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HomeMy WebLinkAboutSuWa207sec10-9Alaska Resources Library & Information Services Susitna-Watana Hydroelectric Project Document ARLIS Uniform Cover Page Title: Wolverine distribution, abundance, and habitat occupancy, Study plan Section 10.9 : Initial study report SuWa 207 Author(s) – Personal: Author(s) – Corporate: Prepared by Alaska Department of Fish & Game AEA-identified category, if specified: Draft initial study report AEA-identified series, if specified: Series (ARLIS-assigned report number): Susitna-Watana Hydroelectric Project document number 207 Existing numbers on document: Published by: [Anchorage : Alaska Energy Authority, 2014] Date published: February 2014 Published for: Alaska Energy Authority Date or date range of report: Volume and/or Part numbers: Study plan Section 10.9 Final or Draft status, as indicated: Draft Document type: Pagination: iii, 7 p. Related work(s): Pages added/changed by ARLIS: Notes: All reports in the Susitna-Watana Hydroelectric Project Document series include an ARLIS- produced cover page and an ARLIS-assigned number for uniformity and citability. All reports are posted online at http://www.arlis.org/resources/susitna-watana/ Susitna-Watana Hydroelectric Project (FERC No. 14241) Wolverine Distribution, Abundance, and Habitat Occupancy Study Plan Section 10.9 Initial Study Report Prepared for Alaska Energy Authority Prepared by Alaska Department of Fish & Game Palmer, Alaska February 2014 Draft INITIAL STUDY REPORT WOLVERINE DISTRIBUTION, ABUNDANCE, AND HABITAT OCCUPANCY STUDY (10.9) Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page i February 2014 Draft TABLE OF CONTENTS Executive Summary ..................................................................................................................... iii 1. Introduction ....................................................................................................................... 1 2. Study Objectives................................................................................................................ 1 3. Study Area ......................................................................................................................... 1 4. Methods and Variances in 2013 ....................................................................................... 2 4.1. Survey Design ......................................................................................................... 2 4.1.1. Variances..................................................................................................... 3 4.2. Occupancy Modeling .............................................................................................. 3 4.2.1. Variances..................................................................................................... 3 5. Results ................................................................................................................................ 3 6. Discussion........................................................................................................................... 4 7. Completing the Study ....................................................................................................... 4 8. Literature Cited ................................................................................................................ 4 9. Figures ................................................................................................................................ 6 LIST OF FIGURES Figure 3-1. Wolverine Study Area, 2013. ....................................................................................... 7 INITIAL STUDY REPORT WOLVERINE DISTRIBUTION, ABUNDANCE, AND HABITAT OCCUPANCY STUDY (10.9) Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page ii February 2014 Draft LIST OF ACRONYMS, ABBREVIATIONS, AND DEFINITIONS Abbreviation Definition AEA Alaska Energy Authority AICc Akaike Information Criteria APA Alaska Power Authority CFR Code of Federal Regulations EPA Environmental Protection Agency FERC Federal Energy Regulatory Commission GMU Game Management Unit ILP Integrated Licensing Process ISR Initial Study Report km kilometer OM Occupancy Modeling PRM Project River Mile Project Susitna-Watana Hydroelectric Project RSP Revised Study Plan SPD study plan determination SUPE Sample Unit Probability Estimator WSA Wolverine Study Area INITIAL STUDY REPORT WOLVERINE DISTRIBUTION, ABUNDANCE, AND HABITAT OCCUPANCY STUDY (10.9) Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page iii February 2014 Draft EXECUTIVE SUMMARY Wolverine Distribution, Abundance, and Habitat Occupancy Study 10.9 Purpose The study team is collecting data on wolverine abundance and distribution to provide pre-construction baseline estimates of population size and habitat occupancy in the Project area. The study team will use this information to estimate the number of wolverines that may be affected by the Project and to evaluate impacts on habitats used in the winter by wolverines. Status Weather conditions necessary to complete a Sample Unit Probability Estimator (SUPE) survey did not develop during winter 2013; however, the study team completed two occupancy surveys, which provided data to develop an occupancy model. Study Components SUPE survey — Provides a precise population estimate of wolverine in the Wolverine Study Area (WSA) that the study team will use to assess the occupancy model density estimation. Occupancy Modeling (OM) — Estimates the proportion of the study area that is occupied by wolverines and provides a population index that has the potential to detect changes in population trends. 2013 Variances RSP Section 10.9 proposed that “a single aerial Sample-Unit Probability Estimator (SUPE) survey will be attempted. If survey conditions are unsuitable for the SUPE in 2013, then an occupancy survey will be flown.” A SUPE survey was not conducted in 2013 because suitable survey conditions did not occur. Thus, no variances from the methods described for aerial surveys were necessary in 2013. Steps to Complete the Study As explained in the cover letter to this draft ISR, AEA’s plan for completing this study will be included in the final ISR filed with FERC on June 3, 2014. Highlighted Results and Achievements The study team completed two occupancy surveys in April 2013, which will be used to develop a model of wolverine occupancy in the study area. INITIAL STUDY REPORT WOLVERINE DISTRIBUTION, ABUNDANCE, AND HABITAT OCCUPANCY STUDY (10.9) Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 1 February 2014 Draft 1. INTRODUCTION On December 14, 2012, Alaska Energy Authority (AEA) filed with the Federal Energy Regulatory Commission (FERC or Commission) its Revised Study Plan (RSP), which included 58 individual study plans (AEA 2012). Section 10.9 of the RSP described the study of Wolverine Distribution, Abundance, and Habitat Occupancy. This section focuses on evaluation of existing information and field surveys, modeling wolverine occupancy, and estimating population trends during and after construction of the proposed Project. RSP Section 10.9 described the goal, objectives, and proposed methods for data collection regarding wolverines. On February 1, 2013, FERC staff issued its study determination (February 1 SPD) for 44 of the 58 studies, approving 31 studies as filed and 13 with modifications. RSP Section 10.9 was one of the 31studies approved with no modifications. Following the first study season, FERC’s regulations for the Integrated Licensing Process (ILP) require AEA to “prepare and file with the Commission an initial study report describing its overall progress in implementing the study plan and schedule and the data collected, including an explanation of any variance from the study plan and schedule” (18CFR 5.15(c)(1)). This Initial Study Report (ISR) on Wolverine Distribution, Abundance, and Habitat Occupancy has been prepared in accordance with FERC’s ILP regulations and details AEA’s status in implementing the study, as set forth in the RSP and as approved in FERC’s February 1 SPD (referred to herein as the “Study Plan”). 2. STUDY OBJECTIVES The overall goal of this study is to collect pre-construction baseline population data on wolverines in the Project area (reservoir impoundment zone; facilities, laydown, and storage areas; access and transmission line routes) to enable assessment of the potential impacts from development of the proposed Project. This information will be used to estimate the number of wolverines that may be affected by the Project and to evaluate impacts on habitats used seasonally by wolverines. The four study objectives are established in RSP Section 10.9.1: 1) Estimate the current population size of wolverines. 2) Establish a population index for wolverines. 3) Describe the distribution of wolverines in late winter. 4) Describe habitat use by wolverines in late winter. 3. STUDY AREA The Wolverine Study Area (WSA; Figure 3-1) is substantially larger than the Project area because of the need to consolidate sampling blocks for the proposed population estimation technique while still encompassing the reservoir inundation zone, dam site, access and INITIAL STUDY REPORT WOLVERINE DISTRIBUTION, ABUNDANCE, AND HABITAT OCCUPANCY STUDY (10.9) Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 2 February 2014 Draft transmission line corridors, and other Project infrastructure and adjacent areas. Most of the WSA is within Game Management Unit (GMU) Subunits 13E and 13A. The study team developed a sampling grid delineated for a Sample Unit Probability Estimator (SUPE) survey of wolverines (Becker et al. 2004; Golden et al. 2007) for the WSA as the primary method for assessing population status of wolverines (Figure 3-1). The study team divided the survey area into equal- sized survey units (e.g., 25 square kilometers; Golden et al. 2007) that were stratified on the basis of predicted density of wolverines (high and medium/low density) from a priori knowledge, harvest information, and habitat characteristics. The WSA contained 338 survey units, of which the study team randomly selected 216 for the SUPE survey. 4. METHODS AND VARIANCES IN 2013 4.1. Survey Design The study team implemented the methods as described in the Study Plan with no variances. The goal of this study is to collect preconstruction baseline population data on wolverine in the Project area (reservoir impoundment zone, facilities, laydown, and storage areas, access and transmission line routes) for future assessment of the potential impacts from development of the proposed Project. The purpose of this study is to use a combination of the SUPE survey technique and Occupancy Modeling (OM) to assess the wolverine population in the WSA. The study team developed survey methods to allow data collected during SUPE surveys to be used in OM without violating the assumptions of either estimator. Because the requirements for conducting a SUPE are more rigorous, the survey design was largely based on the SUPE estimator. RSP Section 10.9.4 proposed that “a single aerial Sample-Unit Probability Estimator (SUPE) survey will be attempted. If survey conditions are unsuitable for the SUPE in 2013, then an occupancy survey will be flown.” Suitable survey conditions did not develop in 2013 to allow the study team to conduct the SUPE as planned, so the study team developed an OM as originally proposed (see Section 4.2 below). The study team used a subset of 25 sampling units from the SUPE grid to model occupancy of the WSA for wolverines. The study team randomly selected the first sample unit, then spaced sample units at approximately 10 km on center, which was the approximate radius of a circular, 300-km2 home range (approximate mean of adult female and male home range size from the 1980s Alaska Power Authority [APA] Project studies [Whitman and Ballard 1984] and mean adult female home range size in the study by Inman et al. [2012]). The study team selected sampling units from the 216 units selected randomly for the SUPE so that data from the SUPE survey, if conducted, would provide the data for the first OM survey (i.e., the first OM sampling survey would not need to be flown in addition to SUPE surveys). The study team flew occupancy surveys following SUPE protocols, using a Cessna 185 fixed- wing aircraft rather than a Piper PA-18. Because the study team only needed to detect wolverine presence (either individual animals or tracks) in each of the sample units and not follow tracks, the greater speed of the Cessna reduced the amount of time needed to survey each unit, and the INITIAL STUDY REPORT WOLVERINE DISTRIBUTION, ABUNDANCE, AND HABITAT OCCUPANCY STUDY (10.9) Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 3 February 2014 Draft lower maneuverability did not affect survey results. Surveys of sample units ended when wolverine sign was detected. Because the SUPE survey was not conducted in 2013, the study team flew two complete occupancy surveys to assess wolverine occupancy in the WSA. The study team flew all sample units for each survey in a single day, with 3 days between the surveys. The study team assigned two aircraft with a consistent pilot/observer team. Each aircraft surveyed half of the sample units during each survey. The study team reversed the sample units assigned to each team for the second occupancy survey to avoid detection bias based on prior knowledge of track locations. 4.1.1. Variances No variances from the methods described for aerial surveys were necessary in 2013. 4.2. Occupancy Modeling The study team used OM to estimate the proportion of the WSA occupied by wolverines (MacKenzie et al. 2006) by calculating adjusted occupancy values (Ψ) that account for imperfect detection of wolverines. The study team analyzed 2013 data using “single season, single species” models in program PRESENCE (MacKenzie et al. 2006). The study team included site (i.e., sample unit) covariates for occupancy and sample (i.e., flight) covariates for detection to adjust occupancy estimates. The study team modeled probability of detection (p) as either constant or varying by survey (sample-varying). The study team modeled Ψ with sample covariates taken from SUPE protocols including (1) snow age in days, classified as 1–2, 3–4, 5–6, or 7+; (2) snow cover, classified as complete, some low vegetation showing, or bare ground showing; (3) light type, classified as bright or flat; and (4) light intensity, classified as high, medium, or low. The study team further included observer/pilot pair as an additional sample covariate. Last, the study team used the Multi-Resolution Land Characteristics Consortium’s National Land Cover Data (EPA 2001) to estimate the proportion of each sample unit in deciduous forest, conifer forest, and mixed forest and used these cover classes as covariates in OM. The study team compared these values to unadjusted occupancy values (naïve occupancy), where unadjusted occupancy was defined as the number of sample units with wolverine detection, divided by the total number of units sampled. Akaike Information Criteria, corrected for small sample sizes (AICc; Burnham and Anderson 1998) were used to compare models. 4.2.1. Variances No variances from the methods proposed for occupancy modeling were necessary in 2013. 5. RESULTS Survey conditions were not suitable for conducting the SUPE survey during the winter of 2012– 2013. However, the study team conducted two surveys for OM as originally proposed. INITIAL STUDY REPORT WOLVERINE DISTRIBUTION, ABUNDANCE, AND HABITAT OCCUPANCY STUDY (10.9) Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 4 February 2014 Draft The study team detected wolverine or track sets of wolverine in 23 of 25 sample units (18 of 20 high density; 5 of 5 medium/low density) during surveys of the WSA conducted on April 11 and April 15, 2013. Occupancy of wolverines uncorrected for imperfect detection (naïve occupancy) was 0.920. Detection probability (p) was 0.953 (SE = 0.033) and Ψ corrected for imperfect detection was 0.922 (SE = 0.055) for the 2013 WSA survey. 6. DISCUSSION While one of the goals of this Project is to estimate the wolverine population size using the SUPE technique, the study team may need to rely on OM as the primary source of information on wolverine population trends if conditions in the second year of study preclude a SUPE survey. OM provided estimates of wolverine occupancy of the WSA in a more flexible survey regime than did alternative trend estimators currently used in Alaska. Occupancy can also potentially be used to determine minimum population size of wolverines (i.e., the numbers of territory holding adults), although the study team was unable to independently corroborate population estimates because the lack of suitable environmental conditions precluded the SUPE population estimation survey in winter 2013. In subsequent surveys, the study team intends to follow the same analytical protocol but will use multi-season occupancy models for analyses after more than one year of data is available. This analysis will model both constant and annually varying rates of colonization, extinction (from sample units), and probability of detection. Spatially explicit OM (e.g., Johnson et al. 2013) also may be evaluated in the future as these approaches evolve to include multi-season modeling. 7. COMPLETING THE STUDY [As explained in the cover letter to this draft ISR, AEA’s plan for completing this study will be included in the final ISR filed with FERC on June 3, 2014.] 8. LITERATURE CITED AEA (Alaska Energy Authority). 2012. Revised Study Plan: Susitna-Watana Hydroelectric Project FERC Project No. 14241. December 2012. Prepared for the Federal Energy Regulatory Commission by the Alaska Energy Authority, Anchorage, Alaska. http://www.susitna-watanahydro.org/study-plan. Becker, E. F., H. F. Golden, and C. L. Gardner. 2004. Using probability sampling of animal tracks in snow to estimate population size. Pages 248–270 in W. L. Thompson, editor. Sampling Rare or Elusive Species: Concepts and Techniques for Estimating Population Parameters. Island Press, Washington, DC. Burnham, K. P., and D. R. Anderson. 1998. Model Selection and Inference: A Practical Information–Theoretic Approach. Springer, New York, NY. INITIAL STUDY REPORT WOLVERINE DISTRIBUTION, ABUNDANCE, AND HABITAT OCCUPANCY STUDY (10.9) Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 5 February 2014 Draft EPA (Environmental Protection Agency). 2001. Multi-Resolution Land Characteristics Consortium: National Land Cover Data. Available online: http://www.epa.gov/mrlc/nlcd-2001.html (accessed April 2013). Golden, H. N., J. D. Henry, E. F. Becker, M. I. Goldstein, J. M. Morton, D. Frost, Sr., and A. J. Poe. 2007. Estimating wolverine Gulo gulo population size using quadrat sampling of tracks in snow. Wildlife Biology 13: 52–61. Inman, R. M., M. L. Packila, K. H. Inman, A. J. McCue, G. C. White, J. Persson, B. C. Aber, M. L. Orme, K. L. Alt, S. L. Cain, J. A. Fredrick, B. J. Oakleaf, and S. S. Sartorius. 2012. Spatial ecology of wolverines at the southern periphery of distribution. Journal of Wildlife Management 76: 778–792. Johnson, D. S., P. B. Conn, M. B. Hooten, J. C. Ray, and B. A. Pond. 2013. Spatial occupancy models for large data sets. Ecology 94: 801–808. MacKenzie, D. I., J. D. Nichols, J. A. Royle, K. H. Pollock, L. L. Bailey, and J. E. Hines. 2006. Occupancy Estimation and Modeling: Inferring Patterns and Dynamics of Species Occurrence. Academic Press, San Diego, CA. Whitman, J. S., and W. Ballard. 1984. Big game studies, volume VII: Wolverine. Susitna Hydroelectric Project, 1983 annual report, Alaska Department of Fish and Game, Juneau. INITIAL STUDY REPORT WOLVERINE DISTRIBUTION, ABUNDANCE, AND HABITAT OCCUPANCY STUDY (10.9) Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 6 February 2014 Draft 9. FIGURES INITIAL STUDY REPORT WOLVERINE DISTRIBUTION, ABUNDANCE, AND HABITAT OCCUPANCY STUDY (10.9) Susitna-Watana Hydroelectric Project Alaska Energy Authority FERC Project No. 14241 Page 7 February 2014 Draft Figure 3-1. Wolverine Study Area, 2013.