One of the better known poems of Robert Frost comes to the conclusion that, “Good fences make good neighbors.” While many people remember this poem to suggest that the presence of fences are a way to maintain friendships, most of the poem questions the need for fences. The presence of fences can have an equally equivocal meaning when used to control wildlife movement. If fences are properly placed, they can keep big game out of agricultural fields and off roads. When improperly utilized, they fragment the landscape and reduce the numbers of game animals.
Fences primarily signify property boundaries and limit wild and domestic ungulate movement. Because fences were historically made with rock and wood, they were so expensive they had limited use. During much of the history of this country, land was considered free range, which meant owners were required to fence if they wanted to keep other people’s cows or sheep off their lands. The invention of the barbed wire in the 1870s, however, greatly increased the use of fencing.
Fences not only alter they movement of big game, they increase their mortality rates. Work conducted by Utah State University in 2006 found that for every 2.5 miles of fence next to roads, one big game animal per year died because of the fences presence. August was when the largest number of deer, elk, and antelope succumbed to these fences as this is the time of year when fawns were weaned. Fences not only disproportionally entangle younger animals when they try to jump them; they separate fawns from their mothers when young animals they can’t find a way through the fence.
How a fence is built greatly influences on the ability of a big game animal to circumvent this obstacle. The biggest factor is whether the fence is woven (often referred to as sheep fence) or consists of four strands. Since woven fences are more difficult to get over and under, they are the most dangerous. In contrast, keeping the top wire of strand fences to three feet high and having the second wire one foot below the top wire makes them easier to hop and reduces the chance of entangling an animal’s back leg. Furthermore, placing the bottom wire 16 to 18 inches off the ground allows wild animals to more easily scramble under these barriers. One change that has been nice to see are more bottom wires not having barbs. The lack of barbs not only benefits game animals, but my dogs appreciate not having to donate a tuft of hair from the scuff of their neck when they shimmy under a low strand of wire.
Another modification that can limit the effects of fences on animals are reflectors on the top strand. These indicators allow mammals to better see fences when they are moving fast and allow them to better judge their jumps.
They also increase the likelihood that a low flying bird such as sage grouse, pheasant, quail or raptor will avoid this obstacle. In my over 40 years of hiking outdoors, I have seen dozens of birds collide with these structures, so I know it is an issue.
One strategy being used more often on public lands are lay down fences. As the name implies, this type of fence is stood up only during the summer when livestock are present. The rest of the year they are laid on the ground where they pose a minimal risk to all animals. Similarly, more single strand electric fences are being used to control the movement of cattle on public and private ground.
Given the many needs for fences in wildland and agricultural settings, it would be foolish to believe that their use will be diminished in the future. At the same time, it is important to recognize the risk that millions of miles of fence pose to wild animal. The goal should be to insure fences do only what they are intended to do, such as keeping cattle and sheep contained and wild animals off roads. In meeting these goals, as fences are repaired and replaced, they should be rebuilt so as to minimize their unintended effects on wildlife. In doing so, fences may not only improve our relationships with human neighbors, but with our wild neighbors as well.