A panel discussion Sunday at the Aztec Four Corners Equus and Arts Fest presented information about mustang management and rescue.
Meeting at the The Leanor hotel, Michael J. Leonard of Jicarilla Mustang Heritage Alliance spoke about fertility control. Bonnie Anderson of the National Mustang Association of Colorado spoke about the horse population in the Mesa Verde National Park area, and Robert Jordan of Homeland Habitat discussed bait trapping.
The three techniques are used together to control mustang populations.
Leonard said they use porcine zona pellucida, or PZP, in dart guns to manage mustang populations in the Carson National Forest, northeast of Navajo Lake. Summer poses a challenge because PZP must remain frozen during treks to remote mustang habitats.
And because they work among ponderosa pines, oak brush, juniper and piñon, they might encounter horses for just a moment before they vanish.
“We're effectively darting wild animals. They are extremely elusive … they have all the senses of deer and elk,” he said.
Effective range for the dart gun is about 30 to 40 yards, but Leonard said he can be effective up to 70 yards.
A darted mare is photographed and documented manually because internet service is often unavailable in the remote areas.
“The PZP vaccine, now registered with the Environmental Protection Agency as ZonaStat-H, has a decadeslong history of use in multiple wildlife species, including wild horses,” according to American Wild Horse Conservation’s website.
“The vaccine produces an immunological response that prevents fertilization. Since it does not affect hormone production, the impacts to behavior are minimal, particularly when compared to the alternatives.”
The normal breeding process still takes place, but the PZP causes the sperm not to recognize the egg.
“They say the efficacy if properly administered is about 90%,” Leonard said, and sterilization is effective for about 22 months. With a booster shot, administered in about six weeks, the period is extended to three years.
Although the fertility management program has lagged, additional volunteer darters have been trained, Leonard said. They depend on money from the U.S. Forest Service and advocacy groups like Homeland Habitat to make it a sustainable effort.
It will take several years to see a noticeable decline in the growth of the mustang population, he said.
The life span of a wild horse is roughly 30 years, Leonard said, as he showed a photo of a white stallion named Cabresto who was taken to the Carson National Forest with 18 or 19 other stallions in the mid-1990s when he was 5 or 6 years old. Leonard photographed him a couple of months ago.
A helicopter count about a 1½ months ago tallied about 280 horses – 60% to 70% of the herd.
The Carson district can handle about 55 head of mustangs in a drought year, and double that in the current non-drought year.
“So it's going to take a cooperative effort to continue to reach a sustainable horse level that we want,” Leonard said.
Anderson said the National Mustang Association of Colorado in Cortez started their involvement with horses in the Spring Creek and Disappointment Valley areas.
“We were the ones that advocated to do fertility control on those horses, and it’s still being done today, and it's very effective,” Anderson said.
“There are lot of wild horses in Southwest Colorado that are not protected by the Wild Horse and Burro Act (on Bureau of Land Management land). They advocated for fertility control instead of removing and taking them to the sale barn,” Anderson said.
Anderson described the automatic detector, created by the Wildlife Protection Management, which will help alleviate challenges of darting and topography.
The technique is used with a bait trap. Three horses can enter on different sides, and in the middle is bait such as grass hay, salts and water. The detector identifies approaching species and closes the bait door to animals such as feral cows.
A panel on the trap scans the horse for an existing microchip, and if none is found, implants one in the horse’s shoulder and darts the horse with PZP. Cameras document the procedure, she said.
Genetic testing of hair samples allows for selective darting, excluding horses that a landowner might want to continue breeding.
Jordan discussed bait trapping in the Carson National Forest and the Jicarilla tribe. They use a rapid trap, a 7-foot tall round corral with an inner corral that allows the horses to keep moving.
“Horses don’t panic if they keep moving,” Leonard said.
The gate can be closed remotely as long as there is cellphone service, he said, and a camera tells them how many horses are trapped in the corral.
The trailer is backed up to the inner corral, and the horses are loaded. He said they’ve captured 250 horses from the Carson National Forest without hurting a person or a horse.
The horses are transported to a facility outside Bloomfield, where they are given a Coggins test, a blood test that screens for equine infectious anemia.
The horses begin the habituation process as they get used to the people who are around them daily. It’s the key to getting them into an adoptable state, Leonard said.
Leonard can be contacted at mleonard3240@gmail.com and Anderson at banderson@nmaco.org.
