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Valuing Wildlife Crossings and Enhancements for Mitigation Credits (2020)

Chapter: 4.0 Considerations for Developing a Program for Advance Mitigation and Crediting for Wildlife Connectivity

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Suggested Citation:"4.0 Considerations for Developing a Program for Advance Mitigation and Crediting for Wildlife Connectivity." National Academies of Sciences, Engineering, and Medicine. 2020. Valuing Wildlife Crossings and Enhancements for Mitigation Credits. Washington, DC: The National Academies Press. doi: 10.17226/25731.
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Suggested Citation:"4.0 Considerations for Developing a Program for Advance Mitigation and Crediting for Wildlife Connectivity." National Academies of Sciences, Engineering, and Medicine. 2020. Valuing Wildlife Crossings and Enhancements for Mitigation Credits. Washington, DC: The National Academies Press. doi: 10.17226/25731.
×
Page 39
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Suggested Citation:"4.0 Considerations for Developing a Program for Advance Mitigation and Crediting for Wildlife Connectivity." National Academies of Sciences, Engineering, and Medicine. 2020. Valuing Wildlife Crossings and Enhancements for Mitigation Credits. Washington, DC: The National Academies Press. doi: 10.17226/25731.
×
Page 40
Page 41
Suggested Citation:"4.0 Considerations for Developing a Program for Advance Mitigation and Crediting for Wildlife Connectivity." National Academies of Sciences, Engineering, and Medicine. 2020. Valuing Wildlife Crossings and Enhancements for Mitigation Credits. Washington, DC: The National Academies Press. doi: 10.17226/25731.
×
Page 41
Page 42
Suggested Citation:"4.0 Considerations for Developing a Program for Advance Mitigation and Crediting for Wildlife Connectivity." National Academies of Sciences, Engineering, and Medicine. 2020. Valuing Wildlife Crossings and Enhancements for Mitigation Credits. Washington, DC: The National Academies Press. doi: 10.17226/25731.
×
Page 42

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Valuing Wildlife Crossings and Enhancements for Mitigation Credits 35 4.0 CONSIDERATIONS FOR DEVELOPING A PROGRAM FOR ADVANCE MITIGATION AND CREDITING FOR WILDLIFE CONNECTIVITY The process to establish, apply, and manage advance mitigation credits for wildlife connectivity would have similarities to the well-established conservation banking program authorized by USFWS and the wetland mitigation banking program administered by USACE. State DOTs could review the lessons learned from mitigation banking a decade ago according to the U.S. Government Accountability Office (2005), and the subsequent U.S. Environmental Protection Agency and USACE guidance in the 2008 compensatory mitigation rule (73 Federal Register 19594). The rule strengthened the planning, implementation, and management of compensatory mitigation by requiring measurable, enforceable ecological performance standards, regular monitoring, and oversight of wetland mitigation banks. The following sections present a general discussion of topics for state DOTs to consider in developing a program for advance mitigation and crediting for wildlife connectivity. In addition to the regulatory environment and policy considerations discussed previously, developing a crediting strategy for wildlife connectivity mitigation will require coordinating with stakeholders; developing an interagency working group; defining the types of wildlife connectivity mitigation measures that could generate credits; defining an appropriate geographic service area; establishing strategies to manage credits and debits; monitoring performance post-construction; and managing long-term commitments. Developing an Advance Mitigation Program poses unique challenges, such as a need for collaboration at a regional scale across agencies and jurisdictional boundaries, as well as the coordination of funding and schedules. This is particularly true when various stakeholders, such as state DOTs and natural resources agencies, do not share the same missions or priorities (Rudnick et al. 2012). State DOTs that have experience with advance mitigation programs, such as North Carolina, Florida, Washington, and California (Lederman 2017), would have an advantage over states without advance mitigation programs because their transportation planners and biologists would have experience with integrative and collaborative planning at the landscape level. These efforts could provide the type of ecological connectivity information necessary to identifying the most useful metrics for valuing wildlife connectivity mitigation. Establishing a dedicated interagency working group to address wildlife connectivity mitigation, at either a statewide or state DOT regional or district level, would bring together transportation planners with the local experts in wildlife ecology, transportation planning, highway safety, and highway engineering. This collaborative effort would advance wildlife connectivity by providing a forum for stakeholders to discuss their concerns and prioritize objectives to ultimately develop a shared vision for incorporating wildlife connectivity into transportation plans and projects. The creation of interagency working groups would address step 1 of the IEF, which includes building support among stakeholders to establish a regional or statewide planning process that can integrate wildlife connectivity enhancement and maintenance into transportation planning and funding efforts. To develop metrics and credits for wildlife connectivity mitigation, it would be most effective for state DOTs to follow the nine steps of the IEF as elaborated in An Ecological Approach to Integrating Conservation and Highway Planning, Volume 2 (NAS 2012). These steps could be applied to wildlife connectivity mitigation as follows:

Valuing Wildlife Crossings and Enhancements for Mitigation Credits 36 Once potential metrics are identified for priority wildlife crossing locations, the working group would need to identify a scientifically defensible quantification method for the number of credits and identify performance standards to ensure that those credits represent viable wildlife connectivity outcomes. At the outset, a site visit would be necessary to confirm site eligibility, the estimation of credits, and the adequacy of performance standards and monitoring plans. The working group could then provide guidance on the acceptable methods to value wildlife connectivity mitigation. To mitigate unavoidable impacts on wildlife from a transportation project, the type of mitigation measures eligible for crediting would need to be effective for the focal species. In addition, using credits for wildlife connectivity mitigation should logically only be used in situations where there is a reasonable level of certainty that the biological benefits to the affected population(s) would be sufficient to mitigate impacts of future transportation projects. To evaluate the effectiveness of wildlife connectivity mitigation measures, Huijser et al. (2008a), in a report to the U.S. Congress, performed a review of more than 34 WVC mitigation methods used by state DOTs to reduce WVCs, such as warning signs, vegetation removal, fencing, and wildlife crossing structures. The estimated effectiveness varied from as low as a 26% reduction in WVCs (seasonal wildlife warning signs) to a 100% reduction in WVCs (overpasses). The most effective mitigation measures were identified as “proven” and, where feasible and appropriate, mitigation credits that could be implemented would include: (1) public information and education; (2) wildlife fencing; and (3) underpasses and overpasses with fencing. However, the report only looked at the measures’ effectiveness in reducing crashes, not in improving connectivity for wildlife. Fencing is an integral component of effective wildlife crossings (Romin and Bissonette 1996). Fences alone, while effective at reducing WVCs, can actually reduce connectivity. Fences used with animal detection systems are limited because they only address large animals. Wildlife crossing structures, combined with fencing that separates wildlife from motorists and directs animals to the crossing structures, reduce WVCs for all types of wildlife and increase connectivity (Andis et al. 2017). Some non-structural wildlife connectivity mitigation measures have been proven to reduce WVCs effectively; these measures include public information and education and animal detection-driver warning systems (i.e., Gagnon et al. 2019). Lastly, local guidance regarding the effectiveness of various wildlife connectivity mitigation should be consulted before applying mitigation credits to various types of mitigation measures. Several state DOTs have developed specific guidelines, such as Caltrans’ (2009) Wildlife Crossings Guidance Manual and Vermont DOT’s Vermont Transportation & Habitat Connectivity Guidance Document (Vermont DOT 2012); an FHWA report by Clevenger and Huijser (2011), Wildlife Crossing Structure Handbook Design and Evaluation in North America, details numerous solutions for effective wildlife connectivity mitigation. In general, based on the above findings, the types of mitigation measures that are proven effective for reducing WVCs and allowing for safe passage of animals across the highway include the following: • new wildlife crossing structures (e.g., overpasses or underpasses) with fencing and jump outs • retrofitting existing drainage structures (e.g., bridges and culverts) with fencing and jump outs for larger animals or other physical barriers for reptiles and amphibians; and, • animal detection-driver warning systems at crosswalks with fencing (for large mammals only).

Valuing Wildlife Crossings and Enhancements for Mitigation Credits 37 Like wetland mitigation banks and species conservation banks, the geographic area where credits could be used for mitigation must be defined. The service area to use credits generated from a wildlife connectivity mitigation measure would likely be defined by the overall range of the focal species or regional population(s). Service areas could also be based on the ecosystems or habitat types used by focal species or an ecoregion. A service area for a species conservation bank is typically determined in the banking agreement. For example, CDFW’s Draft Mitigation Credit Agreement Guidelines for its RCIS program, state that “the MCA must include an ecologically based explanation on how the service area was determined” (CDFW 2019b). Credit issuance under conservation banks approved by USFWS must use the same system (i.e., units of measure) to quantify both the biological values of mitigation sites and the adverse impacts of the development for which the credits could be used as mitigation (USFWS 2003, USDOI 2013). In some instances, mitigation ratios are used to ensure that mitigation is proportionate to the impact being mitigated. For example, in theory, if a transportation project would affect the movement of an estimated number of grizzly bears, then the metric to value credits for a wildlife connectivity mitigation measure should benefit an equal or greater number of grizzly bears. USFWS (2003) notes that the use of mitigation ratios must be based on a sound biological rationale that is easily explained, readily understood, and consistently applied. Determining equivalency between mitigation credits and the impacts of transportation projects is well established for mitigation banks and conservation banks and is generally based on what is being measured or monitored, such as the acreage of wetlands or habitat, or the number of breeding pairs of a species. There is greater uncertainty about equivalency between the ecological gain from a wildlife connectivity mitigation measure and the ecological loss to connectivity from a future transportation project. No straightforward approach yet exists, and practitioners interviewed from California, Colorado, and Florida did not have experience using any metrics that could be evaluated for equivalency. Before creating a system for wildlife connectivity mitigation banking, demand for such mitigation must be assessed. In the Results from a Survey of Conservation Banking Sponsors and Managers, USDOI (2018) found that one of the most substantial obstacles for conservation banking is that demand for bank credits is often weak. Therefore, state DOTs would be advised to analyze their future transportation projects to identify mitigation needs, including the types of impacts that could reasonably be mitigated by wildlife connectivity mitigation. This needs assessment would be step 4 of the IEF (NAS 2012). As an example of current practice, Caltrans, through its Advance Mitigation Program, is performing a statewide advance mitigation needs assessment every two years that will estimate the potential impacts of future planned transportation projects that are part of a 10-year transportation planning document. Impacts are determined by overlaying assumed transportation project footprints with natural resource data layers. The location of forecasted impacts will be used to determine regions for conceptualizing advance mitigation projects. Once the statewide needs assessment is completed, Caltrans will develop regional advance mitigation assessments within the identified regions, identify its understanding of conservation goals and objectives, identify conservation plans and recovery plans for its species of mitigation need, and identify existing mitigation opportunities. Although the statewide needs assessment does not forecast impacts on wildlife connectivity from new transportation infrastructure, increased traffic, or maintenance of the state highway system, wildlife connectivity will be addressed in the regional advance mitigation needs assessment (Caltrans pers. comm. 2019).

Valuing Wildlife Crossings and Enhancements for Mitigation Credits 38 Like other forms of compensatory mitigation, monitoring the effectiveness of wildlife connectivity mitigation is essential to ensure they meet their objectives of reduced impacts on wildlife, increased highway crossings, improved motorist safety, or other targets. A properly designed monitoring program that includes pre-defined performance targets would be required (see Appendix D of Clevenger and Huijser 2011). This would be especially true if a modeling approach were taken, as monitoring would verify if the predicted ecological improvement from a wildlife crossing or other connectivity enhancement sufficiently mitigates impacts from other transportation projects. In wetland mitigation banks and species conservation banks, performance standards, or credit release criteria, are typically required to be met before credits can be sold. However, for wildlife connectivity mitigation, the lack of standard criteria and protocols for monitoring performance standards could be an obstacle to implementing a mitigation crediting program. Although most wildlife crossings in the United States are monitored to evaluate their effectiveness at providing wildlife passage, according to practitioners surveyed, few projects have had clearly defined success criteria other than documenting their use by wildlife. Standard monitoring protocols would need to be developed that are cost-effective to implement and to conclusively measure performance standards for focal species. State DOTs, as transportation agencies and not natural resources agencies, may not have the expertise to develop performance standards and would be advised to consult with state and federal natural resources agencies with permitting authority. Currently, only a few states have developed standardized methods for monitoring wildlife crossings, including Montana, Idaho, Oregon, Washington, and Utah (Kintsch and Cramer 2016). The scope of most monitoring elsewhere is typically narrow, focusing primarily on larger carnivores and ungulates, and almost exclusively on use of the structures. In Colorado, few practitioners have followed standardized protocols, and only some have documented the presence of focal species (Kintsch and Cramer 2016, CDOT pers. comm. 2019). For other types of wildlife connectivity mitigation, such as fence construction or removal, retrofits to existing drainage structures, or jump outs, the lack of standard monitoring protocols would make establishing a performance-based credit release schedule difficult. In such cases, a practice-based performance standard could be agreed upon as adequate, based on previous practices, research or studies, and well-founded assumptions that maintaining or enhancing wildlife connectivity at a particular site would result in species recovery or protection, rather than actual observations. Another consideration when identifying metrics for wildlife connectivity mitigation is the duration of required monitoring. CDFW (pers. comm. 2019a) suggested that, under the RCIS program, future MCAs for wildlife connectivity mitigation would likely include short-term monitoring to evaluate performance standards (i.e., credit release) and long-term monitoring and maintenance to ensure continued effectiveness. The monitoring specified in a MCA would be determined by the metric used to quantify credits and the biology of the focal species and should consider any available past research. Monitoring studies of wildlife crossings structures and other connectivity enhancements have shown that, in general, wildlife use increases slowly over time, over as many as 10 years and varies by species. Thus, for some species, short-term monitoring for less than this duration may mislead stakeholders about the ultimate effectiveness (i.e., ecological gain) of a wildlife connectivity mitigation project (Huijser et al. 2008b). In summary, although some state DOTs have existing WVC and roadkill data-collection programs that could be used to calculate mitigation credits and monitor wildlife connectivity mitigation, the use of such data would depend on the focal species and may not be applicable to many taxa. In certain situations, these metrics could reasonably be used to value wildlife connectivity mitigation that benefits big game, particularly when used in combination with GPS collar data. However, for many focal species that are

Valuing Wildlife Crossings and Enhancements for Mitigation Credits 39 rare or difficult to monitor, developing cost-effective performance standards for credit release would present an obstacle that would need to be overcome before mitigation credits could be generated. Implementing wildlife connectivity mitigation may not be enough by itself to ensure that a focal species is maintained or conserved over the long term. For this reason, a primary obstacle to the siting and construction of wildlife crossings in Florida has been the reluctance by the State of Florida to locate crossings when unprotected private lands exist on either side of a proposed crossing location (USFWS 2005). Thus, in most cases, it would be necessary to include provisions for state DOTs to acquire adjacent lands on either side of the wildlife crossings and facilitate their long-term protection for conservation purposes. Likewise, state DOTs have a long-term commitment to maintain wildlife connectivity mitigation within the right-of-way to ensure the future effectiveness of the mitigation. Like wetland banking, if credits were generated from a wildlife connectivity mitigation measure, then the credit owner would likely be required to maintain the wildlife crossing or other connectivity enhancement to retain any unapplied credits or to demonstrate the persistence of benefits from credits applied to other transportation project. A major advantage of developing a wildlife connectivity mitigation crediting program would be the creation of a dedicated funding source for wildlife crossings and other connectivity enhancements. However, establishing a sustainable statewide funding source for wildlife connectivity mitigation could be a significant hurdle to overcome in many states. In California, Thorne et al. (2015) cautions that advance mitigation funding should not rely on funding sources that could expire. They suggested that, for advance mitigation funding, mandating that a percentage of all project funding be committed to compensatory mitigation would provide Caltrans with funding to purchase mitigation credits before projects have been programmed.

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There is mounting evidence demonstrating the effectiveness of wildlife overpasses and underpasses in improving motorist safety and conserving wildlife.

The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 280: Valuing Wildlife Crossings and Enhancements for Mitigation Credits synthesizes current practices used by state DOTs and their partners for calculating and applying mitigation credits for wildlife crossings and other connectivity enhancements that provide safe passage for wildlife across highways.

Accompanying the report is a Power Point presentation entitled, "Valuing Wildlife Crossings and Enhancements for Mitigation Credits."

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