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Susitna-Watana Hydroelectric Project Document
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Title:
Big game movement and habitat use study : 2012 technical memorandum
SuWa 55
Author(s) – Personal:
Prepared by Alexander K. Prichard, Nathan A. Schwab, and Brian E. Lawhead
Author(s) – Corporate:
ABR, Inc.--Environmental Research & Services.
AEA-identified category, if specified:
2012 Environmental Studies
AEA-identified series, if specified:
Series (ARLIS-assigned report number):
Susitna-Watana Hydroelectric Project document number 55
Existing numbers on document:
Published by:
[Anchorage, Alaska : Alaska Energy Authority, 2013]
Date published:
February 2013
Published for:
Prepared for Alaska Energy Authority
Date or date range of report:
Volume and/or Part numbers:
Final or Draft status, as indicated:
Document type:
Technical memorandum
Pagination:
vii, 27, [19] 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)
Big Game Movement and Habitat Use Study
2012 Technical Memorandum
Prepared for
Alaska Energy Authority
Prepared by
Alexander K. Prichard, Nathan A. Schwab, and Brian E. Lawhead
ABR, Inc.–Environmental Research & Services
February 2013
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ii February 2013
TABLE OF CONTENTS
1. Introduction ........................................................................................................................1
2. Study Objectives.................................................................................................................2
3. Study Area ..........................................................................................................................2
4. Methods ...............................................................................................................................2
4.1. Deviations from the Study Plan .........................................................................3
4.2. Caribou ...............................................................................................................4
4.3. Moose .................................................................................................................4
4.4. Brown Bear ........................................................................................................5
4.5. Black Bear ..........................................................................................................5
5. Results .................................................................................................................................5
5.1. Caribou ...............................................................................................................5
5.1.1. Previous Research ........................................................................... 5
5.1.2. Reanalysis of Historical Telemetry Data ........................................ 7
5.2. Moose .................................................................................................................7
5.2.1. Previous Research ........................................................................... 7
5.2.2. Reanalysis of Historical Telemetry Data ........................................ 8
5.3. Brown Bear ........................................................................................................9
5.3.1. Previous Research ........................................................................... 9
5.3.2. Reanalysis of Historical Telemetry Data ...................................... 10
5.4. Black Bear ........................................................................................................10
5.4.1. Previous Research ......................................................................... 10
5.4.2. Reanalysis of Historical Telemetry Data ...................................... 11
6. Discussion and Conclusions ............................................................................................12
6.1. Caribou .............................................................................................................13
6.2. Moose ...............................................................................................................13
6.3. Brown Bear ......................................................................................................14
6.4. Black Bear ........................................................................................................14
7. Acknowledgments ................................................................ Error! Bookmark not defined.
8. References .........................................................................................................................14
9. Tables ................................................................................................................................17
10. Figures ...............................................................................................................................20
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iii February 2013
11. Appendices ........................................................................................................................27
LIST OF TABLES
Table 1. Home range size of radio-collared moose during 1976–1984, based on
fixed-kernel density analysis for animals with at least 30 relocations .................................. 17
Table 2. Use of the current Project area by 69 radio-collared moose during 1976–1984,
based on fixed-kernel density analysis for animals with at least 30 relocations................... 17
Table 3. Home range size of radio-collared brown bears during 1978–1985, based on
fixed-kernel density analysis for animals with at least 30 relocations .................................. 18
Table 4. Use of the current Project area by 39 collared brown bears during 1978–1985,
based on fixed-kernel density analysis for animals with at least 30 relocations................... 18
Table 5. Home range size of radio-collared black bears during 1980–1985, based on
fixed-kernel density analysis of animals with at least 30 relocations ................................... 19
Table 6. Use of the current Project area by 42 collared black bears during 1980–1985,
based on fixed-kernel density analysis for animals with at least 30 relocations................... 19
LIST OF FIGURES
Figure 1. Location of the Project area in relation to Game Management Units and
the Susitna River basin .......................................................................................................... 22
Figure 2. Seasonal distribution of radio-collared caribou during 1980–1985,
based on fixed-kernel density analysis of telemetry locations .............................................. 22
Figure 3. Estimated seasonal density of the Nelchina Caribou Herd that used
different portions of the current Project area, based on fixed-kernel density
analysis of telemetry locations collected during 1980–1985 ................................................ 23
Figure 4. Spatial distribution of the home ranges (95% UD contour) of 69 radio-collared
moose during 1976–1984 in relation to the current Project area, based on
fixed-kernel density analysis of telemetry locations ............................................................. 24
Figure 5. Spatial distribution of the home ranges (95% UD contour) of 39 radio-collared
brown bears during 1978–1985 in relation to the current Project area, based on
fixed-kernel density analysis of telemetry locations ............................................................. 25
Figure 6. Spatial distribution of the home ranges (95% UD contour) of 42 radio-collared
black bears during 1980–1985 in relation to the current Project area, based on
fixed-kernel density analysis of telemetry locations ............................................................. 26
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page iv February 2013
APPENDICES
Appendix 1. Annual distribution of radio-collared caribou during spring (April 1–May14) 1980–
1985, based on fixed-kernel density analysis of telemetry locations
Appendix 2. Annual distribution of radio-collared caribou during calving (May 15–June 10)
1980–1985, based on fixed-kernel density analysis of telemetry locations
Appendix 3. Annual distribution of radio-collared caribou during summer (June 11–July 31)
1980–1985, based on fixed-kernel density analysis of telemetry locations
Appendix 4. Annual distribution of radio-collared caribou during autumn (August 1–
September30) 1980–1984, based on fixed-kernel density analysis of telemetry locations
Appendix 5. Annual distribution of radio-collared caribou during the rut (October 1–31) 1980–
1984, based on fixed-kernel density analysis of telemetry locations
Appendix 6. Annual distribution of radio-collared caribou during winter (November 1–March
31) 1980–1984, based on fixed-kernel density analysis of telemetry locations
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page v February 2013
LIST OF ACRONYMS AND SCIENTIFIC LABELS
Abbreviation Definition
ADF&G Alaska Department of Fish and Game
ADNR Alaska Department of Natural Resources
AEA Alaska Energy Authority
APA Alaska Power Authority
APA Project Alaska Power Authority Susitna Hydroelectric Project
DCH Delta Caribou Herd
FERC Federal Energy Regulatory Commission
GIS geographical information system
GMU Game Management Unit
GPS Global Positioning System
ILP Integrated Licensing Process
km2 square kilometer
m meter
mi2 square mile
NCH Nelchina Caribou Herd
NEPA National Environmental Policy Act
Project Susitna-Watana Hydroelectric Project
RM River mile based on 1980s project
SD standard deviation
UD Utilization Distribution
VHF Very High Frequency
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page vi February 2013
SUMMARY
Extensive research on wildlife populations was conducted in the Susitna River basin during the
1980s after the Alaska Power Authority (APA) first proposed the Susitna Hydroelectric Project
(APA Project). That research included radio telemetry studies and population surveys of moose,
caribou, Dall’s sheep, bears, and wolves. The goal of the 2012 study was to acquire and analyze
existing data on big game populations in the region in which the Project area is located,
including reanalysis of historical data using newer analytical methods, to determine whether
additional information on distribution or movement patterns needs to be collected during the
2013–2014 study program for the Federal Energy Regulatory Commission (FERC) licensing
process.
The 2012 study had three objectives: (1) identify all relevant data available from the Alaska
Department of Fish and Game (ADF&G); (2) synthesize that information with regard to the
seasonal abundance, distribution, movements, and habitat use of moose, caribou, Dall’s sheep,
brown bears, black bears, and wolves in the Project area; and (3) evaluate the adequacy of that
information for assessing potential Project-related effects on these wildlife resources in the
middle and upper Susitna River basin.
Data-sharing agreements were developed among ADF&G, the Alaska Energy Authority (AEA),
and the Alaska Department of Natural Resources (ADNR), as well as between ADF&G and
ABR, allowing ADF&G survey and telemetry data to be obtained by ABR for analysis. This
study is the initiation of a multi-year data-synthesis effort beginning in 2012 and continuing in
2013–2014. In addition, ADF&G began Project-specific moose and caribou telemetry studies in
2012, which will continue in 2013–2014 (AEA 2012).
The study area varies somewhat by species, depending on the extent of data collection (refer to
accompanying map figures), but is centered on Game Management Unit (GMU) Subunit 13E.
When applicable, analyses will include data collected in adjacent subunits such as 13A, 13B,
14B, 16A, and 20A. The study area includes all areas that may be altered or disturbed by the
proposed dam, reservoir inundation zone, and associated Project facilities such as access road
and transmission line corridors, as well as adjacent seasonal ranges in the upper and middle
Susitna River basin. It is important to note that the areas analyzed for historical telemetry data
were limited by the extent of the 1980s studies, whereas current studies will focus on the entire
Project area.
The availability of telemetry and population survey data varied among different periods. The
historical telemetry data from the original APA studies (primarily Very High Frequency [VHF]
collar locations) were provided by ADF&G for caribou (1980–1985), moose (1976–1984),
brown bears (1978–1985), and black bears (1980–1985). No historical telemetry data were
available for Dall’s sheep or wolves. Previous studies conducted in the 1980s primarily used
minimum convex polygons to delineate home ranges, so a more advanced geospatial analytical
technique (fixed-kernel density analysis) was applied to the historical APA data for the 2012
study. Further consultation and coordination with ADF&G will be necessary to obtain and
analyze other, more recent telemetry and population survey data in 2013 and 2014, including
studies involving currently deployed animals, such as the moose and caribou studies using new
radio collars deployed specifically for the Project (see RSP Sections 10.5 and 10.6 in AEA
2012). The results of the 2012 analyses will be used to inform the analyses of recent and current
telemetry and population survey data that will be conducted in 2013 and 2014, in preparation for
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page vii February 2013
the License Application in 2015 (see RSP Sections 10.5.1, 10.5.7, 10.6.1, and 10.6.7 in AEA
2012).
The proposed Susitna–Watana Hydroelectric Project (Project) has the potential to result in direct
and indirect impacts on big game populations, habitat use, movements, and distribution. The
reservoir inundation zone and proposed access corridor could remove big game habitat and
create potential impediments to movements. Disturbance associated with construction and
vehicle noise and changes in hunting patterns, recreation, and other human activity has the
potential to indirectly affect the numbers and distribution of animals in the region.
The following sections summarize the findings of the 2012 analyses of historical telemetry data:
Moose—The 2012 analysis examined 5,400 telemetry locations of 211 different moose (160
females, 48 males, and 3 of unknown sex) obtained during the historical APA upstream study
period from October 21, 1976, to September 10, 1984. Results demonstrate that moose used the
proposed reservoir inundation zone and the area near the proposed camp facilities at a high level,
especially in winter.
Caribou—The 2012 analysis examined 2,651 telemetry locations of 92 different caribou (74
females, 17 males, and 1 of unknown sex) from the Nelchina Herd, obtained during the historical
APA study period from April 14, 1980, to July 9, 1985. The highest seasonal densities of caribou
in the Project area occurred during autumn, when the peak estimated seasonal density (based on
a herd size of 20,000 animals) was ~1 caribou/km² in the reservoir inundation zone.
Brown Bear—The 2012 analysis examined 3,799 telemetry locations of 90 brown bears (52
females, 38 males) obtained during the historical APA study period from April 9, 1978, to
September 30, 1985. Although the extent of movements was broad, the home ranges of most
collared bears (82%) overlapped with the Project area to some degree. Home ranges calculated
using the fixed-kernel density estimator were substantially larger than the original estimates from
the 1980s, which were calculated using minimum convex polygons.
Black Bear—The 2012 analysis examined 3,457 telemetry locations of 74 black bears (40
females, 34 males) obtained during the historical APA study period from May 1, 1980, to
September 30, 1985. Black bears tended to use lower elevations in river valleys, with most
collared bears using the Susitna River valley and its major tributaries. The reservoir inundation
zone was used by a large proportion (67%) of the collared bears. The original APA study
concluded that such areas were important for black bears, especially in the spring when newly
emerging plants, overwintered berries, and moose calves were available there.
Taken together, the analyses begun in 2012 provide additional details to support the original
conclusions of the initial Project studies, but with application of more rigorous geospatial
analytical techniques. The Project area encompasses historical high-density areas of seasonal use
and movements for the Nelchina caribou herd, important winter habitat for moose, and high-use
areas of seasonal use for both brown bears and black bears.
Most of the data analyzed thus far date from three decades ago. Although basic patterns of
seasonal movements are unlikely to have changed in the intervening period, the populations and
distribution of some big game species have changed. Analyses of more recent data from ADF&G
will provide crucial information for the eventual analysis of Project impacts to be conducted for
the FERC License Application. Those analyses will provide context to understand long-term
population and distribution patterns of big game species in the study area.
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 1 February 2013
1. INTRODUCTION
This report provides the results of the 2012 Big Game Movements – Habitat Use Study, based on
the work outlined in the 2012 Wildlife Habitat Use and Movement Study plan (AEA 2012).
The Alaska Energy Authority (AEA) is preparing a License Application that will be submitted to
the Federal Energy Regulatory Commission (FERC) for the Susitna-Watana Hydroelectric
Project (Project) using the Integrated Licensing Process (ILP). The Project is located on the
Susitna River, an approximately 300-mile-long river in Southcentral Alaska. The Project’s dam
site would be located at river mile (RM) 184 (Figure 1).
This study provided information to inform the 2013–2014 licensing study program, Exhibit E of
the License Application, and FERC’s National Environmental Policy Act (NEPA) analysis for
the Project license.
The Susitna River basin is an important region for subsistence and sport hunting and trapping
because much of it is easily accessible by road from Anchorage and Fairbanks and has sizable
game populations, including moose (Alces americanus), caribou (Rangifer tarandus), Dall’s
sheep (Ovis dalli), brown (grizzly) bear (Ursus arctos), black bear (U. americanus), and wolf
(Canis lupus).
Construction and operation of the Project, as described in the Pre-Application Document (AEA
2011) may result in wildlife habitat loss and alteration, interference with animal movements,
disturbance, and changes in human activity. The Project may result in loss of, or displacement
from, seasonally used sensitive habitats in the middle and upper Susitna River basin, such as
caribou calving areas, bear foraging habitats, and Dall’s sheep lambing areas and mineral licks.
This study was intended to help characterize and further define data gaps regarding wildlife
abundance, distribution, movements, and sensitive habitats and inform subsequent studies
developed under the ILP. This study began a multi-year effort to synthesize existing information
and collect new data, which will continue in 2013–2014.
Extensive research on wildlife populations was conducted in the region during the early 1980s
for the original Alaska Power Authority Susitna Hydroelectric Project (APA Project). That
research included radio-telemetry studies of moose, caribou, brown bear, black bear, and wolf
populations (e.g., Ballard et al. 1984, Miller 1987, Pitcher 1987, Ballard and Whitman 1988).
Since those studies concluded, the Alaska Department of Fish and Game (ADF&G) continued to
conduct research and monitoring of big game species in Southcentral Alaska, although not
necessarily in the same areas studies for the APA Project. Integration of the historical data with
data collected more recently will provide valuable information to inform Project design,
mitigation, and impacts analysis, as well elucidating data gaps to inform decisions on research
needs and study design.
The study effort will continue in 2013–2014, as part of the analyses for Sections 10.5–10.8 of the
Revised Study Plan for the Project, as filed with FERC on December 14, 2012 (AEA 2012).
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 2 February 2013
2. STUDY OBJECTIVES
The objectives of this study were to acquire and analyze relevant data from ADF&G on the
abundance, distribution, movements, and habitat use of moose, caribou, brown bear, black bear,
Dall’s sheep, and wolf in the upper and middle Susitna River basins, and to evaluate the
adequacy of that information for assessing potential Project-related effects on these species. This
information was intended to help identify any remaining data gaps for use in developing 2013–
2014 study plans. An important part of the analytical effort was to apply newer techniques for
conducting spatial analyses with a geographic information system (GIS), which were not
available at the time the original APA Project studies were conducted.
More detailed, species-specific objectives were listed in the 2012 study plan for moose, caribou,
Dall’s sheep, bears, and wolves, which will be carried forward under the Study Plan for the
formal studies in 2013–2014 as more data become available from current ADF&G studies,
including deployment of radio collars on moose and caribou and other population surveys of big
game.
3. STUDY AREA
The study area was defined broadly to include all areas that may be affected directly or indirectly
by Project activities and facilities, the reservoir inundation zone, access roads, and transmission
corridors. The study area included seasonal ranges adjacent to the Project area in the middle and
upper Susitna River basin and was centered on Game Management Unit (GMU) Subunit 13E,
extending as needed into adjacent areas such as Subunits 13A, 14B, and 16A (Figure 1). Caribou
data analyses will incorporate information for both the Nelchina and Delta caribou herds (NCH
and DCH, respectively) in the 2013–2014 studies, although only historical data were available
for the NCH in the 2012 analysis. The study area for bears includes salmon spawning areas
downstream from the Watana Dam site that may be affected by changes in stream flows,
temperatures, and ice conditions.
The APA Project studies in the 1980s examined a large area that differed somewhat from the
current Project area. The analyses reported here focus on the results of radio-telemetry studies
conducted mainly upstream from Devils Canyon, although some data are included farther
downstream when radio-collared animals moved. The historical study areas varied among
species. Because these analyses focused on telemetry data, the areas where animals were
captured and outfitted with telemetry collars were well-defined, but animal movements after
collaring were variable. Thus, the outer extent of all the relocations of collared individuals for
each species defined their respective study areas.
4. METHODS
Data-sharing agreements were established among ADF&G, the Alaska Energy Authority (AEA),
and the Alaska Department of Natural Resources, as well as between ADF&G, AEA, and the
study lead (ABR), allowing ADF&G survey and telemetry data to be obtained for analysis by
ABR and incorporation into the Project geodatabase, while still adhering to state restrictions
regarding access to telemetry locations and harvest data. Although ADF&G began Project-
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 3 February 2013
specific moose and caribou telemetry studies in 2012, no data were available yet from those
efforts to include in this analysis.
ADF&G provided historical telemetry datasets collected during the original APA Project studies
to examine animal distribution and movements in and adjacent to the Project area. Historical
telemetry data for caribou, moose, black bear, and brown bear were reanalyzed, using geospatial
techniques not available in the 1980s, for comparison with the current Project area components
(reservoir inundation zone, associated facility locations, and access and transmission corridors).
Fixed-kernel density analysis was used to delineate range use by the NCH and by individual
moose and bears. Seasonal herd ranges and home ranges were compared with the current Project
area and statistics were compiled regarding the proportion of animals using various portions of
the Project area. Previous studies conducted in the 1980s used the minimum convex polygon
method (Mohr 1947) to delineate animal ranges. That technique simply draws a polygon around
some or all of the outermost animal locations recorded during occasional radio-tracking surveys.
The resulting minimum convex polygon can vary with sample size, is very sensitive to outliers,
can encompass large areas of home range that are not used, and does not differentiate between
areas of high and low use (Burgman and Fox 2003; Franzreb 2006). In contrast, fixed-kernel
density analysis is less sensitive to small sample sizes or outliers (Seaman et al. 1999), is less
likely to include unused areas, and produces a utilization distribution (UD) that estimates the
relative amount of use of each pixel by an animal within the area of analysis (Seaman and Powell
1996). The UD is a three-dimensional surface that can be used to create contour maps identifying
proportional use of the area. For instance, the 50%, 75%, and 95% UD contours used in this
report represent estimates of the areas that encompass the corresponding percentages of range
use by a collared animal. When fixed-kernel density analysis is conducted using the locations of
randomly selected individual caribou from a single herd during a particular season, the UD
estimates the relative proportion of the herd found in each pixel during that season.
4.1. Deviations from the Study Plan
Only historical telemetry data from previous research conducted in the late 1970s and 1980s for
the original APA Project were available for the analyses reported here. Data collected
subsequently to that research for other ADF&G studies have not yet been acquired, but are
planned for inclusion in analyses to be conducted for the 2013–2014 studies. Incorporation of
data from other studies is not necessarily straightforward because of differences in objectives,
study areas, and methods. In addition, the telemetry locations and associated data from the APA
Project wolf and wolverine studies could not be located (R. Strauch, ADF&G, personal
communication), so the reports and publications describing those studies (summarized in ABR
2011) remain as the only sources of Project-specific information on those species. No telemetry
data were collected for Dall’s sheep in the APA Project studies and other population survey data
are scant for the Project area (ABR 2011; also see the separate Technical Memorandum on the
2012 Wildlife Harvest Analysis), so that species will be the focus of a new population survey in
2013 (see RSP Section 10.7 of AEA 2012). Hence, the work reported herein focused on
reanalyzing historical telemetry data for caribou (1980–1985), moose (1976–1984), brown bears
(1978–1985), and black bears (1980–1985).
The historical telemetry datasets consisted entirely of locations of animals that were equipped
with standard Very High Frequency (VHF) radio collars. VHF collars require an observer to
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 4 February 2013
detect the collar’s radio signal and then follow the signal to the animal. These locations often are
imprecise, have long and variable periods of time between locations, and have a limited number
of locations for each individual. The low spatial and temporal resolution of these older datasets
limited the number of analyses that could be conducted in 2012; for example, the sample sizes of
telemetry locations were too small to generate seasonal kernel-density estimates for moose and
bears. Due to the extensive analyses already completed for these data in the APA Project study
reports referenced in the Results below, this reanalysis focused on describing animal distribution
in relation to the current Project area, to illustrate the extent of past use, demonstrate the
applicability of the techniques planned for use in the 2013–2014 studies, and help identify
potential data gaps.
4.2. Caribou
A total of 2,651 telemetry locations of 92 NCH animals (74 females, 17 males, 1 of unknown
sex) were analyzed for the period from 14 April 1980 to 9 July 1985. The mean number of
locations per animal was 28.8 (standard deviation [SD] = 19.7, range = 3–75). The mean length
of time that individual caribou were collared was 2.3 years (SD = 1.4 years, range = 65 days–5.2
years).
Following Pitcher (1987), the year was divided into six different seasons for analysis: spring
(1 April–14 May), calving (15 May–10 June), summer (11 June–31 July), autumn (1 August–
30 September), the rut (breeding season; 1–31 October), and winter (1 November–31 March).
Fixed-kernel densities were calculated for each combination of year and season and for all data
from each season. A plug-in bandwidth estimator (Gitzen et al. 2006) was used for this analysis
and density kernels were calculated using Geospatial Modelling Environment software (Beyer
2012). Overlaying the seasonal UD contours on the Project area components produced estimates
of the proportions of the herd that were within different portions of the Project area during each
combination of year and season. Those proportions were multiplied by the size of the NCH
(approximately 20,000 animals at the time the data were collected) to estimate caribou density
within different parts of the Project area for each combination of season and year.
4.3. Moose
A total of 5,400 telemetry locations of 211 moose (160 females, 48 males, 3 of unknown sex)
were analyzed from the APA Project upstream study area for the period from October 21, 1976,
to September 10, 1984. The mean number of locations per animal was 25.6 (SD = 24.5, range =
1–105). The mean length of time that individual moose were collared was 2.2 years (SD = 1.6
years, range = 1 week–7.9 years).
Fixed-kernel densities were calculated for each collared moose that was located at least 30 times.
A minimum of 30 independent locations should be used when conducting fixed-kernel analysis
(Seaman et al. 1999). Given the long time periods between relocation flights, the locations were
likely to be spatially independent, but they may have oversampled certain seasons in which
multiple tracking flights were conducted.
A plug-in bandwidth estimator (Gitzen et al. 2006) was used for this analysis and kernels were
calculated using Geospatial Modelling Environment software (Beyer 2012). Overlaying the UD
on the Project area components produced estimates of the proportion of time that each collared
individual was within the different portions of the Project area. The 95% UDs of all 69 moose
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 5 February 2013
(62 females and 7 males) with at least 30 locations were mapped and the Count Overlapping
Polygons tool for ArcGIS 10.1 (Environmental Research Systems Institute, Redlands, CA) was
used to quantify how many of those UDs overlapped with each portion of the Project area.
4.4. Brown Bear
A total of 3,799 telemetry locations of 90 different brown bears (52 females, 38 males) were
analyzed for the period from April 9, 1978, to September 30, 1985. The mean number of
locations per animal was 38.2 (SD = 38.2, range = 1–163). The mean length of time individual
brown bears were collared was 1.7 years (SD = 1.6 years, range = 1 day–5.4 years).
Fixed-kernel densities were calculated for each bear with at least 30 relocations, as described
above for moose. The 95% UD contours of all 39 brown bears (29 females and 10 males) with at
least 30 relocations were mapped to quantify how many of those home ranges overlapped each
portion of the Project area, using the Count Overlapping Polygons tool for ArcGIS.
4.5. Black Bear
A total of 3,457 telemetry locations for 74 black bears (40 females, 34 males) were analyzed for
the period from May 1, 1980, to September 30, 1985. The mean number of locations per animal
was 41.3 locations (SD = 32.2, range = 1–142). The mean length of time individual black bears
were collared was 2.0 years (SD = 1.6 years, range = 1 day–5.4 years).
Fixed-kernel densities were calculated for each bear with at least 30 relocations, as described
above for moose. The 95% UD contours of all 42 black bears (26 females and 16 males) with at
least 30 relocations were mapped to quantify how many of those home ranges overlapped each
portion of the Project area, using the Count Overlapping Polygons tool for ArcGIS.
5. RESULTS
For each of the four species for which historical telemetry data were available, a synopsis of
information from previous research is provided, based largely on the wildlife data-gap analysis
report (ABR 2011). That background information is then followed by a summary of the results of
the reanalysis conducted using fixed-kernel density techniques.
5.1. Caribou
5.1.1. Previous Research
Caribou herds in Alaska generally are delineated on the basis of their fidelity to calving grounds,
following the herd concept proposed by Skoog (1968). Caribou occurring in the upper Susitna
River basin belong primarily to the NCH. Pitcher (1982) described annual and seasonal
distribution information among various geographic areas of the herd range that originally were
delineated by Skoog (1968).
Since herd size was first estimated in the late 1940s, the NCH peaked at approximately 70,000
caribou in the early 1960s, then declined precipitously to 7,000–10,000 by the early 1970s. At
the time of the original APA Project studies, the herd had increased to 18,713 by 1980 (Pitcher
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1982) and 27,528 by 1985 (Pitcher 1987). It grew steadily to about 50,000 animals by 1995, then
declined and has remained fairly stable, in the range of 30,000–35,000 caribou, since the mid-
1990s. Based on the most recent population census in June 2012, ADF&G estimates that the
NCH currently numbers approximately 46,500 animals (ADF&G press release, July 31, 2012).
The caribou study conducted by ADF&G for the APA Project began in April 1980 and ended in
October 1985 (Pitcher 1987). The study objectives were to determine the population status of the
NCH, delineate subherds, and investigate range use, movement patterns, migration routes, and
timing, and to predict Project impacts and recommend mitigation strategies. Using VHF
telemetry, researchers tracked 85 collared caribou (including 60 females monitored for two or
more calving seasons) for various periods of time (1–63 months) for a total of 2,651 relocations
(Pitcher 1987). Telemetry data were supplemented with photocensuses and population
composition counts.
In addition to the main NCH, three resident subherds were identified in specific portions of the
herd range, based on radio-tracking. About 400 caribou were estimated to reside year-round in
the headwaters of the Talkeetna River south of the APA Project impoundment zones. Nearer the
Susitna River, the Chunilna Hills had a resident group of about 250 caribou, and about 1,500
caribou used the upper Susitna, Nenana, and Chulitna river drainages year-round. Two additional
subherds were suspected to occur in the western Talkeetna Mountains and in the Clearwater
Mountains along the southern slope of the Alaska Range, northeast of the Project area.
The APA Project area was located at the western end of the NCH annual range. Winter
distribution was highly variable, encompassing a large area east of the Talkeetna Mountains
extending across the Lake Louise flats to the Wrangell Mountains, but did not include areas of
historical winter use in the Talkeetna Mountains and north of that project’s Watana
impoundment zone. The core calving area included the drainages of the Oshetna and Black rivers
and Kosina Creek. Primary summer range for females was on the northern and eastern slopes of
the Talkeetna Mountains. Males tended to lag far behind the females, remaining longer on winter
range and spending most of the summer in low shrublands. During the rut (breeding season) in
October, caribou were spread from the Talkeetna Mountains east to the foothills of the Wrangell
Mountains.
Spruce forests were used primarily during rut, winter, and spring by both sexes. During calving
and summer, males tended to use lower elevation shrubland and tundra–herbaceous sites, while
females used highland tundra–herbaceous habitats. Deciduous or mixed forest types were used
very little.
Spring migration to calving grounds in the eastern Talkeetna Mountains sometimes crossed the
upper portion of the APA Project Watana impoundment zone. Historical records indicated that
reservoir would have intersected a major migratory route used by pregnant females moving to
calving grounds during late April and May, and by females and calves moving from calving
grounds to summer range during late June and July (Pitcher 1982). Crossings generally were
infrequent but, during spring migration in 1984, 50% of the collared female caribou in the NCH
crossed the Susitna River from north to south within the APA Project Watana impoundment zone
(LGL 1985). Skoog (1968) considered the geographic area in which the Watana impoundment
zone would have been located to be among the most important year-round areas for the herd.
Habitat loss was not considered to be an important concern, however, because only a relatively
small area of apparently low-quality habitat would be inundated by the two reservoirs proposed
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for the APA Project (Pitcher 1982). Instead, the principal concern was the need to cross the
impoundment zone.
5.1.2. Reanalysis of Historical Telemetry Data
In the first half of 1980s, NCH animals were distributed near the current Project area during all
seasons, but the highest densities of caribou generally occurred south or east of the Project area
(Figure 2, Appendices 1–6). During calving and summer, the highest densities occurred just
south of the inundation zone, but lower densities extended across the Project area to the Parks
and Denali highways (Appendices 2–3). During autumn, the area of highest density use included
much of the eastern portion of the inundation zone and large portions of the Project area were
within the 75% UD contour (Appendix 4). During rut and winter, the herd shifted its range
farther east, extending across the Richardson Highway (Appendices 5–6). During spring, the
herd moved back toward the west, with a portion of the area of highest density use overlapping
the eastern end of the inundation zone (Figure 2, Appendix 1).
Overall, the highest estimated densities of NCH animals in the 1980s in the Project area occurred
during calving and autumn and the lowest densities occurred during winter (Figure 3). The
reservoir inundation zone had the highest densities among the different Project components, with
the Denali corridor having the second highest densities, and the Chulitna corridor having the
lowest densities (Figure 3). The density patterns among different Project components generally
were similar throughout the year, but the Denali corridor had the highest densities of caribou
during the rut and winter seasons.
5.2. Moose
5.2.1. Previous Research
Baseline studies of moose in the Susitna River basin by ADF&G began several years before the
formal APA Project study program commenced in 1980. The moose studies for the APA Project
were divided into upstream and downstream (above and below Devils Canyon) components,
with different investigators and objectives. The upstream study began with radio-collaring in
1976 and ended in January 1986 (Taylor and Ballard 1979; Ballard and Whitman 1988; Ballard
et al. 1991). The downstream study began in 1980 and continued through 1986 (Modafferi
1987), with monitoring of population dynamics continuing through 1991, using some of the
animals collared for the APA Project studies (Modafferi and Becker 1997).
Between 1976 and 1985 in the upstream study area (upper Susitna River basin), 394 moose were
equipped with VHF radio collars and 69 adults were fitted only with numbered canvas collars
(Ballard and Whitman 1988). Sixty-one animals originally captured as calves (not including 218
neonates) and 115 adults were located 5,421 times from October 1976 through January 1986.
The APA Project upstream study area was reduced in 1983, based on the home ranges of radio-
collared moose, to focus more closely on the two APA Project reservoir zones (Devils Canyon
and Watana).
All moose exhibited seasonal movements within their home ranges, but the magnitude varied
substantially. Home range values were calculated as minimum convex polygons (Mohr 1947),
with some modifications to account for steep terrain and heterogeneous habitats (Ballard and
Whitman 1988). Moose were classified as resident if seasonal ranges overlapped between
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summer and winter, or as migratory if they did not. Ballard et al. (1991) reported that home-
range sizes averaged 290 km² (112 mi²) for resident moose and 505 km² (195 mi²) for migratory
moose. Distances between the summer and winter ranges of migratory animals ranged from 1 to
93 km (0.6–58 miles) (Ballard and Whitman 1988); the moose that moved the farthest were those
that summered in the Clearwater Mountains north of the Denali Highway and wintered along the
Susitna or Maclaren rivers. Three periods of major movements were identified: autumn and
spring migrations and movements during the rut (breeding season). During rut in late September
and early October, some moose made distinctive movements to upland areas not used at other
times of the year. Most movements of radio-collared sedentary moose occurred from higher
elevations in the summer to lower elevations in winter (Ballard and Taylor 1980). Fall migration
began between late October and November and appeared to be correlated with the first heavy
snowfall (>0.3 meter [m], or 1 foot). Spring migration occurred more gradually, from mid-April
through mid-July.
Ballard and Whitman (1988) documented 170 crossings of the Susitna River by 59 (52%) of 113
radio-collared moose, in the two SHP impoundment zones. Several areas near the currently
proposed reservoir inundation zone were used extensively, including the mouth of Tsusena
Creek, the area midway between Watana Creek and Jay Creek, and areas near the mouths of Jay
Creek and Kosina Creek (Ballard and Whitman 1988). Crossings occurred in all months of the
year but were common during late winter, peaking in April, when moose occupied winter ranges
at lower elevations. [Note: These numbers were minimal and crossing locations were
approximate because of the nature of VHF telemetry, which requires tracking from aircraft,
unlike the more frequent monitoring that is now possible using satellite or Global Positioning
System (GPS) telemetry.]
Vegetation types dominated by spruce and willow were used preferentially by moose. Taylor and
Ballard (1979) recorded 70% of moose observations (n = 376) in spruce-dominated habitats and
reported that most locations where calves were first seen (n = 20) were in spruce-dominated
habitats. Areas with relatively low browse biomass were used heavily by moose during winter,
because more browse was available due to shallower snow cover (Ballard et al. 1991). Moose
used lower elevations more often during severe winters and moose survival declined during
severe winters (Ballard and Whitman 1988; Ballard et al. 1991). The number and density of
moose using the SHP Watana impoundment zone varied widely among winters of moderate
severity, ranging from 42 to 580 (0.2 to 2.3 moose/km², or 0.4–6.0 moose/mi²) (Ballard and
Whitman 1988). Based on the carrying-capacity model developed for the APA Project, Becker
(1987) estimated that construction of the two APA Project impoundments would reduce the
carrying capacity of the study area by 405 moose during a moderate winter and 674 moose
during a severe winter.
5.2.2. Reanalysis of Historical Telemetry Data
A total of 69 radio-collared moose (62 females and 7 males) had 30 or more locations in the
historical dataset. The mean home range size, based on the 95% UD contour (i.e., the animal
would be expected to be within that area 95% of the time) was 449.0 km² for females (SD =
528.9 km²) and 884.7 km² for males (SD = 532.5) (Table 1). Of the 69 collared moose, the home
ranges of 51 animals (73.9%) overlapped with the current Project area (Figure 4, Table 2) and
those 51 moose were located in the Project area an average of 11.9% of the time. The reservoir
inundation zone had the highest use, with 66.7% of the 69 collared moose using the area for an
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average of 8.0% of the time (Table 2). The Denali corridor had the lowest use among all portions
of the Project area, with 13.0% of collared moose using it for an average of 0.5% of the time, but
much of that corridor is outside the area in which moose were collared. The number of
overlapping home ranges showed that the highest use by collared moose occurred near the
reservoir inundation zone and the dam and camp facility area (Figure 4).
5.3. Brown Bear
5.3.1. Previous Research
The APA Project stud y of brown bears was conducted upstream of Devils Canyon from 1980 to
1985, during which time 97 individual bears were captured and 53 were equipped with VHF
radio collars. The initial capture and release sites were within an area of 2,170 km2 centered
approximately at the confluence of the Susitna River and Watana Creek (Miller 1987). The
movements of these bears (including some dispersals and long movements to den sites)
encompassed an area of 13,912 km2, based on 2,901 telemetry relocations. Home range sizes
were calculated as minimum convex polygons (Mohr 1947) and were pooled across individuals
and years, producing mean values of 1,941 km2 for males and 501 km2 for females. Radio-
tracking also provided data on population size and density, seasonal movements, dispersal,
demography (litter size, age at first reproduction, reproductive interval, cub survival), den
locations, and rates of predation on moose calves. Key findings were summarized and potential
impacts were discussed in the final report by Miller (1987), which was the primary source of the
following information.
The APA Project bear study area (also referred to as the “impoundment impact zone,” which was
larger than the area that would have been inundated) was defined empirically as the area in
which brown bears would be affected by the proposed reservoirs and was estimated by
delineating the home ranges of 53 radio-collared bears. The mean home-range size (males and
females combined) corresponded to a circular area 37.5 km (23.3 miles) in diameter. Hence, it
was assumed that brown bears would be affected by the APA Project within a corridor extending
37.5 km on each side of the Susitna River, from Devils Canyon upstream to the confluence with
the Oshetna River.
Brown bear density was estimated in a portion of the study area using radio-telemetry and a
capture–mark–resighting technique (Miller 1987; Miller et al. 1997). Density was estimated at
27.9 brown bears/1,000 km² (386 mi²), resulting in an extrapolated estimate of approximately
327 bears using the APA Project impoundment impact zone (including both of the reservoirs
planned for that previous project).
The most significant impact of the APA Project on brown bears was predicted to be loss of
habitat due to flooding of the Watana Reservoir. Approximately 12% of the relocations (n =
1,720) of radio-collared brown bears were in the APA Project Watana Reservoir zone; brown
bears used that area twice as frequently as expected, both in spring and for all months combined.
That pattern of use was evident for males and most females, but not for females accompanied by
cubs of the year. Bears spent the highest proportion of time in the APA Project Watana
impoundment zone during June, foraging on south-facing slopes for roots, new vegetation, and
overwintered berries, and preying on moose calves. Females with young cubs tended to use
higher elevations, probably to reduce the risk of predation by male brown bears.
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Important sources of food for brown bears in the APA Project study area were ungulates,
salmon, and berries. Brown bears preyed on moose calves from late May to early June, with
predation rates declining substantially by mid-July (Ballard et al. 1990). Bears, especially males,
moved to the Prairie Creek drainage, southwest of Stephan Lake (between the Devils Canyon
and Watana dam sites), during July and early August to feed on spawning Chinook salmon (LGL
1985). Despite the availability of protein-rich animal foods, berry production appeared to be the
major factor limiting brown bear productivity in the APA Project study area (LGL 1985).
Crowberries were most abundant in the impoundment zones, whereas blueberries and lowbush
cranberries were distributed more evenly across the entire study area (Miller 1987). Horsetails,
an important spring food, were more abundant outside the impoundment zones (Helm and Mayer
1985).
Brown bears frequently crossed rivers. Of 658 locations for males, 14.9% were on the opposite
side of the Susitna River from the preceding location, as were 9.1% of 1,668 locations for
females. Home ranges of male bears were larger than those of females, and therefore were more
likely to span the river.
5.3.2. Reanalysis of Historical Telemetry Data
A total of 39 brown bears (29 females and 10 males) were relocated 30 or more times. The mean
home range size, based on the 95% UD contour, was 759.7 km² for females (SD = 637.2 km²)
and 3,118.2 km² for males (SD = 2,969) (Table 3). Of the 39 collared brown bears, the home
ranges of 32 animals (82.1%) overlapped with the current Project area (Figure 5, Table 4) and
those animals used the Project area an average of 7.9% of the time. The reservoir inundation
zone had the highest use, with 71.8% of brown bears using the area for an average of 4.0% of the
time (Table 4). The Gold Creek corridor had the lowest use among the Project area components,
with 51.3% of brown bears using it for an average of 1.7% of the time. Overlap among home
ranges showed that the highest use among collared brown bears occurred near the center of the
Project area (Figure 5), reflecting an effect of capture location as well as selection by bears of
areas within the reservoir inundation zone, as was reported by Ballard and Whitman (1988).
5.4. Black Bear
5.4.1. Previous Research
Previous research on black bears for the APA Project was conducted upstream from Devils
Canyon, with the exception of a dietary study in the downstream area. Black bears were studied
between 1980 and 1985; 110 individual bears were captured and 32 were equipped with VHF
radio collars during that period. The initial capture locations (available in Miller 1987) of the 32
radio-collared bears encompassed an area of 1,120 km2 with the subsequent relocations (n =
2,195) encompassing an area of 2,950 km2 (excluding dispersals). Collared bears were tracked to
provide data on population size and density, seasonal movements, dispersal, demography (litter
size, age at first reproduction, reproductive interval, cub survival), den locations, and rates of
predation on moose calves. Key findings, as well as discussion of possible impacts, were
summarized in the final report (Miller 1987).
The upstream study area (“impoundment impact zone”) was defined as the area in which bears
would be directly affected by the two reservoirs proposed for the APA Project. That area was
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estimated by plotting the locations of all unmarked bears observed (n = 282 locations) and of 32
radio-collared bears (n = 2,273 locations) during 1980–1984 and then drawing a line around all
points, excluding those considered to represent erratic movements (Miller 1987). The mean
home-range size, calculated as minimum convex polygons (Mohr 1947) for both sexes
combined, was 134.6 km2 (males = 251.5 km2; females = 67.1 km2). Suitable habitat in the
upstream study area was restricted primarily to the immediate vicinity of the Susitna River and
its major tributaries. The downstream study area below Devils Canyon was based on home-range
estimates for 22 radio-collared bears. In contrast to the upstream area, black bear habitat
occurred over most of the downstream study area (Miller 1987). The black bear study area
differed from the brown bear study area because of differences in habitat preferences and home-
range sizes.
Population density was estimated in a portion of the study area using a combination of radio
telemetry and a capture–mark–resighting technique (Miller 1987, Miller et al. 1997). Density
was estimated at 89.7 black bears/1,000 km² (386 mi²), producing an extrapolated estimate of
107 bears using the two APA Project impoundment zones.
The most significant impact of the APA Project on black bears was predicted to be loss of
habitat, including den sites, due to flooding of the APA Project Watana Reservoir, in which 42%
of the relocations (n = 1,305) of radio-collared black bears occurred (Miller 1987). Bears were
particularly abundant in the Watana impoundment zone during May and June, presumably
foraging for overwintered berries and newly emerged plants such as horsetails, and preying on
moose calves (the same spring food resources used by brown bears). Of 54 dens found in the
vicinity of the proposed Watana Reservoir, 30 (55%) were in the area that would have been
inundated. The rate of reuse of individual dens in the upstream area was high, suggesting that
availability of den sites was limited. Miller (1987) concluded that, although transient black bears
likely would continue to use the area, a resident population would not survive in the vicinity of
the Watana Reservoir.
Although black bears occasionally ate moose calves, berries seemed to be their most important
food source (LGL 1985). Bears spent most of their time in forested areas along creek bottoms,
moving out into adjacent shrublands during late summer as they foraged for berries, particularly
in the area between Tsusena and Deadman creeks (Miller 1987). The potential for human–bear
conflicts was higher in those areas because the shrublands were favored sites for camps, borrow
areas, and permanent residences (Miller 1987).
Black bears made extensive seasonal movements up and down the Susitna River, remaining
within the forested habitats along the river. Effects of the APA Project on movements were
difficult to predict, but crossings may have been inhibited, particularly by the large bay that
would have been created near the mouth of Watana Creek (Miller 1987).
5.4.2. Reanalysis of Historical Telemetry Data
A total of 42 black bears (26 females and 16 males) had at least 30 telemetry relocations. The
mean home range size, based on the 95% UD contour, was 122.8 km² for females (SD = 140.0
km²) and 583.7 km² for males (SD = 477.0) (Table 5). Of those 42 bears, the home ranges of 31
animals (73.8%) overlapped to some degree with the current Project area (Figure 6, Table 6) and
those bears used the Project area an average of 22.6 % of the time. The reservoir inundation zone
had the highest proportional use, with 66.7% of black bears using the area for an average of
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14.2% of the time (Table 6). The Denali corridor had the lowest use among all portions of the
Project area, with 28.6% of black bears using it for an average of 0.4% of the time. These figures
were affected by the locations where bears were captured but also reflect the fact that most black
bear habitat occurs in riverine areas at low elevations. Overlap among home ranges showed that
black bears concentrated at lower elevations along the Susitna River, with the heaviest
concentration in the western portion of the reservoir zone and near the proposed camp facility
area (Figure 6).
6. DISCUSSION AND CONCLUSIONS
Not surprisingly, the reanalysis of telemetry data described above produced results that generally
were consistent with those of previous analyses for the APA Project studies, although the
analytical technique used provided more robust estimates of range sizes and proportional use of
the Project area among species. Because these datasets were analyzed thoroughly in the past for
the APA Project studies, we focused on providing additional description and quantification of the
distribution of caribou, moose, and bears in the current Project area, as summarized in the
sections below for individual species.
Reanalysis of decades-old data can be challenging. Much of the context for understanding
movements can be lost and documentation and metadata often are incomplete. Given their age,
these data were in remarkably good condition, with a large amount of documentation having
been preserved by ADF&G (see Acknowledgments), but some codes were difficult to understand
or interpret. Missing values or inconsistencies in the data were difficult to rectify. Given those
uncertainties and because the previous APA Project analyses were extensive, we focused our
reanalysis on broad patterns of distribution and on evaluating analytical approaches for
application to the more intensive telemetry datasets currently being collected by ADF&G for the
2013–2014 moose and caribou studies.
Our results provide additional details to support the original conclusions of these studies. The
current Project area is located in or near high-density seasonal use areas for caribou, it contains
important wintering habitat for moose, and it is used extensively by both brown and black bears.
Whereas brown bears roam widely over large areas that include the Project area, black bears are
much more constrained to habitats at lower elevation in the Susitna River valley and adjacent
tributaries. Some data gaps in spatial coverage of the current Project area were noted in the
historical telemetry datasets (see Figures 4–6), mainly in the western and northern ends of the
access corridors, due in part to the fact that much of the APA study emphasis in the 1980s was
focused on the two APA Project reservoir impoundment zones, but also because the current
corridors differ somewhat from proposed in the 1980s. Collaring animals over a broader study
area, as is being done for the current Project studies, will provide data to address those gaps for
moose and caribou. Intensive collection of location data from GPS collars will provide much
larger sample sizes for use in evaluating seasonal movements and range use in relation to Project
components.
The historical telemetry data reanalyzed in this report are about three decades old. Although
basic patterns of distribution, movements, and habitat use are unlikely to have changed
significantly, the populations of different species undoubtedly have changed over the intervening
years, resulting in indirect effects on other species. Analyzing other recent data and collecting
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current data will provide important findings and additional context for understand long-term
population and distribution patterns of big game species in the area, thereby providing a basis for
predicting the effects of the current Project during the licensing process.
6.1. Caribou
The current Project area is located in seasonal ranges that generally received medium- and low-
density use by the NCH during 1980–1985. Caribou densities in those years were greater in the
current reservoir inundation zone and the Denali corridor than in the Chulitna or Gold Creek
corridors.
The highest estimated seasonal densities of caribou in the current Project area occurred during
autumn, with high-density use occurring in the eastern end of the reservoir zone. The peak
estimated seasonal caribou density (based on a herd size of 20,000) was 0.97 caribou/km² in the
reservoir inundation zone during autumn (Figure 3). The density would be higher at larger herd
sizes, assuming the herd distribution remains similar to the distribution observed in the early
1980s. For example, at the current (2012) herd size of 46,500 caribou, all estimated densities in
Figure 3 would be 2.3 times higher. Whether these density patterns persist with the current
distribution of the NCH will be elucidated by future analyses of telemetry data currently being
gathered for GPS and VHF radio collars, which will continue through 2014 (see RSP Section
10.6 in AEA 2012).
In addition, portions of the nearby DCH have begun using some areas near the Project area
seasonally (ABR 2011). During 2006–2008, radio-tracking revealed that some DCH animals
moved from the north into the upper Susitna River drainage and crossed the Denali Highway,
moving as far south as far as Butte Lake (Seaton 2009). The results of the current telemetry study
begun for the Project in 2012 and continuing through 2014 will produce a substantial volume of
new data for use in delineating the seasonal ranges and movements of caribou in both herds (see
RSP Section 10.6 in AEA 2012).
6.2. Moose
Reanalysis of the moose data confirmed the results of previous analyses showing that moose
used the Watana Reservoir inundation zone and the vicinity of the proposed camp facilities at a
high level. Although the locations at which moose are captured has a large effect on the results in
a distributional study, the distribution of home ranges was more concentrated in the Watana
Reservoir zone than was the distribution of the initial collar locations (Figure 4), which is
consistent with high use of the reservoir for winter habitat. These findings were corroborated by
population censuses conducted in 1980 and 1983, which found that the highest moose density
occurred upstream from the Watana Dam site, between Watana Creek and Jay Creek (Taylor and
Ballard 1979). The results of the late-winter population survey conducted by ADF&G for this
Project in March 2012, during a winter of unusually heavy snowfall, will provide further insight
into the current importance of the reservoir zone for the regional moose population, producing a
preliminary density estimate (uncorrected for sightability) of 1.59 moose/mi2 (0.61 moose/km2)
in the reservoir inundation zone and immediately adjacent area (K. King, ADF&G, personal
communication). The Watana Reservoir zone was used by both resident and migratory moose in
the 1980s (Ballard and Whitman 1988) and migratory patterns had strong effects on the size of
the home ranges. In general, bull moose had larger home ranges than did cows.
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6.3. Brown Bear
Brown bears have large home ranges, with those of males being much larger than those of
females. Given the broad extent of the movements by this species, the home ranges of most
(82.1%) radio-collared brown bears in the late 1970s and early 1980s overlapped the current
Project area to some degree. The home ranges estimated using the fixed-kernel density technique
were substantially larger than the original estimates derived using minimum convex polygons
(Miller 1987). These differences are thought to have resulted from a combination of using a
different home range estimator and the fact that the reanalysis included only those bears for
which at least 30 locations were obtained. Minimum convex polygon estimates are highly
sensitive to sample size, resulting in lower estimates for animals with few locations.
6.4. Black Bear
Black bears were found at lower elevations in the Susitna River valley and associated tributaries.
The reservoir inundation zone was used by a large proportion (66.7%) of the black bears that
were collared in the 1980s. Telemetry reanalysis confirmed the finding that black bear range use
in the reservoir inundation zone is largely confined to a fairly narrow area centered along the
Susitna River. The reservoir zone was important for black bears, especially in the spring when
newly emergent plants, overwintered berries, and moose calves were available. Miller (1987)
concluded that a resident population would not be likely to persist in the Watana Reservoir zone,
but that transient bears would continue to use the area.
7. REFERENCES
ABR. 2011. Wildlife data-gap analysis for the proposed Susitna-Watana Hydroelectric Project.
Draft report, August 16, 2011. Report for the Alaska Energy Authority by ABR, Inc.—
Environmental Research and Services, Fairbanks, Alaska. 114 pp.
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, Washington, DC.
AEA. 2012. Wildlife Resources. Revised Study Plan: Susitna-Watana Hydroelectric Project
FERC Project No. 14241, Section 10. December 2012. Prepared for the Federal Energy
Regulatory Commission by the Alaska Energy Authority, Anchorage, Alaska.
http://www.susitna-watanahydro.org/wp-content/uploads/2012/12/05-RSP-
Dec2012_5of8-Sec-10.1-10.13-Wildlife1stPart-v2.pdf.
Ballard, W. B., and K. P. Taylor. 1980. Upper Susitna Valley moose population study. Final
report. Federal Aid in Wildlife Restoration Projects W-17-9 through W-17-11, Alaska
Department of Fish and Game, Juneau. 101 pp. [APA Document No. 524]
Ballard, W. B., and J. S. Whitman. 1988. Susitna Hydroelectric Project, final report, big game
studies, Vol. II—Moose upstream. Report prepared by Alaska Department of Fish and
Game, Anchorage, for Alaska Power Authority, Anchorage. [APA Document No. 3494]
Ballard, W. B., J. S. Whitman, L. D. Aumiller, and P. Hessing. 1984. Susitna Hydroelectric
Project, 1983 annual report, big game studies, Vol. V—Wolf. Report prepared by Alaska
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Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 15 February 2013
Department of Fish and Game, Anchorage, for Alaska Power Authority, Anchorage.
40 pp. [APA Document No. 2324]
Ballard, W. B., S. D. Miller, and J. S. Whitman. 1990. Brown and black bear predation on moose
in southcentral Alaska. Alces 26:1–8.
Ballard, W. B., J. S. Whitman, and D. J. Reed. 1991. Population dynamics of moose in south-
central Alaska. Wildlife Monographs 114: 1–49.
Becker, E. F. 1987. Susitna Hydroelectric Project, final report, big game studies, Vol. V—Moose
carrying-capacity estimate. Report prepared by Alaska Department of Fish and Game,
Anchorage, for Alaska Power Authority, Anchorage. 26 pp. [APA Document No. 3498]
Beyer, H. L. 2012. Geospatial Modelling Environment (Version 0.7.1.0) software. URL:
http://www.spatialecology.com/gme
Burgman, M. A., and J. C. Fox. 2003. Bias in species range estimates from minimum convex
polygons: Implications for conservation and options for improved planning. Animal
Conservation 6: 19–28.
Franzreb, K. E. 2006. Implications of home-range estimation in the management of red-cockaded
woodpeckers in South Carolina. Forest Ecology and Management 228: 274–284.
Gitzen, R. A., Millspaugh, J. J. and Kernohan, B. J. 2006. Bandwidth selection for fixed-kernel
analysis of animal utilization distributions. Journal of Wildlife Management 70: 1,334–
1,344.
Helm, D., and P. V. Mayer. 1985. Susitna Hydroelectric Project environmental studies: plant
phenology study. Report prepared by University of Alaska–Fairbanks, Agricultural and
Forestry Experiment Station, Palmer, and Harza–Ebasco Susitna Joint Venture,
Anchorage, for Alaska Power Authority, Anchorage. 250 pp. [APA Document No. 2932]
LGL (LGL Alaska Research Associates, Inc.). 1985. Susitna Hydroelectric Project: Wildlife and
botanical resources impact assessment and mitigation planning summary. Draft report
(revision 1) by LGL Alaska Research Associates, Inc., Anchorage, for Harza–Ebasco
Susitna Joint Venture and Alaska Power Authority, Anchorage. 58 pp. [APA Document
No. 3376]
Miller, S. D. 1987. Susitna Hydroelectric Project, final report, big game studies: Vol. VI—Black
bear and brown bear. Report prepared by Alaska Department of Fish and Game,
Anchorage, for Alaska Power Authority, Anchorage. 276 pp. [APA Document No. 3497]
Miller, S. D., G. C. White, R. A. Sellers, H. V. Reynolds, J. W. Schoen, K. Titus, V. G. Barnes,
Jr., R. B. Smith, R. R. Nelson, W. B. Ballard, and C. C. Schwartz. 1997. Brown and black
bear density estimation in Alaska using radio telemetry and replicated mark–resight
techniques. Wildlife Monographs 133: 1–55.
Modafferi, R. D. 1987. Susitna Hydroelectric Project, final report, Vol. I—Moose downstream.
Report prepared by Alaska Department of Fish and Game, Anchorage, for Alaska Power
Authority, Anchorage, AK. 179 pp. [APA Document No. 3493]
Modafferi, R. D., and E. F. Becker. 1997. Survival of radio-collared adult moose in lower
Susitna River Valley, southcentral Alaska. Journal of Wildlife Management 61: 540–549.
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Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 16 February 2013
Mohr, C. O. 1947. Table of equivalent populations of North American small mammals.
American Midland Naturalist 37: 223–249.
Pitcher, K. W. 1982. Susitna Hydroelectric Project, Phase I final report, big game studies, Vol.
IV—Caribou. Report by Alaska Department of Fish and Game, Anchorage, for Alaska
Power Authority, Anchorage. 101 pp. [APA Document No. 410]
Pitcher, K. W. 1987. Susitna Hydroelectric Project, final report, big game studies, Vol. IV—
Caribou. Report by Alaska Department of Fish and Game, Anchorage, for Alaska Power
Authority, Anchorage. 59 pp. [APA Document No. 3496]
Seaman, D. E., and R. A. Powell. 1996. An evaluation of the accuracy of kernel density
estimators for home range analysis. Ecology 77: 2,075–2,085.
Seaman, D. E., J. J. Millspaugh, B. J. Kernohan, G. C. Brundige, K. J. Raedeke, and R. A.
Gitzen. 1999. Effects of sample size on kernel home range estimates. Journal of Wildlife
Management 63: 739–747.
Seaton, T. 2009. Unit 20A caribou. Pages 122–135 in P. Harper, editor. Caribou management
report of survey and inventory activities, 1 July 2006–30 June 2008. Project 3.0. Alaska
Department of Fish and Game, Juneau.
Skoog, R. 0. 1968. Ecology of the caribou (Rangifer tarandus granti) in Alaska. Ph.D.
dissertation, University of California, Berkeley. 699 pp.
Taylor, K. P., and W. B. Ballard. 1979. Moose movements and habitat use along the Susitna
River near Devils Canyon. Proceedings of the North American Moose Conference
Workshop 15: 169–186.
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 17 February 2013
8. TABLES
Table 1. Home range size of radio-collared moose during 1976–1984,
based on fixed-kernel density analysis for animals with at least 30 relocations.
Sex n
UD Contour
(%)
Mean Size
(km²)
SD
(km²)
Female 62 50 85.0 96.6
75 193.9 230.2
95 449.0 528.9
Male 7 50 181.6 134.4
75 396.2 273.9
95 884.7 532.5
Table 2. Use of the current Project area by 69 radio-collared moose during 1976–1984,
based on fixed-kernel density analysis for animals with at least 30 relocations.
Area % Moose in Area1 Mean % Use2 SD3
Reservoir Inundation Zone 66.7 8.0 8.7
Dam and Camp Facility Area 27.5 7.1 12.1
Gold Creek Corridor 23.2 3.6 5.0
Denali Corridor 13.0 0.5 0.9
Chulitna Corridor 14.5 4.0 5.3
Total 73.9 11.9 12.7
Notes:
1 Individuals that had >0.01% of use of the area, based on the utilization distribution.
2 Mean percentage of time spent in the area by individual moose, for those moose that used the area.
3 Standard deviation of mean percentage of time spent in the area by individual moose, for those moose that used the area.
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 18 February 2013
Table 3. Home range size of radio-collared brown bears during 1978–1985,
based on fixed-kernel density analysis for animals with at least 30 relocations.
Sex n
UD Contour
(%)
Mean Size
(km²)
SD
(km²)
Female 29 50 159.5 109.6
75 344.1 261.4
95 759.7 637.2
Male 10 50 690.8 808.6
75 1,471.7 1,563.1
95 3,118.2 2,969.0
Table 4. Use of the current Project area by 39 radio-collared brown bears during 1978–1985,
based on fixed-kernel density analysis for animals with at least 30 relocations.
Area % Bears in Area1 Mean % Use2 SD3
Reservoir Inundation Zone 71.8 4.0 4.5
Dam and Camp Facility Area 53.8 2.4 3.0
Gold Creek Corridor 46.2 1.7 2.2
Denali Corridor 51.3 1.4 1.8
Chulitna Corridor 53.8 1.6 2.1
Total 82.1 7.9 5.9
Notes:
1 Individuals that had >0.01% of use of the area, based on the utilization distribution.
2 Mean percentage of time spent in the area by individual bears, for those bears that used the area.
3 Standard deviation of mean percentage of time spent in the area by individual bears, for those bears that used the area.
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 19 February 2013
Table 5. Home range size of radio-collared black bears during 1980–1985,
based on fixed-kernel density analysis for animals with at least 30 relocations.
Sex n
UD Contour
(%)
Mean Size
(km²)
SD
(km²)
Female 26 50 23.9 20.7
75 51.8 48.0
95 122.8 140.0
Male 16 50 124.5 107.3
75 271.1 227.7
95 583.7 477.0
Table 6. Use of the current Project area by 42 radio-collared black bears during 1980–1985,
based on fixed-kernel density analysis for animals with at least 30 relocations.
Area % Bears in Area1 Mean % Use2 SD3
Reservoir Inundation Zone 66.7 14.2 13.8
Dam and Camp Facility Area 45.2 11.5 9.5
Gold Creek Corridor 40.5 2.9 4.7
Denali Corridor 28.6 0.4 0.4
Chulitna Corridor 33.3 2.3 2.6
Total 73.8 22.6 15.9
Notes:
1 Individuals that had >0.01% of use of the area, based on the utilization distribution.
2 Mean percentage of time spent in the area by individual bears, for those bears that used the area.
3 Standard deviation of mean percentage of time spent in the area by individual bears, for those bears that used the area.
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 20 February 2013
9. FIGURES
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 21 February 2013
Figure 1. Location of the Project area in relation to state Game Management Units and the Susitna River basin.
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 22 February 2013
Figure 2. Seasonal distribution of radio-collared caribou during 1980–1985, based on fixed-kernel density analysis of
telemetry locations.
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 23 February 2013
Figure 3. Estimated seasonal density of the Nelchina Caribou Herd (based on herd size of 20,000) that used different
portions of the current Project area, based on fixed-kernel density analysis of telemetry data collected during 1980–1985.
0
0.2
0.4
0.6
0.8
1
1.2
Spring Calving Summer Autumn Rut WinterCaribou / km² Season
Gold Creek Corridor
Dam and Camp Facility Area
Denali Corridor
Chulitna Corridor
Reservoir Inundation Zone
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 24 February 2013
Figure 4. Spatial distribution of the home ranges (95% UD contour) of 69 radio-collared moose during 1976–1984 in
relation to the current Project area, based on fixed-kernel density analysis of telelmetry locations.
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 25 February 2013
Figure 5. Spatial distribution of the home ranges (95% UD contour) of 39 radio-collared brown bears during 1978–1985
in relation to the current Project area, based on fixed-kernel density analysis of telemetry locations.
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 26 February 2013
Figure 6. Spatial distribution of the home ranges (95% UD contour) of 42 radio-collared black bears during 1980–1985 in
relation to the current Project area, based on fixed-kernel density analysis of telemetry locations.
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 27 February 2013
10. APPENDICES
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 1 February 2013
Appendix 1:
Annual distribution of radio-collared caribou during spring
(April 1–May 14) 1980–1985, based on fixed-kernel density analysis
of telemetry locations
2012TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 1—Page 1 February 2013
Appendix 1. Annual distribution of radio-collared caribou during spring (April 1–May 14)
1980–1985, based on fixed-kernel density analysis of telemetry locations.
2012TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 2 February 2013
Appendix 2:
Annual distribution of radio-collared caribou during calving
(May 15–June 10) 1980–1985, based on fixed-kernel density analysis
of telemetry locations
2012TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 2—Page 1 February 2013
Appendix 2. Annual distribution of radio-collared caribou during calving (May 15–June 10)
1980–1985, based on fixed-kernel density analysis of telemetry locations.
2012TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 3 February 2013
Appendix 3:
Annual distribution of radio-collared caribou during summer
(June 11–July 31) 1980–1985, based on fixed-kernel density analysis
of telemetry locations
2012TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 3—Page 1 February 2013
Appendix 3. Annual distribution of radio-collared caribou during summer (June 11–July 31)
1980–1985, based on fixed-kernel density analysis of telemetry locations.
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 4 February 2013
Appendix 4:
Annual distribution of radio-collared caribou during autumn
(August 1–September 30) 1980–1984, based on fixed-kernel density
analysis of telemetry locations
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 4—Page 1 February 2013
Appendix 4. Annual distribution of radio-collared caribou during autumn (Aug. 1–Sep. 30)
1980–1984, based on fixed-kernel density analysis of telemetry locations.
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 5 February 2013
Appendix 5:
Annual distribution of radio-collared caribou during the rut
(October 1–31) 1980–1984, based on fixed-kernel density analysis
of telemetry locations
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 5—Page 1 February 2013
Appendix 5. Annual distribution of caribou during the rut (October 1–31) 1980–1984, based on
fixed-kernel density analysis of telemetry locations.
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 6 February 2013
Appendix 6:
Annual distribution of radio-collared caribou during winter
(November 1–March 31) 1980–1984, based on fixed-kernel density
analysis of telemetry locations
2012 TECHNICAL MEMORANDUM BIG GAME MOVEMENT AND HABITAT USE STUDY
Susitna–Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Appendix 6—Page 1 February 2013
Appendix 6. Annual distribution of radio-collared caribou during winter (November 1–March
31) 1980–1984, based on fixed-kernel density analysis of telemetry locations.