Gather Policy, Selective Removal Criteria, and Management Considerations for Reducing Population Growth Rates

IM 2010-135
Instruction Memorandum



June 2, 2010


­­­­­­­In Reply Refer To:

4710 (WO 260) P



Instruction Memorandum No. 2010-135

Expires: 09/30/2011


To:                   All Field Officials (except Alaska)

From:               Assistant Director, Renewable Resources and Planning

Subject:           Gather Policy, Selective Removal Criteria, and Management Considerations for Reducing Population Growth Rates

Program Area:  Wild Horse and Burro Program.

Purpose:  This Instruction Memorandum (IM) establishes gather policy and selective removal criteria for wild horses and burros (WH&B).  


A.  Gather Requirements

1.   Achieve Appropriate Management Level (AML)

Periodic removals will be planned and conducted to achieve and maintain WH&B population size within the established AML range.  Removals below the AML lower limit may be warranted in emergency situations, based on the available forage and water.  Rationale to justify a reduction below the AML lower limit must be included with the gather request consistent with guidance provided in IM 2009-085 (Managing Gathers Resulting from Escalating Problems and Emergency Situations).

2.   National Environmental Policy Act (NEPA) Analysis and Decision

An appropriate site-specific analysis of the potential impacts that could result from implementation of a proposed gather is required, unless an emergency situation exists.  NEPA documentation will include the Standard Operating Procedures (SOPs) for Wild Horse & Burro (WH&B) Gathers (Attachment 1).

A key element of the NEPA analysis is to examine current information and determine whether excess WH&B are present and require immediate removal.  In making this determination, the authorized officer will analyze: grazing utilization and distribution, trend in range ecological condition, actual use, climate (weather) data, current population inventory, WH&B located outside the Herd Management Area (HMA), or in Herd Areas (HA) not designated for their long-term maintenance, and other factors such as the results of land health assessments which demonstrate removal is needed to restore or maintain the range (refer to The Wild Free-Roaming Horses and Burros Act (WFRHBA), 43 USC 133, and Animal Protection Institute of America, 109 IBLA 112 (1989)). 

Excess animals are defined as those which must be removed to preserve and maintain a thriving natural ecological balance and multiple use relationship in that area. 

Among other things, the NEPA analysis will also contain the following:

  1. Results of Win Equus population modeling that forecasts the potential impacts to the wild horse population that could result from the proposed removal and other management actions such as fertility control treatments or sex ratio adjustments.  (The model is not designed for use on burros).
  1. A desired post-gather on-the-range population number, age structure, and sex ratio for the managed population.
  1. Detailed analysis of a range of appropriate management alternatives to reduce population growth rates and extend the gather cycle.  See E. below.
  1. Hair samples will be collected to establish genetic baseline data, as outlined in IM 2009-062 (Wild Horse and Burro Genetic Baseline Sampling).  Genetic material will be collected for all HMAs that do not yet have an established genetic baseline during the next gather.  Once a baseline is established, additional samples should be collected to reassess genetic diversity every other gather (e.g., every 6-10 years).  If initial testing indicates diversity is less than desired, the herd should be reassessed more frequently (e.g., every gather). 

3.   Gathers that have been approved by the Washington Office (WO) through the annual work plan process and that are listed on the National Gather Schedule may proceed without further approval from WO-260.  Changes to the gather schedule involving increased removal numbers for listed gathers, adding new gathers, or substituting gathers require approval by WO-260.  Requests for such gathers will be submitted to WO-260 and National Program Office (NPO) for consideration and approval by the WO-260 Division Chief.

WO-260 approval is not required for the removal of 15 or fewer nuisance WH&B at one time unless one of the national contractors conducts the removal.  An animal may be considered a nuisance if it, for example, poses a safety hazard or strays onto private property and the landowner requests removal. 

4.   A Gather, Removal, and Treatment Summary Report (Attachment 2 – Table 1) is required for each WH&B gather.  The Daily Gather Activity Log (Attachment 2 - Table 2) must be completed daily for each HMA and submitted to WO-260, NPO, State Office, and Field Office representatives every 1-2 days in order to communicate gather progress during large, lengthy gathers.  Final Gather, Removal, and Treatment Summary Reports are required and must be submitted to the State WH&B Lead and NPO (WO-260) within 10 days of gather completion.

B.   Selective Removal Criteria 

The selective removal criteria described below apply to all excess wild horses removed from the range.  These criteria are not applicable to wild burros.  When gathers are conducted, emphasis will be placed on the removal of younger, more adoptable animals.  Occasionally, budgetary limitations may require the consideration of “gate cut” removals and exceptions to the selective removal criteria to achieve population objectives.

In accordance with IM 2009-041 (Euthanasia of Wild Horses and Burros for Reasons Related to Health, Handling and Acts of Mercy), animals with conditions that compromise animal well- being, result in chronic lameness, have a genetic defect, or otherwise meet the criteria for euthanasia should be euthanized instead of being removed or retained in the herd.

  1. Age Criteria:  Wild horses  will be removed in the following order:

a)   Age Class - Four Years and Younger                                                                                                                                                                                                                                         

Wild horses 4 years of age and younger should be the first priority for removal and placement into the national adoption program.

b)   Age Class - Eleven to Nineteen Years 

Wild horses aged 11 to 19 years of age should be removed from the HMA only if management goals and objectives for the herd cannot be achieved by removing horses 4 years and younger or if specific exceptions prevent them from being turned back and left on the range.

     c)   Age Class - Five to Ten Years Old

Wild horses 5 to 10 years of age are the lowest priority for removal and should be removed only if management goals and objectives for the herd cannot be achieved through the removal of animals identified in a) and b) above.

d)   Age Class - Twenty Years and Older 

Wild horses aged 20 years and older should not be removed from the HMA unless specific exceptions prevent them from being turned back and left on the range. In general, this age group can survive on the HMA but can have greater difficulty adapting to captivity and the stress of handling and shipping if removed.

C.  Animal Health and Welfare

Some emergency gather situations caused by such things as extreme drought conditions or wildfire have potential to result in animal health and welfare issues at temporary holding facilities or trap site locations.  If animal health or welfare is a potential concern, the authorized officer will ensure a veterinarian is on call or is onsite (as needed) to provide recommendations to the BLM authorized officer regarding animal care, treatment, and if necessary, euthanasia.  

Animals encountered during gather operations that must be removed but, in the opinion of the authorized officer, may not tolerate the stress of transportation, preparation, and holding, should be euthanized onsite using methods acceptable to the American Veterinary Medical Association (AVMA).  Some situations, such as removals from private land, may require exceptions to this practice.  Any animals affected by a chronic or incurable disease, injury, lameness, or serious physical defect (including severe tooth loss or wear, club feet, and other severe acquired or congenital abnormalities), should also be euthanized in the field according to direction in IM 2009-041. 


  1. Potential Exceptions to Selective Removal Criteria

Animals should be removed irrespective of their age class when they fall into one of the following categories or when one of the following conditions applies.


  1. Nuisance animals.
  1. Animals residing outside an HMA or in a HA not designated for their long-term maintenance.
  1. All captured animals in an HMA have to be removed to attain AML when capture efficiency does not allow enough animals to be captured to practice selective removal.  One exception is that animals 20 years and older should not be removed.
  1. Animals that fall outside of any selective management prescriptions in a land use plan (LUP) or activity plan.  For example, some LUPs or activity plans might identify certain unique characteristics (examples: Spanish characteristics, Bashkir Curly, or other traits), sex ratios, or age classes for which a particular HMA is to be selectively managed.
  1. Total removals required by law or land use plan decisions.
  1. Court-ordered gathers.
  1. Emergency gathers (see IM 2009-085 on escalating problems and emergency gathers).

E.   Management Considerations in Addition to Selective Removal

During gather or herd management area planning, the authorized officer will consider a range of alternatives to reduce (slow) population growth rates and extend gather cycles for all wild horse herds with annual growth rates greater than or equal to 5%.  These alternatives may include (but are not limited to): fertility control, adjustments in the sex ratio in favor of males, a combination of fertility control and sex ratio adjustment, and management of selected HMAs for non-reproducing wild horses.

  1. Sex Ratio Management

Consider managing herds for a sex ratio with a female component less than or equal to 50 percent, as this reduces the population growth rate and extends the gather cycle. 

Adjusting sex ratios to favor males may be appropriate when the suppression of herd growth rates is desired.  This management option should especially be considered in HMAs and complexes where the low end of AML is greater than 150 animals.  This is most feasible and applicable during maintenance gathers that normally occur 3 to 4 years after AML has been achieved.  Sex ratio adjustments may be accomplished by shifting the overall sex ratio to favor males by releasing greater numbers of stallions or geldings to adjust/shift the overall sex ratio so that males comprise 60 to 70 percent of the adult herd.

Initial management efforts involving sex ratio adjustments that favor stallions or a gelding component should be monitored closely.  This monitoring information will be used to determine if sex ratio adjustment is an effective population management technique that should be continued.

  1. Fertility Control

Additional guidance and policy on the use of fertility control as a population management tool is contained in IM 2009-090 (Population-Level Fertility Control Field Trials: Herd Management Area (HMA) Selection, Vaccine Application, Monitoring and Reporting Requirements).  Follow the guidance in IM 2009-090 to prepare Gather Plan/NEPA documents that propose the use of fertility control.  Explain the reasons for applying or not applying fertility control in the decision document.

The authorized officer should apply the 22-month PZP vaccine to all release mares, when the NEPA analysis supports its use.  In herds where sex ratio adjustments are made, fertility control may be implemented in combination with sex ratio adjustments to further reduce herd growth rates. 

3.  Non-Reproducing Wild Horses

Under the WFRHBA (16 U.S.C. § 1333(b)(1)), the authorized officer may determine whether AML should be achieved by removal of excess animals, or if options such as sterilization or natural population controls should be implemented.  Consistent with this authority, some selected HMAs may be managed in whole or in part for non-reproducing wild horses to aid in controlling on-the-range population numbers.

Land use plans should identify the HMAs to be managed for non-reproducing wild horses and identify the criteria for their selection.  Completion of additional site-specific environmental analysis, issuance of a decision, and providing opportunity for administrative review under 43 CFR Part 4.21 may also be necessary for implementation of non-reproducing wild horses. 

Actual on-the-ground implementation would be influenced by gather efficiency and it may take several gathers to work toward an HMA with non-reproducing wild horses.  Animals would be gathered to the extent possible and sterilized for return to the range, or removed.  A safe, effective, and humane means to sterilize males is castration, but a safe, effective and humane means to sterilize females has not yet been perfected.  Therefore, initial efforts should focus on returning sterilized males to the HMA.  Sterilized males from HMAs with similar environments may be added as long as population size remains within AML.  Care should be taken to ensure the animals are introduced and located near other animals in areas with good water and forage. 

Timeframe: This IM is effective immediately.

Budget Impact:  Implementation of this policy will achieve cost savings by reducing the number of excess animals removed from the range and minimizing the numbers of less adoptable animals removed.  Budgetary savings for each foal not born due to fertility control and sex ratio adjustments  are about $600 for capture, $1,100 for adoption prep and short-term holding, $500-1,000 for adoption costs, and approximately $475 per year for long-term holding of animals removed but not adopted.  For each animal that would have been maintained at long-term holding for the remainder of its life after capture, the total cost savings is about $13,000.

Background:  The 1992 Strategic Plan for the WH&B program defined criteria for limiting the age classes of animals removed so that only the most adoptable animals were removed.   The selective removal criteria from Fiscal Years 1992 through 1995 allowed the removal of animals 5 years of age and younger.  In 1996, because of drought conditions in many western states, the selective removal policy was changed to allow for the removal of animals 9 years of age and younger.  In 2002, the removal policy was modified to allow for prioritized age specific removals:  first priority - remove 5 years of age and younger animals, second priority - 10 years and older and last priority - remove animals aged 6 to 9 years if AML could not be achieved. 

The new selective removal policy provides for the long-term welfare of on-the-range populations, emphasizes the removal of the most adoptable younger animals to maintain and achieve AML, and directs that older horses that must be removed but are unadoptable or less able to stand the rigors of capture, preparation, and transportation stay on the range or be euthanized.

Manual/Handbook Sections Affected:  None.

Coordination: Varying policies on selective removal have been in place and coordinated with field staffs since the early 1990s.  The revised policy was developed by the WO, circulated to field offices for review and comment, and presented to the National Wild Horse and Burro Advisory Board.  In addition, the concept of selective removal was part of the FY 2001 Strategy to Achieve Healthy Lands and Viable Herds; The Restoration of Threatened Watersheds Initiative that was widely communicated to Congress and the general public.

Contact: Questions concerning this policy should be directed to Susie Stokke at 775-861-6623.


Signed by:                                                       Authenticated by:

Bud Cribley                                                    Robert M. Williams

Acting, Assistant Director                              Division of IRM Governance,WO-560

Renewable Resources and Planning



2 Attachments

1 - Standard Operating Procedures for Wild Horse Gathers (7 pp)

2 - Gather, Removal and Treatment Summary Report (3 pp)