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Fencing on American Prairie

A common misconception about American Prairie is that we don’t have fences. Not true!

While we are striving to protect and restore a land base that is close to an original state, it is impossible at this point to remove all fences.

American Prairie has nearly 600 miles of fence across its management units. While these fences may create barriers and hazards for wildlife, they are essential for field management and grazing management on adjacent lands. Fences also are used to define property boundaries, keep bison and cattle on approved management units, and keep livestock from wandering onto highways.

A Reserve fence.

There are many factors that influence the use, necessity, and placement of fences, including wildlife movement, property boundaries, public property uses, and grazing management. American Prairie has taken two different approaches regarding fences on our property and managing fences with wildlife in mind:

  1. Remove fences that are dangerous to wildlife and/or not needed for management.  
  2. Replace necessary fences with wildlife-friendly fence that meet management objectives.

Replacing and removing fence can be a monumental task. It requires lots of time, agreements and planning with neighbors and land management agencies, and it is expensive. Making changes to a fence often involves years of planning and approvals, can take many months to complete, and it can cost up to $2,000 per mile for removal and up to $7,000 per mile to replace outdated fence with wildlife-friendly fence. To date, American Prairie has removed 80 miles of fence and replaced or converted 120 miles of fence to meet wildlife-friendly standards.

Fence Design

The fence design we chose is a slightly modified version of the design recommended by Montana Fish, Wildlife & Parks. Following these guidelines has allowed American Prairie to meet two important objectives: keep the bison in approved areas while also allowing wildlife to move as freely as possible through the landscape. Additionally, because research has shown that fence markers reduce bird-fence collisions by 70 percent, American Prairie utilizes fence markers in high traffic bird areas. The Field team tracks bird-fence collisions and adds markers as needed in collision-prone areas.

Modified Fence and Bison Management

A normal response when showing people our bison fence is a head shake and a chuckle followed by the statement “That will keep a bison in?” What many people don’t realize is that bison have very few reasons to leave their management unit, as long as their needs are met. Those needs are primarily food and water, places to feel safe, and the company of their herd. To be sure those needs are met, American Prairie carefully manages the carrying capacity of each unit. In other words, we ensure the number of bison is at the number of animals that the Bureau of Land Management has determined to be appropriate for a management unit to maintain the ecological health of that land. Keeping the carrying capacity within pre-defined ranges allows for plenty of food and water available throughout the year, and it also leaves room for fewer dominant males to get away from competition during the rut.

As an extra preventive measure, we modified the wildlife-friendly fence design by replacing the middle-barbed wire with an electric wire. This helps to deter bison from pushing on the fence or using the fence to scratch an itch while they’re shedding their winter coats.

Testing the electric wire. 

Of American Prairie’s 120 miles of wildlife-friendly fence, 110 miles have been modified with an electric wire. The fences of each unit are divided into zones and powered by solar panels. Each zone is 10-12 miles of fence powered by one 150-watt solar panel and a 12-joule charger, and a 12-volt battery that stores backup power used at night and on cloudy days.

Field staff, chiefly our Field Technicians, spend 40 hours a week monitoring and maintaining all of these miles of fences around our property. All maintenance issues, wildlife collisions, and fence efficiency are documented by employees and are used to identify problem areas and areas of the fence that are causing problems for wildlife movement. That data is used to make continuously better management decisions and to improve wildlife movement around the project area.

Fence monitoring.