Resource Equivalency Analysis: A tool to ensure avian impacts are mitigated?By Brad Norton, Brad Schafer and Karl Dickman

IntroductionResource Equivalency Analysis (REA) is an approach to estimate quantitatively the amount of compensatory mitigation that is needed to mitigate impacts on raptors from windfarm operations. The U.S. Fish and Wildlife Service (USFWS) uses REA to evaluate the mitigation requirements for golden eagles (U.S. Fish and Wildlife Service 2013), but it may also be useful in evaluating the mitigation needs of other species. This poster highlights the �ndings of an example REA for three target species, red-tailed hawks, burrowing owls, and American kestrels, in the Altamont Pass Wind Resource Area (APWRA) and explores the implications of using this type of analysis for mitigation planning.

BackgroundREA is a method of determining the amount of compensatory mitigation required to restore the amount of ecosystem services lost due to the loss of a natural resource. REA, habitat equivalency analysis, habitat evaluation procedures, and other quantitative tools have been used for years to evaluate ways to mitigate environmental impacts and select among various preferred mitigation alternatives. REAs were �rst used in the late 1990s for an oil-spill Natural Resource Damage Assessment (NRDA) case on the North Cape of Rhode Island (Sperduto et al. 2003) and are consistent with federal regulations that authorize trustee agencies to seek monetary compensation for injured natural resources (National Oceanic and Atmospheric Administration 1995). A recent opinion paper by Cole (2011) advocates the use of REA as a method to specify appropriate types and amounts of compensation at windfarms.

MethodsWe adapted the USFWS’s golden eagle REA for use with red-tailed hawks, burrowing owls, and American kestrels. These species were selected because Alameda County and other parties have identi�ed them as focal species for the purposes of measuring the e�ectiveness of management actions to reduce raptor fatalities in the APWRA. The general rationale for designating these species as focal species is that they are abundant in the APWRA, are susceptible to turbine-related fatalities, and are killed in signi�cant numbers. The inputs used in the three species’ REAs are listed in Table 1.

In addition to the life history parameters, the other key parameters informing the REA are (1) the expected annual fatalities for an 80 MW project, (2) the relative bene�ts of the mitigation, (3) the years of bene�t/avoided loss from the mitigation, (4) the start year of the fatalities, and (5) the start year of the mitigation.

The expected annual fatalities for an 80 MW project were estimated using the fatality rates from the �rst year of post construction fatality monitoring at the nearby Vasco winds project site, extrapolated to an 80 MW project.

We modi�ed the USFWS golden eagle REA model to allow for acquisition and management of conservation lands (measured in acres) as the mitigation option of choice as opposed to retro�tting power poles. The relative bene�ts of the mitigation were estimated by assuming that survival bene�ts arise from the management of conservation lands. Management actions would include prohibiting the use rodenticide and of lead shot, which are used to kill California ground squirrels. California ground squirrels are considered a keystone species in the central California foothills ecosystem, and thus survival and productivity would be expected to increase as ground squirrel density and availability increases. Raptors are known to die from secondary poisoning after consuming vertebrate prey that has ingested rodenticides (Mineau et al. 1999); consequently, eliminating rodenticides should increase survival. Considering these factors, we assumed that acquisition and management of each acre of conservation lands would result in a 10% increase in bird years per year for each of the 3 focal species.

The period over which the mitigation would provide bene�ts was assigned a 30-year duration. Although the conserved lands would be preserved in perpetuity, the duration of the average life of a wind project was assigned to the duration of mitigation. To simplify the example and the interpretation of the results, and considering that projects would be phased over time under the repowering program, the start year of the fatalities and the start year of the mitigation were considered to be the same: 2015. The �nal step was to calculate the credit owed as shown below.

References CitedCole, S. G. 2011. Wind Power Compensation Is Not for the Birds: an

Opinion from an Environmental Economist. Restoration Ecology. 19:2. Available: http://dx.doi.org/10.1111/j.1526-100X.2010.00771.x.

Lind, R. 1982. A Primer on the Major Issues Relating to the Discount Rate for Evaluating National Energy Options. in R. Lind (ed), Discounting for Time and Risk in Energy Policy. Washington, DC: Resources for the Future.

Mineau, P., M. R. Fletcher, L. C. Glaser, N. J. �omas, C. Brassard, L. K. Wilson, J. E. Elliott, L. A. Lyon, C. J. Henny, T. Bollinger, and S. L. Porter. 1999. Poisoning of Raptors with Organophosphorus and Carbamate Pesticides with Emphasis on Canada, US and UK. Journal of Raptor Research 33(1):1–37.

National Oceanic and Atmospheric Administration. 1995. Habitat Equivalency Analysis: An Overview. Damage Assessment and Restoration Program. March 21 (Revised October 4, 2000, and May 23, 2006).

Poulin, R., L. Danielle Todd, E. A. Haug, B. A. Millsap, and M. S. Martell. 2011. Burrowing Owl (Athene cunicularia). �e Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology. Retrieved from the Birds of North America Online:

http://bna.birds.cornell.edu/bna/species/061doi:10.2173/bna.61Preston, C. R., and R. D. Beane. 2009. Red-tailed Hawk (Buteo

jamaicensis). �e Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology. Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/052doi:10.2173/bna.52

Smallwood, J. A., and D. M. Bird. 2002. American Kestrel (Falco sparverius). �e Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology. Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/602 doi:10.2173/bna.602

Sperduto, M.B., S.P. Powers., M. Donlan. 2003. Scaling Restoration to Achieve Quantitative Enhancement of Loon, Seaduck, and other Seabird Populations. Marine Ecology Progress Series 264:221–232.

U.S. Fish and Wildlife Service. 2013. Eagle Conservation Plan Guidance. Module 1- Land-based Wind Energy Version 2. April.

Acknowledgement�is work was funded by Alameda County to support mitigation planning for repowering of the APWRA.

Table 1. REA Inputs used to Develop a Framework for Compensatory Mitigation for Take of Red-Tailed Hawk, Burrowing Owl, and American Kestrel from Wind Energy Development in the APWRA

REA Input Parameter Red-tailed hawk Burrowing owl American kestrel

Start year 2015 2015 2015

Estimated take (per year) associated with an 80 MW project

22 5 26

Average maximum lifespan 25 8 11

Age distribution of birds killed 0–1 = 30%1–4 = 45%4+ = 25%

0–1 = 50%1+ = 50%

0–1 = 57%2–11 = 43%

Age at first reproduction 2+(age class 2–3)

1 1

Expected years of reproduction 23 7 10

% of adult females that reproduce annually

84% 100% 80%

Productivity (mean number of individuals fledged per occupied nest annually)

1.4 4.5 3.1

Year 0–1 survival 61% 30% 62.9%

Year 1–2 survival 79% 81% 57.1%

Year 2–3 survival 79% 81% 57.1%

Year 3–4 survival 79% 81% 57.1%

Year 4+ survival 90.90% 81% 57.1%

Percent increase in bird years per acre of conserved land per year

0.10 years/acre/year

0.10 years/acre/year

0.10 years/acre/year

Number of years of avoided loss from mitigation

30 30 30

Discount rate 3% 3% 3%

Note: Life-history data was obtained primarily from the following sources: Preston and Beane 2009; Poulin et al. 2011; Smallwood and Bird 2002.

Red-tailed hawk Burrowing owlAmerican kestrel

Table 3. Relative Productivity of Conserving/Enhancing 1 Acre assuming a 30-Year Bene�t

PV Bird-Years/Conserved AcreYear Red-tailed hawk Burrowing owl American kestrel

Total PV Bird-Years 12.06 3.59 3.12

Table 4. Credit Owed for 10-years of Mortality (for a typical 80 MW wind project)Red-tailed hawk Burrowing owl American kestrel

Total Debit 1,155.12 114.71 352.70 PV Bird-Years

÷ Relative Productivity of Conservation of 1 Acre

12.06 3.59 3.12 Avoided loss of PV bird-years/acre

= Credit owed 96 32 113 Acres to be conserved

Table 2. Total Lost Bird-Years Expected over the Next 10 Years

PV1 Bird-YearsYear Red-tailed hawk Burrowing owl American kestrel

Total PV Bird-Years 1,155.12 114.71 352.70

PV = Present Value- within the context of an REA, refers to the value of debits and credits based on an assumed annual discount rate (3%). This term is commonly used in economics and implies that resources lost or gained in the future are of less value to us today.

1

= Credit OwedTotal Lost Bird Years

Relative Productivity of Conservation

ResultsTotal lost bird years for the 3 focal species resulting from impacts over the �rst 10 years of the project are presented in Table 2, while the expected productivity in bird years of conserving and managing an acre of conservation land over 30 years is presented in Table 3. Impacts were calculated over a 10 year period because Alameda County is requiring compensation in 10 year increments. Productivity of mitigation was calculated over 30 years because this is the duration of project permits, even though conservation would be “in perpetuity”. These metrics were used to calculate the compensatory mitigation requirement for the next 10 years as shown in Table 4. This calculation endeavors to ensure that the compensatory mitigation provides a credit that is equal to the debit for the expected mortality.

ConclusionsThis analysis provides an example of a quantitative evaluation of the mitigation required to o�set impacts to populations of red-tailed hawk, burrowing owl, and American kestrel resulting from wind power projects using an REA framework. Advantages of the REA model include transparency and reproducibility. However, the information required to use the model to obtain accurate results is often lacking or imprecise, and will vary depending on the species and the mitigation used to o�set impacts. Perhaps the biggest challenge in this example was quantifying the amount of bene�t accrued from acquisition and management of conservation lands. Additional research is needed to quantify the relationship between management actions taken to bene�t species as part of a mitigation package and species numbers, survival and productivity. However, the REA framework does hold promise as a useful tool in quantifying appropriate mitigation to o�set impacts from wind farm operations.

Photo credits:APWRA project area: ICF International; Red-tailed hawk: Brocken Inaglory; American kestrel: Greg Hume; Burrowing owl: ICF International.

Ground SquirrelPopulation Response

Increased Survival

IncreasedProductivity

IncreasedPopulation

RaptorPopulation Response

Increased Survival

IncreasedProductivity

IncreasedPopulation

Management Actions

Removal of Rodenticide Removal of Lead Shot