Wildlife-Friendly Fencing Standards
Alec LeSher (author), Jonathan Rosenbloom & Christopher Duerksen (editors)INTRODUCTION
Countless miles of fences run across the U.S.[1] These fences help contain livestock and define property boundaries.[2] However, many traditional styles of fences are impenetrable to wildlife, which need to navigate these obstacles to migrate, feed, and find shelter.[3] Local governments can enact regulations or ordinances to require fencing that effectively contains livestock and defines property boundaries, while ensuring that wildlife can traverse them.
The wildlife-friendly fences that are the focus of this brief allow wildlife to jump over or crawl under without risk of injury.[4] Many traditional fences are either too high for wildlife to jump over, or adorned with barbs, spikes, or razor wire that can fatally injure animals.[5] Further, traditional fences may be hard for low-flying birds to spot, which causes a significant amount of avian deaths each year.[6]
The most common wildlife-friendly fencing typically incorporates smooth wires to prevent injury, caps height at a maximum of forty-two inches to facilitate leaping over, provides at least sixteen inches of clearance between the ground and the lowest beam or wire to allow wildlife to crawl under, has wide spacing between wires or beams to prevent tangling, and incorporates visibility markers to alert wildlife to the presence of an access point to traverse the fence.[7] There are other forms of wildlife-friendly fencing, including “lay-down” or temporary fences that permit wildlife crossing during critical migratory seasons.[8] All of these variations can be used while still effectively containing most common livestock species. In addition to the variables concerning fencing types mentioned above, the applicable regulations may also contain provisions for when traditional fencing must be replaced with wildlife friendly fencing, which zone districts are subject to required wildlife-friendly fencing standards, and exceptions to requirements based on a showing of necessity.
EFFECTS
Regulations that require wildlife-friendly fencing may increase biodiversity in the jurisdiction by protecting critical wildlife corridors and preventing unnecessary wildlife deaths.[9] As stated above, traditional fencing poses serious risks to wildlife. One study found that when crossing fences, seventy percent of all wildlife mortalities were on fences higher than forty inches.[10] The same study found that woven wire fences with a single barbed wire on top, a common design for containing sheep, was found to be the deadliest design for wildlife.[11] A woven wire fence features strands of metal wire that are connected to form a grid from the ground to as high as eight feet. The issue with woven wire fences topped by a barbed wire is that the woven wire cannot be navigated by fawns and calves, sometimes forcing their parents to abandon them.[12] Even mature animals can become tangled between the barbed wire and the stiff woven wire, resulting in a higher likelihood of fatality than any other fence design.[13]
While the total number of wildlife fatalities caused by fences is difficult to accurately estimate, over the course of a year, one study found one dead wild animal every two and a half miles of fencing in certain areas of Colorado and Utah.[14] Wildlife friendly fences have the potential to significantly reduce these deaths, and therefore increase a municipality’s biodiversity.
EXAMPLES
Skamania County, WA
Skamania County is located on the southern border of Washington State and is predominated by the Gifford Pinchot National Forest. The County’s zoning regulations identify critical wildlife habitat areas in which fencing is prohibited unless needed to control livestock, or to exclude wildlife from gardens or orchards (emphasis added).[15] If the fencing is permitted, the fencing must comply with strict requirements to ensure that is does not interfere with wildlife movements.
For example, any new or replacement fencing in deer or elk wintering areas can be no higher than forty-two inches, and the top two wires must be at least ten inches apart to make it easier for animals to free themselves if they become entangled.[16] The bottom wire of any fence must be a smooth wire that is at least sixteen inches off the ground, so that fawns may crawl under it without being snagged.[17] Finally, woven wire fences are only permitted where the landowner demonstrates they are necessary, which normally means to control sheep or hogs.[18]
To view the provisions, see Skamania Cty., WA, County Code § 22.20.030 (B) (2005).
Pitkin County/Snowmass Village, CO
Pitkin County, Colorado (which includes Aspen), sets forth general standards for fencing in sensitive wildlife habitat areas.[19] Any mesh or woven wire fence is strictly prohibited outside the building envelope.[20] Further, wire fences are limited to three strands, forty-two inches in height, and the top wire must be barbless.[21] The middle wire may be barbed, but must be at least twelve inches apart from the top wire, so that leaping mule deer do not get tangled.[22] Finally, the bottom wire must be sixteen inches from the ground so that fawns may crawl under the fence.[23]
Snowmass Village incorporates these County regulations in the Town’s development code, and takes them a step further. The Town generally denies a landowner’s application to fence the perimeter of their property.[24] If the application is granted however, the Town requires that fences in wildlife migration corridors have “lay-down” or removable sections.[25] The Town requires the landowner to actually open up these sections for wildlife when migration is occurring.[26] Finally, any landowner seeking to develop a property within a sensitive wildlife habitat area must submit a plan to bring any existing fences into compliance with the County and Town codes.[27] Over time, these regulations will preserve habitat and corridors for wildlife and increase biodiversity in the region.
To view the provisions, see Pitkin Cty., CO, Land Use Code § 7-20-70 (c) (2006); Snowmass Village, CO, Municipal Code § 16A-4-20 (2000).
ADDITIONAL EXAMPLES
Los Angeles Cty., CA, Code of Ordinances § 22.44.1920 (B) (2014) (prohibiting fences in sensitive wildlife areas, except where necessary to keep wildlife from restoration areas).
Teton Cty., WY, Land Development Regulations § 5.1.2 (2016) (requiring fences to comply with wildlife-friendly design standards as detailed in the introduction above).
Newburyport, MA, Code of Ordinances Sec. 6.5-29 (b) (4) (allowing construction of fencing in protected areas only where the fencing does not pose an obstacle to wildlife).
ADDITIONAL RESOURCES
Christine Paige, A Landowner’s Guide to Wildlife Friendly Fences: How to Build Fence with Wildlife in Mind, (Joe Weigand ed., Montana Fish, Wildlife & Parks Dep’t. 2d ed. 2012) (PDF available at https://perma.cc/U99U-KDMA).
Wendy Hanophy, Fencing with Wildlife in Mind, Colorado Parks & Wildlife (2009), https://perma.cc/ZNU6-W6F6.
Livestock/Wildlife Best Management Practice Manual, Wyoming Dep’t of Envt’l Quality (2013), https://perma.cc/N9U5-HB28 (defining wildlife-friendly fencing for the state and giving design guidelines).
CITATIONS
[1] Christine Paige, A Landowner’s Guide to Wildlife Friendly Fences: How to Build Fence with Wildlife in Mind, at 4 (Joe Weigand ed., Montana Fish, Wildlife & Parks Dep’t. 2d ed. 2012) (PDF available at https://perma.cc/U99U-KDMA).
[2] Id.
[3] Id.
[4] Id. at 10.
[5] Id. at 5-7.
[6] Id. at 12.
[7] Id. at 10, 13, 14.
[8] Id. at 34.
[9] See John Roach, First Evidence that Wildlife Corridors Boost Biodiversity, Study Says, National Geographic News (Sept. 1, 2006), http://perma.cc/674K-UNMW.
[10] Justin L. Harrington, Characteristics of Ungulate Behavior and Mortality Associated with Wire Fences, at 22 (2005) (Master’s Thesis) (available at https://perma.cc/L4W8-GG54).
[11] Id. at 39.
[12] Id.
[13] Id.; Paige, supra note 1, at 5.
[14] Paige, supra note 1, at 7.
[15] Skamania Cty., WA, County Code § 21A.05.050 (2005).
[16] Id. at § 22.20.030 (B) (2).
[17] Id. at § 22.20.030 (B) (2) (c).
[18] Id. at § 22.20.030 (B) (3).
[19] Pitkin Cty., CO, Land Use Code § 7-20-70 (c) (2006).
[20] Id. at § 7-20-70 (c) (3).
[21] Id. at § 7-20-70 (c) (5).
[22] Id.
[23] Id.
[24] Snowmass Village, CO, Municipal Code § 16A-4-20 (f) (1) (h) (2000).
[25] Id. at § 16A-4-20 (f) (1) (h) (3).
[26] Id.
[27] Id. at § 16A-4-20 (f) (1) (h) (4).