ECONNECTION
Fencing
by Karen Dusek

There is an old saying that "fences make good neighbors." That can be true for wildlife as well as humans. Fences can keep livestock and domestic pets from encroaching on and disturbing wildlife and their habitat and, if properly constructed, the converse is also true. They can also prevent the invasion of "pest" species like deer, woodchucks and coyotes from making quick work of your newly sprouted lettuce patch and just-hatched chicks and from spreading disease to livestock and domestic animals.

But fences have their down side, as well. Wire or mesh fences can entangle wild animals, often resulting in serious injury or death. They also obstruct free movement within the animals' range, sometimes inhibiting migration or breeding and hunting patterns or blocking escape routes from disasters, such as forest fires. A study conducted by the University of Florida, for example, indicated that more birds flew between areas that were connected than those that were separated by some type of barrier. Since birds help to disperse seeds, fences and other barriers have an impact on plants as well as animals. Fences create islands or "patches" that are only able to support small populations. If there is little or no movement between the islands, the individuals must breed among themselves. Such inbreeding results in a lack of genetic diversity and can lead to eventual extinction.

Other forms of human construction, such as dirt roads and trails, can act as corridors for some wildlife species, but for others, which like low cover or which become confused by wide open spaces, they become obstacles. Various studies have shown that roads, including logging roads, have a negative impact on wildlife populations. (I will talk more about wildlife corridors in my next column.) Even something as mundane as a ditch will stop some animals in their tracks. I remember my surprise the first time I visited the giraffe enclosure at the San Diego Zoo. There was no fence between the giraffes and the people watching them, just a three-foot deep ditch. Because giraffes are afraid to step down more than a couple of feet, the zookeepers were able to use this simple strategy to keep them enclosed, allowing visitors to see them in a more "natural" environment. The same technique is used in cattle guards, which rely on cows' poor depth perception to be effective.

According to the Jackson Hole (Wyoming) Wildlife Foundation (JHWF), the ideal fence is "one that can be seen (and not run into) and one that can be leapt over or scurried under without injury." They recommend using shrubs and trees to delineate property lines; using low post and rail fences if they are only being used for decorative purposes; and, fencing only the portions of your property where you don't want wildlife to enter, such as gardens, children's play areas and pet runs.

They also suggest that livestock fencing be constructed of smooth wire, rather than barbed wire and that a wooden rail be used on the top so that animals can see it. If it's not possible to put a wooden rail at the top, run the wire through lengths of PVC pipe or tie rags or pieces of caution tape to the top wire to make it more visible. The fencing should be no more than 30 to 40 inches high to allow wildlife to jump over it. If barbed wire is used, the wire should be kept taut and the posts straight to make it less likely that animals will get tangled up in it and smooth wire should be used when the barbed wire needs replacing.

Fencing off ponds and other waterways is also a problem. According to the JHWF, some wild birds, like swans, need as much as 100 feet of clear space to take off. Numerous deaths occur each year because birds do not see fences and crash into them. The Foundation cautions against using barbed wire to fence off waterways and urges people that, if fences are necessary (to keep livestock from overgrazing riparian areas, for example), to protect against bird deaths by using a wooden fence or, at minimum, a wooden rail at the top.

In their book, Wildlife Habitat Management of Forestlands, Rangelands, and Farmlands, Neil F. Payne and Fred C. Bryant discuss ways to build fences for both allowing and restricting wildlife movement. They make recommendations for wire spacing to allow various types of animals to either jump over or crawl under. It is an excellent resource for anyone interested in making or keeping their land wildlife friendly.

Guidelines for Increasing Wildlife on Farms and Ranches, published by the Kansas State University Cooperative Extension Service, is also worth reading. Their recommendation for an "ideal fence for wildlife" is one with four wires spaced, from the ground up, 16, eight, eight and 10 inches. The extra two inches at the top, they note, keeps deer from catching their hind legs when they jump. They also suggest using hedgerows as borders to provide cover and habitat for wildlife.

Although the resources I've mentioned are written with farmers in mind, the information is applicable to homeowners everywhere. As human development continues to encroach on wildlife habitat, wildlife populations will continue to dwindle. Anyone who enjoys watching a deer browse in their back yard or a family of skunks pass by should keep in mind that the fence that provides you some privacy from your neighbors may also impede the ability of those animals to live normal lives and to maintain stable populations in the future.

For more information about fencing visit the JHWF website at www.jhwildlife.org/fencing5.

You may email Karen at karen@lakeshoreguardian.com.