Fertility control and the Corolla wild horses

May 18, 2016 - In an ideal world, wild horses would roam free, unfettered and uncontrolled. In the natural order, the strong survive. Natural predators prey on the weak, and injury, disease, or other natural causes would dictate survival. But in today’s reality – we have traveled far, far from an ideal world for wild horses.

The wild horses of Corolla live among 800 plus houses and thousands of cars on a barrier island that attracts hundreds of thousands of visitors annually. Their habitat is shrinking every year.

In an ideal world, the Corolla Wild Horse Fund would own all the available remaining land and place it in conservation easements. Although we are working with land owners to acquire some available parcels, it is completely and totally unrealistic to think that we could ever control all or even most, of the remaining land and successfully bring development to a halt.

With this knowledge in mind, should we let our herd continue to grow unchecked with no predators except humans? Should we stand by and watch their sources of food and water decline while the herd size increases?

When I accepted the job of the first Executive Director of the Corolla Wild Horse Fund in 2006, our new Herd Manager and I were shocked to observe the body condition of the wild mares.

The winters here are very harsh and the vegetation becomes sparse. After giving birth year after year and often still having last year’s foal nursing in addition to their current foal, mares approached the impending winter months with a body condition of 2 to 3. (On the Henneke scale for equine body condition, 5 and 6 is optimum. A score of 1 is emaciated and life threatening and 9 is obese.)

Our mares rarely rebounded to optimum body condition even when the vegetation was lush and plentiful. Our oldest mares rarely lived past their teens and always looked thin or even emaciated.

Clearly, we humans have changed the natural equation for wild horses by killing off their natural predators, building houses, businesses and highways, fracking, mining, grazing cattle, and drilling for oil. We have destroyed their habitat and cut off or polluted their water sources. Our government defines them as “non-native, feral, invasive, exotic, and pest animals.”

The “ideal world” for wild horses is long gone and it is never coming back. So what do those of us tasked with the welfare of wild horses do? We must responsibly manage and conserve the wild horses that remain.

What does “responsibly manage” mean? In my definition, there is no excuse for overpopulation to the point that even one horse starves to death. I cannot and will not knowingly allow horses to suffer and starve. In my definition, THAT is cruelty.

In my definition, we should all use the readily available, peer reviewed science that has a proven, safe, successful 20-plus year history. We should use this knowledge strategically and skillfully to help wild horses live longer and healthier lives. We should use the PZP fertility control vaccine.

PZP has unequivocally and indisputably given our mares a longer and healthier life.

Since we began responsibly managing the population, our mares have gone from a body score of 3 or lower to a body score of 5 in the winter and 6 in the spring, summer, and fall. Right now, coming off one of the harshest winters in a century, we do not have a mare with a body score lower than 4 and the overwhelming majority have a body score of 5. They are healthy and content.

There are about 24 harems and several groups of bachelor stallions. Our Herd Manager and I spend a lot of time in the field observing harem behavior, location and composition. We see the benefit in every aspect of our mares’ daily health and behavior after the use of PZP. The difference before and after PZP is obvious and compelling.

PZP does NOT maim horses. We are not “drugging” our wild horses. Horses that have optimum body condition and feel good, exhibit more natural behaviors and live longer. Horses that are struggling to maintain body condition must focus all their energy on just surviving – not thriving.

PZP does NOT sterilize mares unless it is administered for 6 or 7 consecutive years. The goal of responsible wild horse management is NOT to zero out wild horses.

Responsible wild horse management allows mature, healthy mares to contribute healthy foals to the population. When they are too young, too old, or have already made several contributions to the gene pool, PZP is a humane, cost-effective tool to manage herd population and health.

Allowing horses to overpopulate to starvation IS irresponsible and cruel. Allowing mares to give birth every year from first estrus to death and then struggle to survive IS irresponsible and unnecessary. Rounding up horses for removal and tearing harems apart IS irresponsible and brutal. Purposely misinterpreting years of research and sound science regarding PZP is not only irresponsible – it is unconscionable.

Look at our before PZP and after PZP photos. A picture is worth a thousand words.

Karen H. McCalpin
Executive Director
Corolla Wild Horse Fund

corolla before

corolla after

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Information: Animal Fertility Control Vaccine
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