Take Action for Onaqui Wild Horses in Utah

Photo of Onaqui horses by Kelly Jay Photography

Comments Due by Friday, March 6, 2015

The Bureau of Land Management (BLM) Salt Lake City, Utah Field Office is seeking public comment on an Environmental Assessment (EA) that analyzes the continued use of PZP fertility control on the Onaqui Mountain wild horses.

The American Wild Horse Preservation Campaign (AWHPC) advocates for more effective use of PZP on the Onaqui wild horses as an alternative to the roundup and removal of these beloved mustangs. The long-range goal is to achieve a balance between natural mortality and reproduction rates in order to eliminate the need for removals, so that every wild horse born in the Onaqui Mountains can live free and die wild in their homes on the range. Additional information on our position on fertility control is available here.

Please help us encourage the BLM to continue on this path to more humane on-the-range management of our beloved wild horses. 


If you prefer, you can send your comments to the address below. All comments must be received no later than Friday, March 6, 2015

Bureau of Land Management
Salt Lake Field Office
Attn: Pam Schuller
2370 South 2300 West
Salt Lake City, UT 84119

Email: blm_ut_cedarmt_onaqui@blm.gov

Constituents outside the United States are not eligible to send an email using our web form above. International comments must be mailed or emailed to the addresses above.

Photo of Onaqui Herd by Kelly Jay Photography


Onaqui Mountain Herd Management Area Fertility Control Environmental Assessment (EA)

Read AWHPC's Position on Fertility Control

Appropriate Management Level (AML) of Onaqui wil horses is 121-210.

Livestock Grazing Forage Allocationsin the Onaqui HMA: ~5,649 Animal Unit Months (AUMs)

Wild Horse Forage Allocation in the Onaqui HMA: - 1.452 - 2,520 AUMs

Quotes from EA:

  • "The purpose is also to stabilize the population in order to reduce the need for larger helicopter gather and removal operations"
  • "The BLM SLFO proposes to apply fertility control to select mares on the Onaqui HMA through 2020 (or as long as it can be reasonably concluded that no new information and no new circumstances have substantially changed in the area of analysis) in order to help maintain a population of 160 adult wild horses which is within the AML range of 121–210 adult wild horses. The fertility control would involve the use of PZP, single dose inoculations and the delivery system would be through the use of dart guns. The proposed action would consist of the administration of remote darting of PZP applied in the one year liquid dose and would start in 2015. The primary window for treatment would be November through February, although previously treated mares could receive a booster any time of the year. If it is determined that a mare or mares cannot be approached within darting range on foot, then baiting would be utilized. The expectations for the proposed action include: the short-term goal is to bring growth rates to less than seven percent and the long-term goal is to reduce the need for gathers and removals, without jeopardizing the genetic health of the herd."
  • "In about late March to early April of 2015, mares that are one year of age would receive a primer inoculation of PZP and 30–60 days following that treatment would receive a booster dose of PZP then be treated annually with single dose of one-year PZP for no more than five (5) consecutive years.To ensure that the genetic diversity of the herd is maintained: After year 5, there would be no further application of PZP until the (approximately 6 year old) mare produces a live foal. Once the mare has foaled, she would then be treated annually for the remainder of her natural life."
  • "From the treatment in February 2012, we did see a reduction in the number of foals born in 2013 as expected. We estimated that the growth rate for the population was 7 percent opposed to 16–20 percent seen before any treatment or in years after the mares returned to fertility."
  • "Safety of the contraceptive agent is an important consideration. The agent to be used in the Onaqui Mountain HMA is liquid, one-year PZP and has been studied and applied to wild horses for 21 years. The vaccine’s contraceptive effects are reversible, if used no more than five consecutive years (Kirkpatrick and Turner 2002). The PZP vaccine is safe to use in pregnant mares: it would not affect the health or survival of foals that were in utero when the mother was treated (Turner and Kirkpatrick 2002). This is important consideration given the 340 day gestation period of horses and the likelihood that some pregnant animals would be treated in the course of management."
  • "Remote-delivery of the fertility control vaccine would result in fewer disturbances to the herd and support a minimum feasible level of management."
  • "Mares on liquid, one-year PZP-treatment had improved body condition scores, decreased herd and foal mortality, and substantially increased longevity (Turner and Kirkpatrick 2002; Kirkpatrick andTurner 2007)."
  • "Aggression between stallions and mares has also been studied in 3 wild horse populations and no difference was found between the treatment groups (Ransom et al 2010)."