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Susitna-Watana Hydroelectric Project Document
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Title:
Terrestrial furbearer abundance and habitat use, Study plan Section 10.10
: Initial study report
SuWa 207
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Prepared by University of Alaska Fairbanks, Institute of Arctic Biology
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Draft initial study report
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Susitna-Watana Hydroelectric Project document number 207
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[Anchorage : Alaska Energy Authority, 2014]
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February 2014
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Alaska Energy Authority
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Study plan Section 10.10
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Draft
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v, 17 p.
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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)
Terrestrial Furbearer Abundance and Habitat Use
Study Plan Section 10.10
Initial Study Report
Prepared for
Alaska Energy Authority
Prepared by
University of Alaska Fairbanks, Institute of Arctic Biology
February 2014 Draft
INITIAL STUDY REPORT TERRESTRIAL FURBEARER ABUNDANCE AND HABITAT USE STUDY (10.10)
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page i February 2014 Draft
TABLE OF CONTENTS
Executive Summary ..................................................................................................................... iv
1. Introduction ........................................................................................................................1
2. Study Objectives.................................................................................................................1
3. Study Area ..........................................................................................................................2
4. Methods and Variances in 2013 ........................................................................................2
4.1. Sample Collection ................................................................................................2
4.1.1. Variances........................................................................................................... 3
4.2. Genetic Analyses ..................................................................................................4
4.2.1. Variances........................................................................................................... 4
4.3. Habitat Use ...........................................................................................................5
4.3.1. Variances........................................................................................................... 5
4.4. Statistical Analyses and Data Interpretation ........................................................6
4.4.1. Variances........................................................................................................... 6
5. Results .................................................................................................................................6
5.1. Sample Collection ................................................................................................6
5.2. Habitat Use and Furbearer Occupancy .................................................................7
5.3. Genetic and Statistical Analyses ..........................................................................7
6. Discussion............................................................................................................................7
7. Completing the Study ........................................................................................................8
8. Literature Cited .................................................................................................................8
9. Tables ..................................................................................................................................9
10. Figures ...............................................................................................................................12
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LIST OF TABLES
Table 5.2-1. Track Counts from Aerial Furbearer Surveys, Winter 2013. ..................................... 9
Table 5.2-2. Furbearer Occupancy (PSI) and Detection Probability (P) as a Function of Survey
Method. .................................................................................................................................. 9
Table 7.3-1. Scat Samples Collected during Terrestrial Furbearer Study, Winter 2013. ............... 9
Table 7.3-2. Hair Samples Collected during Terrestrial Furbearer Study, Winter 2013. ............. 10
Table 7.3-3. Average Number of Hare Pellets per Survey Plot at 15 Survey Locations, Summer
2013...................................................................................................................................... 10
Table 7.3-4. Number of Voles Captured at 15 Survey Locations, Summer 2013. ....................... 11
LIST OF FIGURES
Figure 3-1. Terrestrial Furbearer Study Area and 2013 Survey Area for the Susitna-Watana
Hydroelectric Project. .......................................................................................................... 13
Figure 4.1-1. Location of Ground-based Transect and Occupancy Survey Cells Sampled in
Winter 2013. ........................................................................................................................ 14
Figure 4.1-2. Grid Locations Sampled for Snowshoe Hare and Vole Abundance in Summer 2013
….………………………………………………………………………………………… 15
Figure 4.3-1. Aerial Transects for Track Surveys of Terrestrial Furbearers in Winter 2013. ...... 16
Figure 5.2-1. Track Counts of Terrestrial Furbearers along Each Aerial Survey Transect in
Winter 2013. (Counts were summed across the three surveys.) .......................................... 17
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LIST OF ACRONYMS, ABBREVIATIONS, AND DEFINITIONS
Abbreviation Definition
AEA Alaska Energy Authority
CIRWG Cook Inlet Regional Working Group
DNA Deoxyribonucleic acid
DNPP Denali National Park and Preserve
FERC Federal Energy Regulatory Commission
GIS Geographic Information System.
GPS global positioning system
ILP Integrated Licensing Process
ISR Initial Study Report
Project Susitna-Watana Hydroelectric Project
RSP Revised Study Plan
SPD Study Plan Determination
UAF University of Alaska in Fairbanks
INITIAL STUDY REPORT TERRESTRIAL FURBEARER ABUNDANCE AND HABITAT USE STUDY (10.10)
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EXECUTIVE SUMMARY
Terrestrial Furbearer Abundance and Habitat Use Study 10.10
Purpose The goal of this study is to provide current information on the abundance and
habitat use of four species of terrestrial furbearers (coyote, red fox, lynx, and
marten) for use in evaluating potential Project-related impacts and identifying
appropriate mitigation.
Status Winter and summer field work was conducted as planned in 2013 and
laboratory analyses of DNA from hair and scat samples are currently in
progress. Track data, habitat classifications, and genetic samples were
collected for coyote, red fox, and lynx. The study team estimated snowshoe
hare abundance from counts of fecal pellets and the abundance of voles from
trap grids. Habitat use was evaluated by using a combination of data from
aerial and ground-based surveys.
Study
Components
• Sample collection
• Genetic analysis
• Habitat use and evaluation
• Statistical analysis and data interpretation
2013 Variances Variances became necessary during the winter season due to lack of access to
Cook Inlet Regional Working Group (CIRWG) lands; as a result, marten
surveys were not conducted as planned in RSP Section 10.10.4.1. Sampling
was conducted in as much of the original study area as much as possible, but
no surveys were conducted in the Chulitna and Gold Creek corridors in 2013.
To maximize sampling effort in areas accessible by snowmachine from the
winter base of operations on the Denali Highway, the study team expanded
the 2013 survey area to include areas to the northeast of the study area. The
study team modified the deployment and use of the lynx hair snags (RSP
Section 10.10.4.1) to increase sampling efficiency in the field and to create a
survey layout that allowed better comparison of the lynx survey data with
those from the canid scat collection effort. Snowshoe hare surveys were
conducted in summer primarily as described in RSP Section 10.10.4.1,
although the study team changed the way that the sample grid locations were
allocated to better account for variability of habitats throughout the 2013
survey area. The vole live-trapping survey also involved slight variances from
the Study Plan, in that trapping nights were reduced from the one to five
nights originally proposed to a single night per grid.
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.
INITIAL STUDY REPORT TERRESTRIAL FURBEARER ABUNDANCE AND HABITAT USE STUDY (10.10)
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page v February 2014 Draft
Terrestrial Furbearer Abundance and Habitat Use Study 10.10
Highlighted
Results and
Achievements
Three winter track surveys were flown in February, March, and April 2013.
Summer field work on prey abundance revealed low vole densities across the
study area and variable snowshoe hare abundance. Low prey density may be
affecting current abundance of predator species.
INITIAL STUDY REPORT TERRESTRIAL FURBEARER ABUNDANCE AND HABITAT USE STUDY (10.10)
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) for the Susitna-
Watana Hydroelectric Project No. 14241 (Project), which included 58 individual study plans
(AEA 2012). RSP Section 10.10 described the study of Terrestrial Furbearer Abundance and
Habitat Use. This study focuses on providing current information on the abundance and habitat
use of four terrestrial furbearers: coyote (Canis latrans), red fox (Vulpes vulpes), lynx (Lynx
canadensis), and marten (Martes americana). RSP Section 10.10 describes the goal, objectives,
and proposed methods for data collection regarding terrestrial furbearers.
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. Study 10.10 was one of the
31 studies 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 and initial study report describing its
overall progress in implementing the study plan and schedule and data collected, including an
explanation of any variance from the study plan and schedule” (18 CFR 5.15(c)(1)). This Initial
Study Report (ISR) on Terrestrial Furbearer Abundance and Habitat Use Study 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 as approved in FERC’s February 1 SPD (referred to herein as
the “Study Plan”).
2. STUDY OBJECTIVES
The five objectives of this study are established in RSP Section 10.10.1:
1) Develop population estimates of coyotes and red foxes through fecal genotyping and
genetic capture–recapture analyses, using scats collected along trails and rivers
throughout the study area during winter months (January–March) in 2013 and 2014;
2) Develop a population estimate of marten through DNA-based capture–recapture analysis,
using hair samples collected in the reservoir inundation zone with hair-snag tubes;
3) Develop a population estimate of lynx through DNA-based capture–recapture analysis,
using hair samples collected throughout the study area with hair-snag plates;
4) Assess prey abundance in the study area by conducting snowshoe hare pellet counts and
estimating vole density using a mark–recapture framework from live-trapping sessions;
5) Compile habitat-use data for the furbearer species being studied, using aerial track
surveys.
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3. STUDY AREA
As established by RSP Section 10.10.3, the terrestrial furbearer study area (Figure 3-1) includes
all terrestrial areas that are safely accessible by snowmachine within a 10-kilometer (6.2-mile)
buffer zone surrounding the areas that may be directly altered or disturbed by Project
construction and operations, including facility sites, laydown/storage areas, the reservoir
inundation zone, and access road and transmission-line corridors.
4. METHODS AND VARIANCES IN 2013
The methods implemented for each of the four major study components and variances are
described below.
4.1. Sample Collection
AEA implemented the methods as described in the Study Plan (RSP Section 10.10.4.1), with the
exception of variances explained below (Section 4.1.1).
The study team established five survey transects, each ranging in length from approximately 25
to 50 km (15–30 mi), along natural corridors of animal movement in the study area, such as
creeks, rivers, and the Denali Highway (Figure 4.1-1). Transects along the Susitna River and
Denali access corridor were relatively long (40–50 km), with shorter transects extending up
several tributary drainages (Watana, Tsusena, and Butte creeks). Transect placement ensured
roughly equal coverage of the 2013 survey area and avoided gaps. The study team surveyed
transects daily on a rotating basis, such that each transect was traveled every week between
January 7 and April 15, 2013, collecting all canid (fox and coyote) and felid (lynx) scats along
the transects.
The study team also deployed hair-snag plates every 5 km (3.1 mi) along the transects that were
established for scat collection. Hair-snag stations were checked twice monthly during January
29–April 12, 2013. Five marten hair tubes (Williams et al. 2009) were deployed in forested
locations considered likely to be used by marten to test the effectiveness of the sampling method.
The study team estimated snowshoe hare abundance from counts of fecal pellets in 15 survey
grids in the 2013 survey area (Figure 4.1-2). Pellet grids were placed in contiguous areas of hare
habitat (spruce forest and riparian shrub) located throughout the 2013 survey area in major.
Creek drainages and portions of the Project area, including the Denali corridor and reservoir
inundation zone were specific areas of interest. Four grids established in August 2012 were
resurveyed and 11 new grids were established in 2013.
The study team estimated abundance of voles by using live-trapping in 15 grids (Figure 4.1-2).
One grid established in August 2012 was resurveyed and 14 new grids were established in 2013.
Each grid comprised 100 live-trap sites, spaced at 10-m (32.8 ft) intervals. The study team
deployed traps for one night at each grid. Data from 1-night trapping sessions were compared
with results from 5-night trapping sessions of a similar study in the Denali National Park and
Preserve (DNPP) in which the ratio of recaptured tagged individuals to unmarked individuals
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was used to calculate an estimate of population abundance. This comparison allowed abundance
estimates to be generated while expanding the sampling coverage area 5-fold.
4.1.1. Variances
The 2013 survey area was modified for the following reasons: (1) the long distance to much of
the study area from the winter base of operations at Alpine Creek Lodge on the Denali Highway;
(2) physical barriers that prevented travel by snow machine along the lower sections of the
Susitna River; and (3) the lack of access to Cook Inlet Regional Working Group (CIRWG) lands.
The lack of a suitable base of operations centrally located within the study area made it
impossible to achieve full access to the entire study area. Because Alpine Creek Lodge was the
only feasible option for a base of winter operations, access to sampling sites along the Denali
Highway was convenient, but access to areas closer to the dam site and west of Tsusena Creek
was extremely challenging. The lack of access to CIRWG lands prevented the field crew from
sampling in the western portion of the inundation zone and adjacent area. The combination of
those access restrictions with physical barriers along the Susitna River (cliffs, steep slopes, and
unstable ice conditions) made it impossible or unsafe to cross from the north side of the Susitna
River to the south side in the reservoir inundation zone. Sampling was conducted in as much of
the study area described in the Study Plan as much as possible, but no surveys were conducted in
the Chulitna and Gold Creek corridors in 2013. To maximize sampling effort in areas accessible
by snowmachine from the winter base of operations, the 2013 survey area was expanded to
include areas northeast of the study area (Figure 3-1). These variances allowed sampling to be
conducted in a large enough area that findings can be extrapolated across the entire survey area.
In this way, the study team will still be able to meet the study objectives.
The study team modified the deployment and use of the lynx hair snags to increase sampling
efficiency in the field and to create a survey layout that allowed better comparison of the lynx
survey data with those from the canid scat collection effort. Rather than subdividing the entire
study area into 50 blocks as proposed in the Study Plan, lynx stations were deployed along the
major sampling transect routes that were established for scat collections. Stations were
systematically deployed every 5 km (3.1 mi) along those routes to maintain a similar sampling
density to that described in the Study Plan. This method of station layout and deployment
allowed the field crew to check the hair stations while simultaneously looking for scats, thereby
increasing the efficiency of data collection. Creating spatial overlap of the sample collection
locations provided more descriptive data concerning abundance of canids and lynx as well as
potential interspecific interactions in the shared sampling area. These variances will have no
impact of the study team’s ability to meet study objectives because sampling routes tended to be
located along drainages and therefore encompassed most of the available lynx habitat in the
study area. Areas between sampling routes were generally alpine habitats at higher elevations,
which are considered unsuitable for lynx.
Collection of marten hair samples was not accomplished in 2013 as proposed in the Study Plan
because of the lack of access to CIRWG lands and the difficulty of snowmachine access in the
reservoir inundation zone, which included a large proportion of suitable marten habitat (spruce
forest). That area was outlined in the Study Plan as the primary area to be surveyed for martens
in both years of study. Access to these areas in the next study season will allow the study
objective to be achieved.
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Snowshoe hare surveys were conducted primarily as described in the Study Plan, although the
study team changed the way that the sample grid locations were allocated to better account for
variability of habitats throughout the 2013 survey area. Instead of dividing the study area into
equal-sized blocks as described in the Study Plan, grids were established in parts of the study
area where the desired habitat elements (spruce forest and riparian shrubs) occurred in
contiguous patches. Habitat maps and aerial scouting were used to pinpoint the specific locations
that fit these habitat requirements. The study team chose locations that were evenly spread out
and were close to creek or river drainages, which tended to have the most suitable habitat. The
study team also attempted to establish grids in portions of the proposed Project area, such as the
Denali access corridor. Some sampling bias may have been introduced by the nonrandom
selection of survey locations, but the study team concluded that the revised sampling design
provided a more robust method of estimating snowshoe hare abundance. The study team
increased the number of sample grids from the 8–10 grids proposed in the Study Plan to a total of
15 grids, an increase in sampling effort that was considered necessary because of the high level
of habitat heterogeneity in the study area.
The vole live-trapping survey also involved variances from the Study Plan. As proposed,
trapping grids were established in spruce and meadow habitats. These grids were set up in pairs
(one grid in spruce and one in meadow) throughout several major drainages and the Denali
access corridor (see Section 5.1 below). One grid was set up in a meadow without a paired forest
grid because of the lack of suitable spruce habitat in that location. Trapping nights were reduced
from the one to five nights proposed to a single night per grid. Accordingly, the captured voles
were not marked. This reduction in effort was justified by the strong correlation (r = 0.85; L.
Prugh, unpublished data) between the number of voles caught on the first night of trapping and
the vole density estimated from 5-night mark–recapture trapping sessions in a similar study in
DNPP. Trapping for a single night per grid in this study provided adequate information for use in
estimating vole abundance while allowing sampling coverage to be increased five-fold in the
2013 survey area. By reducing effort at each site to one night of trapping, each grid size could be
increased from the proposed 50 traps per grid to 100 traps per grid and the total number of grids
was increased from 8–10 to a total of 15. Both of these changes increased sample sizes and
provided better coverage of the survey area.
4.2. Genetic Analyses
AEA implemented the methods as described in the Study Plan (RSP Section 10.10.4.2) with no
variances. Samples currently are being processed in the Prugh laboratory at the University of
Alaska (UAF) for completion of analyses during winter 2014, so no results were available for
inclusion in the ISR.
4.2.1. Variances
No variances from the study plan methods for genetic analyses occurred during 2013. However,
analyses were delayed substantially for two reasons: (1) the study team was not able to initiate
laboratory analyses until July 2013, because the study team had to set up a new laboratory in a
new building, and was not able to move into the building until late June 2013; (2) the
development of a new species identification protocol was more difficult and time-consuming
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than originally anticipated. However, the study team does not expect delays in completing and
reporting final genetic analyses in 2014 and thus will be able to meet the study objective.
4.3. Habitat Use
AEA implemented the methods as described in the Study Plan (RSP Section 10.10.4.3), with the
exception of variances explained below (Section 4.3.1).
Habitat use was evaluated by using a combination of data from aerial surveys and ground-based
surveys. Helicopter surveys of wildlife tracks in the snow were conducted on February 26,
March 27, and April 19, 2013. The survey design was based on the helicopter-based track
surveys that were conducted in the Project area in the 1980s (Gipson et al. 1984), using the same
14 transect lines (Figure 4.3-1) to facilitate comparison of current and historical data. An
experienced observer (Dr. Laura Prugh) flew along the transect lines at low altitude (100–200 ft)
and slow speed (20–40 mph) in a Robinson R44 helicopter. The two helicopter pilots used on
different surveys (Troy Cambier and Rick Swisher) were experienced at furbearer track
identification and served as observers during the surveys. A global positioning system (GPS)
receiver was used to record the locations of all furbearer tracks encountered. Associated data
included the species that made the tracks and field descriptions of the habitat in which the tracks
were found, following the same scheme as in the ground-based track surveys. The GPS locations
were overlaid on a wildlife habitat map using a geographical information system (GIS) and
ArcGIS® software (ESRI, Redlands, California) to examine patterns of habitat use in the survey
area for each furbearer species.
4.3.1. Variances
Additional data on habitat use and species occupancy (beyond those described in the Study Plan)
were collected during the ground-based track surveys in winter 2013.
Ground-based track surveys were used to examine habitat associations. Using a GIS, a grid of
2×2-km2 cells was overlain on the study area. Cells were classified as being primarily comprised
of low shrub, tall shrub, forest, or alpine habitat, based on existing vegetation mapping, and
proportional sampling was used to select cells randomly within each habitat stratum. Selected
cells were sampled either by conducting track transects or by placing a motion-triggered camera
(Reconyx® PC800 HyperFire Professional) in a likely travel route within the cell. Camera
stations were deployed for periods of 2–3 weeks, baited with a scent (commercially available
skunk lure) and a bird (grouse or ptarmigan) wing as attractants. All furbearer tracks encountered
along transects were recorded, along with species identity, GPS waypoint, vegetation, and snow
characteristics (depth and compaction). Tracks of hares and voles were also counted. The
percentage of vegetative cover was classified on a scale from 0–4 for the major tree species in
the canopy, understory shrub species, and grass species. When it becomes available, the
vegetation and habitat map that will be produced by the Vegetation and Wildlife Habitat
Mapping Study in the Upper and Middle Susitna Basin (Study 11.5) will be used to evaluate
habitat use by the target species of furbearers.
These additions to the study design will not affect the ability of the study team to meet the study
objectives. Ground-based track surveys will continue to be carried out in the next study season,
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but the use of motion-triggered cameras will be discontinued because the addition of cameras to
the study design in 2013 did not provide useful results.
4.4. Statistical Analyses and Data Interpretation
AEA implemented the methods as described in the Study Plan (RSP Section 10.10.4.4), with the
exception of variances explained below (Section 4.4.1).
4.4.1. Variances
The Study Plan did not propose to include occupancy modeling in the study design; rather, the
study team included this additional analytical element during final project planning. Detections
from photographs were used along with track data to assess furbearer habitat associations using
occupancy models in software programs MARK and RMARK. These computer programs allow
estimation of the proportion of survey cells occupied by each furbearer species, probability of
detections for each species and for each survey method, and occupancy as a function of prey
availability and habitat type.
These additions will benefit the study by increasing the amount of data available to help describe
current furbearer populations. These additions, which will help to achieve the study objective by
providing additional data, will be carried out in the next study season.
5. RESULTS
Data developed in support of this study are available for download at http://gis.suhydro.org/reports/isr.
5.1. Sample Collection
The study team collected 111 fox and coyote scats in 2013. Samples were collected from all of
the targeted furbearer species (Table 5.1-1). Fewer hair samples were collected from the lynx
hair snags than expected (Table 5.1-2). As discussed above, only a small number of marten hair
tubes were deployed in the 2013 field season. However, trial runs of these hair tubes successfully
showed the effectiveness of the traps.
Prey surveys during the 2013 summer field season produced highly variable results. Snowshoe
hare surveys were conducted in the Jay, Watana, Butte, Deadman, Tsusena, Seattle, and
Brushkana creek drainages. Although data analysis is still in process at this writing, the raw data
suggested that hare density was extremely variable throughout the study area (Table 5.1-3).
Several areas of high use were located, as well as areas with little to no hare sign. Overall vole
density in the study area appeared to be extremely low in 2013 (Table 5.1-4). Survey areas
included the Jay, Watana, Butte, Deadman, Tsusena, and Seattle creek drainages and Deadman
Mountain. Capture success was low, with no indication of differences between habitat types. The
range of total captures per survey grid was 0–2 voles. The vole species captured included red-
backed vole (Myodes rutilus), meadow vole (Microtus pennsylvanicus), and singing vole
(Microtus miurus). Although trap mortality can be a common occurrence during small mammal
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surveys, precautions were taken to minimize this during the Susitna trapping sessions. No
mortalities of captured voles occurred during the 2013 sampling.
5.2. Habitat Use and Furbearer Occupancy
A total of 899 sets of tracks were recorded during the three helicopter surveys, 557 of which
were of the four target furbearer species (Table 5.2-1). No coyote tracks were seen on the aerial
survey transects. Furbearer track density increased markedly from west to east, peaking at
Watana Creek (Figure 5.2-1).
Collection of habitat data during aerial and ground-based surveys in the 2013 winter field season
resulted in an extensive database of microhabitat information. Detection of furbearers at remote
camera stations and detection of furbearer tracks along survey transects have been modeled as a
function of survey method (Table 5.2-2) and are currently being modeled as a function of habitat
classification and prey abundance using program MARK.
5.3. Genetic and Statistical Analyses
Genetic analysis of scat and hair samples is ongoing in the UAF lab. The study team obtained
reference tissue samples from museum specimens of known species identity to screen a set of
microsatellite markers. The study team then optimized those DNA markers and began DNA
fingerprinting of scats. Additionally, the study team used the reference tissues and scats to
develop a species identification protocol, which was more difficult to develop than expected due
to the large suite of carnivore species present in the area. This difficulty delayed large-scale
processing of scats because it is generally preferable to verify species identity before determining
individual ID. DNA from approximately 40 percent of the scats have been extracted at this
writing and, of those, 35 percent have been genotyped (DNA fingerprinted) at least once.
6. DISCUSSION
Overall, the study effort has proceeded largely as planned, although progress was hampered by
the lack of access to CIRWG lands, the lack of a centrally located base camp for winter
operations, and delays in getting the genetic signatures for some target species. Implementation
of data collection techniques during the winter and summer field seasons was productive and
closely followed the Study Plan. Aside from the limitations with the marten surveys, the only
variances with data collection methods were small changes in survey design to increase
efficiency in the field. Although the majority of data collection methods were implemented
successfully, the surveys produced mixed results.
One concern from the 2013 season was the low capture success of voles. Upon initial review,
these results may seem to be related to the short, one-night trapping sessions. The study team
considered transitioning to a longer trapping session at each survey grid and reducing the overall
number of survey grids sampled. However, this study followed the exact procedures
implemented in the DNPP study, during the same time frame, and results from the DNPP study
showed much higher vole densities, suggesting that the low capture rates in Susitna may not have
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been a function of the survey technique, but simply a representation of low vole density in the
study area.
Initial results from occupancy analyses indicated that the probability of detection varies
according to species. When modeled as a function of survey method, the study team observed a
wide range of detection probabilities from 0 (coyotes) to 0.45 (red fox). These values indicate
that the survey methods are more suitable for some species than for others. Occupancy estimates
for each species indicate that red fox and coyotes have the highest occupancy probability
throughout the study area. However, it is likely that marten and lynx occupancy is more closely
tied to habitat type because of their narrower habitat preferences. For some of the more elusive
furbearer species in the study area (coyote and lynx), low sample size may also need to be
considered as a confounding effect on both detection probability and occupancy rate. These
results are useful and will help to adjust the survey effort during the next year of study to
increase sample size. Incorporating modified track survey techniques, including two seasons
worth of data, and include habitat and prey abundance covariates, will lead to even more detailed
occupancy models after the next year of study.
Overall, collection of genetic samples in 2013 was a success. Although analyses of population
size, population growth rates, survival, and recruitment of our target species have not yet been
completed, the study team does not expect any changes in the final data products. The delays in
genetic analysis have caused a slight setback, but are not expected to alter the ability of the study
team to achieve the study objective.
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). 2011. Pre-Application Document: Susitna–Watana
Hydroelectric Project FERC Project No. 14241. December 2011. Prepared for the Federal
Energy Regulatory Commission by the Alaska Energy Authority, Anchorage, Alaska.
Gipson, P. S., S. W. Buskirk, T. W. Hobgood, and J. D. Woolington. 1984. Susitna Hydroelectric
Project furbearer studies: Phase I report update. Final report by Alaska Cooperative
Wildlife Research Unit, University of Alaska, Fairbanks, for Alaska Power Authority,
Anchorage. 100 pp.
Hobgood, T. W. 1984. Ecology of the red fox (Vulpes vulpes) in the upper Susitna Basin, Alaska.
M.S. thesis, University of Alaska, Fairbanks. 163 pp.
Williams, B. W., D. R. Etter, D. W. Linden, K. F. Millenbah, S. R. Winterstein, and K. T.
Scribner. 2009. Noninvasive hair sampling and genetic tagging of co-distributed fishers
and American martens. Journal of Wildlife Management 73: 26–34.
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9. TABLES
Table 5.2-1. Track Counts from Aerial Furbearer Surveys, Winter 2013.
Species February 26 March 27 April 19 Total
Marten 93 105 193 391
Weasel 68 43 91 202
Lynx 22 53 39 114
Wolverine 14 40 53 107
Fox 13 28 11 52
Wolf 9 0 11 20
Otter 2 6 4 12
Mink 0 1 0 1
Total 221 276 402 899
DSLS 2 4 9 --
Tracks per DSLS1 110.5 69 44.7 --
Notes:
1 DSLS = Days Since Last Snowfall
Table 5.2-2. Furbearer Occupancy (PSI) and Detection Probability (P) as a Function of Survey Method.
Species PSI1 95% Interval P2 95% Interval
Coyote 0.71 0.37–.091 0 0–1
Red Fox 0.49 0.34–0.64 0.45 0.34–0.57
Lynx 0.38 0.16–0.65 0.14 0.06–0.32
Marten 0.37 0.22–0.54 0.24 0.10–0.48
Notes:
1 Occupancy (PSI) describes the probability that the survey area is occupied by the target species, given that
species are imperfectly detected.
2 Detection probability (P) describes the probability of detecting that species assuming it is present.
Table 7.3-1. Scat Samples Collected during Terrestrial Furbearer Study, Winter 2013.
Species1 Total Number of Scats Collected
Coyote 35
Red Fox 76
Lynx 2
Marten 6
Wolverine 12
Total 131
Notes:
1 Samples were identified in the field based on size and shape of scat, or presence of animal tracks nearby. Not all
samples have been positively identified to species in the DNA lab.
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Table 7.3-2. Hair Samples Collected during Terrestrial Furbearer Study, Winter 2013.
Species1 Total Number of Hairs Collected
Lynx 23
Wolverine 6
Total 29
Notes:
1 Samples were identified in the field based on hair coloration and size, and the presence of furbearer tracks near
the hair snag station. Not all samples have been positively identified to species in the DNA lab.
Table 7.3-3. Average Number of Hare Pellets per Survey Plot at 15 Survey Locations, Summer 2013.
Survey Location Average Number of Pellets/Plot
1) Watana Creek Shrub 2.04
2) Jay Creek Forest 2.24
3) Tsusena Creek Shrub 8.7
4) Deadman Creek Forest 25.84
5) Watana Creek Forest 3.34
6) Upper Butte Creek Forest 0.48
7) Upper Butte Creek Shrub 1.32
8) Seattle Creek Shrub 3.78
9) Seattle Creek Forest 0.33
10) Butte Lake Forest 0.62
11) Butte Lake Shrub 16.48
12) Southern Butte Creek Forest 6.16
13) Southern Butte Creek Shrub 3.28
14) Jay Creek Shrub 45.16
15) Oshetna Creek Forest 29.78
Range 0.33–45.16
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Table 7.3-4. Number of Voles Captured at 15 Survey Locations, Summer 2013.
Survey Location Number of Captured Voles (Species)
1) Watana Creek Forest 1 (Red-backed Vole)
2) Watana Creek Meadow 0
3) Jay Creek Forest 0
4) Jay Creek Meadow 2 (Meadow Vole, Singing Vole)
5) Tsusena Creek Forest 1 (Red-backed Vole)
6) Tsusena Creek Meadow 0
7) West Tsusena Creek Forest 2 (Red-backed Vole)
8) West Tsusena Creek Meadow 1( Red-backed Vole)
9) Upper Butte Creek Forest 1 (Red-backed Vole)
10) Upper Butte Creek Meadow 1 (Red-backed Vole)
11) Upper Watana Creek Forest 1 (Red-backed Vole)
12) Upper Watana Creek Meadow 0
13) Seattle Creek Forest 1 (Red-backed Vole)
14) Seattle Creek Meadow 2 (Red-backed Vole)
15) Deadman Mountain Meadow 0
Total 13
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10. FIGURES
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Figure 3-1. Terrestrial Furbearer Study Area and 2013 Survey Area for the Susitna-Watana Hydroelectric Project.
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Figure 4.1-1. Location of Ground-based Transect and Occupancy Survey Cells Sampled in Winter 2013.
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Figure 4.1-2. Grid Locations Sampled for Snowshoe Hare and Vole Abundance in Summer 2013.
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Figure 4.3-1. Aerial Transects for Track Surveys of Terrestrial Furbearers in Winter 2013.
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Figure 5.2-1. Track Counts of Terrestrial Furbearers along Each Aerial Survey Transect in Winter 2013.
(Counts were summed across the three surveys.)