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Title
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Determining Suitability of Habitat for Reintroduction of the Western Pond Turtle (Actinemys marmorata) at Fort Lewis, Washington
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Date
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2011
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Creator
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Lyon, Ashley Lynn
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Subject
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Environmental Studies
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extracted text
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DETERMINING SUITABILITY OF HABITAT FOR REINTRODUCTION OF
THE WESTERN POND TURTLE (Actinemys marmorata) AT FORT LEWIS,
WASHINGTON
by
Ashley Lynn Lyon
A Thesis
Submitted in partial fulfillment
of the requirements for the degree
Master of Environmental Studies
The Evergreen State College
August 2011
©2011 by Ashley Lyon. All rights reserved.
This Thesis for the Master of Environmental Study Degree
by
Ashley Lynn Lyon
has been approved for
The Evergreen State College
by
________________________
Gerardo Chin-Leo, Ph.D.
Member of the Faculty
________________________
Alison Styring, Ph.D.
Member of the Faculty
________________________
Jim Lynch, M.E.S.
Fort Lewis Fish and Wildlife
________________________
Date
ABSTRACT
Determining suitability of habitat for reintroduction of the western pond turtle
(Actinemys marmorata) at Fort Lewis, Washington
Ashley Lynn Lyon
Amphibians and reptiles have experienced a decline coinciding with the
degradation of aquatic ecosystems. For decades, environmental agencies have
been spending resources restoring threatened species populations and aquatic
systems. One such effort is that of the Washington Department of Fish and
Wildlife (WDFW) with the western pond turtle (Actinemys marmorata, formerly
Clemmys marmorata) which was historically found from southern British
Columbia to Baja, California, but are now endangered over most of their range.
The WDFW has a goal of re-establishing five separate populations in the Puget
Sound. Fort Lewis, is considered to be a possible suitable habitat for
reintroduction because the pond turtle was historically found there. However,
recent successive abundance surveys at nine sites did not find a single turtle. The
goal of this thesis is to review the causes for A. marmorata decline and to
examine if suitable habitat for it exists on Fort Lewis. Habitat data (distance to the
water, distance to the nearest basking site, canopy cover at ten centimeters,
overhead canopy cover, leaf litter depth, distance to the road, bottom substrate
type, shoreline accessibility, vegetation type, and presence/absence of southfacing slope) was collected at all nine sites as well as on the site where current
reintroduction efforts are focused in Lakewood, Washington and compared in
order to determine reintroduction suitability of all the Fort Lewis sites. The data
was also compared among sites to determine the best reintroduction candidates. It
was hypothesized that Johnson Marsh and Clay Pit habitats on Fort Lewis would
be statistically similar to that found at Lakewood, and that Johnson Marsh would
be the most suitable of the nine sites due to its size and ecological complexity. A
hierarchical cluster analysis of the data revealed that Spanaway Marsh was
statistically similar to the Lakewood site habitat (cophenetic correlation
coefficient = 0.811, p-value < 0.0001). A ranked comparison of the Fort Lewis
locations showed the most suitable reintroduction site to be Clay Pit. Suitable
habitat was defined as a site ranked in the upper third for at least three of the
habitat characteristics and no more than once in the lowest third in any one of the
eight habitat categories. All nine Fort Lewis sites, with minimal alteration, would
be potential reintroduction locations. Another promising Fort Lewis habitat,
Nisqually Lake, was considered, but not surveyed because it’s within the
hazardous Artillery Impact Area and study of this area is recommended. Another
recommendation for future work arising from this study would be for WDFW to
determine the habitat characteristics that are most important in defining a suitable
reintroduction site. This thesis also discusses: the possible causes for the decline
of A. marmorata in Fort Lewis and the current status of restoration efforts at the
recovery zone in Lakewood through the efforts of WDFW and the Oregon and
Woodland Park Zoos.
iii
Table of Contents
ABSTRACT....................................................................................................................... iii
List of Figures .................................................................................................................... vi
List of Tables .................................................................................................................... vii
Acknowledgements .......................................................................................................... viii
1. Introduction ..................................................................................................................... 1
1.1. Habitat Requirements and Life History ................................................................... 4
1.2. Distribution and Taxonomy ..................................................................................... 6
1.3. Causes of Decline .................................................................................................... 8
1.4. Current Management of the Western Pond Turtle ................................................. 11
1.4.1. Legal status ..................................................................................................... 11
1.4.2. Current Management Actions ......................................................................... 11
1.4.3. Future Management and Research .................................................................. 15
1.5. Fort Lewis .............................................................................................................. 18
1.5.1. Historical Use of Fort Lewis Aquatic Habitats ............................................... 19
1.5.2. Study Site Selection and Descriptions ............................................................ 20
2. Methods ........................................................................................................................ 29
2.1. Abundance Surveys ............................................................................................... 30
2.2. Habitat Surveys ...................................................................................................... 32
2.3. Data Analysis ......................................................................................................... 35
2.3.1. Abundance Data Analysis ............................................................................... 35
2.3.2. Habitat Data Analysis ..................................................................................... 36
3. Results.......................................................................................................................... 39
3.1. Abundance ............................................................................................................ 39
3.2. Habitat .................................................................................................................... 39
iv
3.2.1. Similarity........................................................................................................ 40
3.2.2. Suitability ....................................................................................................... 41
4. Discussion .................................................................................................................... 42
5. Conclusion ................................................................................................................... 46
Bibliography ..................................................................................................................... 48
v
List of Figures
Figure 1. The historic range of the western pond turtle (Actinemys marmorata)
(Hays et al. 1999). ………………………………………………………………54
Figure 2. A map of the boundaries of Fort Lewis, Washington and its prairies and
oak habitat………………………………………………………………………..55
Figure 3. Map of pond turtle reintroduction sites in Washington (Toubman 2001).
……………………………………………………………………………………56
Figure 4. Map of nine Fort Lewis study sites for potential reintroduction……...57
Figure 5. Dendrogram of the hierarchical cluster analysis of the habitat data
Bray-Curtis distances between each location and the Lakewood reintroduction site
are included down the left side of the diagram……………………………….….58
vi
List of Tables
Table 1. Habitat data parameters collected at the ten sites………………….......35
Table 2. The results of the summation of the rankings for each of the eight
categories for each of the nine locations to determine the most suitable
reintroduction site. The lowest score indicates the most suitable habitat for
reintroduction while higher scores mean those sites are less suitable for
reintroduction. ……………….…………………………………………………..42
vii
Acknowledgements
I would like to thank my friends and family for their support and faith. My
parents taught me to believe in myself and my ability to accomplish whatever I set my
sights on. They have provided every bit of assistance that they were able and prodded me
when I needed prodding. My sisters serve as constant inspiration as they achieve their
own goals in life. I am so lucky to come from such a loving family. Thank you for
motivating me along my journey.
I would like to thank Alison Styring, my original thesis advisor, for helping me
get this project underway. She taught me early on in the MES program the methods that
were later useful in executing this study. She has encouraged me to work on overcoming
my fear of public speaking. I would also like to thank Gerardo Chin-Leo, my final thesis
advisor, for taking me on in the eleventh hour and for always telling me that it was
possible. I am proud to say that through their efforts, I accomplished the seemingly
unattainable goal of completing my thesis.
Without the assistance of Jim Lynch and Dave Clouse with Fort Lewis Fish and
Wildlife, I would still be at square one, as they were of great assistance in identifying a
need for this study. They also helped get me gain access to all of my study sites for data
collection. Michelle Tirhi with WDFW gave me my first glimpse of a western pond
turtle and was a wealth of knowledge and resources. Her dedication inspired me to
complete this study and advance the knowledge for the success of this species.
Most importantly, I would like to give my endless gratitude to my husband,
Michael, for his unceasing belief that I would in fact finish. If we can weather the trials
of this, we can do anything. He has been an amazing support these past years and
especially these last few months. He helped brake brush in the field, dried my tears of
frustration, fixed the computer, and cooked my every meal while I was busy staring
cross-eyed at the data. Thank you from the bottom of my heart!
viii
1. Introduction
The western pond turtle (Actinemys marmorata, formerly Clemmys
marmorata) is considered to be an indicator species of both healthy aquatic
ecosystems and upland grassland habitat due to its semi-aquatic nature (Animals
1991, Bickham and Smolen 1994, Lamb et al. 1995, and Ulsh et al. 2000). Their
contribution to ecosystems can also be significant. Iverson (1982) found that
single species standing crop biomass for turtles, including western pond turtles in
California, were consistently among the highest for vertebrates. This finding
suggests that turtles have a far higher importance in the ecosystem than is
currently understood. The possible ecological importance of turtles makes the
decline of A. marmorata over most of its historic habitat quite serious. In
response to this decline, the Washington Department of Fish and Wildlife
(WDFW) developed the Washington State Recovery Plan for the Western Pond
Turtle in 1999 (Hays et al. 1999). The resources and funds budgeted for the
recovery of A. marmorata every year are relatively small compared to that of
other species in Washington State, and depends on availability of state monies.
Continued budget cuts threaten continuity of the recovery efforts (Budget 2011).
Currently, only one reintroduction site within the Puget Sound recovery
zone, a series of manmade ponds in Lakewood, Washington, is being managed
(Schmidt et al. 2008). This site was selected as it was already being managed as
an urban wildlife park and had the space for an enclosed reintroduction wetland
system. The Lakewood site consists of twelve acres within the South Puget
Sound Wildlife Area (SPSWA), a 90 acre state owned parcel in Pierce County.
Three ponds were constructed from an existing spring seep, native trees and
1
shrubs were planted along the margin, and the entire area was fenced. In the
southwest corner, a nesting hill was built from fill and project debris. The first
turtles were reintroduced in 1996, and, as of 2008, 145 western pond turtles
inhabited SPSWA. Females carry radio transmitters in order to track movements
during the nesting season, and eggs are removed from the nests for head-start
rearing at the Oregon and Woodland Park Zoos (Future 2007, Schmidt et al. 2008,
Slavens 2003, and Slavens and Slavens 1998).
To maximize the limited funds for A. marmorata recovery, the state might
consider using existing suitable reintroduction habitat on federal lands. Fort
Lewis, a US army base in Washington State has already allowed WDFW to
reintroduce the Oregon spotted frog (Rana pretiosa) at one site, Dailman Lake, as
part of a pilot project started in 2007 (Barrentine 2009 and Hawk 2010). Since
2008, approximately 2,300 head-started juveniles have been released at the site.
This thesis project examined the potential of Fort Lewis lands as a
possible reintroduction site. Fort Lewis is within the historic range of the A.
marmorata, and works in partnership with WDFW on the recovery and continued
success of species such as the Streaked Horned Lark (Eremophila alpestris
strigata), Oregon Vesper Sparrow (Pooecetes gramineus affinis), Western
Bluebird (Sialia mexicana), Mazama pocket gopher (Thomomys mazama),
western gray squirrel (Sciurus griseus), mardon skipper butterfly (Polites
mardon), Taylor’s checkerspot butterfly (Euphydryas editha taylori), and Oregon
spotted frog (R. pretiosa). Also, land managers at Fort Lewis currently manage
2
plant species beneficial to these animal species such as rare oak savannah, prairie
grassland, wetland, and riparian habitats.
There are several aquatic locales on Fort Lewis that would make suitable
reintroduction sites for A. marmorata with very little alteration. Suitable habitat
was defined as a site ranked in the upper third for at least three of the habitat
characteristics and no more than once in the lowest third in any one of the eight
habitat categories. This could result in a rank summed score as great as 42. The
reasoning for this definition of suitability is that it would be prohibitively
expensive to alter habitat characteristics in order to make a site suitable, so a site
already meeting a greater portion of those criteria would be most suitable for
reintroduction. This project investigated suitability of the habitats at Johnson
Marsh and Clay Pit and tested if they were similar to habitat found at the
Lakewood site that has been identified by the State as suitable for turtle
reintroduction based on the site’s availability, ecological complexity, size,
proximity to dry native oak/prairie uplands, and the ability for WDFW personnel
to control access to the site (Hays et al. 1999). Of nine historic A. marmorata
locations on Fort Lewis, Johnson Marsh probably ranks the highest for suitability
for reintroduction due to the site’s size and ecological complexity. Thus, it was
hypothesized that this site would most closely match the characteristics of an ideal
A. marmorata habitat. Below is background information on the biology and
ecology of A. marmorata, including information on its decline. Background
information on the Fort Lewis site, the selected study locations, and their potential
3
as restoration sites is also presented. Finally, the questions/hypotheses guiding
this research are discussed.
1.1. Habitat Requirements and Life History
Actinemys marmorata is a semi-aquatic species found in a wide variety of
aquatic habitat types (Hays et al. 1999). However, it has very specific habitat
requirements. Their home ranges are only 0.62 to 2.47 acres in size, though they
are capable of moving distances of up to five kilometers (Holland 1994, as cited
in Hays et al. 1999). They utilize small, shallow lakes, sloughs, rivers, streams,
ponds, and wetlands (Bury 1986 and Hays et al. 1999). They prefer locations
with slow moving water and an abundance of basking sites.
Basking sites include emergent and submerged vegetation, rocks, sand,
downed logs or branches, planks, and even the carcasses of large mammals.
Basking is an important behavior needed to maintain their metabolism,
development of eggs, to rid themselves of skin parasites, and for synthesis of
vitamin D (Lindeman 1999). The prime spots on basking sites are fought over via
aggressive behaviors such as biting, mouth gaping, pushing, leg swiping, and
climbing atop, with larger turtles most often winning the better positions (Bury
and Wolfheim 1973, Lindeman 1999).
Underwater refugia are also important for predator avoidance, and the
pond turtle is a very wary species that rarely basks more than a few meters from a
potential refuge (Bury and Wolfheim 1973, Hays et al. 1999). When scared, a
pond turtle will swim rapidly underwater to hide under submerged refugia. These
may consist of undercut banks, holes, various sized rocks, or submerged logs or
4
vegetation. If the substrate is soft enough, a turtle may even burrow into the mud
for protection.
Pond turtles are dietary generalists that primarily eat aquatic invertebrates
and carrion and, occasionally, small fish and frogs (Hays et al. 1999). They may
also ingest insects from the surface of the water such as grasshoppers or beetles
(Bury and Stringer 1992). Pond turtles do not select food based on general
availability, but rather, they are opportunistic predators that prefer live prey (Bury
1986). Males tend to eat more live vertebrate prey items than do females, and
algae and vegetation make up a greater percentage of the female pond turtle diet.
At certain times of the year, females may ingest large quantities of cattail (Typha
latifolia) or bulrush (Scirpus spp.) roots, water lily pods, or alder (Alnus spp.)
catkins (Hays et al. 1999). Bullfrog (Rana catesbeiana) tadpoles and adults do
not appear to be preyed upon by pond turtles, and this may be due to unpalatable
compounds in the skin of the frogs.
Upland habitat is important at all life stages. Gravid females take multiple
trips on land before nesting, where they bury themselves in dirt and leaf litter
(Reese and Welsh 1997). It is hypothesized that this burial might facilitate
thermoregulation and thus benefit pre-ovipositional embryo development.
Hatchlings were found to overwinter in their upland nest, after an incubation
period of 95-127 days, for up to eight months after the females laid eggs, most
likely for protection from predators and winter scouring of waterways at high
flow periods (Reese and Welsh 1997). Upland habitat is also critical for
overwintering of adults, who leave the aquatic habitat from October through
5
March or April. These turtles hide under logs, leaves, or bury themselves in mud
during this period of hibernation. They prefer sites with 80-90% shrub and tree
canopy cover beneath or near Oregon white oak (Quercus garryana) (Hays et al.
1999).
Individual turtles are slow to sexually mature and can be long-lived.
Males can take up to twelve years to mature, and females can take seven years to
mature (Hays et al. 1999). Although the average life span is unknown, the
estimated maximum is 50-70 years, and the longest lived wild pond turtle lived to
be 42. Females usually only lay two to thirteen eggs per year between the end of
May and early July, and clutch size is positively correlated with female body size
(Forsman and Shine 1995). Eggs are laid in upland nests up to 100 meters from
the water’s edge.
1.2. Distribution and Taxonomy
Historically, Actinemys marmorata was found from southern British
Columbia south through Baja California, mostly west of the Sierra-Cascade crest
(Figure 1; Hays et al. 1999). Its presence in Canada seems to be controversial,
and if it was present, it may not have been very abundant (Storer 1937).
Specimens sent to Canadian museums were not reliably identified, and records are
inadequate. An individual A. marmorata was positively identified near Burnaby
Lake in Vancouver, BC by Ian McTaggert Cowan in 1933, but that is the only
record of this species in that area in the late 1930s (Cowan 1938). In Oregon and
California, the museum records and availability of fossil evidence are better for
establishing the presence of A. marmorata (Brattstrom 1953 and 1955, Bury 1963,
6
Crippen 1962, Graf, Jewett, and Gordon 1939, Mosaur 1935, Ruthling 1915, and
Storm 1949). These records range from a few jaw bones to preserved complete
animals in museums.
Although there is no historic data on the size or dynamics of A. marmorata
populations in the Columbia River Gorge or Puget Sound areas, there are written
accounts of large populations inhabiting Old Fort Lake near Dupont, Washington
in the 1860s (Hays et al. 1999). Additionally, Native Americans recall stories of
gathering turtle eggs at Nisqually Lake, and the Nisqually name for the lake
translates to “place where the turtles came from,” so it is assumed that A.
marmorata was locally abundant in the Puget Sound region. Fossils from the
Pleistocene strata in south-central Washington indicate a wider range than present
distribution (Brattstrom and Sturn 1959). Records indicate that A. marmorata
were found over much of western Washington, although the majority of records
were only single individuals that may have been relocated by humans (Hays et al.
1999). It has been proposed that the Puget Sound population was isolated from
the Willamette drainage by a pyroclastic event from Mount Rainier about 4,700
years ago (Holland pers. comm., as cited in Hays et al. 1999).
Until recently, the pond turtle was taxonomically grouped into the genus
Clemmys which consisted of four species, C. insculpta, C. guttata, C.
muhlenbergii, and C. marmorata (Crother et al. 2003). However, recent work on
the molecular level has supported the assignment of three genera to this group.
The genus name Clemmys has been replaced with the genera Actinemys, Emys,
7
and Emydoidea. A. marmorata is actually a monotypic sister to the other three
species.
There are two distinct subspecies of A. marmorata (McDowell 1964, as
cited in Bickham 1975, Bickham et al. 1996, Bramble 1974, Burke, Leuteritz, and
Wolf 1996, Frair 1982, Gray 1995, Merkle 1975, and Seidel 2002). Studies on
the variations of hemoglobin, sequencing of mitochondrial and nucleic DNA,
serum proteins, and shell morphology helped delineate between the subspecies.
The northern subspecies, A. m. marmorata, is found from the Puget Sound south
to the Sacramento Valley, California (Behler and King 1979, Crother et al. 2003,
and Hays et al. 1999). The southern species, A. m. pallida, overlaps at the north
end of its range with A. m. marmorata and ranges from Monterey, California to
Baja California Norte. Both subspecies are threatened.
1.3. Causes of Decline
The initial cause of Actinemys marmorata population declines was due to
commercial collection for the restaurant and pet trades (Hays et al. 1999). The
South Puget Sound region’s populations were extirpated by the 1980s due to
habitat destruction and fragmentation, predation by introduced species,
environmental toxins, and demographic stochasticity. Only two meta-populations
persisted in the Columbia River Gorge area, both less than 120 individuals (Bury
and Stringer 1992, Hays et al. 1999).
Pond turtles do not thrive in habitats that have been altered by humans
(Hays et al. 1999). Wetland draining, filling, and development and stream and
river damming, dredging, channelizing, and use for irrigation have eliminated
8
suitable habitat over the twentieth century. These actions alter water levels, create
physical barriers, decrease basking site availability, and create suitable habitat for
non-native species. They may also increase sedimentation and water
temperatures and velocities and decrease canopy cover. Grazing by domestic
cattle may remove emergent vegetation and modify aquatic and terrestrial
habitats. Urbanization decreases upland habitat suitability by decreasing the
availability of nesting and overwintering sites. The presence of roads creates
physical barriers between aquatic and terrestrial habitats. Habitat destruction and
fragmentation makes it difficult, if not impossible, for adults to locate new habitat
when occupied habitat becomes unsuitable because habitat is disperse and
disconnected.
Introduced species either prey upon pond turtles directly, or carry
pathogens to which pond turtles are extremely susceptible (Hays et al. 1999). In
the case of sports fish, introductions are a direct result of human action. Sunfish,
red-eared sliders (Trachemys scripta elegans), and snapping turtles (Chelydra
spp.) compete with pond turtles for prey (Thomson et al. 2010). Other
introductions, such as bullfrogs (Rana catesbeiana) and opossums (Didelphis
virginiana), are aided by indirect human actions that make habitat more suitable
for their occupation (Hays et al. 1999). Bullfrogs, naturally found in the eastern
US, were introduced to Idaho in the 1890s, and to Oregon in the 1920s and are
now found throughout the range of the pond turtle. They prey upon juvenile pond
turtles, as well as many other vertebrates. Humans also alter habitat to increase
the presence of native predators, such as raccoons (Procyon lotor).
9
People releasing pet turtles have introduced pathogens into the
environment of the pond turtle. Pathogens include internal and external parasites
and diseases. Leeches (Placabodella spp.) are their only known ecto-parasites.
In 1930, L. G. Ingles found a new parasite (Telorchis sp.) inhabiting the intestines
of pond turtles, and seven different species of trematodes and nematodes were
found by V. E. Thatcher (1954) to infect pond turtles. A syndrome similar to
upper respiratory disease caused a severe decline of the already decimated
Klickitat County population in the Columbia River Gorge in 1990, but tests failed
to identify the causal agent.
The effects of toxins on pond turtles have not been studied in detail (Hays
et al. 1999). Diesel spills and Rotenone, a biodegradable compound used to
eradicate fish species for fisheries management, have been found to kill turtles.
Because of their long lifespan and their tertiary position in the food chain, they
may act as bio-accumulators of heavy metals and other toxins. Endocrine mimics
may interrupt turtle reproduction or detrimentally skew a population’s sex ratio
(Daughton and Ternes 1999 and Hays et al. 1999).
Due to low recruitment rates, pond turtle populations cannot sustain the
increased adult mortality rates caused by human exploitation and increased
predation (Hays et al. 1999). Late sexual maturity and small clutch sizes in this
species put it at greater risk for decline when populations are low. The Klickitat
County population in the Columbia River Gorge was moderately adult-biased,
with about 80% of the population at adult sizes in 1999. Under normal
circumstances, populations are comprised of less than 70% adults, so the Klickitat
10
County population was thought to be declining prior to human intervention. The
Skamania County population was less than 40 individuals in 1994.
1.4. Current Management of the Western Pond Turtle
1.4.1. Legal status
Currently, the pond turtle is listed as Endangered in Washington, a
Sensitive Species in Oregon, a Species of Concern in California, a Federal
Species of Concern, and is extirpated in British Columbia (Hays et al. 1999). The
Washington Department of Fish and Wildlife’s (WDFW) goal, as written in the
recovery plan for the pond turtle, is: “to re-establish self-sustaining populations of
Actinemys marmorata in the Puget Sound/Puget Trough and Columbia Gorge
recovery zones.” It requires that at least five populations of more than 200
individuals with no more than 70% adults be established in both the Puget Sound
region and Columbia River Gorge (Future 2007).
1.4.2. Current Management Actions
The WDFW began taking steps to intervene in the pond turtle’s survival
when the remaining Columbia River Gorge populations suffered severe declines
from an unidentified pathogen (Hays et al. 1999). Current management actions in
Washington include habitat acquisition and restoration, captive breeding and head
start programs for juveniles, predator removal programs, toxicology research,
public education programs, and continued monitoring of population abundance.
Habitat acquisition is probably the most expensive but also most beneficial
management activity. Private lands surrounding the Columbia River Gorge
habitat were either purchased by WDFW or The Nature Conservancy, or
11
easements were granted by the landowners to ensure that the property would not
be developed (Hays et al. 1999). Grazing was discontinued at most sites. An
artificial habitat was constructed near Lakewood, Washington in the Puget Sound
region, consisting of a series of ponds for reintroduction purposes. Enhancement
activities include placing more basking sites, removing non-native shrubs and
grasses from banks, and planting Oregon white oak (Quercus garryana) trees.
The captive breeding and head start programs are the second most
important component for continued survival of the pond turtle, and they are the
most time intensive management activities. It has been determined that hatchling
and juvenile life stages are the most at risk for predation and the most crucial for
the continued survival of this species (Hays et al. 1999). Therefore, a head start
program for juvenile turtles was initiated in 1990, after the unknown pathogen
outbreak in Klickitat County. The goal of the program was to give turtle
hatchlings a “head start” by raising them at the Woodland Park Zoo to a size that
would prevent predation by bullfrogs (Rana catesbeiana). This increase in size
has been shown to increase survival rate from hatchling to juvenile life stages.
Hatchlings were obtained by trapping and equipping females with transmitters in
the spring, monitoring the females until they laid eggs, and then placing frames
over the nest site to exclude predators and capture emerging hatchlings. Head
started hatchlings have been re-released back into Klickitat and Skamania County
populations. As of 2002, 620 head start juveniles had been released with a 95%
survival rating (Slavens 2003). The most recent releases in July of 2008, brought
the total number of released head started juveniles up to almost 1,400, and the
12
survival rate is staying up at about 95% (Future 2007). Some of the latest
Columbia River Gorge releases have been equipped with radio transmitters so that
scientists can learn more about post-release dispersal.
Two reintroduction sites now exist in the Puget Sound, one in Mason
County, and one in Pierce County at the South Puget Sound Wildlife Area
(SPSWA) in Lakewood (Schmidt et al. 2008). The WDFW still needs three
more site to meet their goal of five reintroduction sites in the Puget Sound. The
SPSWA site is 90 acres and is owned by WDFW. The project site for the
recovery of Actinemys mormorata is twelve acres that includes a three acre
wetland mitigation site built in 1994 by Pierce County Public Works from an
existing spring seep. There are currently plans to increase the size of SPSWA by
creating an additional pond complex and providing females with the ideal south
facing slope for nesting in order to meet the goal of 200 individuals at this site.
The site in Mason County, Goat Ranch Pond, had 22 turtles released there from
the head-start program.
The head start program was determined to be neither enough to stabilize
Columbia River Gorge populations nor enough to reintroduce populations back
into the Puget Sound region, so a captive breeding program was developed among
the Woodland Park, Point Defiance, and Oregon Zoos in 1991 (Hays et al. 1999).
Single adults found throughout the Puget Sound region were captured for captive
breeding as they were found. Recent genetic studies have revealed that Puget
Sound populations are more closely related to Willamette Valley populations in
Oregon, so individuals from this area were used to supplement the captive
13
breeding program. However, the out-of-state stock was only used to refine
captive breeding techniques. This program established small populations of less
than 40 individuals in various Puget Sound locations from 1990 through 1998
(Figure 3). As of 1997, the Woodland Park Zoo had successfully reared and
released 38 captive-reared juveniles, and re-sightings of the marked juveniles
indicate that the program is successful. Washington Department of Fish and
Wildlife is planning to reestablish populations at more sites in the Puget Sound
region, but they are still evaluating which sites would be best suited for
reintroduction.
To ensure further survival of juvenile pond turtles, the removal of nonnative predator fish and bullfrogs (Rana catesbeiana) has occurred in areas with
known pond turtle populations (Hays et al. 1999). Gigging and fishing to remove
adult bullfrogs are effective techniques for reducing negative impacts to turtle
populations in small, isolated habitats, and trapping and disposing of bullfrog
tadpoles is also employed. Gillnetting and hoop traps are used for non-native
sports fish such as bass (Micropterus spp.), bullhead (Ameiurus spp.),
pumpkinseed (Lepomis gibbosus), and bluegill (Lepomis macrochirus). Efforts to
minimize the availability of nesting sites for opossum (Didelphus virginiana) and
raccoon (Procyon lotor) are also underway to limit their predation on pond turtles.
Toxicology research is necessary to understand the types of compounds to
which pond turtles are being exposed and what waterborne diseases are present
(Hays et al. 1999). Careful monitoring of water quality in current pond turtle
14
habitat is beneficial in ensuring that levels of heavy metals and pesticides are not
high enough to cause acute toxicity or reproductive failure.
Public education programs on the habitat requirements of A. marmorata
were developed beginning in 1998 (Slavens and Slavens 1998). These programs
provided the general public with information on the dangers of releasing nonnative pet turtles into pond turtle habitat and identification guides to help them
distinguish between A. marmorata, the other native turtle, the painted turtle
(Chrysemys picta), and introduced turtle species (Hays et al. 1999). It was also a
goal to begin education programs and materials for public schools.
Abundance surveys were conducted by biologists and trained volunteers at
128 wetlands in 1991, and 88 sites the following year using standardized
methodology to locate any remaining unknown populations in western
Washington (Hays et al. 1999, Slavens and Slavens 1998). The surveys were
conducted over the historic range of the turtle, especially at sites with known
historic populations. Abundance surveys have been continuously conducted by
biologists and volunteers on an annual basis. Trapping, baiting, and artificial
basking sites are used to increase the likelihood of visually observing an
inhabitant pond turtle. These surveys provide useful information on habitat use,
population numbers, and sex ratios.
1.4.3. Future Management and Research
It is critical that WDFW continue their current management actions, as
well as take further action to determine upland habitat requirements, identify
more, suitable reintroduction sites, establish information management systems
15
and communications among all participants, and evaluate and enforce restrictions
designed to protect the pond turtle. This will be difficult to do, as WDFW faced a
combined 36.2 percent State General Fund budget cut from the 2007-09 biennium
to the 2011-13 biennium (Budget 2011). The other major contribution to the
budget comes from recreational license fees, which was predicted to fall short by
$10 million at the start of the 2011-13 biennium.
Relatively little is known about the upland habitat requirements of
Actinemys marmorata. It is understood that they can travel considerable distances
in search of nesting and overwintering sites, as well as new aquatic habitat (Reese
and Welsh 1997, Hays et al. 1999). However, because of their wary nature and
the fact that they hide under vegetation and downed logs for extended periods
during upland habitat use, much is still unknown. The nesting behaviors of
females are equally mysterious (Rathbun, Siepel, and Holland 1992). It is
believed that by laying eggs in upland habitat rather than near aquatic habitat may
be multi-functional; it could decrease the likelihood of loss due to flooding, be
necessary for short incubation times, or decrease the probability of predation by
raccoons.
A more recent telemetry study of pond turtles in Trinity County,
California found extensive terrestrial activity in adults, especially by gravid
females (Reese and Welsh 1997). Pond turtles in Washington may experience
very different environmental pressures due to dissimilarities in climate that result
in different terrestrial habitat use. It would be safe to conclude, however, that the
16
riparian habitat serves an essential role in the life history of the turtle and should
be protected through land acquisition and restoration efforts.
Because this project has numerous stakeholders and agencies involved, it
is critical that there is an information management and sharing system available to
coordinate efforts (Hays et al. 1999). This will assist in local and regional trends
and improvement of methodology. Although there is a bimonthly electronic
newsletter available online for interested parties, it is not necessarily the most
efficient way to share information and large data files (Slavens and Slavens 1998,
Slavens 2003).
Currently, harming, harassing, or killing A. marmorata or destroying their
nests or eggs are prohibited by Washington state law (Hays et al. 1999).
Regulations on exotic pets need to be more effective in order to prevent the
release and establishment of non-native species and their pathogens. It may be
possible to distribute information to the public when any pet turtle is purchased.
This project costs about $150,000 to $180,000 per year to meet all tasks,
but that is shared among a variety of agencies and stakeholders, and is subject to
the availability of funding (Hays et al. 1999). This amount is a relatively low
cost for a single species conservation, especially when compared to the millions
of dollars spent on salmon (Oncorhynchus spp.) and the Spotted Owl (Strix
occidentalis) in Washington each year (Budget 2009). Volunteer resources are
also utilized in monitoring, captive breeding and head start programs, and habitat
restoration which minimize project costs. State and federal agencies that are
involved in the funding of this project include: WDFW, the Washington Wildlife
17
and Recreation Program, the Forest Service, and the US Fish and Wildlife.
Weyerhaeuser Company has donated trees for habitat restoration efforts. The
Woodland Park, Point Defiance, and Oregon Zoos are involved in the captive
breeding and head start programs. The Nature Conservancy and Washington
Conservation Corps are also heavily involved in habitat acquisition and
restoration for A. marmorata in Washington. Many other private organizations
contribute funding and volunteers for this ongoing project.
1.5. Fort Lewis
Fort Nisqually was established in 1833, in the area north of the Nisqually
River by the Hudson Bay Company for two primary reasons; it served as a site for
the booming fur trade and strengthened British claims to the area (Maris 1991). A
$2 million bond approved by the people of Pierce County in January of 1917 was
used to purchase 61,000 acres which was donated to the federal government for
the establishment of a new military base. Thus, Camp Lewis was founded on the
land that lies between present-day Olympia and Tacoma, Washington. With the
passing of the Housing Program Act of 1926, to create a standing federal military,
Camp Lewis was renovated over a period of ten years and renamed Fort Lewis
(Figure 2). It was, and still is, used as a training center for recruits, which
includes weapons and maneuver training, and it houses the I Corps.
Fort Lewis continued to acquire new land until it grew to its present size
of 86,500 acres (McCausland 2001). The majority, 63,000 acres, is used for
training, 12,500 acres are used for impact, and the other 10,500 are used for
cantonment (Maris 1991). The fort lands include mixed forest (56%), prairies
18
(20%), oak woodland (4%), ponderosa pine savannah (5%), wetlands (5%), and
27 lakes (Fort Lewis 2004). Lewis falls under the jurisdiction of the Department
of Defense’s Forces Command (FORSCOM) division of the Department of the
Army (McCausland 2001).
1.5.1. Historical Use of Fort Lewis Aquatic Habitats
Fort Lewis’ oak savannahs and prairie grasslands provide the military with
the perfect setting for a variety of training activities because there is high
visibility over long distances and expansive spaces for large maneuvers and
airborne operations. Various military and civilian activities occur on the training
lands that may impact the habitat. These include large and small ammunition live
fire, foot and wheeled vehicle maneuver training, hunting, boating, fishing, dog
training, horseback riding, and model airplane flying. Activities that occur
against permit regulations include dirt biking, civilian off-road vehicle maneuver,
unauthorized horse-back riding, and trash dumping.
Other factors influencing the landscape include industrial and business
practices. In 2006, a petroleum product pipeline and fiber optic cable were
upgraded and installed through Training Area 15 and Muck Creek. In addition,
commercial timber harvesting is permitted in the forests adjacent to wetlands and
lakes. These industrial activities can threaten the habitat by trampling native
vegetation, introducing exotic species, compacting soil structure, and increasing
soil erosion and runoff.
Fort Lewis contains many wetlands and ponds that are among the least
disturbed aquatic habitats left in the South Puget Sound region (Bury 1993).
19
Several herpetofauna studies conducted over much of Fort Lewis in the 1990s
found only a few remaining individual pond turtles, and reintroductions have
already occurred in nearby locations in Lakewood, Washington (Bury 1993, Bury
and Stringer 1992, Carey and Bury 1992, Forrester and Storre 1992). Aquatic
habitat at Fort Lewis is not widely used for training, although some sites
experience heavy recreational use. Many are surrounded by relatively
undeveloped upland habitat because they are active training lands (Bury and
Stringer 1992, Bury 1993). According to Bury (1993), several waterways and
ponds on Fort Lewis have fair to excellent habitat conditions and the reason for
the pond turtle’s absence is unknown.
1.5.2. Study Site Selection and Descriptions
Sites were selected from a list of locations that were last surveyed for
Actinemys marmorata inhabitants in 1992 (Forrester and Storre). Of the ten
locations surveyed in 1992, six were initially included in this study: Sequalitchew
Lake, Spanaway Marsh, Chambers Lake, Lewis Lake, Nisqually Lake, and
Fiander Lake (Figure 4). Clay Pit, Johnson Marsh, Jolly Lake, and Ranger Lake
were also included due to the presence of grassland and/or deciduous trees in the
surrounding upland habitat. Jolly Lake and Ranger Lake are also at least two and
a half miles, as the crow flies, from areas that receive substantial military or
recreational activity and had the potential to contain small, previously undetected
populations of A. marmorata.
20
Chambers Lake, T18N R2E S23, S26, and S27. Chambers Lake had a water
control structure built at the south end in the 1960s to control the water levels of
Muck Creek for salmon (Oncorhynchus spp.) runs, and it is now a popular fishing
spot with many boat launches at the south end (Bury and Stringer 1992). Dense
aquatic vegetation at the northern end prohibits access by boat (Forrester and
Storre 1992). Water flows through the Muck Creek stream channel, and the water
there is much colder (Bury and Stringer 1992). The water is still elsewhere and is
generally clear. The lake has 40-80% emergent vegetation cover, which is
composed of reed-canary grass (Phalaris arundinacea), rushes (Juncus and
Luzula spp.), pond lilies (Nuphar spp.), and hardhack spirea (Spiraea douglasii).
Basking sites are few, mostly small logs under the overhang along the eastern
shoreline, so they do not receive much direct sunlight (Bury and Stringer 1992,
Forrester and Storre 1992). The upland canopy has scattered deciduous trees on
the prairie along the southwestern shore, and elsewhere it is mixed conifer (Bury
and Stringer 1992). The upland forest overhangs the water on the southeastern
shoreline, the bank is steep in places, and the entire shoreline has dense reedcanary grass up to five meters out from dry land. Signs of other species observed
at this site include bullfrog (Rana catesbeina), red-legged frog (Rana aurora),
northwestern salamander (Ambystoma gracile) egg masses, Lesser Canada Goose
(Branta canadensis), Wood Duck (Aix sponsa), raptor nests, and a beaver (Castor
canadensis) dam.
21
Clay Pit, the confluence of Muck Creek in Training Area 15. Clay Pit lies falls
just outside of 13th Division Prairie, one of Fort Lewis’ most highly utilized
landscapes, and Rogers Drop Zone, the most frequently used drop zone. Training
Area 15 is heavily used by Reserve Officer Training Corps for training in the
summer months. It is also popular with horseback riders and dog trainers due to
its close proximity to the rural town of Roy, Washington.
Fiander Lake, T17N R1E S21. Fiander Lake has been primarily left in a natural
state due to its remote location (Bury and Stringer 1992, Forrester and Storre
1992). However, there are two public access points, all located along the northern
shore (Forrester and Storre 1992). A third was closed in 2006 by the Fort Lewis
Fish and Wildlife Program to facilitate western toad (Bufo boreas) migration
(Lynch 2011, personal communication). Emergent vegetation covers 10-30% of
the lake and consists of cattails (Typha latifolia), reed-canary grass (Phalaris
arundinacea), pond lilies (Nuphar spp.), and rushes (Juncus and Luzula spp.)
(Bury and Stringer 1992). The water appears to be very dark and acidic and has a
slight current (Bury and Stringer 1992, Forrester and Storre 1992). The mixed
conifer upland forest comes to the water’s edge on all shores, and the immediate
shorelines are dominated by shrub vegetation. Basking logs are abundant around
the entire shoreline, and the logs in the northeastern corner are usually in direct
sunlight. Bullfrog (Rana catesbeiana), Mallard (Anas platyrhynchos), and Redtailed Hawk (Buteo jamaicensis) are all present in the area (Bury and Stringer
22
1992). Extensive flagging in the forest on the lake’s eastern side indicates active
logging.
Johnson Marsh, T18N R2E S13. Johnson Marsh is a larger, more complex habitat
with 60-80% emergent vegetation cover of cattails (Typha latifolia), reed-canary
grass (Phalaris arundinacea), pond lilies (Nuphar spp.), hardhack spirea (Spireae
douglasii), and rushes (Juncus and Luzula spp.) (Bury and Stringer 1992). There
is a water control structure at the southern end, but the marsh remains in a fairly
natural state. Other than a slight north to south current in the middle, the water is
still and clear with a mud bottom. The bank varies from gentle to steep and is
choked with reed-canary grass and cattails in most locations, although several
places have grassy banks next to open waters where Canada geese (Branta
canadensis) have clipped the grass short. There are occasional basking logs
throughout the water. The mixed conifer forest comes to within ten meters of the
shoreline on the eastern side, and there is open deciduous woodland on the
southwestern side. This diverse marsh provides habitat for various fish and snail
species as well as bullfrog (Rana catesbeiana), red-legged frog (Rana aurora),
Pacific tree frog (Pseudacris regilla), Wood Duck (Aix sponsa), Cinnamon Teal
(Anas cyanoptera), American Coot (Fulica americana), Hooded Merganser
(Lophodytes cucullatus), Pied-billed Grebe (Podilymbus podiceps), Great Blue
Heron (Ardea herodias), lesser Canada Goose (Branta canadensis), Mallard
(Anas platyrhynchos), Red-winged Blackbird (Agelaius phoeniceus), and Barn
Swallow (Hirundo rustica).
23
Jolly Lake, T17N R1E S9. This natural lake has 70-90% emergent vegetative
cover of pond lilies (Nuphar spp.), reed-canary grass (Phalaris arundinacea),
rushes (Juncus and Luzula spp.), and cattails (Typha latifolia), with a notable
cattail mat in the middle (Bury and Stringer 1992). The standing water is murky
with a muddy bottom. There are a few basking logs along the edge, though they
are partially shaded. The upland canopy cover is dominated by mixed conifer
trees, and it comes to within less than ten meters of the water’s edge. Other
species seen in the area include bullfrog (Rana catesbeiana), Pacific tree frog
(Psuedacris regilla), rough-skinned newt (Taricha granulosa), and several
species of duck.
Lewis Lake, T17N R2E S4 and S5. Lewis Lake is a medium sized lake that
attracts a moderate amount of human activity, but its 50 acres still provide some
locations with low disturbance (Forrester and Storre 1992). Military activities
occur on the southwestern end, there is a practice jump tower on the southwestern
shore, and recreation occurs on the north end of the lake (Bury and Stringer
1992). Cattails (Typha latifolia), reed-canary grass (Phalaris arundinacea), pond
lilies (Nuphar spp.), and rushes (Juncus and Luzula spp.) cover 10-20% of the
lake, but there are numerous sections of bare shoreline due to human activities
(Bury and Stringer 1992, Forrester and Storre 1992). Basking sites are limited,
but there are some along the northern and eastern edges. The lake has a current to
the north, and the water is still along the edge. The mud and gravel bottom is
visible through the clear water. The upland canopy is dominated by mixed
24
conifers and comes to within ten meters of a portion of the shore. Large mouth
bass (Micropterus salmoides), other fish species, bullfrog (Rana catesbeiana), and
duck inhabit the area, and a painted turtle (Chrysemys picta) was reported in 1991
(Gilbert et al. 1991, as cited in Bury and Stringer 1992).
Nisqually Lake, T17N R1E S1 to T18N R1E S9. Nisqually Lake is located in the
middle of the Artillery Impact Area (AIA) where a majority of heavy live fire
training occurs (Forrester and Storre 1992). This limits human access, so the lake
has remained in a fairly natural state. The majority of military disturbance
happens at the southern end, but there is no access to the northern end and appears
minimally disturbed. Emergent vegetation dominates the shoreline, and aquatic
vegetation is abundant throughout. Though there are no basking logs present,
vegetative mats could provide basking sites along the western edge. The western
end has a gradually sloped bank and receives direct sunlight during the morning
and mid-day hours.
Ranger Lake, T17N R1W S27. Although Ranger Lake remains a relatively
natural habitat, there is a duck blind in the middle of the lake, and there is a lot of
military barbed wire, mortar shells, and smoke canisters from military training
activities in the surrounding forest (Bury and Stringer 1992). Emergent
vegetation covers about 50-70% of the lake and consists of pond lilies (Nuphar
spp.), cattails (Typha latifolia), rushes (Juncus and Luzula spp.), reed-canary grass
(Phalaris arundinacea), and other woody species. There is no bank, the shoreline
25
is almost fully vegetated, and the mixed conifer forest comes almost to the water’s
edge. The water is still and clear with a mud bottom, and the lake contains a few
basking logs, but they are within the canary grass. There are documented
occurrences of bullfrog (Rana catesbeiana), snail, Mallard (Anas platyrhynchos),
various species of leech (Placabodella spp.), and raccoon (Procyon lotor).
Sequalitchew Lake, T19N R2E S19. Sequalitchew Lake is located near the
southern end of American Lake and north of Interstate 5 (Forrester and Storre
1992). Although it is heavily used for recreational fishing and military watercraft
training, many small coves around the lake are relatively undisturbed by human
activity. The relative lack of emergent vegetative cover, only 5-10%, is in part
due to the boat put-in locations (Bury and Stringer 1992, Forrester and Storre
1992). In the undisturbed coves, the clear water has little current, and there are an
abundance of logs suitable for basking. The mixed conifer forest comes to the
water’s edge except at the eastern end (Bury and Storre 1992). Other species
inhabiting this lake include: painted turtle (Chrysemys picta), red-eared slider
(Trachemys scripta elegans), various fish, bullfrog (Rana catesbeiana), Wood
Duck (Aix sponsa), Canada Goose (Branta canadensis), Mallard (Anas
platyrhynchos), and Pileated Woodpecker (Drycopus pileatus). There was also a
sighting of an individual Actinemys marmorata reported in 1991 in the
northeastern cove by Jim Stephenson (Forrester and Storre 1992).
26
Spanaway Marsh, T19N R2E S32. Spanaway Marsh’s history includes being
diked and drained for agricultural purposes, as indicated by submerged telephone
poles and fencing that show obvious historical flooding (Lynch 2011, personal
communication). In 1993, Fort Lewis Fish and Wildlife personnel installed a
water control structure to restore wetland function. It is restricted to recreational
uses because of nearby bald eagle nests, but it is heavily fished (Bury and Stringer
1992). Cattail (Typha latifolia) mats, reed-canary grass (Phalaris arundinacea),
hardhack spirea (Spireae douglasii), pond lilies (Nuphar spp.), and other woody
species cover 70-80% of the marsh, and the cattail mats make the southern end
inaccessible. The water varies from clear to murky and flows through the cattail
mats in channels. There are a few basking sites consisting of submerged fencing
and woody debris in the deeper north end. The shoreline is almost completely
choked with reed-canary grass, except for where the grass on the banks is kept
short by geese and fisherman, and in some locations the mixed conifer forest
reaches the shoreline. Various fish species, bullfrog (Rana catesbeiana),
northwestern salamander (Ambystoma gracile), Canada Goose (Branta
canadensis), Mallard (Anas platyrhynchos), Pileated Woodpecker (Drycopus
pileatus), Red-winged Blackbird (Agelaius phoeniceus), Barn Swallow (Hirundo
rustica), and Great Blue Heron (Ardea herodias) inhabit the marsh.
Given the dire condition of the pond turtle in Washington State and the
current goals of the WDFW to establish three self-sustaining South Puget Sound
populations of Actinemys marmorata, despite continually reduced budgets, Fort
27
Lewis’ undeveloped oak savannah and prairie grassland habitats offer the best
locations for reintroduction and recovery of the species. The focus of this thesis
is to determine which sites within Fort Lewis would offer the most suitable
habitat for reintroduction and continued success based on the requirements of the
species. In order to evaluate nine potential sites on Fort Lewis, two questions
were posed: is the habitat at any of the nine Fort Lewis locations significantly
different from the habitat at the current reintroduction site in Lakewood,
Washington, and of the nine Fort Lewis sites, which ranks the highest as a
potential reintroduction site based on ten habitat characteristics (distance to
shoreline, distance to basking site, percent canopy cover at ten centimeters,
percent overhead canopy cover, leaf litter depth, distance to a road, bottom
substrate type, shoreline accessibility, upland vegetation type, and presence or
absence of a south-facing slope)? It was hypothesized that the habitat at Johnson
Marsh and Clay Pit are statistically similar to the habitat at Lakewood because
both Johnson Marsh and Clay Pit provide grassy upland habitat with a gentle
slope leading to accessible shorelines. The second hypothesis was that Johnson
Marsh would rank the highest of the nine Fort Lewis locations as a potential
reintroduction site due to the site’s size and ecological complexity. Its ecological
complexity would provide more opportunity for basking and predator avoidance
while presenting a suitable location for nesting females and overwintering adults.
28
2. Methods
Prior to all surveys, aerial maps of each study site were constructed using
ESRI ArcView© GIS software and Public Works’ aerial photographs of Fort
Lewis from 2007. These maps were useful in navigating to sites and selecting
random starting points for the habitat surveys. Access to each project site was
coordinated through Fort Lewis Fish and Wildlife and Area Access passes for all
vehicles and surveyors were obtained from Fort Lewis Range Control. On the
days of surveys, it was required that observers check in with Range Control to
make sure that the desired Training Areas were open to the public and not closed
due to training. Due to the highly dangerous Artillery Impact Area surrounding
Nisqually Lake, surveyors were never able to gain access to that project site for
abundance or habitat surveys. Therefore, that project site was not included in the
final analysis for habitat suitability.
There appears to be very few studies of the impacts of US military
artillery on animals. The majority of research examines the impacts of
underwater sonar Naval testing on marine megafauna, but there is one thesis that
looked at the effects of artillery detonated on land at Fort Richardson on the
Harbor porpoise (Heenehan 2009). Sparling et al. (1998) looked at the effects of
white phosphorus, an artillery impact marking compound, on blood characteristics
in mallards and found liver and kidney damage attributed to the contaminant. It is
likely that artillery impacts would have a negative effect on Actinemys
marmorata, which is an easily spooked creature. The noise could cause them to
abandon basking sites prematurely or abandon the location altogether in search of
29
a quieter locale. The explosions also pose a threat to nests and overwintering
turtles.
2.1. Abundance Surveys
Five of the study sites were surveyed by Forrester and Storre in 1992.
These included Fiander Lake, Spanaway Marsh, Sequalitchew Lake, Chambers
Lake, and Lewis Lake. The other four sites successfully surveyed, Jolly Lake,
Clay Pit, Ranger Lake, and Johnson Marsh were included in this study in the
recommendation of Joint Base Lewis-McChord Fish and Wildlife personnel, Jim
Lynch. Nisqually Lake, originally included in the list of sites for this study and in
Forrester and Storre’s 1992 study, was excluded due to access restrictions. Its
location within the main Artillery Impact Area made it unsafe and inaccessible for
this study. If a surveyor were to gain regular access to this site, it would be
critical for them to examine the impacts, both direct and indirect, of artillery on
the species found in this area. Especially since the AIA is a rare species hot spot
containing the Streaked Horned Lark (Eremophila alpestris strigata), Oregon
Vesper Sparrow (Pooecetes gramineus affinis), Mazama pocket gopher
(Thomomys mazama), mardon skipper butterfly (Polites mardon), and the
Taylor’s checkerspot (Euphydryas editha taylori).
Abundance surveys were conducted between May 1st and July 18th, 2009.
They were conducted twice at all sites, except for the Clay Pit site due to access
constraints. The first surveys were completed between May 1st and June 27th and
the second surveys took place at least three weeks later. Surveys began no earlier
than 10:30 AM to allow time for the sun to rise above the tree line and begin
30
warming potential basking sites. Surveys concluded no later than 4:30 PM in the
early months of the study and 6:30 PM in the later months, as the sun stayed
higher on the horizon. This often allowed observers to conduct more than one
abundance survey at different sites in the same day. A minimum of one hour was
spent at each survey location to allow time for any turtles spooked by the
observers’ arrival to re-emerge from concealed cover and return to basking
activities.
Surveys were conducted from the shoreline at a fixed position from which
multiple suitable basking locations were visible. Prior to the start of the
abundance survey, a Kestrel thermometer was used to measure and record the
starting ambient air temperature. Also noted was the wind speed using the
Beaufort wind force scale, the overhead cloud cover percentage, and the time at
the start of the survey. Observers sat for a minimum of one hour in relative
silence while visually scanning potential basking sites and the shoreline for signs
of A. marmorata inhabitants; binoculars were also used to scan distant shoreline
and basking locations within line of site. During this time, a sketch of the study
site was made to include all visible shoreline, basking locations, and vegetation
grouped into five categories: emergent vegetation, grass, shrubs, and coniferous
and deciduous trees. If any roads or other manmade structures were visible from
the observation location, they were also included in the sketch. A list of all other
animal species seen or heard during that time, as well as any noteworthy human
activity observed other than the surveyors’ presence, was compiled. Any turtles
observed were identified to species using distinct markings and a copy of
31
National Audubon Society Field Guide to North American Reptiles and
Amphibians (Knopf 1979). Upon concluding the one hour abundance surveys,
observers would again measure the ambient air temperature and record it in order
to calculate an average ambient air temperature for the hour of survey time.
2.2. Habitat Surveys
Habitat surveys were conducted once for each project location at every
site where abundance surveys were conducted. Data at the Fort Lewis study sites
were collected from May 1st through June 27th (2009). Habitat data at the
Lakewood reference site was collected on September 22nd, when the last of the
successful nesting sites were excavated for transport to the Oregon Zoo.
Upon arrival to each of the eight Fort Lewis locations, surveyors would
navigate to a randomly selected starting point. The time was noted and the
ambient air temperature was measured using a Kestrel thermometer and recorded.
The wind speed, using the Beaufort wind force scale, and the overhead cloud
cover percentage were estimated and recorded, as well.
The surveyor then performed a random walk to select the first random data
plot. The surveyor started facing the water’s edge, but then flipped a coin to
determine a right or left turn of 90 degrees. After turning, they consulted a
prepared random number list of numbers ranging from 1-187. The number
corresponded to the number of paces that the surveyor then took in order to arrive
at the next point. One-hundred eighty-seven was the predetermined maximum
number of paces for the random walk because that is the average distance a gravid
female pond turtle will travel from the water’s edge for nesting (Holland 1991a,
32
as cited in Hays et al 1999). Once at the next point, the surveyor would repeat the
coin flipping, turning, and random pace process for a minimum of three iterations.
After the third random number of paces, the surveyor would once more flip the
coin, turn the appropriate direction 90 degrees, and throw a one-meter surveyor
flag over their shoulder. The location of the flag upon landing was the location of
the first subplot.
The Universal Transverse Mercator (UTM) position of the subplot was
determined using a Garmin eTrex ® Global Positioning System (GPS) unit and
recorded. The predominant vegetation type within the surrounding twenty-five
meters was recorded by categories of: “conifer/shrub,” “conifer/deciduous,”
“grass/conifer” “grass,” “conifer,” and “shrub/grass.” The canopy cover overhead
was visually estimated to the nearest percentage as was the canopy cover of the
one square meter area centering over the subplot at ten centimeters above the
ground. A meter stick was used to measure the leaf litter depth of the subplot to
the nearest tenth of a centimeter and recorded.
The location of the nearest water’s edge was also recorded using the GPS
unit, and the accessibility to the water was evaluated using a categorical system of
“accessible,” “ok,” and “not accessible.” “Accessible” denoted a shoreline with a
slope less than twenty degrees and grassy vegetation shorter than one meter.
“Ok” shorelines had a slope greater than twenty degrees but less than forty-five
degrees entering the water and some shrubby vegetation. “Not accessible”
shorelines had a slope of greater than forty-five degrees and/or dense, shrubby
vegetation taller than one meter.
33
The distance to the nearest basking site from the water’s edge was
measured using a laser range finder, and this distance was later added to the
distance between the subplot and the water’s edge to get the total distance from
the subplot to the nearest basking site. Basking sites were primarily emergent
logs and tree branches but also included dense emergent vegetation. The bottom
substrate of the aquatic habitat was recorded as “mud,” “grassy,” or “gravel.”
Prior to leaving the site, it was noted whether that site had a southern exposed
slope, which is most ideal for the development of eggs and overwintering
juveniles. Also, the ambient air temperature was again measured and recorded in
order to calculate the average ambient air temperature during the survey, in the
event that a turtle was seen.
Once all of this data was collected and recorded for the first subplot, the
random walk method was again employed, starting from the first subplot, in order
to select the subsequent subplots at the location. A minimum of two subplots per
study location were surveyed, and more data was obtained as time permitted.
Data for each Fort Lewis site was collected once on a single visit. The same data
was collected at the Lakewood reintroduction site at four actual nest locations on
the day that the eggs from each nest were excavated for transport to the headstart
facility at the Oregon Zoo. A total of twenty-seven subplots were surveyed at the
eight Fort Lewis study sites, and four subplots were surveyed at the Lakewood
site.
Data on the distance from the nearest road to each subplot at the study
sites and the nesting locations at the Lakewood reference location were obtained
34
using the same ESRI ArcView© GIS software and Public Works’ aerial
photographs that were used to make the aerial maps of each study location.
2.3. Data Analysis
The abundance and habitat data were entered into Microsoft Excel ©
spreadsheets with their corresponding meta-data and notes (Table 1). For the
habitat data, distances between subplots and nearest shoreline were calculated
using the Pythagorean Theorem, and the distance from the subplots to the nearest
basking site were calculated by adding the distance to the shoreline and the
distance from the shoreline to the basking site.
Table 1. Habitat data parameters collected at the ten sites.
Parameter
Distance to water
Distance to basking site
Distance to road
Canopy cover at 10 cm
Canopy cover overhead
Leaf litter depth
Vegetation type
South-exposed slope
Shoreline accessibility
Bottom substrate
Measurement
Meters
Meters
Meters
Percent cover
Percent cover
Centimeters
Categorical
Presence/Absence
Categorical
Categorical
2.3.1. Abundance Data Analysis
Since there were no turtles of any species seen at any of the eight Fort
Lewis study sites, there is no analysis for that data.
35
2.3.2. Habitat Data Analysis
To test the first hypothesis that the habitats at Johnson Marsh and Clay Pit
are the most similar to the habitat found at the Lakewood site, the means for each
quantitative habitat category (distance to basking site, distance to the water,
distance to the road, leaf litter depth, canopy cover at ten centimeters, and canopy
cover overhead) at each site was calculated, and a hierarchical cluster analysis
was performed on the means of the data. A hierarchical cluster analysis separates
the locations into groups while looking for similarities between groups within the
data. The cluster analysis seeks to minimize within-group variance and maximize
between-group variance.
However, the first assumption of a hierarchical cluster analysis is that the
data are independent of each so, prior to running the hierarchical cluster analysis,
it was necessary to perform a test for correlation among the habitat variables. The
test for correlation revealed a strong correlation between “distance to water” and
“distance to basking site” variables (correlation coefficient = 0.966), and
moderate correlations between “canopy cover at ten centimeters” and both
“overhead canopy cover” and “leaf litter depth” (correlation coefficient = 0.517
and 0.683, respectively). Therefore, both “distance to basking site” and “canopy
cover at ten centimeters” variables were not included in the hierarchical cluster
analysis. The second assumption of a hierarchical cluster analysis is that the data
are standardized to minimize variation due to differing ranges or scales of
measurement so the distance measurements for the remaining categories (distance
to water, leaf litter depth, and distance to road) were all standardized to meters. A
36
Bray and Curtis ordination was calculated for each of the location pairs to
determine how similar each location was to the others. The location with the
smallest Bray and Curtis ordination when paired with the Lakewood site is
considered most similar to that site.
The qualitative habitat data was converted to ordinal data to again test for
similarities between the Fort Lewis sites’ habitat data and the Lakewood habitat.
For the bottom substrate category, “mud” was given a ranking of one, “grass” was
given a ranking of two, and “gravel” was given a ranking of three based on the
fact that mud would be the easiest for a pond turtle to seek refuge in, and grass
and gravel are subsequently harder to dig through. Shoreline accessibility was
given an increasing ranking of one through three for “accessible,” “ok,” and
“inaccessible.” Of the upland dominant vegetation type, grassland was the most
optimum for nesting and, therefore, received a ranking of one. “Shrub/grass” and
“deciduous” were considered of equal quality for overwintering habitat and
assigned a rank of two (Van Leuven et al. 2004). “Conifer/deciduous” received
the next rating of three since there was a high likelihood that oaks were present
and pond turtles have a high affinity for habitat containing oak trees.
“Grass/conifer,” “conifer/shrub,” and “conifer” vegetation types are decreasingly
desirable and, therefore, received rankings of four, five, and six, respectively.
Subplots with south-exposed slopes were assigned a ranking of one, while those
without received a zero (Rathbun et al. 1992). The converted qualitative data was
then averaged for each location and included for a second hierarchical cluster
37
analysis to see if including the qualitative data revealed similarities in habitats that
was not apparent when the quantitative data was compared alone.
To test the second hypothesis that of the nine Fort Lewis sites, Johnson
Marsh was the most suitable reintroduction site, each site was ranked within each
of the eight independent habitat data categories based on the most desirable
characteristics for a reintroduction site. The assumption for a ranked summation
is that the variables are independent from one another so the categories for
“distance to basking site” and “canopy cover at ten centimeters” were removed
from the ranking calculation. Within the category for “distance to water’s edge,”
a greater average distance is considered most desirable since fluctuating water
levels during the winter threaten the success of nesting. Therefore, this category
was ranked from greatest average distance to least average distance to the water’s
edge, and the location with the greatest average distance received a score of 1.0
for this category, and the location with the least average distance was assigned a
score of 9.0. For the category of “overhead canopy cover,” it is considered most
desirable to have more exposure to sunlight for egg and juvenile development
within the nest, so the locations were put in order based on the lowest to highest
average percentage canopy cover. “Leaf litter depth” category was ranked from
highest to lowest average litter depth because greater litter depth provides female
turtles with more material to build their nests. The “distance to road” category
was ranked for each location from least to greatest average distance since vehicle
maneuvers pose a threat to turtles moving away from aquatic habitats for nesting
or overwintering in upland habitat. The qualitative habitat data had already been
38
ranked when it was converted to ordinal data based on most desirable
characteristics for each of the remaining four categories of “bottom substrate,”
“shoreline accessibility,” “vegetation type,” and “presence of south-facing slope.”
Each location was ranked lowest to highest based on the averages for each of
these four ordinal categories. If locations had the same value for a single
category, both locations were assigned the lowest possible ranking. The ranks
were then summed for each site for all eight categories, and the site with the
smallest overall score was considered the most suitable.
3. Results
3.1. Abundance
Although no Actinemys marmorata were detected during any of the Fort
Lewis site surveys, this was by no means an exhaustive search for their presence.
Limited time and resources allowed only simple stationary visual surveys at no
more than two locations per site. Baited traps, artificial basking structures, boat
surveys, and snorkel surveys are all possible means to increase the likelihood of
detecting the presence of A. marmorata, but surveyors were not allowed to leave
equipment such as traps or basking structures in place in the military training
areas (Forrester and Storre 1992). Additional surveys at these locations may
possibly turn up a few individual turtles.
3.2. Habitat
The inclusion of the ordinal data in the hierarchical cluster analysis did not
show a dramatic difference from the hierarchical cluster analysis of just the
39
quantitative data habitat data alone, so it will not be discussed further in the
results. The results of the hierarchical cluster analysis show that Spanaway Marsh
is the most similar to the Lakewood reintroduction site (Bray-Curtis distance =
0.222). The Bray-Curtis distance means that the variance between Spanaway
Marsh and the Lakewood site for all variables summed to 0.222. A Bray-Curtis
distance closest to zero means that there is more similarity among that particular
grouping of locations than in other groupings with greater Bray-Curtis distances.
The results of the rank summation of the habitat data reveal that Clay Pit
is ranked as the most suitable of the nine Fort Lewis sites for reintroduction of
Actinemys marmorata (ranked summed score = 20). Clay Pit’s ranked summed
score of 20 was the lowest out of the nine Fort Lewis sites, and this is primarily
because it ranked first in three of the habitat characteristics: overhead canopy
cover, bottom substrate type, and upland vegetation type. It also only ranked in
the lowest third for the leaf litter depth category. Jolly Lake would also be
considered suitable habitat for reintroduction based on the definition since it
ranked in the top one third in at least three habitat categories and no more than
once in the lower third ranking for any one category. It had a ranked summed
score of 23.
3.2.1. Similarity
The results of the hierarchical cluster analyses reveals that the habitat at
Spanaway Marsh was the most similar to the habitat at the Lakewood
reintroduction site (Bray-Curtis distance = 0.222, p-value < 0.0001). Clay Pit is
the second most similar site when compared to the Lakewood reintroduction site
40
with a Bray-Curtis distance of 0.275. The dendrogram of the cluster analysis
shows that Johnson Marsh is, in fact, the least similar site to the rest of the
clustered sites (Figure 5). It had a Bray-Curtis distance of 0.774 when paired with
the Lakewood site. The dendrogram has a cophenetic correlation coefficient of
0.811 which is the measure of how well the dendrogram represents the similarities
of the original distances used to construct the dendrogram. A coefficient of 1.0 is
the strongest correlation, but our correlation coefficient of 0.811 is fairly strong.
3.2.2. Suitability
Since some locations were tied in a single category, some categories in the
ranked summation had an overall score less than 45, which is the maximum total
for a single category given that the sum of the numbers one through nine equal 45.
Therefore, the total sum of ranks for all ten categories was 308, not 360. The
hypothesis that Johnson Marsh was the most suitable reintroduction site was
rejected as it scored 34 points and ranked fifth overall (Table 2). Clay Pit ranked
as the most suitable reintroduction site with a total score of 20. Jolly Lake was a
close second with 23 points. The least suitable site was Fiander Lake with the
highest score of 51.
Clay Pit ranked first in the “overhead canopy cover” category, and it tied
for first in the ordinal categories “bottom substrate,” “vegetation type,” and
“presence of a south-facing slope.” These first place rankings led to its lowest
overall score and overall most suitable ranking.
41
Table 2. The results of the summation of the rankings for each of the eight
categories for each of the nine locations to determine the most suitable
reintroduction site. The lowest score indicates the most suitable habitat for
reintroduction while higher scores mean those sites are less suitable for
reintroduction.
Location
Clay Pit
Jolly Lake
Chambers Lake
Lewis Lake
Johnson Marsh
Spanaway Marsh
Sequalitchew Lake
Ranger Lake
Fiander Lake
Final Score
20
23
30
32
34
35
37
46
51
4. Discussion
The similarity analysis of the habitat data did not support the first
hypothesis that the habitat at both Johnson Marsh and Clay Pit would be
statistically similar to the habitat at the Lakewood reintroduction site, Clay Pit
was the second most similar site after Spanaway Marsh. Also, the second
hypothesis that Johnson Marsh would be the most suitable habitat for
reintroduction of Actinemys marmorata because of its ecological complexity was
not supported by the suitability analysis of the habitat data. In fact, Clay Pit was
ranked as the most suitable site of the nine locations.
Spanaway Marsh, with its Bray-Curtis distance of 0.222, was the most
similar site to the Lakewood site, and fell in the middle of the ranked summation
in fifth with a final score of 35. It lies adjacent to Spanaway Lake, a popular
42
recreation spot just outside the boundary of Fort Lewis, and is itself a popular
recreational fishing location. However, since the military is already unable to use
Spanaway Marsh for training because of the presence of bald eagle nests, they
may be more inclined to also restrict recreational use by means of a gated fence in
order to protect introduced A. marmorata. It does not have a south facing slope
for nesting, which would be ideal, but neither does the Lakewood site. The
solution for Lakewood is to construct a south facing nesting slope, and this could
also work at Spanaway Marsh.
Although the results indicate that Clay Pit is the second most similar site
to the Lakewood site and ranked as the most suitable habitat of the nine Fort
Lewis sites, it is important to note that its proximity to 13th Division Prairie, the
largest contiguous prairie habitat outside of the AIA, and to the towns of Yelm
and Roy make it a highly used area for both military training and recreationalists.
If there had been a measurement of use included in this analysis, the results may
have been different. A solution, utilized at the Lakewood site to keep unwanted
people out of the turtles’ habitat, would be to completely fence of the portion used
by the turtles for basking, feeding, nesting, etc., and restricting access to the site
by use of a locked gate. However, this solution is only feasible for the area
between the confluence of North and South Muck Creek that is already fenced
and off-limits to vehicle maneuvers. The western portion of this site as it is an
important active training area and near a main DZ, Rodgers DZ, and could not be
fenced-off and locked. Additionally, Clay Pit is staked off with Seibert stakes to
prevent vehicles from damaging sensitive riparian zones, but there are authorized
43
fords where large military vehicles are allowed to drive through (Seibert, no date).
These concrete hardened fords might appear as optimal basking locations for
Actinemys marmorata and draw them into hazardous contact with vehicles.
Jolly Lake scored the second highest position for most suitable
reintroduction site with 23 points, and was fourth most similar to Lakewood with
a Bray-Curtis distance of 0.359. It had the highest average distance from a road
which is most favorable, and it had the second highest average leaf litter depth
which is necessary for overwintering and nesting. Furthermore, it had moderate
overhead canopy consisting of mixed deciduous and coniferous upland
vegetation. Although oak/prairie savannah is optimal, a mixed
deciduous/coniferous vegetation type can provide the oaks A. marmorata prefer to
nest near as well as the conifers that will make good basking logs in the near
future.
Even though Johnson Marsh actually was the least similar site when
compared with the Lakewood reference site and only fell in the middle of the rank
summation for most suitable at fifth place with a score of 34, it does merit some
consideration as a potential reintroduction site. It ranked second highest in both
the “overhead canopy cover” and “vegetation type” categories and already has a
south facing slope for nesting. Fencing off a portion of the marsh to restrict
access or posting signs to limit access during certain key time periods, such as
during nesting, would increase the suitability of this site for reintroduction.
Trimming reed-canary grass would also be helpful in increasing the accessibility
of the water and basking sites for A. marmorata. It may not be most suitable now,
44
but neither was the Lakewood site before it was specifically managed for the
success of A. marmorata.
Nisqually Lake, while unfortunately excluded from this study due to its
hazardous location within the AIA, likely remains the most suitable site for
reintroduction. It is surrounded by some of the highest quality upland prairie
grassland and oak habitat, has a south facing slope for nesting and is not
accessible for recreation or vehicle training. However, the direct and indirect
impacts of artillery explosions on A. marmorata, and wildlife in general, pose an
unstudied and unknown threat to their success. Additionally, it would be
necessary for there to exist a legal guarantee that if A. marmorata were
reintroduced at Nisqually Lake, that any future population declines at that location
would not result in closure of the AIA for military training.
If WDFW was able to determine the habitat characteristics that are most
important when evaluating a potential site for suitability, it would provide a more
accurate assessment of sites and increase the likelihood of success for the
recovery of A. marmorata. This study was conducted as if all habitat
characteristics were equally important, and therefore they were analyzed without
a weighted rank summation. Determining the most important characteristics
could lead to a prediction model that is more accurate than the simple cluster
analysis and rank summation used in this study.
45
5. Conclusion
It was hypothesized that Johnson Marsh and Clay Pit habitats on Fort
Lewis would not be significantly different from that found at Lakewood, and that
Johnson Marsh would be the most suitable of the nine sites for Actinemys
marmorata reintroduction due to its size and ecological complexity. However,
the results of the habitat analysis indicate that the habitat at Spanaway Marsh is,
in fact, the most similar to the Lakewood site, not Johnson Marsh or Clay Pit.
Additionally, Clay Pit is ranked as the most suitable site of the nine Fort Lewis
locations based on desired habitat characteristics for A. marmorata reintroduction.
The difference between the outcomes of the habitat comparison and suitability
ranking may be due to the fact that the habitat comparisons between each of the
nine Fort Lewis sites and the existing Lakewood reintroduction site does not take
into account that the Lakewood site is still undergoing alterations by WDFW to
make it more suitable, and the suitability rankings are based on the optimum
characteristics for each of the eight habitat categories. The Lakewood site still
has further improvements before it can be considered most suitable for A.
marmorata habitat.
If the military were willing to grant exclusive access to WDFW for either
Spanaway Marsh or Clay Pit, on the condition that future population declines
would not result in closure of military training, they would be excellent
candidates for reintroduction sites. However, since the area west of Clay Pit is a
piece of prime training lands, WDFW should consider the already fenced portion
of Clay Pit between North and South Muck Creek for reintroduction, which is not
46
extensive in size and limits the possibility of expansion with increasing
population size. More remote and less used sites such as Spanaway Marsh and
Jolly Lake might make more likely candidates for reintroduction and allow for
expansion and improvement. It is important to note that Nisqually Lake was not
ruled out nor evaluated in this study, and is already a restricted access location
that boasts some of the highest quality upland habitat. It, too, should be
considered as a possible reintroduction site for A. marmorata.
With a dwindling budget and few undeveloped aquatic and grassland
habitats remaining in the Puget Sound, WDFW needs to look at federal lands for
potential sites if they are to meet their recovery goals for A. marmorata. Fort
Lewis holds the largest remaining high quality prairie grassland and oak savannah
habitats and already has experience working with state agencies and the Oregon
and Woodland Park Zoos on recovery efforts of a semi-aquatic species.
Volunteers are already in place to keep bullfrog (Rana catesbeiana) populations
down in order to minimize the threat to native species.
Although the majority of the historic range of A. marmorata is already
developed beyond a point of usefulness for these efforts, there are still sites that
have been relatively undisturbed and, with minimal effort, would be suitable for
reintroduction of the pond turtle and other aquatic wildlife.
47
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53
Figure 1. The historic range of the western pond turtle (Actinemys
marmorata) (Hays et al. 1999).
54
Figure 2. A map of the boundaries of Fort Lewis, Washington and its prairies
and oak habitat.
55
Figure 3. Map of pond turtle reintroduction sites in Washington (Toubman
2001).
56
Figure 4. Map of nine Fort Lewis study sites for potential reintroduction.
57
Figure 5. Dendrogram of the hierarchical cluster analysis of the habitat data.
Bray-Curtis distances between each location and the Lakewood reintroduction site
are included down the left side of the diagram.
58
Lyon_ALMESthesis2011.pdf