Durango Herald: Managing park horses isn’t as hard as you may think

Durango, Colo., Aug. 31, 2014 -- It’s a problem that demands a quick fix: Many members of the public are rightfully disturbed by the recent horse deaths in Mesa Verde National Park. But this isn’t a new problem. And it’s not going away without some serious discussion and planning.

Here’s our situation, not just in Mesa Verde, but across the West: We have too many horses on too little land.

It can be debated whether these horses are feral or wild and whether they belong where they live. But those arguments don’t solve the problem about what to do with them.

As response to the Mesa Verde story shows, tough-love tactics such as depriving horses of water in hopes that they will leave are not acceptable to the public. Culturally, we are a people who appreciate horses.

What’s needed is a plan to control the population of these horses, so they have less of a negative impact on other animals and the natural ecology of the park. Ironically, the National Park Service itself has experience with just such a plan.

Assateague Island National Seashore in Maryland also had an overpopulation problem with horses but for the past 20-plus years has managed it with the contraceptive vaccine PZP. Over the course of the vaccine program, the park has hit its target population numbers time and again, the horses have longer, healthier lives and the herd remains a popular tourist draw. Also, the impact on the island’s ecology has been lessened to an acceptable level.

This is an example of a good approach – one that doesn’t harm or kill horses and isn’t permanent. Along with causing no harm to horses, PZP is reversible. If horses aren’t revaccinated within two years, they can become pregnant again. This provides flexibility in wildlife management. The vaccine also won’t harm or end a mare’s pregnancy, and it can’t pass to other animals or into the surrounding environment.

Along with Assateague, PZP is used in more than 20 horse-management areas in the United States. It also is used in several elephant preserves in South Africa and in the wild bison herd on Catalina Island in California. It is noteworthy that north of Mesa Verde National Park, BLM managers implemented a PZP program at Spring Creek Basin Herd Management Area in 2011. In its third year – second foaling season – PZP is 100 percent successful in preventing darted mares from foaling.

Mesa Verde managers should consider implementation of PZP contraception to help control and manage the horse population of the park.


Opinion by TJ Holmes and Kathryn Wilder.

Originally published in the Durango Herald, Aug. 30, 2014

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