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Featured image: Kaibab-Pausagunt (Grand Staircase) Wildlife Corridor (c) Steve Bridgehouse

Recommended Wildlife Corridor Goals and Objectives

Drafted for The Rewilding Institute by Kim Crumbo, TRI Wildlands Coordinator
With input from Bob Howard, TRI; and Ron Sutherland, Wildlands Network

Featured image: Kaibab-Pausagunt (Grand Staircase) Wildlife Corridor (c) Steve Bridgehouse

Ecological connectivity is the unimpeded movement of species and the flow of natural processes that sustain life on Earth.[1] This definition has been endorsed by the Convention on Migratory Species[2] and underlines the urgency of protecting connectivity and its various elements, including dispersal, seasonal migration, fluvial processes, and the connectivity that is inherently present in large wild areas.[3] An ecological or wildlife corridor is a clearly defined geographical space that is governed and managed over the long term to maintain or restore effective ecological connectivity.[4] The following terms are often used similarly: ‘linkages,’ ‘MegaLinkages,’ ‘wildway,’ ‘safe passages,’ ‘ecological connectivity areas,’ ‘ecological connectivity zones,’ and ‘permeability areas.’  The term corridor suggests a single conduit, whereas the term linkage is commonly used to refer to a connectivity area with multiple strands.[5]

An ecological (wildlife) corridor or linkage is a swath of natural land, or stepping stones of natural land, that is conserved to enhance the ability of plants and wildlife to move among larger habitat patches.[6] It should be clearly delineated,[7] and have specific ecological objectives and be governed and managed to achieve connectivity outcomes.[8] A wildlife corridor’s purpose is to maintain connectivity, especially in regions where natural habitat has been badly fragmented and yet extensive connectivity is required to retain that region’s elements and processes.[9] Ecological corridors are one of the best—and possibly only—viable management tools to maintain biodiversity at large scales and to allow species, and ecological processes, to track climate change.[10]

The most critical step in documenting a wildlife corridor is defining its objectives for ecological connectivity.[11] Connectivity can be established or maintained for any one or a combination of the following purposes, all of which depend on movements between habitat patches: (1) genetic exchange; (2) movement of individuals to meet life-cycle needs, including migration; (3) provision of habitat for daily to multi-generational movement; (4) maintenance of ecological processes; (5) movement and adaptation responses to global change, including climate change; (6) or recovery and recolonization after disturbance. A wildlife corridor should have clear and measurable ecological objectives meeting at least one of the above purposes.[12]

Grand Canyon Watershed National Monument Working Draft Map (Source: Grand Canyon Wildlands Council, now Wild Arizona)

Grand Canyon Watershed National Monument Working Draft Map (Source: Grand Canyon Wildlands Council, now Wild Arizona) Click to enlarge.

General

  • Make wildlife corridors, also known as ecological corridors, wildways, or habitat links, as wide and wild as possible. Although the size of a wildlife corridor will vary, it should be large enough to achieve its specific ecological connectivity objectives over the long term.[13] Wildlife corridors should be designated so they contain sufficient ecologically effective habitat to facilitate wildlife movement for daily, seasonal and long-term needs in a safe manner.[14]
  • Allow for latitudinal and elevational range shifts in response to climate change.[15]
  • Maintain ecological integrity of all wildlife habitat types and migration routes.[16]
  • Evaluate proposed activities, including recreational use, for their potential to adversely affect relevant wildlife values in the corridor. Do not permit any activities that interfere with adequate protection of those values.[17] Eliminate or minimize mechanical intrusions within the corridor.
  • Manage area to protect migration and movement routes for mule deer and other wide-ranging wildlife, and especially keystone species[18] such as wolves, cougars, and other carnivores.[19] This includes identification and mitigation of barriers such as highways, canals, fencing, and man-made dams.[20]
  • Ensure that protective fencing prevents wildlife from accessing the road/railway or canal interior while simultaneously funneling wildlife to a safe crossing structure. In addition to protective fencing along roads, rails and canals, ensure that all fencing within the ecological corridor is wildlife friendly and clearly marked with non-threatening or deterring markers.[21]
  • Close the area to renewable and other energy developments. Including ostensibly renewable forms. For example, flyway corridors require consideration of their vertical dimension with an emphasis on threats such the placement of wind turbines that intercept and kill migrating avifauna.[22]
  • Protect riparian habitat for aquatic species (native fish, beaver, river otter, mink, invertebrates, etc.).[23]
  • Activities currently authorized by the agency in any corridor shall coexist with wildlife movement, migration, and dispersal. Changes to current activities and infrastructure may be required if found incompatible with the corridor’s wildlife values.
  • Disallow hunting or trapping of large carnivores and other sensitive species within wildlife corridors.
  • For private lands within wildlife corridors, provide strong economic incentives for wildlife-friendly practices; and have funds ready for conservation acquisition by land trust or government agency, should the owners decide to sell.

Retain Public Ownership

  • Retain public land in federal ownership allowing for the protective management of crucial habitat and movement corridors for mule deer, elk, pronghorn, other wide-ranging wildlife and especially top carnivores, like wolf and cougar, and ecosystem enhancers, like beaver and prairie dogs.
  • Encourage the acquisition of non-federal lands within the corridor through purchase from willing sellers, exchange (but never trading away other ecologically critical lands), transfer, or donation. Acquired lands should be managed consistent with the corridor’s standards and guidelines.
  • Again, where possible, augment wildlife values through purchase from willing sellers, exchange, transfer, or donation of additional acreage of crucial wildlife habitat for their migration, movement, and dispersal.[24]
  • Establish and implement in a timely manner mitigation measures for roads, fencing, and other fragmenting structures to allow the safe movement of wildlife. Busy roads should have safe wildlife overpasses and underpasses where wildlife want to cross.

Minimize and Mitigate Roads, Canals, and Railroads

Road mortality (road kill) occurs when animals die from collisions with vehicles. These collisions kill between 89 million and 340 million birds annually on US roads,[25] and may contribute to global declines of insect populations.[26] Canals are typically a nearly-complete barrier to wildlife movement because they are often bordered by tall chain-link fences, often have nearly vertical concrete sides, and are filled with deep, swiftly-moving water forming a complete barrier for all or almost all reptiles, non-flying mammals, and non-flying invertebrates.[27]

  • Avoid building roads, canals, or railroad tracks in linkages and avoid having these infrastructures bisect linkages whenever possible.[28]
  • Provide a variety of safe crossing structures over or under roads, railways, or canals, and whenever possible maintain the structures to contain natural vegetation while still remaining free of debris. Maintain high-quality natural areas on either end of crossing structures.[29]
  • When roads are unavoidable, use speed abatements to reduce traffic speed within and adjacent to corridors.[30]
  • Manage motorized vehicular use as “Limited to Designated Roads and Trails.”
  • Establish road and motorized trail density standards within the management area to conform to the best scientific recommendations, generally less than one-half mile per square mile.[31] Ensure that there will be no net increases in road densities above a scientifically credible threshold to maintain the security of core habitat areas.[32]
  • Close existing designated roads or trails if conflicts with wildlife cannot be mitigated.[33]
  • Establish and implement in a timely manner safe wildlife crossings and mitigation standards for existing roads and primitive roads or highways crossing public land to facilitate movement of wildlife and reduce mortality of wildlife from vehicle collisions.[34]
  • Ban new permanent roads within the corridor in order to maintain unfragmented habitat for wildlife migration and dispersal.[35]

Prohibit Mining

  • Subject to valid existing rights, mining, oil and gas exploration, and development is prohibited within corridor management areas.[36]
  • Close the corridor to fluid mineral leasing and to mineral materials sales.[37]
  • Close the corridor to all locatable and leasable minerals exploration and development (including geothermal and sodium), and mineral material disposals.
  • Withdraw the corridor from location and entry under the Mining Law, subject to valid existing rights.
  • Close to recreational placer mining outside of active mining claims.
  • Prohibit surface occupancy and surface-disturbing activities.

Phase Out Livestock Grazing

  • Mitigate ecological impacts due to livestock grazing. Grazing domestic cattle and sheep has been the leading cause of watershed, stream, and grassland degradation.[38] Wildlife corridors should incorporate grazing guidelines that state that livestock grazing may be permitted only where, and in such a manner, that it serves positive ecological roles.[39]  
  • Reduce or eliminate grazing within or adjacent to the linkage.[40] Encourage coexistence ranching husbandry practices to reduce livestock depredations, and consider payment programs to compensate ranchers for livestock losses from wildlife.[41]
  • Permanent voluntary retirement of grazing permits offers an effective resolution of habitat integrity-livestock conflicts and end gratuitous lethal control of carnivores.[42]
  • Evaluate any proposed changes in grazing fencing guidelines for wildlife—such as timing and intensity of use—for impacts on relevant wildlife values. Implement those changes that benefit wildlife.[43]
  • Minimize fencing for livestock and make all fences wildlife friendly.[44]

Vegetation Treatments

  • Only allow vegetation treatments determined beneficial by the best available science relevant to ecosystem values.
  • Minimize homogenous forests where diverse, mixed-age forests would be more natural. Consider prohibiting the practice of even-aged silvicultural management and timber harvesting within the special corridor management areas).[45]
  • Discourage the spread of invasive species by removing unneeded roads and power-lines and allowing natural wildfires to burn where safe.

Enforce Existing Regulations

Insist on aggressive enforcement of existing regulations.[46] Within the United States, the Clean Water Act of 1972, as amended in 2009, restricts the dumping of soil, agricultural waste, and trash in streams and restricts the intensity of farming, mining, and building along streams and on floodplains.[47] Adequate enforcement of existing policies would go a long way toward improving riparian zone and stream habitat quality along corridors in the United States.[48] In areas of the world where such policies do not exist, the enactment of policies that restrict the dumping of soil, human waste, and trash in streams, as well as policies which restrict the intensity of farming, mining, and building allowed along streams and on floodplains should be sought.[49]

Grand Canyon Wildlands Network Design Map (Source: Grand Canyon Wildlands Council, now Wild Arizona)

Grand Canyon Wildlands Network Design Map (Source: Grand Canyon Wildlands Council, now Wild Arizona) Click to enlarge.

References:

Beier, Paul, Dan Majka, Shawn Newell, Emily Garding. 2008. Best Management Practices for Wildlife Corridors. https://scholar.google.com/scholar?q=Best+Management+Practices+for+Wildlife+Corridors&hl=en&as_sdt=0&as_vis=1&oi=scholart&sa=X&ved=0ahUKEwji57fKhujaAhVF2IMKHb6hCVQQgQMIJTAA

Belsky, A.J., and D.M. Blumenthal. 1997. Effects of Livestock Grazing on Stand Dynamics and Soils in Upland Forests of the Interior West. Conservation Biology 11:315-327.

Bureau of Land Management [BLM]. 2006. Record of Decision and Approved Dillon Resource Management Plan. February 2006.

Bureau of Land Management [BLM]. 2012. Lower Sonoran Record of Decision and Approved Resource Management Plan.  https://eplanning.blm.gov/epl-front-office/projects/lup/11856/40127/42156/01-LSDA_ROD-ARMP_FINAL_2012-09-19_web-with-Links_sans-map-pages.pdf

Bureau of Land Management [BLM].  2015. Draft Resource Management Plans: Beaver Dam Wash National Conservation Area, Red cliffs National Conservation Area; and Draft Amendment to the St. George Field Office Resource Management Plan; and Draft Environmental Impact Statement. Chapter 4—Environmental Consequences. http://www.blm.gov/style/medialib/blm/ut/st__george_fo/planning/rmp-eis_5-8.Par.98394.File.dat/5-Chapter4-Environmental%20Consequences.pdf

CMS (Convention on the Conservation of Migratory Species of Wild Animals). 2020. Improving Ways of Addressing Connectivity in the Conservation of Migratory Species, Resolution 12.26 (REV.COP13), Gandhinagar, India (17-22 February 2020). UNEP/CMS/COP13/ CRP 26.4.4. https://www.cms.int/en/document/improving-ways-addressing-connectivity-conservation-migratory-species-1

Davidson, Diane W., William D. Newmark, Jack W. Sites, Jr., Dennis K. Shiozawa, Eric A. Rickart, Kimball T. Harper, and Robert B. Keiter. 1996. Selecting Wilderness Areas to Conserve Utah’s Biological Diversity. Great Basin Naturalist 56(2):95-118.

Dobson, Andy, Katherine Ralls, Mercedes Foster, Michael  E. Soulé, Daniel Simberloff, Dan Doak, James A. Estes, L. Scott Mills, David Mattson, Rodolfo Dirzo, Hector Ariita, Sadie Ryan, Elliott A . Norse, Reed F. Noss, and David Jones. 1999. Corridors: Reconnecting Fragmented Landscapes. Pp. 129- 170 in M.E. Soulé and J. Terborgh (eds.) Continental Conservation, Washington, D.C. Island Press.

Dobson, Andy, Katherine Ralls, Mercedes Foster, Michael  E. Soulé, Daniel Simberloff, Dan Doak, James A. Estes, L. Scott Mills, David Mattson, Rodolfo Dirzo, Hector Ariita, Sadie Ryan, Elliott A . Norse, Reed F. Noss, and David Jones. 1999. Corridors: Reconnecting Fragmented Landscapes. Pp. 129- 170 in M.E. Soulé and J. Terborgh (eds.) Continental Conservation, Washington, D.C. Island Press.

Foreman, D., K. Daly, R. Noss, M. Clark, K. Menke, D.R. Parsons, and R. Howard. 2003. New Mexico Highlands Wildland Network Vision: Connecting the Sky Islands to the Southern Rockies. Richmond, Virginia: The Wildlands Project. https://wildlandsnetwork.org/wp-content/uploads/2017/02/NM-Highlands-WND.pdf

Fox, R.A. 1989. Mule Deer (Odocoileus hemionus) Home Range and Habitat Use in an Energy-Impacted Area of the North Dakota Badlands. Masters Thesis, University of North Dakota. Grand Forks, ND.

Gregory, Andrew, Emma Spence, Paul Beier, and Emily Garding. 2021. Toward Best Management Practices for Ecological Corridors. Land 2021, 10, 140. https://doi.org/10.3390/land10020140 

Groom, Martha, Deborah B. Jensen, Richard L. Knight, Steve Gatewood, Lisa Mills, Diane Boyd-Heger, L. Scott Mills, and Michael E. Soulé. 1999. Buffer Zones: Benefits and Dangers of Compatible Stewardship. Pp. 171-197 in M.E. Soulé and J. Terborgh (eds.) Continental Conservation, Washington, D.C. Island Press.

Hilty, Jodi, Graeme L. Worboys, Annike Keeley, Stephen Woodley, Barbara Lausche, Harvey Locke, Matt Carr, Ian Pulsford, James Pittock, J. Wilson White, David M. Theobald, Jessica Levine, Mell Reuling, James E.M. Watson, Rob Ament, and Gary M. Taylor. 2020. Guidelines for Conserving Connectivity Through Ecological Networks and Corridors. IUCN Best Practices Guidelines Series No. 30. https://doi.org/10.2305/IUCN.CH.2020.PAG.30.en.

Hilty, J.A., Keeley, A.T.H., Lidicker Jr., W.Z, and Merenlender, A.M. 2019. Corridor Ecology: Linking Landscapes for Biodiversity Conservation and Climate Adaptation. 2nd ed. Washington, DC: Island Press

Jakes, Andrew F., Paul F. Jones, L. Christine Paige, Renee G. Seidler, and Marcel P. Huijser. 2018. A Fence Runs Through It: A Call for Greater Attention to the Influence of Fences on Wildlife and Ecosystems. Biological Conservation 227: 310–318. https://doi.org/10.1016/j.biocon.2018.09.026

Loss, S., T. Will, and P. Marra. 2014. Estimation of Bird-Vehicle Collision Mortality on US Roads. Journal of Wildlife Management, 78: 763–771. DOI: 10.1002/jwmg.721

Lyon, L. J. 1979. “Habitat Effectiveness for Elk as Influenced by Roads and Cover.” Journal of Forestry, October, 658-660.

Montana Fish, Wildlife, and Parks [MFWP]. 2012. A Landowner’s Guide to Wildlife Friendly Fences: How To Build Fence with Wildlife in Mind. http://fwpiis.mt.gov/content/getItem.aspx?id=34461

Noss, Reed F., and A.Y. Cooperrider. 1994. Saving Nature’s Legacy: Protecting and Restoring Biodiversity. Washington, D.C.; Covelo, CA: Island Press. 416 pages.

Paige, C. 2012. A Landowner’s Guide to Fences and Wildlife: Practical Tips to Make Your Fences Wildlife Friendly. Wyoming Land Trust, Pinedale, WY. 52 pp. http://tetonconservation.org/perch/resources/wy-fence-guidefinal.pdf

Rao, R.S.P., and M.K.S Girish. 2007.  Road Kills: Assessing Insect Casualties using Flagship Taxon. Current Science, 69:830–837.

Reed, Rebecca A., Julia Johnson-Barnard, and William L. Baker. 1996. Contribution of Roads to Forest Fragmentation in the Rocky Mountains. Conservation Biology 10(4):1098-1106.

Stone, Suzanne Asha, Erin Edge, Craig Miller, and Charlotte Weaver. 2016. Livestock and Wolves: A Guide to Nonlethal Tools and Methods to Reduce Conflicts. 2nd Edition. Defenders of Wildlife. 24 pages. https://www.defenders.org/publications/livestock_and_wolves.pdf

Strittholt, James R., and Dominick A. DellaSala. 2001. Importance of Roadless Areas in Biodiversity Conservation in Forested Ecosystems: Case Study of the Klamath-Siskiyou Ecoregion of the United States. Conservation Biology 15(6):1742-1754.

Trombulak, S. C., and C.A. Frissell. 2001. Review of Ecological Effects of Roads on Terrestrial and Aquatic Communities. Conservation Biology 14(1):18-26.

VanDyke, F. G., Brocke, R. H., and Shaw, H. G. (1986a). Use of Road Track Counts as Indices of Mountain Lion Presence. Journal of Wildlife Management. 50(1):102-109.

VanDyke, F. G., Brocke, R. H., Shaw, H. G., Ackerman, B. B., Hemker, T. P., and Lindzey, F. G. (1986b). Reactions of Mountain Lions to Logging and Human Activity. Journal of Wildlife Management. 50(1): 95-102.


Endnotes

[1] CMS, 2020, cited in Hilty et al., 2020:2.
[2] CMS, 2020.
[3] Hilty et al., 2020:xii.
[4] Hilty et al., 2020:4, Box 1.
[5] Gregory et al., 2021:1.
[6] Diamond, 1976; Bennett, 2004; Hilty et al., 2006; Beier et al., 2008; Beier and Gregory, 2012; Resasco, 2019; and Hilty et al., 2020.
[7] Hilty et al., 2020:27.
[8] Hilty et al., 2020:24.
[9] Hilty et al., 2020:24.
[10] Gregory et al., 2021:1.
[11] Examples of the seven ecological connectivity objectives are provided in Hilty et al., 2020:25, Box 2.
[12] Hilty et al., 2020:25.
[13] Hilty et al., 2020:27.
[14] Modified from BLM 2012:2-55. See also Dobson et al. 1999, and Groom et al., 1999, both articles cited in Foreman et al., 2003:148.
[15]Dobson et al. 1999, cited in Foreman et al., 2003:148.
[16] Groom et al., 1999, cited in Forman et al., 2003: 148.
[17] Modified from BLM 2006:21; and BLM 2015:882; Section 4-49.2.1.
[18] A “keystone, or strongly interactive” species is one whose absence or unusual rarity causes cascading, dissipative transformations in ecosystems, including alterations or simplifications in ecological structure, function, or composition (Soulé et al. 2005:170).
[19] Modified from BLM 2015d:881; Section 4-49.2; and BLM 2008:2-45,47.
[20] Beier et al., 2008.
[21] Gregory et al., 2021: Table 1, Section 3.
[22] Hilty et al., 2020:28.
[23] Dobson et al. 1999, cited in Foreman et al., 2003:148.
[24] Modified from BLM 2015 2015d:882; Section 4-49.2.1; BLM 2006:21.
[25] Loss et al., 2014.
[26] Rao et al., 2007.
[27] Gregory et al., 2021:5, Figure 2.
[28] Gregory et al., 2021: Table 1, Section 3.
[29] Gregory et al., 2021: Table 1, Section 3.
[30] Gregory et al., 2021: Table 1, Section 3.
[31] H.R. 1321-Northern Rockies Ecosystem Protection Act, 02/22/2019, Sec. 203(b)(3)(B), https://www.congress.gov/bill/116th-congress/house-bill/1321/text?q=%7B%22search%22%3A%5B%22Northern+Rockies+Ecosystem+Protection+Act%22%5D%7D&r=2&s=3; Lyon 1979; Van Dyke et al. 1986a,b; Fox 1989. Trombulak and Frissell 2000; Reed et al. 1996; Strittholt and DellaSala 2001; and Davidson et al. 1996. See Groom et al., 1999, cited in Forman et al., 2003: 148. Dobson et al. 1999 (cited in Foreman et al., 2003:148) recommends a road density in wildlife corridors of no more than 0.25 miles per square mile.
[32] Forest Service 2012: unpaginated, Tables 16b-9 and 16b-10.
[33] BLM 2012:2-55.
[34] BLM 2012:2-55.
[35] BLM 2006:21.
[36] H.R. 1321-Northern Rockies Ecosystem Protection Act, 02/22/2019, Sec. 203(b)(2), https://www.congress.gov/bill/116th-congress/house-bill/1321/text?q=%7B%22search%22%3A%5B%22Northern+Rockies+Ecosystem+Protection+Act%22%5D%7D&r=2&s=3;
[37] BLM 2015d:882,883; Section 4-49.2.2.
[38] Belsky et al., 1999, Fleischner 1994, Donahue 1999; and Noss and Cooperrider, 1994.
[39] Fleischner et al., 1994.
[40] Gregory et al., 2021: Table 1, Section 6.
[41] Gregory et al., 2021: Table 1, Section 6.
[42] Stone et al., 2016.
[43] Modified from BLM, 2006:21.
[44] MFWP 2012; Jakes et al., 2018; and Paige 2012.
[45] H.R. 1321-Northern Rockies Ecosystem Protection Act, 02/22/2019, Sec. 203(b)(1), https://www.congress.gov/bill/116th-congress/house-bill/1321/text?q=%7B%22search%22%3A%5B%22Northern+Rockies+Ecosystem+Protection+Act%22%5D%7D&r=2&s=3.
[46] Gregory et al., 2021:10.
[47] Gregory et al., 2021:10,11.
[48] Gregory et al., 2021:11.
[49] Belsky et al., 1999.

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Deirdre Ryan - December 9, 2020

Is there any movement of rewilding cities, maybe that’s an oxymoron. In the Hollywood Hills for example I witnessed deer roaming in my backyard. Few fences then compared to now, it’s all fenced. I’ve wondered how the community would respond to the idea of removing their fences to allow the return of deer etc. The dry overgrowth issue no one seems to talk about would be resolved, quickly I imagine. We’re so attached to our boundaries I fear I might be balked at. Is city rewilding happening anywhere? Thanks

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Lyle Ball - February 27, 2021

There is nothing here for humans. Saving land only for wildlife is worthy of considerations but there are ways to involve humans by expanding their knowledge about wildness and giving increased incentive for the maintenance of these areas and benefits for local small rural communities benefitting economically while at the same time benefitting the wild way as well.
Doing what we can for rural communities adds incentive for politicians to pass such bills.
the way this is written shows no benefit for rural communities and is therefore shortsighted. More study should include human community benefits. This not creative enough.

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