegill 1,2
Centrarchidae Potuoxis nigromaculatus Black crappie 1
Centrarchidae Lepoais miggolopnys Red-ear sunfish 1
Percidae Perea flavescens Yellow perch .1,2
Pelobatidae Scaphiopus bonbifrons Plains soadefoot B 1,2
Bufonidae Bufo w.woodhousei Uoodhouse's toad B . 1,2
Bufonidae Bufo cognatus Great Plains toad B 1 3 M1-
Hylidae Acris . crepitans Cricket frog 1
Ranidae Rana pipiens Leopard frog B 1,2
Ranidae Rana catesbeiana Bullfrog B 1,2
Anbystonidae Asbystoma tigrinum Tiger salamander B 1,2

Appendix A (continued).
Faiiily Genus Species LOWon name status* JUUI LC Document**
Chelydridae Chelydra s. serpentina Snapping turtle b 1,2
Testudinidae Chryserays picta belli Painted turtle B 1,2
Testudinidae Terrapene o. ornata Western box turtle B 1,2
Trionychidae Trionyx spiniferus har. Soft-shelled turtle b 1,2
Iguanidae Holbrookia m.maculata Earless lizard B 1,2-
Iguanidae Sceloporus undulatus eryt. Fence lizard B 1,2
Iguanidae Phyrnosoma douglassi Short-horned lizard B 1,2
Iguanidae Sceloporus undulatus gam. No.prairie lizard B 2
Scincidae Eumeces obsoletus Great Plains, skink 1
Scincidae Euaieces a.multivirgatus Many-lined skink B 1,2
Teiidae Cnemidophorus sexlineatus vi. Six-lined racerunner B 1,2
Colubridae Heterodon n. nasicus W. Hognose snake B 1,2
Colubridae Coluber constrictor fl. Racer B 1,2
Colubridae Pituophis melanoleucus s. Bullsnake B 1,2
Colubridae Lampropeltis triangulum Milk snake B 1,2
Colubridae Thamnophis sirtalis parie. Common garter snake B 1,2
Colubridae Thamnophis radix haydeni Plains garter snake B 1,2
Colubridae Tropidoclonion l.lineatum Lined snake B 1,2
Colubridae Thamnophis elegans vagrans Terrestrial garter B 2
Colubridae Masticophis flsgelluis test. Coachwhip B 0 u
Colubridae Nerodia sipedon sipedon Northern water snake B 2
Colubridae Opheodrys vernalis blanc. Smooth green snake B 2
Viperidae Crotalus viridis viridis Prairie rattlesnake B 1,2
Gaviidae Gavia iinmer Common loon M 1,2,3
Gaviidae Gavia arctica Arctic loon M 1,2
Gaviidae Gavia stellata Red-throated loon M 1,2
Podicipedidae Podiceps grisegena Red-necked grebe M 1,2
Podicipedidae Podiceps auritus Homed grebe M 1,2,3
Podicipedidae Podiceps nigricollis Eared grebe b 1,2,3
Podicipedidae Aechraophorus occidentalis Western grebe B 1,2,3
Podicipedidae Podilyabus podiceps Pied-billed grebe R 1,2.3,4
Pelecanidae Pelecanus erythrorhyrichos White pelican n 1,2,3
Phalacrocoracidae Phalacrocorax auritus Dble-cr. cormorant B 1,2,3
Phalacrocoracidae Phalacrocorax olivaceus Olivaceous cormorant M 1,2
Anhingidae Anhinga . anhinga Anhinga 1
Ardeidae Ardea herodias Great blue heron R 1,2,3,4
firdeidae Butorides striatus Green-backed heron M 1,^,3
Ardeidae ' Egretta caerulea Little blue heron M 1,2,
Ardeidae Bubulcus . ibis Cattle egret n 1,2
Ardeidae Casmerodius albus Great egret n 1,2,3
Ardeidae Egretta thula Snowy egret B 1,2,3
Ardeidae Egretta tricolor Tri-colored heron M J,*-
Ardeidae Nyct icorax nycticorax Bl. crown night heron B 1,2,3
Ardeidae Ncyticorax violaceus Ye night heron b 1,2,3
Ardeidae Botaurus lentiginosus American bittern b 1,2,3

Appendix A (continued).
Family Genus b'pecies Lomison name SldlUb' Document**
Ciconiidae flyctaria americana Hood stork 1
Threskiorniithidae Pleoadis chihi White-faced ibis M 1,2,3
flnatidae lor columbianus Whistling swan 1
flnatidae Branta bernicla Brant M 1,2
flnatidae Branta canadensis Canada goose R 1,2,3,4
flnatidae ftnser albifrbns White-fronted goose M 1.2
flnatidae Chen caerulescens Snow goose M 1,2,3
flnatidae Chen rossii Ross's goose M 1.2
flnatidae Anas platyrhynchos Mallard R 1,2,3,4
flnatidae Anas diazi Mexican duck 1
flnatidae Anas rubripes Black duck M 1,2
flnatidae Anas fulvigula Mott led duck 1
flnatidae Anas strepera Gadwall R 1,2,3,4
flnatidae Anas acuta Pintail R 1,2,3,4
flnatidae Anas crecca Green-winged teal R 1,2,3
flnatidae Anas discors Blue-winged teal B 1,2, 3,4
flnatidae Anas cyanoptera Cinnamon teal B 1.2,3,4
flnatidae Anas arnericana American wigeon R 1,2,3,4
flnatidae ftnas clypeata Northern shoveler R 1,2.3,4
flnatidae flix sponsa Wood duck R 1,2,3
flnatidae , fiythya americana Redhead R 1,2,3,4
flnatidae fiythya collaris Ring-necked duck W 1,2,3,4
flnatidae flythya valisineria Canvasback N 1,2,3
flnatidae fiythya marila Greater scaup M 1,2,3
flnatidae flythya affinis Lesser scaup W 1,2,3
flnatidae Bucephala clangula Common goldeneye W 1,2,3
flnatidae Bucephala islandica Barrows goldeneye W 1,2
flnatidae Bucephala albeola Bufflehead U 1,2,3
flnatidae Clangula hyemalis Oldsquaw M 1,2,3
flnatidae Somateria mollissina Common eider 1
flnatidae Melanitta fusca White-winged scoter M 1,2
flnatidae Melanitta perspicillata .Surf scoter M 1,2
flnatidae Melanitta nigra Black scoter M 1,2
flnatidae Oxyura janaicerisis Ruddy duck B 1,2,3
flnatidae Lophodytes cucullatus Hooded merganser W 1,2,3
flnatidae Mergus merganser Common merganser U 1,2,3
flnatidae Mergus serrator Red-breast merganser M 1,2.3
Cathartidae Cathartes aura Turkey vulture B 1,2,3
Accipitridae flccipiter gentilis Goshawk B 1,2
flccipitridae Accipiter striatus Sharp-shinned hawk B 1,2,3
flccipitridae flccipiter cooperii Coopers hawk B 1,2,3
flccipitridae Buteo jamaicensis Red-tailed hawk R 1,2,3,4
flccipitridae Buteo lineatus Red-shouldered hawk M 1,2
flccipitridae Buteo platypterus Broad-winged hawk M 1,2
flccipitridae Buteo swainsoni Swainsons hawk B 1,2,3,4
flccipitridae Buteo lagopus Rough-legged hawk W 1,2,3,4
flccipitridae Buteo regal is Ferruginous hawk R 1,2,3,4
flccipitridae flquila chrysaetos Golden eagle R 1,2,3
flccipitridae Haliaeetus leucocephalus Bald eagle W 1,2,3

Appendix A (continued).
Fanily Genus Species Common Mane Status* Source Document**
ftccipitridae Circus cyaneus Northern Harrier R 1,2,3,4
Pandionidae Pandion haliaetus Osprey M 1,2
Falconidae Falco rusticolus Gyrfalcon M 1,2
Falconidae Falco nexicanus Prairie falcon R 1,2,3
Falconidae Falco peregrinus Peregrine falcon M 1,2,3
Falconidae Falco colunbarius Berlin U 1,2,3
Falconidae Falco sparverius American kestrel R 1,2.3
Tetraonidae Tympanuchus phasianellus Sharp-tailed grouse R|E 1,2
Phasianidae Phasianus colchicus Ring-necked pheasant R 1,2,3,4
Phasianidae fllectoris chukar Chukar N 1,2
Phasianidae Colinus virginianus Bobwhite R 1,2
Phasianidae Callipepla squamata Scaled quail b 2
Gruidae Grus canadensis Sandhill crane M 1,2,3
Keleagrididae Meleagris gallopavo Wild turkey R 1,2
Rallidae Rail us limicola Virginia rail> R 1,2.3
Rallidae Pcrzana Carolina Sora B 1,2,3
Rallidae Coturnicops noveboracensis Yellow rail 1
Rallidae Laterallus jaaaicensis Black rail . 1
Rallidae Gallinula chloropus , Common gallinule 1
Rallidae Fulica americana American coot' R 1,2,3,4
Charadriidae Charadrius semipalaatus' SeuipalEated plover M 1,2,3
Charadriidae Charadrius aielodus' Pipingvplover 1,2,
Charadriidae Charadrius alexandrinus Snowy plover M 1,2
Charadriidae Charadrius vociferus . Killdeer R 1,2,3
Charadriidae Charadrius nontahus Mountain plover b 1,2
Charadriidae Pluvialis dosinica Asier. golden plover M 1,2
Charadriidae Pluvial is squataroia Black-bellied plover M 1,2,3
Scolopacidae flrenaria interpret Ruddy turnstone M 1,2
Scolopacidae Philc-hela ainor American woodcock 1
Scolopacidae Gallinago gallinago Coctnon snipe R 1,2,3
Scolopacidae Numenius aaericanus Long-billed curlew M 1,2,3
Scolopacidae Numenius phaeopus Whinbrel M 1,2
Scolopacidae Bartramia longicauda Upland sandpiper b 1,2 .
Solopacidae Actitis raacularia Spotted sandpiper B 1,2,3 .
Scolopacidae Tringa solitaria Solitary sandpiper M 1,2,3
Scolopacidae Tringa aelanoleuca Greater yellowlegs M 1,2,3,4
Scolopacidae Tringa .. flavipes Lesser yellowlegs M 1,2,3J4
Scolopacidae Catoptrophorus semipalaatus Willet M 1,2,3
Scolopacidae Calidris canutus Red knot M 1,2
Scolopacidae Calidris aelanotos Pectoral sandpiper M 1,2,3
Scolopacidae Calidris fuscicollis Wh.-ruap sandpiper M 1,2
Scolopacidae Calidris bairdii Baird's sandpiper M 1,2,3
Scolopacidae Calidris minutilla Least sandpiper M 1,2,3
Scolopacidae Calidris alpina Dunlin M 1,2
Scolopacidae Calidris pusilla Seaipala.sandpiper M 1,2,3
Scolopacidae Calidris inauri Western sandpiper M 1,2,3
Scolopacidae Calidris alba Sanderling M 1,2,3
Scolopacidae Lianodroaius griseus Short-bill dowitcher M 1,2
Scolopacidae Lianodronus scolopaceus Long-bill dowitcher M 1,2,3

Appendix A (continued).
Family benus species uuiuuun mace jvobua* UUUt bC Document**
Scolopacidae Calidris himantopus Stilt sandpiper M 1,2,3
Scolopacidae Tryngites subruficollis Bufffareast sandpiper M 1,2
Scolopacidae Limosa haemastica Hudsonian godwit M 2
Scolopacidae Limosa fedoa Marbled godwit M 2
Recurvirostridae Recurvirostra americana American avocet B 1,2,3,4
Recurvirostridae Hinantopus mexicanus Black-necked stilt M 1,2,3
Phalaropodidae Phalaropus fulicaria Red phalarope M 1,2,
Phalaropodidae Phalaropus lobatus Northern phalarope M 1,2
Phalaropodidae Phalaropus tricolor Wilson5 phalarope B 1,2,3
Stercorariidae Stercorarius pomarinus Pomarine jaeger M 1,2
Stercorariidae Stercorarius parasiticus Parasitic jaeger M 1,2
Laridae Larus ininutus Little gull M 0 L.
Laridae Larus marinus gull W 2
Laridae Larus hyperboreus Glaucous gull W 1,2
Laridae Larus glaucoides Iceland gull 1
Laridae Larus argentatus Herring gull W 1,2,3
Laridae Larus thayeri Thayer's gull W 1,2
Laridae Larus californicus California gull N 1,2,3
Laridae Larus delawarensis Ring-billed gull N 1,2,3
Laridae Larus atricilla Laughing gull M 1,2
Laridae Larus pipixcan Franklins gull M 1,2,3
Laridae Larus Philadelphia Bonaparte'5 gull M ltd, 3
Laridae Pagophila eburnea Ivory gull 1
Laridae Rissa tridactyla Bl. legged kittiwake M 1,2
Laridae Xenia sabini Sabine's gull M 1,2
Laridae Laras forsteri Forsters tern B 1,2,3
Laridae Sterna hirundo Common tern M 1,2
Laridae Sterna paradisaea Arctic tern 1
Laridae Sterna albifrons Least tern 1
Laridae Chlidonias niger Black tern B 1,2,3
fllcidae Synthliboramphus antiouus Ancient murrelet 1
Columbidae Coluaba livia Rock dove R 2,3
Colrabidae Zenaida wacroura Mourning dove R 1,2.3
Colunibidae Columba fasciata Band-tailed pigeon B g
Cuculidae Coccyzus americanus Yellow-bill cuckoo b 1,2
Cuculidae Coccyzus erythropthalmus Black-billed cuckoo b 1,2
Tytonidae Tyto alba Barn owl R 1,2
Strigidae Otus kennicottii Western screech owl R 2
Strigidae Otus asio Screech owl R 1,2,3
Strigidae Bubo virginianus Great horned owl R 1,2,3
Strigidae Nyctea scandiaca Snowy owl U 1,2
Strigidae Glaucidium gnoma Pygmy owl W 1,2
Strigidae fithene cunicularia Burrowing owl B 1,2,4
Strigidae Strix occidentals Spotted owl M 1,2
Strigidae Asia otus Long-eared owl R 1,2,3
Strigidae Asia flammeus Short-eared owl R 1,2
Strigidae Aegolius acadicus Saw-whet owl R. 1,2
Caprimulgidae Phalaenoptilus nuttalii Common poorwill B 1,2,3
Caprimulgidae Chordeiles minor Common nighthawk B 1,2,3

Appendix A (continued).
Family Genus Species Common Name Status* Source Document**
Apodidae Chaetura pelagica Chimney swift B 1,2
Trochilidae firchilochus alexandri Bl.-chin hummingbird 1
Trochilidae Selasphorus platycercus Br.-tail hummingbird B 1,2,3
Trochilidae Selasphorus rufus Rufous hummingbird M 1,2
Trochilidae Stellula calliope Calliope hummingbird B 2
Alcedinidae Ceryle alcyon Belted kingfisher R 2
Picidae Colaptes auratus Common flicker R 1,2
Picidae Melanerpes carolinus Red-belly woodpecker M 1,2
Picidae Melanerpes erythrocephalus Red-head woodpecker B 1,2,3
Picidae Melanerpes lewis Lewis's woodpecker R 1,2
Picidae Sphyrapicus varius Yel.-belly sapsucker N 1,2
Picidae Picoides villosus Hairy woodpecker R 1,2,3
Picidae Picoides pubescens Downy woodpecker R 1,2,3
Tyrannidae Tyrannus tyrannus Eastern kingbird B 1,2,3
Tyrannidae Tyrannus verticalis Western kingbird B 1,2,3
Tyrannidae Tyrannus vociferans Cassins kingbird b 1,2,3
Tyrannidae Tyrannus forficatus Scis.tail flycatcher M 1,2
Tyrannidae Myiarchus crinitus Gr-crest flycatcher M 1,2
Tyrannidae Myiarchus cinerascens flshthroat flycatcher M 1,2
Tyrannidae Sayornis phoebe Eastern phoebe M 1,2
Tyrannidae Sayornis saya Say's phoebe B 1,2,3
Tyrannidae Empidonax traillii Willow flycatcher M 1,2,3
Tyrannidae Empidonax alnorum Aider flycatcher 1
Tyrannidae Empidonax minimus Least flycatcher M 1,2
Tyrannidae Empidonax hammondii Hammonds flycatcher M 1,2.3
Tyrannidae Empidonax oberholseri Dusky flycatcher M 1,2,3
Tyrannidae Empidonax difficilis Western flycatcher M 1,2,3
Tyrannidae Contopus virens Eastern wood pewee 1
Tyrannidae Centopus sordiriulus Western wood pewee B 1,2,3
Tyrannidae Contopus borealis Oliv-sid.flycatcher M 1,2,3
Tyrannidae Pyrocephalus . rubiniis Vermill. flycatcher M 1,2
Alaudidae Eremophila alpestris Horned lark R 1,2,3
Hirundinidae Tachycineta thalassina Violet-green swallow M 1,2,3
Hirundinidae Tachycineta bicolor Tree swallow B 1,2,3
Hiirundinidae Riparia riparia Bank swallow B 1,2,3
Hirundinidae Stelgidopteryx serripennis Rough-winged swallow B 1,2,3
Hirundinidae Hirundo rustica Barn swallow B 1,2,3
Hirundinidae Hirundo pyrrhonota Cliff swallow B 1,2,3
Corvidae Cyanocitta cristata Blue jay R 1,2,3
Corvidae Nucifraga Columbiana Clark's nutcracker M 1,2
Corvidae Corvus corax Common raven W 2
Corvidae Pica pica Black-billed magpie R 1,2
Corvidae Corvus cryptoleucus Chihuahuan raven M 1,2
Corvidae Corvus brachyrhyncnos Common crow R 1,2,3
Corvidae Gymnorthinus Cyanocephalus Pinyon jay M 1,2
Paridae. Parus atricapillus Black-cap chickadee R 1,2,3
Paridae Parus gambeli Mountain chickadee W 1,2,3
Paridae Psaltriparus minimus Bushtit 1
Sittidae Sitta carolinensis Wh.breasted nuthatch R 1,2,3
ro ro ro

Appendix A (continued).
Family Genus Species Common Name status* source Document#*
Sittidae Sitta canadensis Rd-breasted nuthatch R 1,2,3
Sittidae Certhia americana Brown creeper R 1,2
Troglodytidae Troglodytes aedon House wren B 1,2,3
Troglodytes Troglodytes troglodytes' Winter wren W 1,2
Troglodytidae Thryoaanes bewickii Bewicks wren W 1,2
Troglodytidae Thryothorus ludovicianus Carolina wren M 1,2
Troglodytidae Telmatodytes palustris Long-bill marsh wren 1
Troglodytidae Salpinctes obsoletus Rock wren b 1,2,3
Troglodytidae Cistothorus palustris Marsh wren R 2
Miraidae Minus polyglottos Mockingbird R 1,2,3
Mimidae Dumetella carolinensis Gray catbird B 1,2,3
Minidae Toxostoma curvirostre Curved-bill thrasher 1
Mimidae Toxostoma rufun Brown thrasher B 1,2,3
Minidae Oreoscoptes raontanus Sage thrasher B 1,2,3
Turdidae Turdus ciigratorius American robin R 1,2
Turdidae Hylocichla ffiustelina Wood thrush M 1,2
Turdidae Catharus ustulatus Swainsons thrush B 1,2,3
Turdidae Catharus minimus Gray-cheeked thrush M 1,2
Turdidae Catharus fuscescens Veery B 1,2,3
Turdidae Sialia sialis Eastern bluebird M 1,2
Turdidae Sialia mexicana Western bluebird B 1,2,3
Turdidae Myadestes townsendii Townsends solitaire W 1,2,3
Turdidae Sialia currucoides Mountain bluebird B 1,2,3
Cinclidae Cinclus mexicanus Dipper U 1,2
Sylviidae Polioptila caerulea Bluegray gnatcatcher M 1,2,3
Sylviidae Regulus satrapa Golden-crown kinglet W 1,2,3
Sylviidae Regulus calendula Ruby-crowned kinglet H 1.2,3
Motacillidae Anthus spinoletta Water pipit M 1,2,3
Motacillidae Anthus spragueii Sprague's pipit M 1,2
Boabycillidae Borabycilla garrulus Bohemian waxwing W 1,2
Bombycillidae Bombycilla cedrorus Cedar waxwing W 1,2
Ptilogonatidae Phainopepla niters Phainopepla 1
Laniidae Lanius excubitor Northern shrike U 1,2,3
Laniidae Lanius ludovicianus Loggerhead shrike B 1,2,3
Sturnidae Sturnus vulgaris Starling R, I 1,2,3
Vireonidae Vireo bellii Bell's vireo 1
Vireonidae Vireo flavifrons Yellowthroated vireo 1
Vireonidae Vireo solitarius Solitary vireo B 1,2,3
Vireonidae Vireo olivaceus Red-eyed vireo B 1,2,3
Vireonidae Vireo philadelphicus Philadelphia vireo M 1,2
Vireonidae Vireo gilvus Warbling vireo B 1,2,3
Parulidae Mniotilta varia SI. 4 white warbler M 1, 3
Parulidae Protonotaria citrea Prothonotary warbler M 1,2
Parulidae Vermivora celata Grange-crown warbler M 1,2,3
Parulidae Vermivora peregrina Tennessee warbler M 1,2,3
Parulidae Vermivora chrsoptera Golden-wing warbler M 1,2
Parulidae Vermivora pinus Blue-winged warbler M 1,2
Parulidae Veroivora ruficapilla Nashville warbler M 1,2,3
Parulidae Vermivora virginiae Virginia's warbler B 1,2,3
Co to

Appendix A (continued).
Family Genus Species Common Name Status* Source Document**
Parulidae Parula araericana Northern parula N 1,2,3,
Parulidae Dendroica petchnia Yellow warbler B 1,2,3
Parulidae Dendroica magnolia Magnolia warbler H 1,2
Parulidae Dendroica caerulesceris Blackthroat warbler M 1.2
Paulidae Dendroica coronata Yellowrumped warbler M 1,2,3
Paulidae Dendroica nigrescens Bl.throat gr.warbler M 1,2
Parulidae Dendroica. townsendi Townsends warbler N 1,2.3
Parulidae Dendroica virens Bl.throat green warb M 1,2,3
Parulidae Dendroica cerulea Cerulean warbler 1
Parulidae Dendroica graciae Grace's warbler 1
Parulidae Dendroica fusca Blackburnian warbler M 1,2
Parulidae Dendroica dominica Yellowthroat warbler PI 1,2
Parulidae Dendroica pensylvanica Chestnutside warbler M 1,2,3
Parulidae Dendroica castanea Bay-breasted warbler B 1.2
Parulidae Dendroica striata Blackpoll warbler M 1,2,3
Parulidae Dendroica pinus Pine warbler 1
Parulidae Dendroica paloaruo Palm warbler M 1,2
Parulidae Seiurus aurocapillus Ovenbird B 1,2,3
Parulidae Seiurus noveboracensis Northern waterthrush H 1,2,3
Parulidae Oporornis tolmiei MacGillivray warbler PI 1,2,3
Parulidae Geothlypis trichas Common yellowthroat B 1,2,3
Parulidae Icteria virens Yellow-breasted chat B 1,2,3
Parulidae Uilsonia citrina Hooded warbler M 1,2
Parulidae Uilsonia pusilla UiIson's warbler M 1,2,3
Parulidae Uilsonia canadensis Canada warbler PI 1,2
Parulidae Setophaga ruticilla American redstart B 1,2,3
Parulidae Helmitheros verraivorus Uorm-eating warbler PI 1.2
Passeridae Passer domesticus House sparrow R,I 1,2,3
IctEridae Dolichonyx oryzivorus Bobolink B 1,2
Icteridae . Sturnella neglecta Western meadowlark R 1,2,3
Icteridae Xanthocephalus xanthocephalus Yellowhead blackbird B 1,2,3
Icteridae Agelaius phoeniceus Red-winged blackbird R 1,2,3
Icteridae Icterus spurius Orchard oriole B 1,2,3
Icteridae Icterus galbula Northern oriole B 1,2,3
Parulidae Euphagus carolinus Rusty blackbird U 1,2
Parulidae Euphagus cyanocephalus Brewers blackbird R 1,2,3
Icteridae Quiscalus quiscula Common grackle B 1,2,3
Icteridae Plolothrus ater Brown-headed cowbird B 1,2,3
Thraupidae Piranga ludoviciana Western tanager B 1,2
Thraupidae Piranga olivacea Scarlet tanager PI 1,2
Thraupidae Piranga rubra Summer tanager PI 1.2
Fringillidae Cardinal is cardinalis Cardinal N 1,2
Fringillidae Pheucticus ludovicianus Rose-breast grosbeak PI 1,2,3
Fringillidae Pheucticus melanocephalus Blackheaded grosbeak B 1,2,3
Fringillidae Guiraca caerulea Blue grosbeak B 1,2,3
Fringillidae Passerina cyanea Indigo bunting B 1,2,3
Fringillidae Passerina amoena Lazuli bunting B 1,2,3
Fringillidae Passerina ciris Painted bunting PI 1,2
Fringillidae Spiza americana Dickcissel B 1.2
ro ro

Appendix A (continued).
Family Genus Species Common Name Status* Source Document**
Fringillidae Coccothraustes vespertinus Evening grosbeak R 1,2
Fringillidae Carpodacus purpureus Purple finch U 1,2
Fringillidae Carpodacus cassinii Cassin's finch W 1,2
Fringillidae Carpodacus mexicanus House finch R 1,2,3
Fringillidae Pinicola enucleator Pine grosbeak U 1,2
Fringillidae Leucosticte arctoa Rosy finch W 2
Fringillidae Leucosticte atrata Black rosy finch 1
Fringillidae Leucosticte australis Brown-cap rosy finch 1
Fringillidae Carduelis flammea Common redpoll W 1,2,3
Fringillidae Carduelis pinus Pine siskin R 1,2,3
Fringillidae Carduelis tristis American goldfinch R 1,2,3
Fringillidae Carduelis psaltria Lesser goldfinch B 1,2
Fringillidae Loxia curvirostra Red crossbill R 1,2
Fringillidae Loxia leucoptera White-wing crossbill U 1,2
Fringillidae Pipilo chlorurus Green-tailed towhee b 1,2,3
Fringillidae Pipilo erythrophthalraus Rufous-sided towhee B 1,2,3
Fringillidae Pipilo fuscus Brown towhee 1
Fringillidae Calamospiza melanocorys Lark bunting B 1,2,3
Fringillidae Passercuius sandwichensis Savannah Sparrow B 1,2,3
Fringillidae Ammodramus savannarum Grasshopper sparrow B 1,2
Fringillidae Ammodramus bairdii Bairds sparrow M 1,2
Fringillidae Aamiodramus leconteii Le Contes sparrow 1
Fringillidae Pooecetes granineus Vesper sparrow B 1,2,3
Fringillidae Chondestes gramaacus Lark sparrow B 1,2,3
Fringillidae Aimophila ruficeps Rufous-crown sparrow 1
Fringillidae Aimophila cassinii Cassin's sparrow b 1,2
Fringillidae Amphispiza bilineata Black-throat sparrow M 1,2
Fringillidae Amphispiza belli Sage sparrow M 1,2
Fringillidae Junco hyemalis Dark-eyed junco W 1,2,3
Fringillidae Spizella arborea Tree sparrow W 1,2,3
Fringillidae Spizella passerina Chipping sparrow B 1,2,3
Fringillidae Spizella pallida Clay-colored sparrow M 1,2,3
Fringillidae Spizella breweri Brewers sparrow B 1,2,3
Fringillidae Spizella pusilla Field sparrow M 1,2
Fringillidae Passerella iliaca Fox sparrow U 1,2
Fringillidae Melospiza melodia Song sparrow R 1,2,3
Fringillidae Melospiza lincolnii Lincolns sparrow M 1,2,3
Fringillidae Melospiza georgiana Swamp sparrow W 1,2
Fringillidae Zonotrichia leucophrys White-crown sparrow U 1,2,3
Fringillidae Zonotrichia querula Harriss sparrow w 1,2,3
Fringillidae Calcarius mccownii McCown's longspun M 1,2
Fringillidae Calcarius lapponicus Lapland longspur W 1,2
Fringillidae Plectrophenax nivalis Snow bunting U 1,2
Didelphidae Didelphis virginiana Opossum b 1,2
Soricidae Sorex cinereus Masked shrew B 2
Soricidae Sorex Bterriani Merriaw's shrew B 1,2

Appendix A (continued).
Family Genus Species Common Name Status* Source Document**
Soricidae Cryptotis parva Least shrew B 1,2,3
Vespertilionidae Myotis lucifugus Little brown bat 1
Vespertilionidae Myotis leibii Small-footed myotis 1
Vespertilionidae Lasionycteris noctivagans Silver-haired bat 1
Vespertilionidae Eptesicus fuscus Big brown bat 1
Vespertilionidae Lasiurus borealis Red bat 1
Vespertilionidae Lasiurus cinereus Hoary bat 1
Leporidae Sylvilagus floridanus Eastern cottontail B 1,2,3
Leporidae Sylvilagus audubonii Desert cottontail B 1,2,3,4
Leporidae Lepus townsendii Uhitetail jackrabbit B 1,2,3
Leporidae Lepus californicus Blacktail jackrabbit B 1,2,3,4
Sciuridae Sperraophilus tridecemlineatus 13-1ined gr. squirrel B 1,2,3,4
Sciuridae Spermophilus spilosoma Spotted gr.squirrel B 1,2,3
Sciuridae Cynomys ludovicianus Black-tail B 1,2,4
Sciuridae Sciurus niger Fox squirrel B 1,2,3
Sciuridae Eutamias minimus Least chipmunk B 2
Sciuridae Spermophilus variegatus Rock squirrel B 2
Gsomyidae Thotcomys talpoides North.pocket gopher B 1,2
Geomyidae Geotnys bursarius Plains pocket gopher B 1,2,3
Heterotnyidae Perognathus fasciatus Olive-bk pock.mouse B 1,2
Heteromyidae Perognathus flavescens Plains pocket mouse B 1,2,3
Heterotnyidae Perognathus flavus Silky pocket mouse B 1,2,3
Heteromyidae Perognathus hispidus Hispid pocket mouse B 1,2,3
Heterotnyidae Dipodomys ordii Ords kangaroo rat B 1,2,3,4
Castoridae Castor canadensis Beaver B 1,2
Cricetidae Reithrodontonys icontanus Plains harvest mouse B 1,2
Cricetidae Reithrodontomys megalotis West, harvest mouse B 1,2,3
Cricetidae Peromyscus maniculatus Deer mouse B 1,2,3
Cricetidae Onychotnys leucogaster N.grasshopper mouse B 1,2,3
Cricetidae Microtus pennsylvanicus Meadow vole B 1,2,3
Cricetidae Microtus ochrogaster Prairie vole B 1,2,3
Cricetidae Ondatra zibethicus Muskrat B 1,2,3,4
Muridae Mus musculus House mouse B,1 1,2
Muridae Rattus norvegicus Norway rat B,I 1,2
Zapodidae Zapus hudsonius Meadow jumping mouse B 1,2
Erethizontidae Erethizon dorsatura Porcupine B 1,2,3
Canidae Canis latrans Coyote B 1,2,3,4
Canidae Vulpes vulpes Red fox B 1,2,3
Canidae Vulpes velox Swift fox B 1,2,3
Canidae Urocyon ciriereoargenteus Gray fox B 1,2,3
Procyonidae Procyon lotor Raccoon B 1,2,3
Mustelidae Mustela errainea Ermine 1
Mustelidae Mustela frenata Long-tailed weasel B 1,2,3
Mustelidae Mustela nigripes Black-footed ferret E 1,2.3
Mustelidae Mustela vison Mink b 1,2
Mustelidae Taxidea taxus Badger b 1,2,4
Mustelidae Mephitis mephitis Striped skunk . B 1,2,3
Mustelidae Spilogale putorius Spotted skunk B 1,2
Felidae Felis rufus Bobcat B 1,2

Appendix A (continued).
Family Genus Species Common Name Status* Source Document**
Cervidae Odocoileus heaionus Mule deer B 1,2,3, A
Cervidae Odocoileus virginianus Miite-tailed deer B 1,2,3,4
Antilocapridae flntilocapra americana . Pronghorn B 1,2,3
* Status:B=Definite breeder b=Likely breeder E=Eridangered G=Garee ^Introduced M=Migrant
n=Non-breeder (^Resident W=Winter visitor
**Source Document: l=EIfl.1976.Fairbanks,R.L. I J. Kolmer. 2=Colorado Division of Wildlife Latilong
Studies 3=Barr Lake Mammal Checklist 4=0bserved on site 5=Information from D. Thorne, PMQ, RMft.