The following  his article is based on a letter written by our local CPW Big Game Biologist, Elissa Slezak

To read the full Colorado Parks and Wildlife brochure on various wildlife-friendly fences, check out the Fencing With Wildlife In Mind brochure.
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Because we live in the mountains where wildlife is plentiful, it is important to take into consideration wildlife when constructing or repairing fences.  While fences are important for keeping domestic animals in, they can also prevent the movement of wildlife within their home ranges. Seasonal migrations between summer and winter habitat are essential for some species, and some non-wildlife friendly fences may disrupt these migrations.  Sadly, every year barbed wire fences claim the lives of deer, elk, pronghorn, and moose that attempt to cross them.Though we cannot save them all, there are fencing options that landowners can use to minimize wildlife loss due to tangling.

Elissa Slezak, of Colorado Parks and Wildlife, lists a few suggestions for constructing wildlife friendly fences in a letter she wrote to the Lower Blue Planning Commission:

The "best" wildlife friendly fence is 3-Strand Smooth Wire Fence (p. 9 Fencing With Wildlife In Mind brochure):

• Three strands of smooth (barbless) high-tensile wire.
• Top wire 40 to 42" maximum height from ground.
• Center wire 30" above ground, at least 12" below top wire.
• Bottom wire minimum of 16" above the ground.
• No vertical stays.
• Wood or steel  posts set at minimum 16 - 16.5 foot intervals

 For all wooden fences:

• Construct rail fences with three  rails or fewer, a two-rail fence is preferable. " Avoid using boards or planks, they create a visual barrier for wildlife.
• Limit fence height to 42" above ground.
• Provide 16" clearance between rails for younger animals to pass through.
• Place the bottom rail at least 16" above the ground.
• Place intermittent gaps with top rail(s) removed in areas where wildlife are likely to cross.

Pipe Fencing, Vinyl/PVC Fencing & Tubular Panel Fencing: These fences are often used for horses.

• Limit the height of the fence to 42" above the ground.
• Keep the bottom rail or pipe at least 16" from the ground.