Horse News

Wild Horses: Selective Breeding and Roundups Are Driving Herds To Extinction

The Bureau of Land Management (BLM) and the U.S. Forest Service are undermining the long-term survival of native species American wild horses

The Bureau of Land Management (‘BLM’) is arguably guilty of willful ignorance in the ongoing grossly negligent management of native species American wild horses.

Wild Horses are ‘keystone herbivores’ and are critical components in a balanced ecosystem: Image from Rewilding Europe

Moreover, the BLM is guilty of intentionally spreading misinformation about native species wild horses, by misinforming the public and elected officials with made-up ‘facts’ that are contrary of genuine science.

One example, is this false statement made by the BLM:

“Wild horses have no natural predators …”

This a manifestly false statement promoted by the BLM in order to deceive the public into thinking that their management using roundups and drugging wild horses with PZP is the only alternative, which is contrary to facts and available alternatives.

That false *statement appears in a so-called management plan that was presented to the Congress of The United States in writing titled; ‘Report To Congress – Management Options For A Sustainable Wild Horse And Burro Program’.

*Executive Summary, Page-1, paragraph 5:

FACT: Mountain lions, bears, wolves, and coyotes are all the co-evolved predators of wild horses in North America. [1]

Only a corrupted or ignorant agency or organization would propose to manage any resource based upon misinformation.

The BLM is intentionally engaged in a campaign of roundups designed to reduce wild horse populations to sub-minimal levels required for genetic vigor.

According to the best available science, when herds are brought down to populations under the minimum of 250 breeding adult wild horses, inbreeding begins, which leads to the loss of genetic vigor and results in genetic erosion.

The term ‘Appropriate Management Level’ (‘AML’) is an oxymoron.

There is nothing that is genetically or ecologically ‘appropriate’ about reducing the population of any species of protected wildlife below the minimum population required to maintain genetic strength and diversity.

Further exacerbating this situation is that many of the mares that are allowed to remain on the range, or that are subsequently released back onto the range by the BLM (merely a photo-op for the BLM), are treated with chemicals that render mares infertile (non-breeding).

Selective Breeding of Native Species American Wild Horses Using Drugs

The BLM and wild horse non-profit organizations and activists who are engaged in selective breeding of native species American wild horses are meddling with natural processes that are critical for the long-term survival of the species.

When a human decides which animals get to breed and/or which do not, that is selective breeding. And that is contrary to the intent of the Wild Free-Roaming Horses and Burros Act (WFRHBA).

Selective breeding of wild horses by humans disintermediates the evolutionary process of ‘Natural Selection’, which is critical to the continued survival and genetic vigor of wild horses. It is an essential evolutionary process in any co-evolved predator-prey relationship. This is why it is flawed management to maintain wild horse populations that are commingled with livestock populations in Herd Areas that have been made devoid of apex predators. This is great for livestock production, but terrible for wild horses, which require and depend upon their co-evolved predators for their genetic vigor and population equilibrium within any ecosystem.

Regardless of ‘good intentions’ by some wild horse non-profit organizations and activists, doing the wrong things for wild horses is harmful and inexcusable.

Excuses that posit the use of chemical contraception (PZP and GonaCon) on native species American wild horses as the best solution for overpopulation are examples of a poor understanding of evolutionary science. And this ignorance is driving the irreversible damage that is being done to the remaining populations of American wild horses.

Egregiously, these highly-flawed management tactics are being used by the BLM and non-profit organizations while concurrently there exists a superior paradigm for managing wild horses naturally and allowing them to remain truly ‘wild and free’. That ‘superior paradigm’ allows wild horses to resume their longstanding evolutionary roles in the wilderness as keystone herbivores, which balance ecosystems and help to mitigate the intensity and frequency of wildfires via reductions of prodigious grass and brush.

An article at GrazeLIFE explains this novel paradigm in greater detail:

“Fertility control in free‐roaming wildlife populations has been associated with changes in immigration (Ramsey 2005; Merrill, Cooch & Curtis 2006), decreased group fidelity (Nuñez et al. 2009; Madosky et al. 2010), increased survival (Caughley, Pech & Grice 1992; Kirkpatrick & Turner 2007; Williams et al. 2007), altered reproductive behavior (Nuñez, Adelman & Rubenstein 2010; Ransom, Cade & Hobbs 2010) and shifted phenology (Ransom, Hobbs & Bruemmer 2013)” ~ Ecological feedbacks can reduce population‐level efficacy of wildlife fertility control. [2]

The use of chemicals to control wild horse populations (wildlife) disintermediates evolutionary Natural Selection and leads to genetic erosion and social disruptions in wild horses (equids). And using chemicals offers no genuine long-term sustainable benefits for either side of the wild horse management debate. [2]


Aside from the social breakdown of family bands, genetic erosion and selective breeding that are all part of using PZP on free-roaming native species American wild horses, we find:

“Even on a large animal struck correctly, the dart (contraceptive PZP and GonaCon darts) can cause hemorrhage and hematoma. Misplaced shots can break bones or even kill the animal” (Thomas and Marburger 1964). Report–Muzzle report can cause problems in darting either captive or free-ranging animals. In captive situations, the noise can be more disturbing to animals than getting struck with a dart. Disturbed animals are then more difficult to approach, or the entire group of animals may run away” ~ Page 32; Overview of Delivery Systems for the Administration of Contraceptive to Wildlife”, by Terry J. Kreeger


Violating The Intent of the 1971 Wild Free Roaming Wild Horse and Burro Protection Act.

Stalking and shooting wild horses with powerful gas-powered firearms is in itself a ‘harassment’ of wild horses and is an arguable violation of both the intent and codified specifications of the 1971 Wild Free Roaming Wild Horse and Burro Protection Act.

Based-on Terry J. Keeger’s study, by promoting the use of PZP and using PZP on American wild horses, non-profit organizations who support PZP, are arguably using donation funds to encourage harming wild horses in violation of the intent of very Act that seeks to protect them.


1. Knopff KH, Knopff AA, Kortello A, Boyce MS. (2010). Cougar Kill Rate and Prey Composition in a Multiprey System. Journal of Wildlife Management 74(7):000–000; 2010; DOI: 10.2193/2009-314. Downloaded at 7
French, Brett. (2010, December 9). Ferocious appetites: Study finds mountain lions may be eating more than previously believed. Billings Gazette. Retrieved from

Turner JW Jr and Morrison ML. (2001). Influence of Predation by Mountain Lions on Numbers and Survivorship of a Feral Horse Population. The Southwestern Naturalist. Vol. 46, No. 2 (Jun., 2001), pp. 183-190. Available at

Greger, Paul D. and Romney, Evan M. (1999). High foal mortality limits growth of a desert feral horse population in Nevada. Great Basin Naturalist: Vol. 59: No. 4, Article 10. Available at:

French, Brett. (2004, August 12). Lions blamed for deaths of Pryor foals. Billings Gazette. Retrieved from 89-31a1-5110-8fb5-a21e9f753de7.html

2. ‘Ecological feedbacks can reduce population‐level efficacy of wildlife fertility control’

‘Consequences of porcine zona pellucida immunocontraception to feral horses’

‘Genetic variation, inbreeding and chemical exposure—combined effects in wildlife and critical considerations for ecotoxicology’

‘Immunocontraception in wild horses (Equus caballus) extends reproductive cycling beyond the normal breeding season’

‘Effects of porcine zona pellucida immunocontraceptives in zoo felids’

‘Is Wildlife Fertility Control Always Humane?’

Gray ME and Cameron EZ. (2010). Does contraceptive treatment in wildlife result in side effects? A review of quantitative and anecdotal evidence. [“Two main impacts of immunocontraception have been proposed; 1) genetic resistance could evolve, similar to the response seen to other biological control agents (Magiafoglou et al. 2003), and 2) immunocontraceptives could be selecting for immuno-compromised individuals since those treated females that do breed have a lower immune response to the contraceptive (Nettles 1997, Cooper & Herbert 2001).”] Reproduction 139, 45-55. Online publication date: 1-Jan-2010. Retrieved at

Knight, Colleen M., Rubenstein, Daniel I. (2014). The Effects of Porcine Zona Pellucida Immunocontraception on Health and Behavior of Feral Horses (Equus caballus). [“Inducing sterility … may have unintended consequences on population dynamics by increasing longevity and eliminating the mares’ ability to contribute genetically.”] Princeton University Thesis, Ecology and Evolutionary Biology. Available at

3. ‘Influence of ruminant digestive processes on germination of ingested seeds’

‘Ruminant Digestion’:

4. ‘Collapse of the world’s largest herbivores’:
“By altering the quantity and distribution of fuel supplies, large herbivores can shape the frequency, intensity, and spatial distribution of fires across a landscape”. William J. Ripple1, Thomas M. Newsome1,2,Christopher Wolf1, Rodolfo Dirzo3, Kristoffer T. Everatt4, Mauro Galetti5, Matt W. Hayward4,6, Graham I. H. Kerley4, Taal Levi7, Peter A. Lindsey8,9, David W. Macdonald10, Yadvinder Malhi11, Luke E. Painter7, Christopher J. Sandom10, John Terborgh12 and Blaire Van Valkenburgh13

5. ‘Can Wild Horses Help Prevent Wildfires in the West?’

#Wild Horses, #WildHorses, #BureauofLandManagement, #USFS, #Ecology, #Rewilding

William E Simpson
Wild Horse Ranch Productions
+1 858-212-5762
email us here

Wildfire continues to devastate the American West. According to some, the plan that could combat the danger of forest fire lies in the role of the wild horse.

7 replies »

    • Man is definitely not wild horses only predator. As the article states: FACT: Mountain lions, bears, wolves, and coyotes are all the co-evolved predators of wild horses in North America. Young foals especially are predated on.

      Liked by 1 person

      • AND of course – the issue of humans “selectively breeding” any species has turned out so very well in the past, right? The idea that the BLM or FS or any government agency can decide which animal has “worth” & deserves to continue to live in the wild & breed is asinine. I have to agree that man isnt the ONLY predator, but he sure is the one doing the most damage!

        Liked by 2 people

  1. Thank you. I have abhorred the use of PZP and am sickened by the sight of “advocates” and “herd management groups” standing out there with their dart guns aimed at our wild horses.

    Liked by 1 person

  2. Sadly Australia if following blindly along your stupid BLM tradition.
    Can’t this department be dismembered?
    Fighting for individual groups of horses and burrows is good, but I feel we need to be collectively bringing down the problematic dept that is blatantly lying and abusing their authority by playing cowboys with these animals lives.
    They are costing not only their personal existence in wages but hitting your entire country billions of dollars in chopper fees, cartage fees, and the massive never ending feeding cost by tormenting these innocent animals., AND ENDangering peoples livlihood, homes and very lives!
    It is all about Animal Cruelty and this BLM dept MUST be stopped and disbanded forever….Never to be allowed near ANY SPECIES OF ANIMAL AGAIN!
    My thoughts and views as I can see this horror unfolding in our country, because they are so dumb that they follow blindly what the BLM use for excuses to do the same thing here.
    Cattle ranchers/graziers get the money and priority in both our countries, to destroy our lands.

    Liked by 1 person

  3. Great article and while I originally thought PZP would be a way to manage the herds now I’m looking at things differently. I’ve wept so much over the debacle of the 2021 roundups and cursed Cattoor Livestock so often I’ve lost count. Writing anyone in the government seems futile though necessary. Donating what we each can to a variety of sanctuaries who are on the front lines of either the kill pens or BLM “sales” is an option for a few of the thousands that are being slaughtered (either in spirit or in real time.) Not sure where to go from here…


  4. Worth pointing out here that when apex predators are removed from ecosystems, this creates havoc with all the interlaced occupants.So it affects wild horses and benefits (?) livestock but also alters the other natural prey and their population dynamics. Interestingly, this practice is also selecting for dumber livestock less and less able to survive without massive human intervention, even in remote range situations.

    And indiscriminate wild horse roundups also remove the combined wisdom earned on that landscape by generations of animals, such that there are instances reported of youngsters left behind dying without knowing they could find water just a mile or two away, though their parents knew. Adaptations are dynamic and earned; interventions can reliably result in unintended consequences and losses. This is basic science but why is it ignored, and in the name of “science?”


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