U.S. Department of the Interior

Bureau of Land Management

Wyoming State Office

Rock Springs Field Office January 2001

Late Winter Gathering of Wild Horses in the

Rock Springs Field Office Area

(WY-040-EA01-019)
MISSION STATEMENT

It is the mission of the Bureau of Land Management to sustain the health, diversity,

and productivity of the public lands for the use and enjoyment of present and future

generations.

BLM/WY/PL-01/004+1060


Environmental Assessment

Late Winter Gathering of Wild Horses in the 

Rock Springs Field Office Area

EA Number WY-040-EA01-019

Bureau of Land Management

Rock Springs Field Office

January 2001
2

TABLE OF CONTENTS

TABLE OF CONTENTS ........................................................... iii

ABBREVIATIONS ................................................................ v

CHAPTER I - INTRODUCTION ...................................................... 1

INTRODUCTION ........................................................... 1

PURPOSE AND NEED ....................................................... 1

CONFORMANCE WITH LAND USE PLAN ...................................... 3

RELATIONSHIP TO STATUTES, REGULATIONS, AND OTHER PLANS .............. 3

PUBLIC SCOPING .......................................................... 4

CHAPTER II - PROPOSED ACTION AND ALTERNATIVES ............................... 7

PROPOSED ACTION ....................................................... 7

NO ACTION ALTERNATIVE ................................................. 8

ALTERNATIVES CONSIDERED BUT DROPPED FROM FURTHER CONSIDERATION

................................................................... 8

CHAPTER III - AFFECTED ENVIRONMENT .......................................... 11

GENERAL ENVIRONMENT ................................................. 11

Late Winter Climatic Conditions ........................................ 11

Terrain/Topography .................................................. 13

Human-Made Hazards ................................................ 13

WILD HORSES ........................................................... 13

WILDLIFE ............................................................... 14

Big Game Species .................................................... 14

Raptors ............................................................ 15

Greater Sage-Grouse ................................................. 15

Other Species of Interest .............................................. 15

VEGETATION/SOILS/RANGELAND HEALTH .................................. 16

CHAPTER IV - ENVIRONMENTAL CONSEQUENCES .................................. 17

PROPOSED ACTION ...................................................... 17

Wild Horses ........................................................ 17

Wildlife ........................................................... 18

Big Game Species ............................................. 18

Pronghorn Antelope ..................................... 18

Mule Deer ............................................. 18

Rocky Mountain Elk ..................................... 19

Raptors ..................................................... 19

Greater Sage-Grouse ........................................... 19

Other Species ................................................. 20

Vegetation/Soils/Rangeland Health ....................................... 20

Residual Impacts .................................................... 21

NO ACTION ALTERNATIVE ................................................ 21

Wild Horses ........................................................ 21
3

Wildlife ........................................................... 21

Big Game Species ............................................. 21

Pronghorn Antelope ..................................... 21

Mule Deer ............................................. 22

Rocky Mountain Elk ..................................... 22

Raptors ..................................................... 22

Greater Sage-Grouse ........................................... 22

Other Species of Interest ........................................ 22

Vegetation/Soils/Rangeland Health ....................................... 23

Residual Impacts .................................................... 23

CHAPTER V - CONSULTATION AND COORDINATION ................................ 25

LITERATURE CITED ............................................................. 29

APPENDIX 1, Maps

Map 1, Wild Horse Herd Management Areas

Map 2, Known Raptor/Sage Grouse Nest Sites

Map 3, Big Game Crucial Winter Ranges

Map 4, Known Golden Eagle, Great-Horned Owl Nest Sites

APPENDIX 2, Letter from Rock Springs Grazing Association

APPENDIX 3, Species Listed and Proposed for Listing and Memorandum from U.S. Fish and Wildlife

Service
4

ABBREVIATIONS

AML - Appropriate Management Level

BLM - Bureau of Land Management

CFR - Code of Federal Regulations

DR - Decision Record

EA - Environmental Assessment

EIS - Environmental Impact Statement

FWS - (U.S.) Fish and Wildlife Service

HMAs - Wild Horse Herd Management Areas

RMP - Resource Management Plan

RSFO - Rock Springs Field Office

RSGA - Rock Springs Grazing Association

WGFD - Wyoming Game and Fish Department
1

CHAPTER I - INTRODUCTION

INTRODUCTION

The Bureau of Land Management (BLM) prepared a comprehensive environmental assessment (EA) in 1999

to analyze the potential impacts of gathering and removing excess wild horses in the Rock Springs Field

Office area (RSFO). The Decision Record (DR) was approved in July 1999 and specifically stated that BLMRSFO would analyze spring gathering in a separate EA. BLM has since changed the term “spring” to “late

winter” to more accurately reflect the time of year of proposed gathering (see below). In addition, the 1999

DR approved the capture plan and other mitigation to reduce the potential impacts to wild horses and other

resources. This EA is tiered to and incorporates by reference the Environmental Assessment for Wild Horse

Gathering Inside and Outside Wild Horse Herd Management Areas and the associated Decision Record

for Wild Horse Gathering Inside and Outside Wild Horse Herd Management Areas approved July 14, 1999.

These documents can be downloaded from the following internet addresses:

EA: http://www.wy.blm.gov/currentnews/wildhorses/env_docs/RSWHEAfinal99.pdf

DR: http://www.wy.blm.gov/currentnews/wildhorses/env_docs/Rock%20Sprgs%20DR%20&%20F

ONSI.pdf 

Wild horse herd management areas (HMAs) are identified on Map 1, Appendix 1.

PURPOSE AND NEED

The purpose of this EA is to address the potential impacts of gathering and removal of excess wild horses

during the period from February 15 through March 31, now called late winter gathering. The need for this

action is to allow the BLM-RSFO the option to remove excess wild horses during this time period should

favorable climatic conditions allow for the safe gathering and removal of wild horses. Removal of excess

wild horses during this period allows for more efficient use of government facilities and personnel, while

reducing existing wild horse populations to appropriate management level (AML). The BLM recognizes that

gathering of wild horses during the period proposed will not, by itself, allow the short-term achievement,

nor long-term maintenance of AML.

First priority for gathering and removal of wild horses would be in the area known as the checkerboard

(Map 1, Appendix 1), an area where every other square mile is owned by private or state entities. Other

areas in the RSFO may be subject to removal operations if weather conditions allow for gathering

operations.

A 1981 order from the District Court of Wyoming (Mountain States Legal Foundation and Rock Springs

Grazing Association v. Cecil Andrus, C79-275K) requires BLM-RSFO to “remove all wild horses from the

checkerboard grazing lands in the Rock Springs District except for the number which the Rock Springs

Grazing Association (RSGA) voluntarily agrees [emphasis added] to leave in said area.” Most of the private

lands within the Wild Horse Herd Management Areas (HMAs) are owned or controlled by the RSGA. These

private lands make up a considerable portion of three HMAs including:
1Target Number (range).

2

Great Divide Basin HMA Salt Wells HMA White Mountain HMA

25% 36% 38%

BLM incorporated the AML proposed by RSGA and wild horse advocacy groups into the land use planning

process. Wild horses that exceed properly established AMLs, as approved in the 1997 Green River Resource

Management Plan (RMP), are considered excess as defined by the Wild and Free-Roaming Horse and Burro

Act and the Federal Land Management and Policy Act. The established AMLs, when achieved and

maintained will allow for compliance with the Wyoming Standards For Rangeland Health (1997). The

Standards were presented in the 1999 EA in Appendix B. Managing wild horse populations within

established AMLs will ensure that any failure to comply with the standards will not be the result of the

presence of excess wild horses.

The number of wild horses subject to removal is based on the latest census conducted between February

2000 and June 2000 (see Table 1).

Table 1

Appropriate Management Level and Latest Wild Horse Populations

Area AML1

2000

Population

Count

2000

Wild Horses

Removed

2001

Projected Population

Great Divide Basin HMA 500 (415-600) 1,210 354 923

White Mountain HMA 250 (205-300) 527 189 363

Little Colorado HMA 100 (69-100) 200 0 240

Salt Wells HMA 365 (251-365) 1,020 24 1071

North Baxter/Jack

Morrow Hills Area

(outside HMAs)

0 293 1 350

Totals 1,215 (940-1,365) 3250 474 2952

Actions proposed in the Adobe Town HMA are administered by the Rawlins Field Office. In addition, the

area is inaccessible during the late winter, hence the RSFO does not propose any late-winter gathering

operations in this HMA.
3

CONFORMANCE WITH LAND USE PLAN

Gathering and removal of excess wild horses in the RSFO is in conformance with the RMP approved August

8, 1997. AMLs were negotiated with private land owners and wild horse advocacy groups and confirmed

(established for Little Colorado HMA) in the RMP ( Map 1, Appendix 1) in compliance with the 1981 District

Court Order. Ignoring existing policy, land use plan decisions, and agreements reached pursuant to the

District Court Order are not considered options, nor are they within the scope of this EA. Therefore, they

will not be given consideration in this EA.

The North Baxter/Jack Morrow Hills area is outside the established HMAs and is generally located between

the White Mountain HMA and the Great Divide Basin HMA, south of Wyoming Highway 28. All wild horses

residing in this area are considered excess and subject to removal in conformance with the RMP.

RELATIONSHIP TO STATUTES, REGULATIONS, AND OTHER PLANS

Gathering of excess wild horses is in conformance with Public Law 92-195 (Wild and Free-Roaming Horse

and Burro Act of 1971), as amended by Public Law 94-579 (Federal Land Policy and Management Act) and

Public Law 95-514 (Public Rangelands Improvement Act). Public Law 92-195, as amended, requires the

protection, management, and control of wild free-roaming horses and burros on public lands.

As provided in 43 CFR 4700.0-6(a-c), BLM policy for management of wild horses is to: a) “. . . manage as

self-sustaining populations of healthy animals in balance with other uses and the productive capacity of their

habitat; b) . . . considered comparably with other resource values; and c) . . . maintaining free-roaming

behavior.” Priority shall be given to removing wild horses from private lands when the landowner submits

a written request to BLM for their removal.

As provided for in the 1981 Court Order, the private land owners (the RSGA) agreed to allow a certain

number of wild horses to occupy and use their deeded lands. This agreement established a partnership

relationship between the BLM and the RSGA in the management of wild horses in the RSFO. This

partnership is unique within the BLM wild horse program not only for the relationship between the BLM

and the land owners, but also for the scope of the area covered. The land use plan and activity plans (Wild

Horse Herd Area Management Plans) have recognized and authorized AMLs in accordance with this

partnership. These partners expect the BLM to comply with these plans and to control wild horse

populations to AML.

Annual written request from the RSGA for removal of excess wild horses from these private lands is not

necessary. In March of 1999, the BLM received correspondence from the RSGA reminding the BLM of the

responsibility to manage wild horses to AML. A copy of this letter is included in Appendix 2. The BLM

requires livestock operators who hold grazing permits on public lands in the RSFO to limit their livestock

use to that specified in the grazing permit. If the operator does not, there are procedures in the grazing

regulations to recover the value of excess forage used in addition to assessment of punitive damages. Some

of these same grazing permit holders own or control approximately 836,025 private acres within HMAs in

the RSFO. They allow federally-managed wild horses use of these privately owned lands free-of-charge.

The BLM should be expected to limit wild horses to established AMLs.
2BLM is proposing to gather wild horses in late winter as a strategy to help reach AML.

4

The Proposed Action is also in compliance with the following sections of the Code of Federal Regulations:

43 CFR 4720.1 - “Upon examination of current information and a determination by the authorized

officer that an excess of wild horses or burros exists, the authorized officer shall remove the excess

animals immediately.”

43 CFR 4720.2 - Removal of strayed or excess animals from private lands.

43 CFR 4710.4 - “. . . management of wild horses and burros shall be undertaken with the objective

of limiting the animals distribution to herd areas.”

43 CFR 4710.3-1 - HMAs shall be established (through the land use planning process) for

maintenance of wild horse and burro herds.

43 CFR 4180 - “Fundamentals of Rangeland Health and Standards and Guidelines for Grazing

Administration.”

PUBLIC SCOPING

The BLM released a scoping notice for the proposed late winter gathering operations on September 29, 2000,

and identified those issues recognized internally by BLM. Nine comment letters were received. The

following issues were identified and considered during development of this EA:

Wyoming Game and Fish Department

S Supports removal of excess wild horses

S Avoidance of disturbance to winter concentrations of antelope

S Avoidance of sage grouse leks and nesting habitat

S Avoidance of raptor nesting habitat

Colorado Wild Horse and Burro Coalition

S Potential impacts to late-term pregnant mares

S Use of current monitoring/inventory data

S Seasonal migration of wild horses outside of HMAs

S Wild horse adoption market at this time of year2

Animal Legal Defense Fund

S Use of current monitoring/inventory data to show overpopulation of wild horses contributing

to rangeland degradation

S Seasonal migration of wild horses outside of HMAs

S Removal of wild horses from private lands (written requests)
3Gathering in the RSFO area is not a national issue. Late winter gathering operations are proposed to take

advantage of the availability of the wild horse facility located in Rock Springs, Wyoming.

4All “unadoptable” wild horses will be placed in sanctuaries based on current removal policy.

5

S Potential impact of spring gathering to wild horses at that time of year: additional expenditure

of energy, lower immunological resistence to disease due to stress cause by gathering, handling,

and transportation

S Risk of late-term mares aborting their fetuses due to stress caused by roundups

Fund for Animals, Animal Protection Institute, Doris Day Animal League

S Analyze reasonable range of alternatives including scheduling later roundups, expansion of

existing holding facilities, using contract crews and holding facilities in adjacent states (later

roundups), use of alternative facilities

S Contingency plan should weather prevent roundups

S Potential impacts to the terrain

S Potential impacts to vegetation

S Potential impacts to wildlife including threatened, endangered, proposed, and candidate species

S Potential impacts to late-term pregnant mares and foals

S Status of current adoption pipeline

S Discuss coordination with National Wild Horse and Burro program to eliminate need for spring

gathering3

S Use of low-flying helicopters on winter-stressed wildlife and wild horses

S Gathering of young foals less than 2 months old (compression injuries)

Wyoming Advocates for Animals

S Use current census

S Status of adoption pipeline at this time of year4

U.S. Fish and Wildlife Service (FWS)

S Threatened, Endangered, and Proposed Species potentially affected by spring gathering

operations:

Bald eagle

Black-footed ferret

Mountain plover 

Whooping crane

Ute ladies’-tresses

Colorado River listed fish species (only if water depletion is proposed)
6
7

CHAPTER II - PROPOSED ACTION AND ALTERNATIVES

PROPOSED ACTION

The late winter population of wild horses in the RSFO is estimated to be 2,952 animals (see Table 1). This

number of wild horses is over two and one-half times (2.5) the established AML of 1,215. The BLM

proposes to gather and remove excess wild horses during the period from February 15 through March 31

in the RSFO (see Map 1, Appendix 1, for HMA location and name). Removal of excess wild horses would

be in accordance with current wild horse removal policy. All captured wild horses would be removed from

the range. Those horses deemed “unadoptable” would be placed in sanctuaries. This is an interim policy

that suspends previous selective removal criteria (see Appendix B of the 1999 DR). The current policy is

in effect to achieve AML, in a shorter period of time, by not returning older horses to the range. Funding

for this effort, in fiscal year 2001, has been approved by the U.S. Congress.

Annual winter wild horse census activities will occur in January and February of 2001. These data were not

available for this analysis. Actual numbers of wild horses removed and from where, will be determined

after the census has been completed. No HMAs will have horses removed below the established lower limit

of the AML.

First area of priority for gathering and removal operations would be on checkerboard lands (Map 1,

Appendix 1). Other areas, where wild horses congregate, may be considered if weather conditions allow

for gathering operations.

Gathering and removal operations would be in accordance with the Wild Horse Capture Plan found in

Appendix A of the 1999 DR. In addition to those protective measures identified in the capture plan,

gathering operations would proceed only if the following weather conditions are occurring on the day of

scheduled operations at the trap site:

- dry or frozen roads

- temperature above 10 degrees (Aviation Safety Manual 9430)

- clear to partly cloudy skies

- winds less than 25 miles per hour

- generally little or no snow cover (certain areas may have drifted snow cover)

Should these conditions not be met on the day of scheduled gathering, operations would be suspended for

that day.

A third-party Veterinarian will assess the physical condition of the wild horses in the field prior to the

beginning of late winter gathering. The Veterinarian will determine the condition of the animals and

recommend to the BLM whether the horses are fit for gathering.

Traps would be constructed in accordance with the Capture Plan (Appendix A of the 1999 DR) and would

be located adjacent to county, BLM, or other existing roads. No new roads would be constructed to

accommodate trap sites. All horses identified for gathering operations would be within 10 miles of the

constructed trap sites. Horses would be moved at their own pace via the helicopter until close to the trap,

at which time, horses would be driven into the trap in accordance with the capture methods and herding and

stress reduction procedures outlined in the Capture Plan (Appendix A, 1999 DR). Should any mares be
8

encountered with foals less than 2 months old, they would be separated from the gathering operation. If the

mares with young foals cannot be separated, then the herd would be dropped from the gathering operation.

BLM late winter gathering operations and trap sites would avoid the following areas:

• Known active raptor nesting sites as reviewed by a BLM Wildlife Biologist

• Trap locations would avoid known raptor nesting sites (Map 2, Appendix 1)

• Use of cliff areas as part of the trap where active raptor nesting is occurring

• Prairie dog town/complexes

• Greater sage-grouse leks and nesting areas (2-mile radius)

• Concentrated herds of antelope

• Crucial winter range for mule deer

• Crucial winter range for elk

• Fenced areas associated with highway corridors and deeded property

• Riparian, wetland, or open or frozen water areas

Monitoring

Monitoring of the proposed action is identical to that identified on page nine of the 1999 EA.

NO ACTION ALTERNATIVE

Late winter gathering of excess wild horses would not be conducted.

ALTERNATIVES CONSIDERED BUT DROPPED FROM FURTHER CONSIDERATION

Increasing Local Corral Capacity

Increase corral capacity at the RSFO facility to preclude the need for late winter gathering. The BLM is in

the process of redesigning the RSFO horse facility. The corral will be redesigned to process wild horses

more efficiently and the holding capacity will be increased slightly. However, design of the corral will not

preclude the need for late winter gathering operations for the following reasons: scheduling conflicts with

the helicopter and gathering crews, use of the facility by other BLM offices, limited availability of local staff

to process wild horses, feed budgets, and the facility is not yet available for use during the late winter of

2001.

In addition, BLM is in the process of developing long-term care facilities for placement of unadopted excess

wild horses in accordance with current BLM policy.

Use of Contracted Crews/ In-State or Out-of-State Facilities

Use of contracted crews or out-of-state facilities to preclude the need for spring gathering. BLM is currently

working with groups, and county and state agencies to negotiate additional corral space. Use of contracted

crews and out-of-state facilities are an option but contracted crews may not be readily available due to

scheduling conflicts, and out-of-state or other private facilities may be filled to capacity due to conditions

beyond BLM’s control (i.e., severe drought in another state). BLM-RSFO, maintains a staff of qualified

wranglers who are immediately available for gathering operations.
9

The 1999 EA discussed several other alternatives (see pages 9-10) but dropped them from consideration.

The rationale for dropping those alternatives still applies. Hence, those alternatives will not be given

consideration in this document.
10
5

See Appendix 3 for rationale and FWS memorandum in response to public scoping.

6

Source: http://www.wunderground.com/US/WY/Rock_Springs.html.

11

CHAPTER III - AFFECTED ENVIRONMENT

The resources potentially affected by the Proposed Action and No Action alternatives include wild horses

(including early foals, mid-to-late term pregnant mares, condition of wild horses during the late winter, use

of a helicopter during late winter roundups), wintering pronghorn antelope herds utilizing crucial winter

range, other wildlife including mule deer, elk, greater sage-grouse and raptors, vegetation, soils, and

rangeland health.

The following critical elements of the human environment and other potential concerns were considered but

determined not to be affected or impacted by the Proposed Action. Hence, these elements are not discussed

further:

S Air Quality

S Areas of Critical Environmental Concern

S Cultural, Historic, and Paleontologic Resources

S Environmental Justice

S Hazardous Wastes

S Native American Concerns

S Prime or Unique Farmlands

S Threatened, Endangered, Candidate, Proposed, or Sensitive Plant or Animal Species5

S Water Quality or Sole Source Aquifers

S Wild and Scenic Rivers

S Wilderness Areas or Wilderness Study Areas

GENERAL ENVIRONMENT

A discussion of the environment can be found on pages 11 through 17 in the 1999 EA. The following

discussion tiers to that found in the 1999 EA and concentrates on conditions found in the RSFO during the

period from February 15 through March 31.

Late Winter Climatic Conditions

The RSFO area is considered to have a dry continental temperate climate. Precipitation, wind speed, and

temperature are the most important climatic factors controlling late winter wild horse gathering operations.

Maximum average temperature ranges from approximately 33 degrees on February 15 to 49 degrees on

March 31 in Rock Springs, Wyoming. Precipitation ranges from 7 to 9 inches a year with approximately

20% in the form of snow. Average snow depth on February 15, in the last six years, has been approximately

1 inch at Rock Springs, Wyoming. Table 2 provides the mean, minimum, and maximum temperatures; snow

depth; and maximum sustained wind on February 15 for the years between 1995 and 2000. Table 3 provides

the same information for March 31.

Table 26
7

Source: http://www.wunderground.com/US/WY/Rock_Springs.html.

8

Source: USDA, National Resources Conservation Service, National Water and Climate Center web site,

ftp://162.79.124.23/support/climate/taps/wy/56037.txt 

12

Temperature, Snow Depth, Wind Speed on February 15th

February 15,

Year

Mean

Temperature

(F)

Maximum

Temperature (F)

Minimum

Temperature (F)

Snow

Depth 

(inches)

Maximum

Sustained Wind

(mph)

2000 24.4 26.6 21.2 0 5.7

1999 23.9 30.2 17.6 2.0 10.36

1998 28.8 35.6 21.2 3.9 No Data

1997 31.5 37.4 28.4 0 No Data

1996 34.3 50.0 27.0 0 No Data

1995 11.8 19.9 5.0 0 No Data

Average 25.8 33.3 20.0 1 No Data

Table 37

Temperature, Snow Depth, Wind Speed on March 31st

March 31, 

Year

Mean 

Temperature

(F)

Maximum

Temperature (F)

Minimum

Temperature

(F)

Snow Depth

(inches)

Maximum

Sustained wind

(mph)

2000 30.4 41.0 21.2 0 13.81

1999 35.1 51.8 24.8 0 12.66

1998 30.4 42.8 23.0 0 12.77

1997 46.6 57.2 35.6 0 No Data

1996 38.7 52.9 25.9 0 No Data

1995 33.6 46.9 25.0 0 No Data

Average 35.8 48.8 25.9 0 No Data

Another source of weather information provided average maximum and minimum temperatures and average

total snowfall for the years 1961 through 1990 for various points found throughout Sweetwater County.

Table 4 provides this information for the months of February and March.

Table 48

Average Temperature and Snowfall at Sites within Rock Springs Field Office
13

Area

Average 

Maximum Temperature

(F)

Average

 Minimum Temperature

(F)

Average Total Monthly

Snowfall (inches)

Feb Mar Feb Mar Feb Mar

Rock Springs 34.2 41.7 14.2 20.4 5.5 7.5

Wamsutter 32.6 40.8 10.1 17.5 2.7 3.1

Bitter Creek 35.5 43.0 10.2 17.7 3.0 1.9

Farson 31.7 40.5 -1.1 11.7 3.7 6.6

Green River 36.6 45.1 7.3 17.7 3.5 3.8

Terrain/Topography

Terrain found within the RSFO is highly variable, ranging from mostly flat to slightly rolling foothills carved

by drainages and desert mountains featuring steep slopes, cliffs, and canyons. Preferred habitat for wild

horses during the late winter period is open terrain within the sagebrush/grass and saltbush vegetative

community types. During severe weather the horses will seek out thermal cover in protected areas provided

by topographic relief.

Human-Made Hazards

Portions of the boundaries associated with HMAs found in the RSFO are fenced. This fencing is usually

associated with highways, BLM Field Office boundaries, and the state line. The minimal fencing found

within HMAs is usually associated with deeded property. Within the checkerboard, fencing is associated

with the major highway corridors of Interstate 80 and U.S. Highway 191.

WILD HORSES

Current wild horse populations are estimated at 2,952 animals (Table 1). This is the number of horses

estimated to remain after the removal of 568 animals during the summer of 2000. The AML for the HMAs

included in the Proposed Action is 1,215. Current populations are therefore estimated to be over two and

one-half times that of established AML. During calendar year 2000, the RSFO experienced a severe drought

and had more acreage consumed by wild fire than during the past two decades combined. None of the wild

fires affected the wild horses and they survived the drought in good shape. Forage was available to sustain

them until the present time. Some concentration of use areas occurred due to scarcity of surface water

supplies. No increased mortality was documented.

The majority of pregnant mares will be in the third trimester of pregnancy during the proposed gathering

period. Data contained in the BLM Wild Horse and Burro Information System documents that the majority

of wild horse foals in this area are born on or around June 1 each year. Ninety-six percent (96%) of mares

are foaled between April 15 and June 30 each year. No gathering of wild horses is proposed between April 1

and July 14.
14

During this time of year, wild horses commonly migrate from solid block (public lands) areas of HMAs to

the checkerboard portions of the HMAs. North of Interstate 80, this movement is from the north to south.

South of Interstate 80, the movement is from the south to the north. This seasonal migration occurs with

HMA boundaries and is not generally responsible for horses straying to areas outside of HMAs. Outmigration (east to west) is largely a function of density dependent factors related to social and breeding

activity.

WILDLIFE

The RSFO area is home to over 350 species of wildlife including big game, furbearers, waterfowl,

shorebirds, songbirds, amphibians, and reptiles, to name a few. Many species are not affected by this action

since they migrate to wintering ranges outside of the State of Wyoming. Of those species that make

southwest Wyoming home during the proposed late winter gathering time frame, big game (antelope, mule

deer, and elk), certain raptors, and greater sage-grouse could potentially be affected by the Proposed Action

or No Action alternatives. Since gathering operations are not proposed around water areas, those species

that inhabit such areas (e.g., moose, fish) are not affected, henceforth they are not addressed further in this

document.

Big Game Species

Pronghorn Antelope - The Wyoming Game and Fish Department (WGFD) identified certain antelope herds

as potentially affected by the Proposed Action: portions of the Sublette, South Rock Springs, and Bitter

Creek herds. Antelope live year round in much of the RSFO. Crucial winter range within the RSFO is

shown on Map 3, Appendix 1. The current population is estimated at approximately 60,000 (WGFD Annual

Herd Unit Reports, 1999). During the winter months, these animals form loose aggregations and feed

primarily on sagebrush. Antelope will consume snow for their water needs when sources of open water are

not available. Meeker (1982) found dietary overlap between feral horses and antelope suggesting a 1:1

replacement ratio between horses and antelope. Stephenson (1982) found a 60% overlap between

pronghorn antelope and feral horses.

Mule Deer - Mule deer occur throughout the Field Office area. Most populations are below Wyoming Game

and Fish Department population objectives (pers. comm. Christiansen) with the population estimated at

27,000 (WGFD Annual Herd Unit Reports, 1999). Crucial mule deer winter range is shown on Map 3,

Appendix 1. Mule deer utilize both rangelands and forests where they feed primarily on brush and trees

during the winter months. Stephenson (1982) found a 65% dietary overlap between mule deer and feral

horses. It is reasonable to expect that wild horses compete with mule deer for water resources and space.

Rocky Mountain Elk - The estimated elk population is approximately 2,800 (WGFD Annual Herd Unit

Reports, 1999). Within some herd units, populations are over objective levels (pers. comm. Christiansen).

Crucial winter range for elk is shown on Map 3, Appendix 1. Elk feed mostly on grasses and saltbush for

the majority of their forage requirements but switch to shrubs and certain trees during the winter months.

Stephenson (1982) found a 71% dietary overlap between elk and feral horses, indicating potential

competition for available forage. It is reasonable to expect that wild horses compete with elk for water

resources.

Raptors
15

There are 17 species of raptors with potential nesting habitat in the RSFO. Golden eagles and great-horned

owls inhabit the field office area year-round and may start nesting as early as February (pers. comm.

Deibert). Golden eagle nests are most often found on cliffs, canyon walls, and pinnacles; occasionally,

golden eagles also nest in the tops of snags or open trees. Great-horned owls nest primarily in open trees

and snags; occasionally, these owls will nest on cliffs and pinnacles. Known golden eagle and great-horned

owl nest sites are shown on Map 4, Appendix 1.

Ferruginous hawks, ground-nesting raptors, generally arrive in the area in mid-April to begin courtship and

subsequent nesting in late April and early May (pers. comm. Cerovski). Another ground-nesting raptor, the

burrowing owl, nests in abandoned prairie dog burrows or burrows they excavate themselves in May. Other

raptor species found in the RSFO area arrive after the close of proposed late winter gathering operations and

would not be affected by the Proposed Action.

Greater Sage-Grouse

The greater sage-grouse (American Ornithologists’ Union, 2000) can be found throughout much of the

RSFO area where there is sufficient sagebrush habitat. Long-term trends have shown a 30% decrease in

populations over the last 30 years. The chick survival rate in the summer of 2000 was very poor due to the

drought conditions and is expected to have a negative impact on local populations (pers. comm.

Christiansen). These birds usually arrive on their traditional strutting grounds, known as leks, in March

although if weather should permit, they could arrive as early as mid-February. Leks are generally

characterized by an open, relatively flat area adjacent to sagebrush habitat. Known greater sage-grouse leks

and 2-mile nesting buffers are shown on Maps 2 and 4, Appendix 1.

Other Species of Interest

Prairie dogs - Prairie dogs inhabit the field office area in areas where there are suitable soils and flat

topography.

Swift fox - This diminutive fox occurs in the eastern portion of the RSFO area (pers. comm. Wooley). This

species inhabits areas of low vegetation and flat topography often in association with prairie dog towns.

Other species of interest that may be present in the RSFO but not likely to be affected by gathering

operations include bobcat, black bear, mountain lion, ground squirrels, badger, red fox, coyotes, rodents,

weasels, bats, waterfowl, song birds, fish, invertebrates, amphibians, reptiles, and others.
16

VEGETATION/SOILS/RANGELAND HEALTH

During the late winter period, most vegetation is dormant and soils are frozen. If these conditions do not

exist, vehicular access would be extremely limited and may preclude gathering activities. The conditions

under which gathering could proceed are included in the Proposed Action.

Some grazing allotments within existing HMAs have been determined to not be in compliance with the

Wyoming Standards for Rangeland Health (1997). Impacts from grazing animals, including wild horses,

have often been determined to be a causative factor in the failure to comply with the standards. One of a

number of appropriate actions identified to address this situation is to reduce wild horse numbers to AML

and to totally remove wild horses from areas outside established HMAs.
17

CHAPTER IV - ENVIRONMENTAL CONSEQUENCES

This section tiers to and incorporates Chapter IV of the 1999 EA. The impacts described in the 1999 EA

continue to apply to this action. The discussion below is limited to the potential impacts specific to gathering

and removing excess wild horses during the period from February 15 through March 31, for the following

resources: wild horses, wildlife, and vegetation (includes soils and rangeland health). The direct, indirect,

and cumulative impacts are addressed for each resource.

With one exception the cumulative impact analysis done during the development of the Green River RMP

Environmental Impact Statement (EIS) and the 1999 EA applies to this Proposed Action. The additive

effects of wild horse gathering coupled with other reasonably foreseeable resource uses (e.g., oil and gas

development, livestock grazing) on the environment were analyzed in that EIS and are not repeated here.

The exception to that cumulative analysis was the effect on wild horses from gathering during the late winter

time period, when other conditions (late winter physical condition, mare pregnancies, etc.) may be stressing

the physiological health of the horses. A cumulative analysis was done for that potential impact on wild

horses and can be found in the below discussion.

PROPOSED ACTION

Wild Horses 

Direct and Indirect Impacts - Review of the Wild Horse and Burro Information System (information is

available upon request) and consultations (pers. comm. Glenn), it was confirmed that avoiding

unaccustomed stress after the onset of the 38th week of pregnancy was an appropriate safeguard to avoid

stress-induced abortion during removal and processing. It has also been determined that shutting down

gathering activities between April 1 and July 14 is effective in avoiding subjecting mares to unaccustomed

stress after their 38th week of pregnancy. This would occur at least 85% of the time, as this is the

documented percentage of mares that foal between April 1 and June 30 each year. It was further determined

that the only way to avoid, with absolute certainty, the possibility that any pregnant mare would ever be

subjected to any unaccustomed stress, was to never remove any group of horses which might contain a

pregnant mare. This would, in effect, make it essentially impossible to ever schedule and complete any

removal, subverting the well-being of the entire herd and the habitat that supports them.

Hansen and Mosley (2000) in studies in Idaho and Wyoming on the effects of helicopter roundups on the

behavior and reproduction of wild horses determined “. . . in our study roundups did not decrease

reproductive rates of feral horses.” The authors go on to state “Feral horses in our study apparently adapted

easily to any stress caused by roundups. We found no evidence that roundups had deleterious effects on

behavior or reproduction of feral horses.”

The actual foaling period has been determined from several sources (pers. comm. Glenn). In 1978 and 1979,

wild horses were observed in the field. During these two years, 85% and 87% of foals were born after

April 1 and before June 30. Field observations were also conducted in 1999. Seventy-six percent of foals

were born between May 15 and July 1 and 91% of foals were born after April 1. Analyses of data from the

Wyoming Horse and Burro Information System, over the period of 1986 through 1998, established that 96%

of foals were born between April 15 and June 30 and that 85% were born after May 14. Therefore, less than

four percent of any potential foal crop could be born prior to the dates of the proposed action, and 85% of

foals would not be born until at least six weeks after activities under the proposed action had ceased.
18

Cumulative Impacts - The potential cumulative effects on wild horses from the impacts of gathering

operations coupled with potential impacts to their health from the lower quality and quantity of forage, cold

weather, and mare pregnancy was evaluated. Several measures were developed in the Proposed Action to

prevent a possible cumulative impact that could result in the death of a horse or loss of an unborn foal.

These measures include specifying mild weather conditions, specific guidelines on herding the horses by

the helicopter, shutting down gathering operations on April 1 through July 15 to protect unborn and recently

born foals and use of an outside Veterinarian to evaluate individual herd conditions prior to gathering. With

implementation of these features, no cumulative impacts on wild horse health are anticipated from late

winter gathering.

Mitigation Measures - With implementation of the committed measures identified under the Proposed

Action, no additional mitigation measures are identified.

Wildlife

In general, wildlife species would benefit from the Proposed Action Alternative. Any action taken to

achieve and maintain AML should result in the improvement of the overall quality of the rangeland

conditions potentially benefitting all species inhabiting the range.

Big Game Species

Pronghorn Antelope

Direct and Indirect Impacts - BLM may conduct gathering operations in antelope crucial winter range (see

Map 3, Appendix 1), but as stated in the Proposed Action, BLM would avoid concentrated populations of

antelope. Therefore, no direct impacts to such herds would be expected. Antelope in the general area during

trap construction or gathering operations could be temporarily disturbed by these activities or by the

helicopter as it passes by.

Cumulative Impacts - Based upon the findings of both Meeker (1982) and Stephenson (1982), removing

excess wild horses should improve the overall health of the range, thereby benefitting antelope due to a

reduction in competition for forage and water resources. Such reductions in competition for forage and

water would be particularly beneficial for antelope during severe winters or times of drought.

Mule Deer

Direct and Indirect Impacts - As stated under the Proposed Action, the BLM would avoid gathering

operations in mule deer crucial winter ranges (see Map 3, Appendix 1). Therefore, no direct or indirect

impacts to mule deer are anticipated. In the event that mule deer happen onto areas outside of their winter

range during gathering operations, those individuals could be momentarily disturbed by the helicopter and/or

the wild horses as they pass by. Any such impact would be temporary and unlikely to pose a serious threat

to the animal.

Cumulative Impacts - Removing excess wild horses to achieve AML should benefit the overall health of the

rangeland which should benefit all inhabitants of the range. Mule deer should benefit in particular due to

reduced competition for forage, water, and space. Achieving AML would be essential for mule deer during

severe winters or times of drought.
19

Rocky Mountain Elk

Direct and Indirect Impacts - As stated under the Proposed Action, the BLM would avoid gathering

operations in elk crucial winter ranges (see Map 3, Appendix 1), thus no direct or indirect impacts to elk are

anticipated. In the event that an elk finds its way into an area outside of their winter range during gathering

operations, those individuals could be momentarily disturbed by the helicopter and/or wild horses as they

pass by. Any such impact would be temporary and unlikely to pose a serious threat to the animal.

Cumulative Impacts - Since elk and wild horses are both grazers that eat primarily grasses and saltbush for

the majority of their forage requirements, removing excess wild horses to achieve AML should benefit

overall rangeland health and specifically elk, due to reduced competition for forage and water. Achieving

AML would be imperative for elk during severe winters or times of drought.

Mitigation Measures - With implementation of the committed measures identified under the Proposed

Action, no additional mitigation measures have been identified for big game.

Raptors

Direct and Indirect Impacts - As stated under the Proposed Action, the BLM would avoid known active

nesting sites as determined by BLM Wildlife Biologist. Therefore, no direct or indirect impacts to nesting

raptors, specifically nesting golden eagles or great-horned owls (Map 4, Appendix 1), are anticipated. Wild

horses passing by or the helicopter flying overhead could disturb raptors in the immediate area where such

operations are occurring. Any such encounter, however, would be momentary and individuals would likely

resume their normal activity shortly thereafter.

Cumulative Impacts - Removal of excess wild horses should improve the overall health of the range, thereby

benefitting the prey species raptors depend upon.

Mitigation Measures - No additional mitigation measures are identified.

Greater Sage-Grouse

Direct and Indirect Impacts - As stated under the Proposed Action, the BLM would avoid a 2-mile radius

around leks (see Maps 2 and 4, Appendix 1) during gathering operations. Therefore, no direct or indirect

impacts to those grouse actually occupying leks during the late winter gathering time frame would occur.

However, should greater sage-grouse happen upon areas where gathering operations are actually occurring,

outside of the 2-mile radius around leks, there is potential for individuals to be trampled if they do not move

out of the way.

Cumulative Impacts - Removal of excess wild horses should improve the overall health of the range, thereby

benefitting greater sage-grouse nesting and brood rearing habitats.

Mitigation Measures - With implementation of the committed measures identified under the Proposed

Action, no additional mitigation measures are required.

Other Species
20

Direct and Indirect Impacts - As stated under the Proposed Action, the BLM would avoid prairie dog towns,

open or frozen water, and fenced areas; hence, direct or indirect impacts to those species (i.e., prairie dogs,

swift fox, etc.) inhabiting those areas would be avoided. Where gathering operations are actually occurring,

species within the immediate area would either temporarily move away or hide.

Cumulative Impact - Removal of excess wild horses should improve the overall health of the range, thereby

benefitting all species inhabiting the range.

Mitigation Measures - No additional mitigation measures are required.

Vegetation/Soils/Rangeland Health

Direct and Indirect Impacts - The removal of excess wild horses from inside the four wild horse HMAs and

areas outside of HMAs (i.e., the North Baxter/Jack Morrow Hills area) could avoid potential over-utilization

of forage and reduction in vegetative ground cover. Vegetation composition, cover, and vigor could

improve or be maintained near water sources where wild horses tend to congregate. An improvement in

forage condition could lead to improved livestock distribution, which would prevent over-utilization and

reduction in vegetation cover.

Removal of excess wild horses should help maintain vegetation cover. Potential for competition for forage

and water between wild horses, wildlife and livestock, and surface disturbing activity in general around

water sources should be reduced. Quantity of forage should increased. The increased vegetation cover

should protect soils and reduce erosion of the surface soil layer.

Reducing wild horse populations to established AMLs should ensure that adequate amounts of vegetative

ground cover remain at the beginning of each growing season to support water infiltration rates, maintain

soil moisture storage and transport, stabilize soils, allow natural rates of water release to support hydrologic

function, and to maintain subsurface soil conditions that support permeability rates and other processes

appropriate to the site.

Reducing wild horse populations to established AMLs will allow the management of other forage/vegetation

uses to maintain, restore, or improve riparian plant communities and proper stream function.

Cumulative Impacts - Managing wild horses at established AMLs will ensure that the combined levels of

forage use will maintain, enhance, or restore habitats for federally threatened or endangered species and

other federal or state species of concern. This action will also maintain or enhance the physical and

biological conditions necessary to sustain native animal populations and healthy rangeland plant

communities. Maintaining wild horse populations at AML would produce no cumulative negative impacts

to vegetation and soils. Managing wild horse populations at AML would assist in compliance with the

Wyoming Standards for Rangeland Health.

Mitigation Measures - Compliance with the committed measures described under the Proposed Action

precludes the necessity for additional mitigation.

Residual Impacts

See page 21 of the 1999 EA for a discussion of these impacts. They are expected to remain the same.
21

NO ACTION ALTERNATIVE

Wild Horses 

Direct and Indirect Impacts - No wild horses would be gathered or removed from public or private lands.

Previously identified impacts to wild horses from gathering, transporting, handling and entry into private

care (this document and the 1999 EA) would not occur.

Cumulative Impacts - Excess wild horses would not be captured and removed to achieve AML, during the

proposed gathering period. Pregnant mares that remain on the range will produce new foals adding to an

already overpopulation of wild horses. Gathering activities later in the year may mitigate this impact, only

if sufficient horses could be captured and processed. Current analyses (1999 EA Appendix D, Population

Modeling) indicate that to capture sufficient excess wild horses to achieve AML will require at least three

years at total capacity of the Rock Springs facility and available labor. It is for this reason that gathering of

wild horses, as prescribed under the Proposed Action, allows for more efficient use of facilities and labor,

thereby increasing the ability to achieve AML.

Mitigation Measures - Removing and processing more wild horses during the July 15 through early winter

gathering period could mitigate the short-term direct and indirect impacts and long-term cumulative impacts.

Existing and potential future limitations in facilities, labor, budget, weather, and adoption demand could

render this mitigation ineffective to address the long-term cumulative impacts to the wild horses and their

habitat.

Wildlife

In general, wildlife species could be adversely impacted by the No Action Alternative. Not achieving or

maintaining AML could result in a reduction in the quality of habitat due to increased competition for forage

and space, and degradation of water-related habitats.

Big Game Species

Pronghorn Antelope

Direct and Indirect Impacts - No direct or indirect impacts to antelope are expected should the No Action

alternative be implemented.

Cumulative Impact - By not achieving AML, overpopulation of wild horses left on the range is expected to

have detrimental effects on antelope over the long term. Continued competition for forage and water

resources could contribute to the decline of antelope populations and habitat conditions, especially during

times of severe weather events (i.e., severe winter, drought).

Mule Deer

Direct and Indirect Impact - No direct or indirect impacts to mule deer are expected should the No Action

alternative be implemented.

Cumulative Impact - Based on Stephenson’s (1982) findings, there would be increased competition for

forage and water resources should the wild horse population be allowed to increase unchecked. Continued
22

competition for such resources would likely contribute to the decline of mule deer populations and habitat

conditions, especially during times of severe weather events (i.e., severe winter, drought).

Rocky Mountain Elk

Direct and Indirect Impact - No direct or indirect impacts to elk are expected should the No Action

alternative be implemented.

Cumulative Impact - Based upon Stephenson’s (1982) findings, elk would likely be severely impacted by

unchecked wild horse population increases. Continued and increased competition for forage, space, and

water could contribute to the decline of elk populations and habitat conditions, especially during times of

severe weather events (i.e., severe winter, drought).

Mitigation Measures - With increasing numbers of wild horses, a reduction in the numbers of pronghorn

antelope, mule deer, and Rocky Mountain elk may be required.

Raptors

Direct and Indirect Impacts - No direct or indirect impacts to raptors would be expected with implementation

of the No Action alternative.

Cumulative Impacts - By not achieving AML, growth in wild horse populations could lead to range

degradation resulting in a reduction of prey species.

Mitigation Measures - No additional mitigation measures have been identified.

Greater Sage-Grouse

Direct and Indirect Impacts - No direct or indirect impacts to greater sage-grouse would be expected with

implementation of the No Action alternative.

Cumulative Impacts - Braun (1987) and Dobkin (1995) found indirect evidence suggesting that excessive

grazing in breeding and brood-rearing habitat may have an adverse impact on greater sage-grouse

populations. Reductions in cover and forage caused by grazing and trampling by excess free-roaming wild

horses could lead to further population decline.

Mitigation Measures - No additional mitigation measures have been identified.

Other Species of Interest

Direct and Indirect Impacts - No direct or indirect impacts to other species would be expected with

implementation of the No Action alternative.

Cumulative Impacts - A reduction in rangeland health could lead to population declines for other species.

Mitigation Measures - No additional mitigation measures have been identified.

Vegetation/Soils/Rangeland Health
23

Direct and Indirect Impacts - The 1999 EA addresses the direct and indirect impacts of the No Action

alternative. There are no additional direct impacts to these resources due to the No Action Alternative.

Achievement of compliance with rangeland health standards where excessive forage removal has been

determined to be a causative factor would not result from the No Action alternative. Selection of the No

Action Alternative would require more time to improve rangeland health, if possible at all. Reductions of

other forage uses to accommodate the current and projected over-population of wild horses may need to

occur. Horses not removed prior to the growing season would continue to use forage. This could hinder

potential plant growth affecting the vegetation and soil resources, and therefore rangeland health.

Cumulative Impacts - Since not gathering wild horses may have only short-term impact on achieving AML,

cumulative impacts to soils and vegetation would be difficult to predict. These impacts would depend upon

the ability to achieve AML through the removal of wild horses outside of the February 15 to March 31

period.

If wild horse numbers are allowed to continue to increase to multiples of AML, so does the likelihood that

adverse cumulative impacts to plants and other animals would occur over time. See cumulative impact

analysis sections under Wild Horses and Wildlife for specific discussion.

Mitigation Measures - Additional wild horses would need to be captured at times other than that identified

under the Proposed Action to assure that authorized wild horse numbers are achieved and maintained.

Removing and processing more wild horses during the July 15 through early winter gathering period could

mitigate the short-term direct and indirect impacts and long-term cumulative impacts to rangeland health.

Existing and potential future limitations in facilities, labor, budget, weather, and adoption demand could

render this mitigation ineffective to address the long-term cumulative impacts to the health of the public

rangelands.

Residual Impacts

Residual impacts are addressed in the 1999 EA on page 24 and would remain the same.
24
25

CHAPTER V - CONSULTATION AND COORDINATION 

Chapter V of the 1999 EA provides further discussion of the history of wild horse gathering in the RSFO

area and checkerboard lands.

This EA has been distributed to the public for review and comment. Copies of this EA are available at the

Rock Springs Field Office and on the internet at: http://www.wy.blm.gov/currentnews/

wildhorses/WILDHORSEADOPTION.HTML.

This EA has been sent to those individuals or organizations who specifically requested continued

participation during public scoping period. These individuals and organizations include:

Individuals:

Ida Anderson

Jon Child

Lloyd Eisenhauer

Dr. Patricia Fazio

C. Fuhrmann

Laurie Hamilton (email)

Leonard Hay

James Magagna

Chadwick McBurney

Dave Pauli

Bill Taliaferro

Clark Weber

Carricaburu-Jauregui

Organizations:

American Mustang & Burro Association

Animal Legal Defense Fund

Animal Protection Institute

Colorado Wild Horse & Burro Coalition

Doris Day Animal League

Earthjustice Legal Defense Fund

Fund for Animals

Rock Springs and Green River Chambers of

Commerce

Rocky Mountain Elk Foundation

SPCA

Sweetwater Wildlife Association

Taurus Production

Western Wyoming Mule Deer Foundation

Wyoming Advocates for Animals

Governmental Agencies/Representatives:

BLM - Wyoming State Office and Rawlins and White River Field Offices

Commissioners for Sublette, Fremont, Sweetwater Counties

Mayor of Superior

Pati Smith, Representative for U.S. Senator Craig Thomas

Rock Springs Library

State Representatives: Stephen Watt, Louie Tomassi

U.S. Congressional Representatives

U.S. Fish and Wildlife Service

University of Wyoming, Department of Renewable Resources, Collections Department

Wyoming Game and Fish Department

Wyoming Office of Federal Land Policy

Wyoming State Grazing Board
26

Western Wyoming Community College (WWCC)

Livestock Operators:

Grey’s River Livestock Co

Rock Springs Grazing Association, Marty and Ragsdale (attorney for RSGA)

A press release was issued to the following local and state media informing the public that this EA is

available for review.

Newspapers:

Associated Press - Cheyenne

Bridger Valley Pioneer

Casper Star-Tribune

Green River Star

Jackson Hole News

Jackson Hole Guide

Kemmerer Gazette

Little Chicago Review

Pinedale Roundup

Rawlins Daily Times

Rock Springs Daily Rocket-Miner

Sublette County Journal

Uinta County Herald

Wyoming State Journal

Radio Stations:

K2 Radio Network

KEVA - Evanston

KMER - Kemmerer

KMTN - Jackson

KPIN - Pinedale

KQSW/KRKK/KSIT - Rock Springs

KUGR/KYCS - Green River

Wyoming Radio Network

Television Stations:

KFNB-TV - Casper

KGWC-TV - Casper

KTWO-TV - Casper
27

Preparers and Document Review

Teri Deakins - Environmental Protection Specialist, Rock Springs Field Office

Thor Stephenson - Rangeland Management/Wild Horse Specialist, Rock Springs Field Office

Lorraine Keith - Wildlife Biologist, Rock Springs Field Office

Jim Glennon - Botantist, Rock Springs Field Office

Bernie Weynand - Assistant Field Manager for Resources, Rock Springs Field Office

Vic McDarment - Lead Wrangler, Rock Springs Field Office

Angelina Pryich - Editor, Rock Springs Field Office

Dave Roberts - Wildlife Biologist, Wyoming State Office

Don Glenn - Wild Horse and Burro Specialist, Wyoming State Office

Tim Bottomley - Environmental Protection Specialist, Wyoming State Office

Ron Shane - BLM Contracted Helicopter Pilot, Timberline Helicopters
28
LITERATURE CITED

American Ornithologists' Union 2000. Forty-second supplement to the American Ornithologists' Union,

Check-list of North American Birds. Auk 117:847-858.

BLM 1997. Standards for Healthy Rangelands and Guidelines for Livestock Grazing Management for Public

Lands Administered by the Bureau of Land Management in the State of Wyoming. 08/27/97. 16 pages.

Braun, CE 1987. Current issues in sage grouse management. Proceedings of the Western Association of

Fish and Wildlife Agencies. 67:134-144.

Dobkin, D.S. 1995. Management and conservation of sage grouse, denominative species for the ecological

health of shrub steppe ecosystems. U.S. Dept. of Interior, Bureau of Land Management, Portland, Oregon.

Hansen, Kyle V., and Mosley Jeffrey C., 2000. Effects of roundups on behavior and reproduction of feral

horses. J. Range Mgmt., 53: 479-482.

Meeker, J.O. 1982. “Interactions between pronghorn antelope and feral horses in northwestern Nevada,”

J.M. Peek and P.D. Dalke, Editors, 1982, in Wildlife-Livestock Relationships Symposium: Proceedings 10.

University of Idaho. Forest, Wildlife and Range Experiment Station, Moscow, Idaho. 614 pages.

Stephenson, Thor E. 1982. “Diet Botanical Composition for Pronghorn Antelope and Other Ungulates in

Northcentral New Mexico.” Masters Thesis. New Mexico State University, Las Cruces, New Mexico.

Wyoming Game and Fish Department 1999. Green River Region Annual Herd Unit Reports 1999.
APPENDIX 1

MAPS




APPENDIX 2

LETTER FROM ROCK SPRINGS GRAZING ASSOCIATION










APPENDIX 3

SPECIES LISTED and PROPOSED FOR LISTING
The FWS provided a list with the following species as potentially affected by the Proposed Action. The

matrix below shows the occurrence of and effect on these species.

Threatened, Endangered, and Proposed Species

Listed and Proposed Species:

Species Status Expected Occurrence Affect

Black-footed ferret

(Mustela nigripes)

Endangered Potential resident in

prairie dog (Cynomys sp.)

colonies

No affect.

Prairie dog towns are

avoided due to potential

for injury to wild and

domestic horses.

Whooping crane

(Grus americana)

Experimental Resident. Migrant No affect.

No potential habitat

involved in gathering

areas or at trap sites.

Bald eagle

(Haliaeetus leucocephalus)

Threatened Nesting. Winter resident. 

Migrant

No affect.

No potential habitat

involved in gathering

areas or at trap sites.

Mountain plover

(Charadrius montanus)

Proposed Grasslands statewide No affect.

Late winter gathering and

removal operations occur

prior to nesting period.

Ute Ladies’-tresses

(Spiranthes diluvialis)

Threatened Platte River drainages

below Alcova and

Cheyenne and Niobrara

drainages (possible in

Uinta and Sweetwater

counties).

No affect.

No spring gathering

operations or trap sites

proposed in potential

habitat. Plants dormant.

Colorado River Fishes:

Bonytail chub

(Gila elegans)

Colorado pikeminnow

(Ptychocheilus lucius)

Humpback chub (Gila cypha)

Razorback sucker 

(Xyrauchen texanus)

Endangered Downstream resident of

Green River System.

No affect. 

No water depletions

planned.