How Are Wild Horse Populations Managed?
Although cherry blossoms are a hallmark of spring in my mid-Atlantic neck of the woods, another annual event marks the arrival of warmer months out west: the Bureau of Land Management’s (BLM) Wild Horse and Burro Adoptions. The 2014 schedule is up and tentatively lists over thirty towns that host adoption days for the mustangs and burros that are periodically rounded up off BLM land.
The Wild Free-Roaming Horses and Burro Act of 1971 gave BLM the authority to manage and protect these living symbols of the American west. Although folks may question the need to manage such animals, this act was created in response to a grassroots campaign against the shipping of wild stock to slaughterhouses.
To manage over-population, the BLM orchestrates regular round-ups, where wild horses are collected for adoption. A strict management process dictates these round-ups. The BLM tracks the balance between herd sizes and range capacity and when data identifies when a certain area is about to be pushed beyond sustainability for the herd as well as other wildlife, vegetation, and domestic cattle that graze the same lands, a round-up occurs.
One interesting aspect about mustangs from a veterinary perspective is the concept of population control. Other than adoptions, which are understandably labor-intensive, actual birth control is now used on mustang herds and is a neat epicenter for research on the subject.
The BLM now uses the porcine zona pellucida (PZP) vaccine in certain mustang herds to help with population control. Administered in the muscle via dart gun, this vaccine stimulates the production of antibodies in a female’s body that prevent sperm from attaching to an egg, therefore preventing fertilization.
Apart from the cool science, this vaccine has other perks. Experts estimate controlling populations in this manner can actually add ten years to a female horse’s life by preventing pregnancies and the physical hardships and dangers that come with bearing young in the wild.
I have yet to have the opportunity to work with a mustang. Although many of the animals at these BLM adoptions are completely untrained, some round-ups offer halter-trained animals, or occasionally animals that are saddle-broke. These are offered at a premium. Prices for untrained animals are usually around $125.
Before animals are taken to private homes, they are dewormed, vaccinated, tested for a blood disease called Equine Infectious Anemia and found to be negative, and freeze branded on the neck with a unique symbol that identifies the animal as one from the BLM, its estimated year of birth, and state of origin.
The closest things we have here to the mustang are the wild ponies of Chincoteague. These fuzzy, round-bellied beasts that live off the salty sea grass on Chincoteague and Assateague Islands in Maryland and Virginia are rounded up once every summer for adoption. Like the mustangs, the PZP vaccine is used with these animals as well.
I have been lucky enough to work with a Chincoteague pony once, although I’m sure he wasn’t as thrilled about the experience as I. I recall him being a cute brown colt that was surprisingly well-mannered and easy to handle and was made even more so after my visit, since I was there to castrate him! Ah, well. I’ll take my wild horse experiences where I can get them.
Dr. Anna O'Brien