PZP is a risky pesticide. Will it ruin the treasured herd?
By Marybeth Devlin
The issue underpinning the use of PZP and the continuing cycle of removals of wild horses from the Pryor Mountain Wild Horse Range is: Whether there are excess wild horses. No, there aren’t. BLM creates the illusion of an overpopulation by administratively setting the maximum herd-size below minimum-viable population. The International Union for the Conservation of Nature determined that, if a herd were managed carefully per a stud-book, it could sustain itself genetically at a minimum of 500 individuals. Compare that number to BLM’s maximum: 120.
In fact, according to the latest genetic analysis, the Pryor Mountain herd is evidencing “a general trend for a decline in variations levels of the herd.” The recommendation was to “increase population size.” Yet, BLM stubbornly insists on its own failed approach of artificially limiting herd-size, declaring that it disagrees with the scientific “interpretation.”
But can the range accommodate more horses? Yes. By way of comparison, BLM allots 38 acres per cow or calf when setting the stocking-rate for livestock grazing. Thus, the 33,187 acres that compose the Pryor Mountain habitat can support 500 to 873 horses. When the WHR is restored to its original configuration, 44,920 acres, the high-bound can be increased to 1,182.
As for PZP, numerous independent studies have disproved the old theory that PZP merely blocks sperm attachment. In fact, PZP’s mechanism of action is to alter ovarian function, causing inflammation of the ovaries and cyst formation. PZP provokes an auto-immune response, wherein the pig-ovary-derived PZP antibodies attack the mares’ ovaries, resulting in dystrophy of those reproductive organs. Despite being hyped as a non-hormonal contraceptive, PZP causes “markedly depressed oestrogen secretion” in mares treated for just three consecutive years. The latter finding was disclosed by Dr. Kirkpatrick himself 23 years ago. PZP-use is associated with stillbirths, altered ovarian structure and cyclicity, interference with normal ovarian function, permanent ovarian damage, prolonged breeding season, and unusually-late birthing dates. A particularly troubling finding suggests that PZP can be selective against a certain genotype in a population.
PZP is touted as reversible; however, a recent study warned that just three years of treatment, or administration of the first PZP injection before puberty, may trigger infertility in some mares. Thus, only two PZP injections could be viewed as relatively safe, but it appears that even one injection is risky. The researchers warned that inducing sterility may have unintended consequences on population dynamics by, ironically, increasing longevity while eliminating the mares’ ability to contribute genetically.
Most pertinent to the Pryor Mountain herd is a longitudinal study on three herds treated with PZP — Little Book Cliffs, McCullough Peaks, and … Pryor Mountain. The researchers found that the birthing season lasted nearly year-round: 341 days. Out-of-season births put the life of the foals and the mares at risk. That same longitudinal study found that, following suspension of PZP injections, there was a delay in the mares’ recovery of fertility that lasted 411.3 days (1.13 years) per each year of PZP treatment. Thus, mares injected for four consecutive years (per BLM’s “prescription”) would be expected to take 1,645.2 days (4.51 years) to regain reproductive capacity. If disaster were to befall the Pryor Mountain horses, even if PZP were stopped immediately, it would take years for the herd to recover, if ever.
PZP has neither stopped nor slowed the roundups. Only lack of holding space has done that. Even the Pryor Mountain herd, injected for decades with PZP, is facing removals again this summer (per the usual three-year cycle) in addition to an intensified PZP “prescription” to be administered per an “equal opportunity program” eerily similar to Communist-China’s one-child policy. What’s ironic is that, for all the interference, BLM has achieved basically the same — or worse — record as has been attained the International Society for the Protection of Mustangs and Burros. ISPMB complies with the “hands-off” minimum-feasible management approach stipulated by the Wild and Free-Roaming Horses and Burros Act. ISPMB’s two wild herds grew 8.73 and 5.08 percent, respectively, without PZP and without removals. Pryor Mountain’s most recent report — reflecting management with PZP and with removals — grew by 8.26 percent.
BLM needs to get out of the way of Nature. Let the Pryor Mountain herd find its own appropriate population level.
(Note: Beware of petitions pushing PZP. Be sure to read everything you sign these days especially the fine print!)
Please donate to Protect Mustangs’ Legal Fund: https://www.gofundme.com/mustanglaw2016 to help the voiceless in court. Thank you!
There are no extra mustangs in the Pryors. No round ups and no PZP! PZP will eventually eliminate these horses. There is no valid reason to do this other than greed and cattle. Cattle destroy land horses help new vegetation through feces. Leave our horses alone BLM
Plain and simple… BLM’s master plan of managing our wild horses is, “to extinction”. BLM continues to roundup wild horses resulting in lower and lower herd numbers and genetic viability. At the roundups they remove horses as well as repeatedly apply PZP which eventually sterilizes the mares. As a result of BLM’s interference, herd structure, relationships and the natural functioning of family bands is destroyed. Unless this mistreatment and abuse of our wild horses is stopped, they will become extinct.
The Salazar Plan is in its final stage….
The removal and poisoning of our wild mustangs has got to stop. PZP is a pesticide. It is not a birth control for our wildlife. We demand the removal/poisoning stop. The ranchers don’t own this land the American public does. We are not interested in camping, hiking, picnicking, fishing and/or hunting among cattle and the cattle’s waste.
I am so disappointed in advocates THAT say they love the Pryor Mountain horses and then feel that PZP
should be used to control their ability to breed or even worse,slowly kill the herds off. I am so tired of these self onfulvent ideas. We need more wild horses. There are not enough. May they all come to their senses before our wild horses disappear forever.
The Pryors mountain Herds population is already low. There is no logical reason to remove anymore of this Herd. PZP is a pesticide & that means you will eventually break down the health of the genetics of these horses into extinction. We have expressed over & over to stop the reduction. It’s is past time that BLM listens to the Tax payers, who own this land. The welfare ranchers do not own America’s FreeLand or wild horses…American’s own them. We are speaking to you (BLM) right now.
No More PZP or removal of any of The Pryor Herd.
The BLM lies, horses die! PZP is the end for our iconic wild horses. Humans have a choice of whether to use birth control and many suffer the consequences from making that choice. There are consequences. We have no right to choose this risky pesticide for our horses, just to benefit welfare ranchers, mining companies, the oil and fracking industry and the devils at the BLM!! There are too many cattle and sheep, there are NOT too many wild horses!! Expose the BLM’s lies, save the horses!!
The BLM has been bought and paid for and is in bed with the horse-hating, wealthy cattle ranchers. Their only goal is to eradicate every wild mustang and burro in the west to appease their rancher buddies and allow ‘cattle only’. For far too many years they have ignored the American public’s outrage, our petitions, our emails, phone calls, faxes and letters. They request the public’s ‘comments’ before each round-up, but only because they are required to do so by law and, they ignore every comment we submit. Of course, the BLM will forever ignore ‘scientific research’, which proves they are all nothing but a bunch of liars, spinning their web of lies to the unknowing American public. The BLM will never stop the removals or poisoning our wild mustangs with PZP. Unfortunately, there is a well-known anti-horse slaughter, anti-roundup, non-profit organization that is pushing the BLM to continue poisoning our wild mustangs with PZP. Be very careful what petitions you sign…read every petition thoroughly before signing and sharing!
Excellent article and factual exposing the PZP set up for what is a non-viable level population of wild horses in the Pryor Mtns. to begin with! Yes, let the wild horses and the ecosystem indicate the right level, not people with selfish and greedy agendas which blind them to the greater truth!
These magnificent Wild Horses should never be touched by anyone. This whole removing Wild Horses so BLM can accommodate the ranchers has got to STOP!!!! NOW!!! THE BLM HAS TORTURED LITERALLY THOUSANDS OF AMERICAS WILD MUSTANGS!!! IT HAS TO STOP OR WE WILL BE BUILDING HUMAN BARRIERS VERY SOON!!! THE BLM IS OUT OF CONTROL, THEY HAVE SHOT PREGNANT WILD MARES IN THE HEAD THEY HAVELEFT HER TO DIE IN THE FREEZING SNOW!!!! THEY KEEP OVER 50,000 OF OUR WILD HORSES IN HITLER PRISON STYLE CONCENTRATION CAMPS!!!!!
SO NOW THEIR GOING TO DO THIS TO CLOUDS HERD!!!! STOP IT STOP IT STOP IT!! NO MORE ROUNDUPS, TOO CRUEL!!! WE ARE BEGGING OUR GOVERNMENT TO STOP HURTING OUR HERITAGE AND TRUEST SYMBOLISM OF FREEDOM!! RESTORE OUR WILD HORSES TO THEIR RIGHTFUL FREEDOM!!!!
This has to be stopped, and thank you Protect Mustangs for doing what you are to try to protect the remaining wild herds we have left.
I say this every time I am asked to comment. Why does the BLM constantly insist on continually rounding up our horses, burros & donkeys? Leave them them the hell alone. Let them live in peace with their families. Let them control their own herds, in their own way. Naturally.
I am so disillusioned with the government & BLM. The Wealfare Ranchers are in the pockets of our leaders and have been for a long time. American’s are learning about the plots to exterminate the wild horses. So many we under false pretense they were being managed & protected & when they now learn of the deceit, they are shocked and have to process what is going on several times before they believe me. PZP is not the solution, all it will do is eventually exterminate the wild Mustangs from existence. Thank You for your educational information! Your research on this is all truth. We must continue the Stand through prayer and in going activism & teaching the public the truth.