Influences of Abiotic and Biotic Habitat Characteristics

Home , Pika

INFLUENCES OF ABIOTIC AND BIOTIC HABITAT CHARACTERISTICS

ON PIKA OCCUPANCY IN SELECT REGIONS OF THE

GALLATIN NATIONAL FOREST, MONTANA

Lindsay Paterson Hall

A professional paper submitted in partial fulfillment of the requirements for the degree

Master of Science

Science Education

MONTANA STATE UNIVERSITY Bozeman, Montana

July 2015

Lindsay Paterson Hall

2015

ACKNOWLEDGEMENTS

First and foremost, I am extremely appreciative of the entire MSSE program and its faculty. The opportunities for science teachers to pursue meaningful scientific research whilst maintaining a full teaching schedule are limited; I am tremendously grateful for the opportunity to deepen my understanding of science education and research through the MSSE program.

Second, I would like to extend sincere gratitude to my project advisor, Dr. John

Winnie Jr. for his endless patience, knowledge, and passion for science. Without his continual insight and mentorship, I would still be up in the talus fields figuring out my initial methodology. I would also like to extend my thanks to Dr. Dave Willey who made meaningful suggestions to improve my writing.

Finally, I would like to extend my endless appreciation to my friends and family who endlessly listened, supported, and facilitated this process. My MSSE classmates served as wonderful sounding boards, editors, and inspiring friends. In particular, Jenny

Edwards spent countless hours helping brainstorm, revise, and trouble shoot, & I am endlessly appreciative of her support. Additionally, my husband Terrill Paterson provided significant data analysis guidance, encouraged me in every step of the process, and kept me well hydrated with Lime-Aide, for which I am eternally grateful.

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TABLE OF CONTENTS

1. INTRODUCTION AND BACKGROUND ...... 1

Objectives ...... 1 Study Area ...... 2

2. CONCEPTUAL FRAMEWORK ...... 5

Diet ...... 5 Feeding and Haying Behaviors ...... 6 Thermoregulation ...... 7 Talus Habitat ...... 8 Territory Marking and Dispersal Patterns...... 9 Extirpation of Pika Populations ...... 10 Hypotheses & Predictions ...... 11 Abiotic Habitat Site Characteristics ...... 12 Biotic Habitat Site Characteristics ...... 15

3. METHODOLOGY ...... 16

Site Selection ...... 16 Abiotic Habitat Site Characteristics ...... 16 Biotic Habitat Characteristics ...... 18 Site Occupancy ...... 20

4. DATA AND ANALYSIS ...... 22 5. RESULTS ...... 23

Abiotic Habitat Site Characteristics ...... 23 Slope, Aspect, and Solar Insolation ...... 23 Elevation ...... 28 Talus Field Area and Mean Boulder Size ...... 31 Distance to Nearest Neighbor ...... 34 Biotic Habitat Site Characteristics ...... 35 Vegetation Characteristics ...... 35

6. INTERPRETATION AND CONCLUSION ...... 38

Implications for Pika Populations ...... 38

TABLE OF CONTENTS (CONTINUED)

7. VALUE ...... 43

Implications for Personal Practice & Teaching Science ...... 43 Implications for Science Education ...... 44

8. REFERENCES CITED ...... 46 9. APPENDICES ...... 51

APPENDIX A: Abiotic Characteristics Transects Data Table ...... 52 APPENDIX B: Vegetation Transects Data Table ...... 54 APPENDIX C: Survey Site Data & Characteristics ...... 56 APPENDIX D: Abiotic Site Characteristics & Pika Occupancy Box and Whisker Plots ...... 58 APPENDIX E: Mean Elevation and Pika Equivalent Elevation ...... 60 APPENDIX F: Average Percentage of Vegetation Category and Pika Occupancy Box and Whisker Plots ...... 62

LIST OF TABLES

1. Study Regions and Corresponding Mean Slope, Aspect, and Solar Insolation ...... 24

2. Mean Percentage of Vegetation By Category in Occupied and Unoccupied Sites ...... 35

3. Abiotic Characteristics Transects Data Table ...... 53

4. Vegetation Transects Data Table ...... 55

5. Survey Site Data and Characteristics ...... 57

6. Mean Elevation and Pika Equivalent Elevation...... 61

LIST OF FIGURES

1. Study Area Overview & Regional Insets...... 4

2. Location of Idealized Boulder Transects Across a Talus Field...... 18

3. Location of Idealized Vegetation Transects Extending Out Fom Talus Field...... 19

4. Ticker Counters to Facilitate Vegetation Categorization Along a 1 m tTansect ...... 20

5. Example of Fresh Pellets ...... 21

6. Haypile Categorized as “Inactive” and Haypile Categorized as “Active.” ...... 21

7. Example of Urine Stain and Pellets Left by Animal Other Than a Pika...... 22

8. Mean Slope (Degrees) and Pika Occupancy...... 25

9. Mean Slope (Degrees) and Pika Occupancy Within Hyalite Canyon...... 26

10. Mean Aspect (Degrees) and Pika Occupancy...... 27

11. Solar Insolation and Pika Occupancy Hyalite Canyon...... 28

12. Mean Elevation (Meters) and Pika Occupancy...... 29

13. Mean Elevation (Meters) and Pika Occupancy Hyalite Canyon...... 30

14. Mean Elevation (Meters) and Pika Occupancy Portal Creek...... 31

15. Mean Area (Meters2) and Pika Occupancy...... 32

16. Mean Boulder Size Across All Site Regions...... 33

17. Mean Boulder Size (Boulders / Meter) and Pika Occupancy in Hyalite Canyon...... 34

18. Distance to Nearest Neighbor (Meters) and Pika Occupancy...... 35

19. Average Coverage (Percentage) of Woody Plants and Pika Occupancy...... 37

20. Average Bare Ground Coverage (Percentage) and Pika Occupancy...... 38

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ABSTRACT

This research project explores how several abiotic and biotic habitat characteristics influence occupancy probabilities of the North American pika, Ochotona princeps within select regions of the Gallatin National Forest. Pikas are possible indicator species for climate change, as they are obligatory talus dwellers found in alpine and subalpine ecosystems, and are extremely sensitive to high temperatures. Slope, aspect, elevation, talus field dimensions, and mean boulder size likely influence how pikas experience ambient temperatures within specific habitat sites and consequently may influence occupancy probabilities. In addition, vegetation diversity and abundance may also influence the likelihood of a talus field being occupied by pikas. I investigated the relationship between abiotic and biotic habitat site characteristics and pika occupancy. I visited three sites within the Gallatin National Forest: Beehive Basin, Portal Creek, and Hyalite Canyon during the summer and fall of 2014. I surveyed 28 talus fields, quantifying a suite of habitat variables and determining pika occupancy of each site. The results of this study indicate that slope, aspect, and elevation were the strongest predictors of pika occupancy, whereas solar insolation, talus field area, mean boulder size, and distance to nearest neighbor were of less importance. Additionally, vegetation type and abundance did not prove statistically significant as a predictor of pika occupancy. Broadly speaking, pika occupancy within the Gallatin National Forest will likely depend on specific combinations of local abiotic and biotic habitat attributes.

INTRODUCTION AND BACKGROUND

Objectives

The North American pika, Ochotona princeps, is a small (120 – 180 g), diurnal, philopatric lagomorph typically found in rocky, mountainous regions throughout western

North America (Smith & Weston, 1990). They are obligatory talus dwellers and are very sensitive to high temperatures, with relatively brief exposure (as few as six hours) in the mid-70s Fahrenheit being fatal (Smith, 1974b). Due to their sensitivity to high temperatures, pikas are viewed by many as early indicators of the effects of climate change on alpine ecosystems. Some research suggests pikas are experiencing extirpations at lower elevations, sites with less annual precipitation, and average temperatures higher than those of extant population sites (Beever, Brussard, & Berger. 2003; Beever, Ray,

Mote, & Wilkening, 2010; Erb, Ray, & Guralnick, 2011; Grayson, 2005; Hafner, 1991;

McDonald & Brown, 1992). Consequently, in 2007, the pika was petitioned under

California State and federal laws to receive designation as an endangered species (Wolf,

Nowicki, & Siegel; 2007a, Wolf, Nowicki, & Siegel, 2007b). Research dedicated to understanding the habitat requirements of the pika can reveal characteristics necessary for site occupancy, persistence, and offer insights into possible management actions to mitigate the effects of climate change.

The purpose of this study was to compare abiotic and biotic characteristics of occupied and unoccupied talus slopes in an attempt to determine which factors determine suitable pika habitat. The objectives of this project were to: 2

1. Assess pika occupancy of talus slopes through absence/presence surveys (i.e.

currently occupied, past occupied, never occupied).

2. Compare the abiotic characteristics between occupied and unoccupied talus slopes

(e.g. slope, aspect, solar insolation, elevation, talus field area, distance to nearest

neighbor, mean boulder size).

3. Compare relative abundance and type of vegetation (e.g. graminoids, forbs,

woody plants, and cushion plants) between occupied and unoccupied talus slopes.

Study Area

I conducted this research project over 11 weeks in summer and fall 2014 and investigated a series of lower and higher elevation pika habitat sites in southwestern Montana. As pikas characteristically live in talus fields in montane ecosystems and use adjacent meadows for foraging (Smith and Weston, 1990), I sought study sites that met this habitat requirement. I divided the study area into three regions: Beehive Basin, Portal Creek, and 3

Hyalite Canyon (

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Figure 1). 4

Bozeman HC8 HC12 HC11 HC9 HC10 HC14

H y a li te HC13 C BB2 re e BB1 k

Beehive Basin Hyalite Reservoir HC5 Hyalite Canyon

Study Area HC7 HC6 k

C e HC4 t i l a Gallatin National y E H a

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Hidden Lakes 0km 12 0km 2 PC1

Figure 1. Study area overview & regional insets.

Beehive Basin is located in the Spanish Peaks area of Lee Metcalf Wilderness and the three survey sites here ranged in elevation from 2403 – 2946 m above sea level

(Beehive Basin inset, Figure 1). Beehive Basin is a tributary watershed within the Middle

Fork of the Gallatin River. Portal Creek is a small tributary that feeds into the Gallatin

River about six miles south of Big Sky along US 191. The 11 survey sites along Portal

Creek ranged in elevation from 1845 to 2804 meters (Portal Creek inset, Figure 1). In

Hyalite Canyon, 14 survey sites ranged from a high elevation of 2810m (near Emerald and Heather Lakes) down to mid-elevation sites of ~ 2100m (near Palisade and Grotto

Falls), to low elevation sites along Hyalite Canyon ranging from 1594 to 1893 meters

(Hyalite Canyon inset, Figure 1). 5

CONCEPTUAL FRAMEWORK

Extensive research suggests that pikas are an indicator species reflecting climate related changes within alpine ecosystems of North America (Beever et al., 2003; Beever et al., 2010; Grayson, 2005; Hafner, 1993; McDonald & Brown, 1992). Pika habitat is typically a mosaic of talus fields and meadows that contain a variety of vegetation options for foraging (Smith and Weston, 1990). These generalist herbivores have two distinct diets: one for immediate consumption (summer diet) and another collected and stored in a haypile that sustains them throughout the winter months (winter diet) (Barash,

1973; Dearing, 1996; Dearing, 1997). Pikas establish and maintain adjacent territories through the use of vocalization, scent marking, droppings, urination, and aggressive behavior (Barash, 1973; Kilham, 1958). These territories are actively defended by pikas through the pursuit of potential intruders to protect boundaries and haypiles (Kawamichi,

1976; Jeffress, Rodhouse, Ray, Wolff, & Epps, 2013).

Diet

Pikas’ foraging behavior is categorized as either feeding (gathering food for immediate consumption in their summer diet) or haying (gathering food for storage for their winter diet) (Barash, 1973). In the summer, pikas consume plants that are high in nitrogen and low in plant secondary compounds, selecting species such as Parry's clover

(Trifolium parryi) leaves, moss campion (Silene acaulis), Ross avens leaves (Geum rossii), American bistort (Bistorta bistortoides) leaves and flower heads, and a variety of graminoids (Dearing, 1996); however, no single species composes more than 50% of their summer diet. Pikas infrequently collect cushion plants because they are hard to 6 harvest due to their morphology and provide relatively low nutritional returns (Dearing,

1997). Pikas preferentially select plants with high levels of toxic secondary compounds, such as phenolics, for storage in their haypiles; these plant toxins may delay plant decomposition (Dearing, 1996). As winter progresses, these toxins break down, increasing food palatability. Dearing (1996) argued that the high concentration of phenolic compounds in G. rossii give the plant superior preservative qualities which in turn cause it to be strongly selected by pikas for their winter diet. In her study area

(Dearing, 1996), G. rossii comprised on average 60 – 77% of the winter diet, far more than expected based on its relative abundance and summer diet. This delayed consumption of a plant high in toxic secondary compounds allowed pikas to broaden their diet without requiring specialized detoxification abilities (Barash, 1973; Dearing,

1996; Dearing, 1997).

Feeding and Haying Behaviors

Pikas typically forage immediately adjacent to their talus habitat, as the risk of predation increases substantially as distance from talus increases. Predators including long-tail weasel (Mustela frenata), red fox (Vulpes vulpes), golden eagle (Aquila chrysaetos), great-horned owl (Bubo virginianus), Northern goshawk (Accipiter atricapillus), and swainson’s hawk (Buteo swainsoni) provide substantial threat to pikas thus the increased risk of foraging far from the refuge of the talus fields restricts their movement. Observations of foraging habits suggest pikas’ efforts decline exponentially with distance to talus and foraging efforts are primarily focused within < 1 – 2 m of the 7 talus edge, with the outer limit of foraging activity rarely exceeding 20 m (Huntly, Smith,

& Ivans, 1986; McIntire, 2005).

Barash (1973) noted that pikas create several haypiles within their territory, the primary function of which is to provide the foundation of the winter diet. Pikas do not exhibit cooperation in the construction of haypiles and are highly territorial, especially toward the end of the summer, suggesting strong intraspecific competition for resources

(Barash, 1973). Both adults and juveniles demonstrate feeding and haying behaviors throughout the day, but as the summer progresses into July and August, haying trips increase significantly (Barash, 1973). Dearing (1997) found that on haying trips, pikas collect an average of 1.18% of their body weight in vegetation, and need to make an average of 13 haying trips on each of the 70 summer days to collect enough vegetation to build large enough haypiles to sustain them throughout the winter. Broadbooks (1972) found that while there is some individual and annual variation in the commencement of the haying season, most pikas across North America have a well-established haypile by the middle of August. The duration of the haying season likely depends on the relative maturity and moisture content of the vegetation. Pikas assess the nutritional value of the plants, probably through sampling, to collect the most nutrient-rich plants available

(Dearing, 1996). As the season progresses, the moisture and protein content of plants declines and pikas cease haying as plant quality decreases below some apparent threshold

(Dearing, 1996; Dearing, 1997; Millar, 1974; Smith 1974a).

Thermoregulation 8

Pikas have thick fur and maintain constant high body temperature, 40.1°C, across a wide variety of daily and seasonal ambient temperatures, allowing them to tolerate very low temperatures (MacArthur, 1972). MacArthur (1972) suggested the observed basal metabolic rate (BMR) in pikas (1.53cc O2/g h) was relatively high for a mammal of similar size and weight, whereas thermal conductance was relatively low. This combination of a high BMR and insulating pelt may have two important and contrasting implications: 1), pikas are able to endure extremely low ambient temperatures without hibernation or torpor to survive winter temperatures (Wang, J., Zhang, & Wang, D.,

2006), and 2), the combination of a high BMR and insulating pelt is disadvantageous in the summer, as pikas experience thermal stress at relatively low summer ambient temperatures (MacArthur, 1972). Thus it is not surprising that when confined in cages in full sun with a moderate ambient temperature (25.5°C), pikas died within six hours, as their mean body temperature of 40.1°C is very close to a lethal temperature (Wang et al.,

2006; MacArthur, 1972; Smith, 1974b). This suggests that high ambient temperatures are stressful to pikas and are subsequently avoided (MacArthur, 1972; Smith 1974b).

Talus Habitat

Pikas require a talus habitat to allow them to freely move about the interstices to evade predators and to behaviorally thermoregulate (Millar & Westfall, 2010; Smith &

Weston, 1990). Typical rock size within talus range from 0.2 – 1.0 m diameter, as these sizes provide critical gaps that allow pikas to escape heat and predators below the surface

(Tyser, 1980). In the summer, subsurface temperatures are frequently several degrees cooler than surface temperatures, while the opposite effect occurs in the winter, providing 9 much needed refuge for the thermally restricted pika (Millar & Westfall, 2010; Tyser,

1980). Additionally, there is some evidence to suggest that this cooler summertime microclimate contributes to vegetation abundance and diversity immediately adjacent to the talus field (Varner, 2014; Millar & Westfall, 2010). Observation of pika movement within the talus fields reveals a decline in mid-day activity, especially on clear days when the ambient temperature and risk of hyperthermia is presumably the highest (Smith,

1974b). Low-altitude pikas are even less active midday due to ambient temperature and internal heat production and thus less likely to travel far from haypiles (Beever et al.,

2003; Jeffress et al., 2013; Smith, 1974b; Tyser, 1980).

Territory Marking and Dispersal Patterns

Each pika maintains a territory ranging from 60 – 410 m2 and establishes boundaries through rubbing cheek secretions on rock slopes, urination, and fecal droppings, especially along perimeter boundaries (Barash, 1973; Kilham, 1958). These scent markings serve as an identification tool to help distinguish both the identity and the sex of resident and neighboring pika (Barash, 1973; Kawamichi, 1976; Svendsen, 1979).

Territories frequently overlap between pikas, which results in repeated encounters between the resident and neighboring pika and subsequent movements to chase out neighbors (Kawamichi, 1976; Kilham, 1958; Svendsen, 1979). Breeding patterns may prompt territorially motivated behavior, such as approaches and chases, which decrease from the height of the breeding period in mid June (Barash, 1973). Young pikas wander freely within their natal territories until weaning (approximately two weeks after emergence), and as they seek new territories, they are frequently chased by adults as they 10 cross territorial boundaries (Barash 1973; Kawamichi 1976; Kilham, 1958; Svendsen,

1979).

Smith (1974a, 1974b) observed dispersal patterns and suggested movement of pikas from one habitat site to another is likely due to population density, specifically the crowding due to additional juveniles (as a local habitat becomes saturated, juvenile density first increases, then decreases). He observed that low-altitude territories are more closely spaced than high-elevation sites, suggesting temperature is a critical environmental factor contributing to the initial success of dispersing juveniles. Smith’s

(1974a, 1974b) results also suggest that while dispersal patterns appear to be random, the percentage of unoccupied islands increases with distance from the primary population source or occupied habitat islands and poorly accessible sites were less saturated than those more accessible. Distances greater than 300 meters, specifically in areas free of talus fields, proved especially challenging for dispersing juveniles; this may have been due to increased predation when pikas traveled away from the protection of talus fields

(Smith, 1974a; 1974b).

Extirpation of Pika Populations

In response to observed regional climate changes (e.g. Beever et al., 2010), southern pika populations have been observed to shift upslope, and several local populations have been extirpated, and others have experienced population declines

(Beever et al., 2010; Erb et al., 2011; Manning, 2011; Rodhouse et al., 2010; Stewart,

2012; Varner, 2014). Several studies indicate that local habitat characteristics such as substrate, topography, and vegetation covariates may have influenced pika demographics, 11 distribution, juvenile dispersal, and, depending on the combination of factors, may have mitigated some potential negative impacts of climatic change (Barash, 1973; Kreuzer &

Huntly, 2003; Millar & Westfall, 2010; Rodhouse et al., 2010; Smith, 1974a; Smith,

1974b).

Beever et al. (2003) proposed that anthropogenic influences including grazing, proximity to roads, and land administration policies likely combine with longer-term factors such as climatic influences and habitat area to contribute to apparent extirpations.

Beever et al. (2003) suggested extirpations most frequently occurred in livestock-grazed areas, sites with small talus habitats, sites with limited talus habitats, or on lands within the Bureau of Land Management’s jurisdiction (i.e., often relatively low in elevation).

His data also suggested extirpated population habitat areas experienced 19.6% less annual precipitation and average temperatures 7.7 – 10.2% higher than those of extant population sites. His work and that of several other studies suggests that warmer temperatures and reduced precipitation seem to contribute to pika population losses as pikas move up-slope in attempt to seek cooler temperatures (Beever et al., 2003; Beever et al., 2010; Grayson, 2005; McDonald & Brown, 1992). Additionally, because snow provides winter insulation, a reduction in precipitation and snowpack due to climatic changes may contribute to local pika extirpations.

Hypotheses & Predictions

Given that climate change appears to negatively affect some pika populations, resulting in upslope migration, dispersal into less suitable habitat, localized extirpations, and population declines (Beever et al., 2010; Erb et al., 2011; Manning, 2011; Rodhouse 12 et al., 2010; Stewart, 2012; Varner, 2014), understanding which habitat characteristics most influence occupancy may inform future management actions, such as habitat alteration, to make local pika populations more resilient in the face of warmer climate.

To better understand how habitat characteristics influence current pika occupancy, I characterized a series of lower and higher elevation pika habitats to determine what, if any, generalizations can be made regarding suitable pika habitat. I examined a variety of abiotic and biotic habitat characteristics to evaluate sources of variation in current-year occupancy.

Abiotic Habitat Site Characteristics

In an effort to understand the relationship between abiotic variables and pika occupancy, I developed series of a priori hypotheses for each variable and then evaluated the strength of evidence between covariates. The predictions (shown below) represent the ecological factors that could influence the precipitation and snowpack covariates that presumably affect pika occupancy.

Slope, Aspect, and Solar Insolation. As obligatory talus inhabitants, pikas rely heavily on the stability of these fields and interstices to build their haypiles, evade predators, and seek refuge from the environment. The angle at which granular material comes to a natural rest is known as the angle of repose; while this angle varies depending on the substrate composition, slopes steeper than >33° exceed the angle of repose, and talus will not stabilize (Angle, 2000; Carson, 1977).

Research suggests pikas avoid movement during the day when ambient temperature is highest. Slope and aspect interact to create a solar insolation index where 13 ambient microclimate conditions are affected by the orientation and steepness of a habitat site. The solar insolation index consequently predicts how pikas experience local weather conditions. Potential summer solar insolation (insol) can be quantified by the equation: insol = sine (mean slope) X cosine (mean aspect), resulting in values ranging from -1 to

1. Steeper, north-facing slopes that receive relatively little solar exposure are represented as larger positive values (1), and steeper, south-facing slopes are represented by larger negative values (-1) (Barash, 1973; Jeffress et al., 2013; Verner, 2014).

Considering the factors of slope, aspect and solar insolation, I made three predictions: the probability of pika occupancy would be lower at sites where the mean slope exceeds the angle of repose (i.e., >33°); pikas would be less likely to occupy talus fields with south-facing aspects; and finally, because slope and aspect interrelate to create the solar insolation index, I also predicted pika occupancy at lower-elevation sites would be positively correlated with the solar insolation index and solar insolation would be of less significance at higher-elevation sites.

Elevation. Several studies have indicated that pika occupancy is limited by temperature, which varies widely across elevation; the effects of elevation are further affected by geographic location: as latitude and elevation increase, temperature decreases

(Hafner, 1993, Jeffress et al., 2013; Rodhouse et al., 2010, Smith 1974a; Smith, 1974b).

The ‘pika-equivalent elevation,’ as determined by Hafner’s (1993) equation E (m)=

14087 – 56.6 (°N) – 82.9 (°W), accounts for these interacting attributes, and predicts the lower elevation limit for pika populations throughout North America after adjusting for latitude and longitude. In this equation, E represents the minimum elevation (in meters) 14 of pika, and °N and °W are the latitudinal and longitudinal positions (in decimal degrees) of a specific site (at 0°N and 0°W, the lower elevation limit would be 14087 meters).

This equation implies that the predicted elevation limit will decrease 56.6 m per 1° degree increase in latitude and decrease 82.9 m per 1° degree increase in longitude. I predicted that the probability of pika occupancy would increase with elevation.

Talus Field Area and Mean Boulder Size. The properties of talus fields, such as overall area, interstices, and depth of rocks, provide essential refuge for pikas in a variety of ways: The matrix of microenvironments within the rocky field permit escape from higher ambient temperatures in the summer, insulation from extreme cold temperatures in the winter, and protection from predators. Additionally, the amount of talus habitat within the range is a strong predictor to pika population persistence, as larger area supports more territories, while smaller isolated patches of talus habitat are more likely to become extirpated (Barash 1973; Beever et al., 2003; Beever et al., 2010; Erb et al, 2011,

Kawamichi, 1976; Millar & Westfall, 2010; Stewart, 2012; Svendsen, 1979). Some research indicates that temperature may be even more of a limiting factor than elevation, so pockets of cooler air in talus provide essential respite from the heat as well as contribute to vegetation abundance and diversity in the surrounding area (Hafner, 1993;

Millar & Westfall, 2010). Pikas frequently occupy talus fields where a majority of the boulders are within a range of 0.20 – 1.0 m (Tyser, 1980; Varner 2013). Therefore, I hypothesized pikas would preferentially occupy sites where the mean boulder size was in the preferred range, especially at lower-elevation sites, and second, the probability of pika occupancy would be higher at larger talus fields. 15

Distance to Nearest Neighbor. Smith (1974b) indicated that while dispersal patterns for juvenile pikas appear to be random, the percentage of unoccupied habitat islands increases with distance from the primary population source or occupied habitat islands. This may be due to increased predation when pikas are dispersing between talus fields without protection. When juveniles disperse, low-altitude pika territories are more closely spaced than those of pikas at high-altitude sites, likely a consequence of high- ambient temperatures that inhibit the dispersing pikas’ movement capabilities (Manning,

2011; Smith 1974a; Smith 1974b). The low mobility and need for talus fields creates a small dispersal range for pikas (Smith 1974a; Smith 1974b). Consequently, I hypothesized occupancy would be negatively associated with distance to nearest neighbor.

Biotic Habitat Site Characteristics

Pika occupancy is also directly linked to available food sources (Dearing, 1996;

Dearing, 1997; Huntly et al., 1986; Jeffress et al., 2013; McIntire, 2005; Wilkening et al.,

2011); consequently, I developed a priori hypotheses for each specific biotic variable, noted below and evaluated the strength of evidence between covariates. These predictions reflect the availability of key food sources that likely influence pika occupancy.

Vegetation Characteristics. While pikas are generalist herbivores and frequently seek out the most nutrient-rich plant matter for immediate consumption, they also select alternatives with different physical, chemical, and nutritive properties to store in haypiles.

Several studies indicated diversity and abundance of vegetation positively correlated with pika occupancy (Dearing 1996; Dearing 1997; Jeffress et al., 2013; Huntly et al., 1986; 16

McIntire, 2005; Wilkening, Ray, Beever, & Brussard, 2011), and there is some evidence to support the idea that forb cover correlated positively and graminoid cover correlated negatively with pika occupancy (Rodhouse et al., 2010). Therefore, I hypothesized pika occurrence probabilities would increase in areas with higher percentage of vegetation coverage due to pikas’ tendency to forage as central place and generalist herbivores.

METHODOLOGY

Site Selection

Potential pika habitats were established initially through analysis of satellite imagery to locate talus slopes within the study areas and then through personal observations in the field. All sampling sites were biased towards roads and trails for practical purposes; however, previous studies (Jeffress et al., 2013; Rodhouse et al.,

2010) provided no evidence that pika occurrence probabilities were biased away from roads and trails. I also established a minimum criterion that sites must contain ≥10% target habitat (talus rock size ranging from 0.20 – 1.00 m) to be surveyed (Tyser, 1980;

Varner, 2013).

Abiotic Habitat Site Characteristics

Upon arrival at each talus field, I utilized a GPS device to record UTM location and elevation, used a compass equipped with inclinometer to document slope and aspect, and recorded observations on the ambient temperature and weather conditions, employed a laser range finder to determine distance to forest edge (DF), calculated talus field area

(TFA), and distance to nearest neighbor (DNN), as determined by the nearest location of a second talus field (Appendix A). During analyses, I used the maptools program in R 17 software (version 3.2.1) to obtain more precise measurements of the TFA (meters2), mean slope (SLP), aspect (ASP), elevation (ELV), and DNN of each site (R Foundation, 2015).

Pikas typically do not forage beyond 20 m from the edge of their home talus field (Huntly et al., 1986; McIntire, 2005). Therefore, I considered a talus field distinct if it was more than twice that distance (40 m) from the closest talus field. I placed transects along a contour line extending into the talus from the edges of the field, with attempts to evenly disperse the three transects within the talus field’s elevation gradient. The highest transect in the site was labeled T1, with medium and lower elevations labeled as T2 and T3

T1: 20 m

T2: 20 m

T3: 20 m

respectively (

Figure 2). 18

T1: 20 m

T2: 20 m

T3: 20 m

Figure 2. Location of idealized boulder transects across a talus field.

I counted every rock that fell directly underneath the 20 m rope and then calculated the ratio of boulders per meter for each transect to establish an index of the relative mean boulder size (MBS) for each site.

Biotic Habitat Characteristics

I quantified vegetation characteristics along five 20 m transects within each talus slope at 1 m, 2 m, 4 m, 8 m, and 16 m out from the edge of the talus field. I placed transects along contour lines extending out laterally from the edges of the talus field, with attempts to place four transects along similar elevation lines on either edge of the talus field and a fifth transect extending off the lowest elevation edge of the talus field, labeled

A – E (Figure 3). 19

D E

B C

1 m vegetation A categorization at 1 m,

2m, 4m, 8m, and

16m from talus edge.

Figure 3. Location of idealized vegetation transects extending out from talus field.

Occasional safety concerns prohibited this exact pattern for transects, so I placed alternative transects as close to the original intended location as possible. I used a 20 m rope, marked in m increments, to set the transect line, and flags at 1 m, 2 m, 4 m, 8 m, and 16 m along the rope indicated sample plot locations. At each sample plot, I utilized a

1 m tape measure, to classify vegetation every 1 cm and utilized individual ticker 20 counters to record abundance within each vegetation category (Figure 4).

Figure 4. Ticker counters (left) to facilitate vegetation categorization along a 1 m transect (right).

I classified vegetation as graminoid (AVGG), forb (AVGF), cushion plant

(AVGC) (including ferns, bryophytes, and lichens), woody plant (AVGW) (including woody debris, trees, or forest litter such as leaves, needles) or bare ground (AVGB)

(including dirt, and rock). I then calculated the percentage of each vegetation category to establish the proportion of vegetation abundance per site (Appendix B).

Site Occupancy

Pika presence was recorded based on visual sightings, presence of calling individuals, fresh feces (i.e., pellets) and active haypiles. A site was considered

“occupied” with the presence of fresh pellets, active haypiles, visual sightings, calling individuals, or a combination of these sources of evidence. A pellet was considered fresh

(<1 year old) if it was dark green or dark brown in color, containing greenish plant 21 material, or if it was cemented to a rock by urine in groups of 2 – 50 pellets (Figure 5).

Figure 5. Example of fresh pellets

A pellet was considered old (>1 year old) if it was gray color, lacking an internal green color, or was scattered. Haypiles were characterized as active or inactive, as determined by the vegetation status within the haypile: green color of plant tissue for active, brownish color for inactive (Figure 6).

Figure 6. Haypile (left) categorized as “inactive” and haypile (right) categorized as “active.”

Pikas leave a distinctive white urine stain along the rocks where they perch

(Broadbanks, 1965). However, urine stains alone are not a definitive indicator of current occupancy, as the white stains left on rocks can persist for years and species such as the 22 bushy-tailed wood rat (Neotoma cinerea) can leave similar urine stains (Figure 7)

(Manning, 2011; Nichols, 2010; Rodhouse et al., 2010).

Figure 7. Example of urine stain and pellets left by animal other than a pika.

A site was considered ‘past-occupied’ if there was evidence of inactive haypiles, old pellets, or urine stains, and “unoccupied” if there was none of these evidence markers. Given the reliance on multiple sources of prominent evidence to determine occupancy, and previous studies’ findings of constantly high detection rates for similar pika evidence sources, I assumed that the accuracy of my site categorization as

“occupied,” “past occupied,” and “never-occupied” was high (90%) (Beever, Wilkening,

McIvor, Weber, & Brussard, 2008; Beever et al., 2010; Erb et al., 2011; Jeffress et al.,

2011; Moyer-Horner & Smith, 2012).

DATA AND ANALYSIS

I surveyed a total of 28 sites, recording habitat characteristics, and occupancy from 11 July to 8 November 2014. I detected pikas at 47% of sites (Appendix C). Survey sites varied broadly within both abiotic and biotic habitat variables. I completed vegetation transects (N=140) on all 28 survey sites to provide data on vegetation categories and abundance. The initial analysis included one-way ANOVA tests on all 23 abiotic habitat and biotic vegetation attributes to assess the correlation between each variable and pika occupancy, as well as factorial ANOVA tests to assess the interactions between occupancy and multiple variables. Combining all three major site areas (Beehive

Basin, Hyalite Canyon, and Portal Creek) tended to mask trends between each variable and occupancy, while separating into drainages revealed insights into factors influencing pika.

RESULTS

Abiotic Habitat Site Characteristics

Some of the variability observed for abiotic habitat attributes is correlated with current-year pika occupancy; other sources of variation demonstrate little statistical significance or biological relevance. Appendix D provides an overview of box and whisker plots for each abiotic variable as it relates to occupancy.

Slope, Aspect, and Solar Insolation

Mean slope ranged from 11.9° to 45.2° across all three survey regions, with a mean value of 30.50° for all sites, 23.64° for occupied sites, and 35.34° for unoccupied sites (Table 1).

Table 1 Study Regions and Corresponding Mean Slope, Aspect, and Solar Insolation Circular Mean Mean Solar Site Area Mean Slope Aspect Insolation All Study Areas 30.50° 171.83° -0.07 Occupied 27.30° 201.36° 0.08 Unoccupied 26.76° 146.10° -0.18 Beehive Basin 29.79° 220.03° -0.30 Occupied 28.51° 245.08° -0.19 Unoccupied 32.36° 169.92° -0.51 Portal Creek 33.03° 139.40° -0.05 Occupied 32.48° 157.00° -0.10 Unoccupied 33.23° 132.80° -0.04 Hyalite Canyon 28.66° 186.84° -0.04 Occupied 23.64° 207.07° 0.01 Unoccupied 35.34° 159.87° -0.10

As predicted, pikas were less likely to occupy sites with a steeper slope angle

(p=0.00175), and the data suggest there is an upper-limit to slope angle and pika occupancy: pikas did not occupy sites where the mean slope exceeded 32° (Figure 8). 25

F(1, 26)=12.170, p=.00175 Vertical bars denote 0.95 confidence intervals 40

MeanSlope 28

20 no yes Occupied

Figure 8. Mean slope (degrees) and pika occupancy.

These values are in line with the predicted maximum angle of repose for this substrate type, which suggests that talus will not stabilize on slopes exceeding 33 – 37°

(Angle, 2000; Carson, 1977). This finding is likely more a function of slope exceeding the angle of repose than it is pikas preferentially avoiding steeper slopes: without a stable talus field to establish a territory, pika occupancy is likely limited. Analysis by drainage reveals pika occupancy is strongly correlated with slope in Hyalite Canyon (p=0.005)

(Figure 9). 26

Hyalite Canyon F(1, 12)=11.248, p=.00574 Vertical bars denote 0.95 confidence intervals 45

n 30

M 25

15 no yes Occupied

Figure 9. Mean slope (degrees) and pika occupancy within Hyalite Canyon. Across the three major study areas, mean aspect ranged from 1.1° (north) to

307.4° (northwest), with circular mean values of 171.83° (south), 201.36° (south- southwest, occupied), and 146.1° (south-southeast, unoccupied). There is compelling evidence to suggest pikas are more likely to occupy southern facing talus fields than northern facing fields (p=0.05) (Figure 10). 27

F(1, 24)=4.3921, p=.04683 Vertical bars denote 0.95 confidence intervals 300 280 260 240

l 220

r i 200

e 180

A 160

a e 140

M 120 100 80 60 no yes Occupied

Figure 10. Mean aspect (degrees) and pika occupancy.

Mean solar insolation also showed considerable variation, ranging from -0.61

(steeper and south facing) to 0.61 (steeper and more north facing). The data provided here do not suggest solar insolation is a significant variable to predict pika occupancy (Figure

11). 28

F(2, 22)=.30568, p=.73970 Vertical bars denote 0.95 confidence intervals 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8 MeanSolarInsolation -1.0 Site Beehive Basin -1.2 Site Hyalite Canyon -1.4 Site Portal Creek -1.6 no yes Occupied

Figure 11. Solar insolation and pika occupancy. Steeper, north-facing slopes are represented as larger positive values (1), and steeper, south-facing slopes are represented by larger negative values (-1).

Elevation

I established pika occupancy in sites ranging in elevation from 1773.7 to 2948.4 m (mean = 2135.3 m), and the elevation of talus fields in which I identified as unoccupied ranged from 1740.5 to 2901.0 m (mean = 2124.8 m). All occupied and unoccupied sites were within the range of expected values from Hafner’s (1993) ‘pika- equivalent elevation’ (Appendix E). The minimum ‘pika equivalent elevation’ for this study area is 2271 m and the maximum is 2758 m. Elevation was a strong predictor of pika occupancy across the three surveyed regions (Figure 12). As predicted, pika occupancy in this study area was positively correlated with elevation (p=0.022), which 29 supports the findings of several studies (Hafner, 1993, Jeffress et al., 2013; Rodhouse et al., 2010, Smith 1974a; Smith, 1974b).

F(1, 26)=11.501, p=.00223 Vertical bars denote 0.95 confidence intervals 2700 2600 2500 2400 2300 2200 2100

MeanElev 2000 1900 1800 1700 1600 no yes Occupied

Figure 12. Mean elevation (meters) and pika occupancy.

Occupancy, particularly within Hyalite Canyon and Portal Creek (Figure 13, Figure 14) was significantly and positively correlated with elevation (p=0.005, p=0.04 respectively).

It is worth noting that within Beehive Basin, the sample size was very small (N=3), so the 30 lack of data likely contributes to the inconclusive evidence within that drainage.

Hyalite Canyon F(1, 12)=11.275, p=.00570 Vertical bars denote 0.95 confidence intervals 2600 2500 2400 2300 2200

v 2100

n 2000

M 1900 1800 1700 1600 1500 1400 no yes Occupied

Figure 13. Mean elevation (meters) and pika occupancy Hyalite Canyon. 31

Portal Creek F(1, 9)=5.8162, p=.03914 Vertical bars denote 0.95 confidence intervals 2700 2600 2500 2400 2300

e l 2200

e 2100

M 2000 1900 1800 1700 1600 no yes Occupied

Figure 14. Mean elevation (meters) and pika occupancy Portal Creek. Talus Field Area and Mean Boulder Size

As predicted, there is evidence suggesting a positive correlation with talus field area and pika occupancy (p=0.19), which supports the findings of several studies (Figure

15) (Barash, 1973; Beever et al., 2003; Beever et al., 2010; Kawamichi, 1976; Stewart,

2012; Svendsen, 1979). Metapopulation theory suggests that smaller, isolated patches of habitat are most likely to become extirpated, as a larger area is needed to support 32 successful breeding for several generations (Hanski, 1999).

F(1, 26)=1.7708, p=.19484 Vertical bars denote 0.95 confidence intervals 7E5 6E5 5E5 4E5 3E5 2E5

Area 1E5 0 -1E5 -2E5 -3E5 -4E5 no yes Occupied

Figure 15. Mean area (kilometers2) and pika occupancy.

There was no significant difference between occupied and unoccupied sites in regards to mean boulder size, and all values were within the expected range of 0.2 m –

1.0 m (Figure 16). 33

0.35 0.32 0.29 0.29 0.30 0.26 0.26 0.24 0.25 0.24 0.25 0.20 0.19 0.20 0.19 Mean 0.20 0.15 Occupied 0.10 Unoccupied

0.05 Mean Boulder (m) SizeMean Boulder 0.00

Site Location & Occupied vs. Unoccupied

Figure 16. Mean boulder size across all site regions, Hyalite Canyon (HC), Portal Creek (PC), and Beehive Basin (BB) color-coded by mean, occupied, and unoccupied.

Analysis of individual drainages reveals, as predicted, pikas preferentially occupied sites where the mean boulder size was in their preferred range of 0.20 – 1.0 m.

Within Hyalite Canyon, mean boulder size was a strong predictor of pika occupancy

(p=0.026) (Figure 17). 34

Hyalite Canyon F(1, 12)=6.3684, p=.02673 Vertical bars denote 0.95 confidence intervals 7.5 7.0 6.5 6.0 5.5

. r 5.0

r 4.5

d l 4.0

B 3.5 3.0 2.5 2.0 1.5 no yes Occupied

Figure 17. Mean boulder size (boulders / meter) and pika occupancy in Hyalite Canyon. Distance to Nearest Neighbor

There is little support for the original prediction that occupancy would be negatively associated with distance to nearest neighbor (Figure 18). This result is in opposition to the frequently cited need for limited distance between available talus habitat

(Smith, 1974a, 1974b). However, more recent work by Peacock (1997) suggests pikas may be capable of traveling farther than previously thought. 35

F(2, 22)=.08799, p=.91609 Vertical bars denote 0.95 confidence intervals 1.4 Site Beehive Basin 1.2 Site Hyalite Canyon 1.0 Site Portal Creek 0.8 0.6 0.4 0.2 0.0

NearestNeighbor -0.2 -0.4 -0.6 -0.8 no yes Occupied

Figure 18. Distance to nearest neighbor (kilometers) and pika occupancy.

Biotic Habitat Site Characteristics

Vegetation Characteristics

Vegetation categorization of abundance did not reveal any significant difference between occupied versus unoccupied sites (Appendix F). Overall, occupancy was not strongly correlated with percent cover of any vegetation type, but there were some general trends (Table 2).

Table 2 Mean Percentage of Vegetation By Category in Occupied and Unoccupied Sites Vegetation Occupied Unoccupied Difference Category Graminoid 28.3% 24.4% 3.9% Forb 20.2% 17.6% 2.7% Cushion Plan 3.2% 3.6% -0.4% Woody Plant 11.5% 11.0% -0.5% Bare Ground 37.2% 42.9% -5.6%

The occupied sites had 3.9% more graminoid coverage, 2.7% more forb coverage,

0.4% less cushion plant coverage, 0.5% more woody plant coverage, and 5.6% less bare ground than unoccupied sites. This corroborates the evidence of many studies (Dearing,

1996; Dearing, 1997; Huntly et al., 1986; Jeffress et al., 2013; McIntire, 2005; Wilkening et al., 2011) that indicate that species diversity and abundance in vegetation positively correlates to pika occupancy; however there is no biological relevance to any of these differences. Of the specific vegetation categories, there is compelling evidence to suggest that a higher percentage of woody plants is positively correlated with pika occupancy

(Figure 19). 37

F(1, 26)=3.5234, p=.07177 Vertical bars denote 0.95 confidence intervals 30

AVG.Woody.Plant 5

-5 no yes Occupied

Figure 19. Average coverage (percentage) of woody plants and pika occupancy.

I used percentage of bare ground to establish vegetation abundance, which did not prove statistically significant (p = 0.42) within any of the drainages (Figure 20). 38

F(2, 22)=.90815, p=.41786 Vertical bars denote 0.95 confidence intervals 100

AVG.Bare.Ground

-20 Site Beehive Basin Site Hyalite Canyon -40 Site Portal Creek

-60 no yes Occupied

Figure 20. Average bare ground coverage (percentage) and pika occupancy.

INTERPRETATION AND CONCLUSION

Implications for Pika Populations

The results of this study suggest North American pika occupancy probabilities within the Gallatin National Forest likely depend on specific combinations of local abiotic and biotic habitat attributes. Overall, habitat characteristics that have been identified as important by other authors (e.g. talus rock size and elevation), proved significant in this study. That other variables did not show significant correlations with occupancy does not necessarily mean that they are unimportant. Rather it could mean the 39 range of these variables within my study area was entirely within that tolerated or preferred by pikas.

Elevation was a strong predictor of occupancy, suggesting that regardless of substantial increases in ambient temperature, occurrence probabilities will likely remain unchanged at higher elevation sites, a finding consistent to that of other research (Jeffress et al., 2013; Rodhouse et al., 2010, Smith 1974a; Smith, 1974b). Interestingly, Hafner

(1994) argued that temperature was an even stronger predictor of occupancy and reasoned that pikas have historically survived warmer temperatures by seeking refuge in areas where alpine permafrost could persist. Lower elevation sites, where presumably warmer temperatures might appear earlier, would feel the impact of this change sooner than higher elevation sites. In the face of climatic changes, potential temperature increases will likely affect precipitation and subsequent snowpack. Areas that experience a reduction in snowpack may in turn experience extirpations since snow insulates the talus fields from extreme winter temperatures (Beever et al., 2003; Hafner, 1994; Millar

& Westfall, 2010; Wilkening et al., 2011).

Pikas are philopatric and only 25% of juveniles may seek new territories (Smith,

1987); consequently, talus field area and distance to nearest neighbor are important factors in population persistence. A larger talus field area will support a higher population density, as young pikas seeking new territories will encounter territorial adults who chase them off (Barash, 1973). Larger talus fields allow these juvenile pikas to find suitable territories within the talus field and are critical to their long-term reproductive success.

The work here suggests a positive correlation with talus field area and pika occupancy, 40 consistent with the work of several others (Barash, 1973; Beever et al., 2003; Beever et al., 2010; Kawamichi, 1976; Stewart, 2012; Svendsen, 1979). Beever et al. (2003) suggested pika populations experience extirpations consistent with the minimum-area hypothesis, or that only populations found in talus fields larger than a minimum threshold will survive. In this study area, nearly all high elevation sites were occupied, regardless of area, suggesting that elevation is a stronger predictor of occupancy than talus field area.

Given their obligatory association with isolated talus patches, successful dispersal across forested regions is limited (Smith, 1974a, 1974b). Frequently, this dispersal capability is listed as a limiting factor in pikas’ distribution patterns, implying that pikas will preferentially occupy talus fields that are closer to a suitable alternative field (Smith,

1974a, 1974b). The data provided in this study do not suggest a correlation between distance to nearest neighbor and pika occupancy, a result consistent with others (Beever et al., 2003; Peacock, 1997). Beever et al. (2003) investigated the maximum-isolation hypothesis and found that populations closest to the source population were not significantly more likely to survive than those more distal. His work suggests the amount of talus habitat within the range as a strong predictor to population persistence. Peacock

(1997) documented gene flow in pikas at distances up to 2 km, implying that pikas were traveling several times the previously documented distance of 300 m across forested regions. However, there is relatively little research dedicated specifically to dispersal patterns and long-distance capabilities. Further work should be conducted to effectively study pikas’ dispersal patterns and capability. 41

The results provided here indicate that in specific areas, pikas preferentially occupy sites where the mean boulder size ranged from 0.2 – 1.0 m rock diameter. This finding is unsurprising, as the network of rocks allows pikas to retreat from predation and thermal stress (Millar & Westfall, 2010; Smith & Weston, 1990; Tyser, 1980). These interstices may become increasingly important if climatic changes increase ambient temperatures or reduce precipitation within this region.

Climatic changes may also affect vegetation characteristics and thus impact occupancy probabilities. Warmer summer temperatures may alter the abundance and type of available vegetation, and an overall reduction of forage may cause subsequent extirpations (Hafner, 1994). However, Beever et al. (2008) documented pikas within his study area that collected Cheatgrass (Bromus tectorum), an introduced graminoid species not previously documented in haypiles, suggesting pikas are capable of adopting a more flexible diet. The results of this study indicate that occupancy was not correlated with percent cover of any vegetation type. While the results presented here are not statistically significant, they are in line with that of others (Dearing, 1996; Dearing, 1997; Huntly et al., 1986; Jeffress et al., 2013; McIntire, 2005; Wilkening et al., 2011).

Additionally, the ways in which pikas experience local ambient temperatures, through slope, aspect, and solar insolation are important occupancy predictive variables worth consideration. While solar insolation did not prove statistically significant within this study, aspect was positively correlated with pika occupancy, and pikas preferentially selected talus fields with a southern aspect. Southern facing talus fields, while presumably hotter due to longer sun exposure, may also experience a longer growing 42 season with more abundant vegetation and thus supporting higher occupancy probabilities (Wilkening et al., 2011). Higher ambient temperatures within these sites may support quantity and quality of forage available (Huntly et al., 1986; Dearing, 1997,

Kruezer & Huntly, 2003), especially forbs and woody plants that contain toxic chemicals that prohibit immediate consumption but delay haypile decomposition (Dearing 1996,

Dearing, 1997) and thus improve over-winter survival. Results of this study indicate compelling evidence to suggest that a higher percentage of woody plants is positively correlated with pika occupancy.

Recent studies suggest the habitat requirements of pikas are likely more complex than previously understood, as pikas have been discovered in what had been earlier considered atypical habitat (Beever et al., 2003; Beever et al., 2008; Manning, 2011).

Beever et al. (2008), documented pikas in the northwestern portion of the Great Basin region at sites with higher ambient temperatures than all other sites (extant and extirpated) within the region. On the western slope of the Cascade Range in Oregon,

Manning (2011) observed pikas establishing new territories in low-elevation, non-alpine, man-made talus fields. These imperfect sites reflect the adaptability of pikas as they begin to seek out alternative habitat sites. In conclusion, the results of this study suggest that pika populations within the studied area in the Gallatin National Forest can persist in a wide range of habitats and will likely continue to exist at higher elevations. Lower elevation sites may experience climatic changes more acutely and would be more likely to experience extirpations sooner. Data such as these are important as baseline surveys 43 that can be used to inform management decisions and interpretation of pika population status within this region.

VALUE

Implications for Personal Practice & Teaching Science

I feel incredibly fortunate to have had the opportunity to do this research project and deepen my understanding of the scientific method. This project has increased my commitment to science education, especially in regards to asking testable questions. One of the most challenging and rewarding aspects of this project was the process of constructing meaningful questions that would be relatively simple to investigate and answer. Many of my students struggle with this fundamental skill, and often attempt to design experiments that are too complex or have too many covariates to meaningfully assess.

Once I worked through the experimental design and began trouble-shooting the methodology issues in the field, most of the data collection was fairly simple and straightforward, and would be easy for my 7th grade students to replicate. My school’s current science standards include a series of standards that directly correspond to this topic; while some of my data analysis is beyond the scope of middle school students, the data collection is most certainly within their ability and developmentally appropriate. For example, a series of dichotomous keys to help students categorize vegetation type would be a reasonable activity, and students could easily count the type of plants found within a one meter transect or complete abiotic habitat surveys. Re-working my current curriculum on abiotic and biotic habitat characteristics to include certain aspects of this 44 study would be an excellent way to incorporate real data sets, authentic scientific exploration, and hands-on field work. Students love the opportunity to actively engage with science on field trips, and all of my sites are within bussing distance from our school.

Another aspect of this project that will certainly improve my teaching practice is the tenacity and passion for science I have developed over the last year. All of the scientists who supported me in this project face their own research with seemingly endless determination, dedication, and attention to detail. At times of frustration or loss of enthusiasm, I found myself wondering how an academic scientist would work through a problem, answer a question, or circumvent an obstacle. Moreover, I found myself inspired by their scientific curiosity in their attempts to understand the implications of the data collected. Working through seemingly simple problems often proved to be very complicated, and I learned an incredible amount from the scientists with whom I worked just by listening to their thought processes. I am confident that my students can benefit from this experience – I find myself more confident in my depth of knowledge, experimental design skills, and ecological principles.

Implications for Science Education

As our state moves forward to adopting the Next Generation Science Standards in the next several years, I am gravitating towards creating meaningful learning opportunities for scientific inquiry that challenge students to utilize quantitative and observational skills to make inferences about the world around them. Engaging in actual scientific data collection and analysis allows students to test their own hypotheses in a 45 manner that extends beyond the walls of the classroom, a standardized test, or artificial performance task. One of the core disciplines of the Next Generation Science Standards is the nature of interdependent relationships in ecosystems; research projects such as this might empower students to connect their learning to empirical evidence, evaluate solutions, and consider possible consequences of their actions within our local and global ecosystems.

This project has helped me grow personally and professionally and I am empowered to share this the process of research project with other teachers within my school district. It is rare in the current higher educational system for science teachers to actively engage in scientific research projects that have potential implications beyond the scope of their classroom. Regardless of the subject matter at teacher chooses to pursue, I believe it is critical that we each take opportunities to actively engage in the scientific community. If educators and administrators truly want our students to become the innovators and scientific leaders of the future, it is imperative that science teachers take as many opportunities to deepen their own content knowledge, keep abreast of current scientific literature and research within their field, and challenge themselves to improve their own experimental design skills. While there were certainly moments of personal frustration, confusion, and even defeat throughout this process, I am excited to share this process with other educators.

REFERENCES CITED

Angle of Repose. (2000). In D. Thomas et al. (Eds.), The dictionary of physical geography. Oxford, United Kingdom: Blackwell Publishers. Retrieved from http://proxybz.lib.montana.edu/login?qurl=http%3A%2F%2Fsearch.credoreferenc e.com.proxybz.lib.montana.edu%2Fcontent%2Fentry%2Fbkphsgeo%2Fangle_of _repose%2F0. Barash, D. (1973). Territorial and Foraging Behavior of Pika (Ochotona princeps) in Montana. American Midland Naturalist: January 1973, 89(1), 202 – 207. Beever, E. A., Brussard, P. F., & Berger, J. (2003). Patterns of Apparent Extirpation among Isolated Populations of Pikas (Ochotona princeps) in the Great Basin. Journal of Mammology 2003, 84(1), 37 – 54. Beever, E. A., Ray, C., Mote, P. W., & Wilkening, J. L. (2010). Testing Alternative Models of Climate-Mediated Extirpations. Ecological Applications 2010, 20(1), 164 – 178. Beever, E. A., Wilkening, J. L., McIvor, D. E., Weber, S. S., & Brussard, P. F. (2008). American Pikas (Ochotona princeps) in northwestern Nevada: A newly discovered population at a low-elevation site. Western North American Naturalist, 68, (1) 8 – 14. Broadbanks, H.E. (1965). Ecology and Distribution of the Pikas of Washington and Alaska. American Midland Naturalist: April 1965, 73(2), 299 – 335. Bruggeman, J.E. (2010). Pilot Study on Factors Affecting Pika Populations in the North Cascades Ecosystem. (Report). Beartooth Wildlife Research, LLC. February 2010. Carson, M. A. (1977), Angles of repose, angles of shearing resistance and angles of talus slopes. Earth Surface Process, 2: 363 – 380. Dearing, M. D. (1996). Disparate Determinants of Summer & Winter Diet Selection of a Generalist Herbivore (Ochotona princeps). Oecologia, 108 (3), 467 – 478. Dearing, M. D. (1997). The Function of Haypiles of Pikas (Ochotona princeps). Journal of Mammology, 78 (4), 1156 – 1163. Erb, L. P., Ray, C., & Guralnick, R. (2011). On the generality of a climate-mediated shift in the distribution of the American pika (Ochotona princeps). Ecology, 92 (9), 1730 – 1735. Grayson, D. K. (2005). A brief history of Great Basin pikas. Journal of Biogeography, 32, 210 3 – 2111. Hafner, D. J (1993). North American pika (Ochotona princeps) as a late Quaternary biogeographic indicator species. Quaternary Research, 39, 373 – 380. 48

Hanski, I. (1999). Metapopulation Ecology. New York: Oxford University Press. Huntly, N.J., Smith, A.T., & Ivans, B. L. (1986). Foraging Behavior of the Pika (Ochotona princeps), with Comparisons of Grazing versus Haying. Journal of Mammalogy, 67(1), 139 – 148. Huntly, N.J. (1987). Influence of Refuging Consumers (Pikas: Ochotona princeps) on Subalpine Meadow Vegetation. Ecologyy, 68(2), 274 – 283. Jeffress, M.R, Rodhouse T. J., Ray, C., Wolff, C. & Epps, C.W. (2013). The Idiosyncrasies of Place: Geographic Variation in the Climate–Distribution Relationships of the American pika. Ecological Applications 23:864 – 878. Kawamichi, T. (1976). Hay Territory & Dominance Rank of Pikas (Ochotona princeps). Journal of Mammology: February 1976, 57(1), 133 – 148. Kilham, L. (1958). Territorial Behavior in Pikas. Journal of Mammalogy, 39 (2), 307. Kreuzer, M. P., & Huntly, N. J. (2003). Habitat-Specific Demography: Evidence for Source-Sink Population Structure in a Mammal, the Pika. Oecologia, 134 (3). 343 – 349. McDonald, K. H. & Brown, J. H. (1992). Using Montane Mammals to Model Extinctions Due to Global Change. Conservation Biology, 6(3), 409 – 415. MacArthur, R. A. & Wang, L. C. H. (1972). Physiology of thermoregulation in the Pika, Ochotona princeps. Canadian Journal of Zoology, 51, 11 – 16. Manning, T. & Hagar, J. C. (2011). Use of Nonalpine Anthropogenic Habitats by American Pikas (Ochotona princeps) in Western Oregon. Western North American Naturalist 2011, 71(1), 106 – 112. McIntire. D. H., B.J.E. (2005). Influences of Chronic and Current Season Grazing by Collared Pikas on Above-Ground Biomass and Species Richness in Subarctic Alpine Meadows. Oecologia, 145(2), 288 – 297, Millar, J. S. (1972). Timing of breeding of pikas in southwestern Alberta. Canadian Journal of Zoology, 50, 665 – 669. Millar, J. S. (1974). Success of Reproduction in Pikas, Ochotona princeps. Journal of Mammalogy, August 1974, 55(3), 527 – 542. Millar, C. I., & Westfall, R. D. (2010). Distribution and Climatic Relationships of the American Pika (Ochotona princeps) in the Sierra Nevada and Western Great Basin, U.S.A.; Periglacial Landforms as Refugia in Warming Climates. Arctic, Antarctic, and Alpine Research, February, 42(1), 76 – 88. 49

Moyer-Horner, L., & Smith, M. M. (2012). Citizen Science and Observer Variability During American Pika Surveys. The Journal of Wildlife Management, 76 (7). 1472 – 1479. Nichols, L.B. (2010). Fecal Pellets of American Pikas (Ochotona princeps) provide a crude chronometer for dating patch occupancy. Western North American Naturalist, 70 (4), 500 – 507. Peacock, M. M (1997). Determining natal dispersal patterns in a population of North American pikas (Ochotona princeps) using direct mark-resight and indirect genetic methods. Behavioral Ecology, 8(3), 340 – 550. R Foundation (2015). R. A Language and Environment for Statistical Computing and Graphics. Retrieved from http://www.R-project.org/. Rodhouse, T. J., Beever, E.A., Garrett, L.K., Irvine, K.M., Mackenzie, R. Jeffress, M.M. Ray, C. (2010). Distribution of American pikas in a Low-elevation Lava Landscape: Conservation implications from the range periphery. Journal of Mammalogy, October 2010, 91(5), 1287 – 1299. Smith, A. (1974). The Distribution and Dispersal of Pikas: Consequences of Insular Population Structure. Ecology: Summer 1974, 55(5), 1112 – 1119. Smith, A. (1974). The Distribution and Dispersal of Pikas: Influence of Behavior and Climate. Ecology: November 1974, 55(6), 1368 – 1376. Smith A. (1987). Population Structure of Pikas: Dispersal versus Philopatry. In Chepko- Sade B. D., Halpin Z. T. (Eds.), Mammalian Dispersal Patterns: The Effects of Social Structure on Population Genetics (Chepko-Sade B. D., Halpin Z. T., eds.) (pp. 128 – 142). University of Chicago Press, Chicago, Illinois. Smith, A. & Weston, M. (1990). Ochotona princeps. The American Society of Mammalogists, 352, 1 – 8. Stewart, J. A. E, & Wright, D. E. (2012). Assessing persistence of the American pika at historic localities in California's Northern Sierra Nevada. Wildlife Society Bulletin, 26 (4). 759 – 764. Svendsen, G. E. (1979). Territoriality and Behavior in a Population of Pikas (Ochotona princeps). Journal of Mammology: May 1979, 60(2), 324 – 330. Tyser, R. W. (1980). Use of Substrate for Surveillance Behaviors in a Community of Talus Slope Mammals. American Midland Naturalist: 104, 32 – 38. Varner, J., & Dearing, M. D. (2014). The Importance of Biologically Relevant Microclimates in Habitat Suitability Assessments. PLoS ONE, 9(8), e104648. doi:10.1371/journal.pone.0104648 50

Wang, J. Zhang, Y., & Wang, D. (2006). Seasonal Thermogenesis and Body Mass Regulation in Plateau Pikas (Ochotona curzoniae). Oecologia 149 (3), 373 – 382. Wilkening, J.L, Ray, C., Beever, E., & Brussard, P. (2011). Modeling contemporary range retraction in Great Basin pikas (Ochotona princeps) using data on microclimate and microhabitat. Quaternary International: 235, 77 – 88. Wolf, S., Nowicki, B., & Siegel, K. (2007). Petition to List the American Pika (Ochotona princeps) as Threatened under the California Endangered Species Act. San Francisco: Center for Biological Diversity publication. Wolf, S., Nowicki, B., and Siegel, K. (2007). Petition to List the American Pika (Ochotona princeps) as Threatened under the United States Endangered Species Act. San Francisco: Center for Biological Diversity publication.

APPENDICES

APPENDIX A

TABLE 3: ABIOTIC CHARACTERISTICS TRANSECTS DATA TABLE 53

Table 3 Abiotic Characteristics Transects Data Table Distance Distance to Weather Type of to Near Talus Talus Forest temp, Evidence: Neighbor UTM UTM Elev Past Field Field 0, 1- Site Date Time Slope Aspect wind, Occupied V, S, US, 0, 1-30m, T1 T2 T3 E N (m) occupied Dim. Dim. 30m, 31- cloud P, HP, 31-100m, Length Width 100m, cover All 101-300, 101-300, >300 >300

Note. V = Visual sighting, S = Sound, US = Urine stains, P = Pellets, HP = haypile. T1 = lowest boulder transect, T2 = mid- range boulder transect, T3 = highest boulder transect. (N=28 sites). 54

APPENDIX B

Table 4: VEGETATION TRANSECTS DATA TABLE 55

Table 4 Vegetation Transects Data Table

Site Trans VG1 VF1 VC1 VW1 BG1 SUM VG2 VF2 VC2 VW2 BG2 SUM VG4 VF4 VC4 VW4 BG4 SUM VG8 VF8 VC8 VW8 BG8 SUM VG16 VF16 VC16 VW16 BG16 SUM VA VB VC VD VE VA VB VC VD VE VA VB VC VD

VE Note. VA = Vegetation Transect A, VB = Vegetation Transect B, VC = Vegetation Transect C, VD = Vegetation Transect D, VE = Vegetation Transect E. VG = Graminoid, VF = Forb, VC = Cushion Plants, VW = Woody Plants, BG = Bare Ground. Each number (1, 2, 4, 8, 16) represents meters distal from the talus field edge. Sum category was utilized to ensure accuracy of totals per 1 meter transect. (N=140 transects over the 28 sites). 56

APPENDIX C

TABLE 5: SURVEY SITE DATA & CHARACTERISTICS 57

Table 5 Survey Site Data and Characteristics Mean Mean ASP Mean SLP Mean MBS Site ID ELE (m) (deg.) (deg.) SLI TFA (m2) UTM (E) UTM (N) Occupied (m) AVGG AVGF AVGC AVGW AVGB BB1 2901.0 170.0 32.4 -0.5 33600.3 469746 5018614 No 0.2 1.2 19.8 30 24.2 24.8 BB2 2948.4 238.8 30.1 -0.2 50175.0 468892 5021546 Yes 0.2 22.6 5.6 1.2 13.8 56.8 BB3 2581.2 251.3 26.9 -0.1 1120.5 468778 5021700 Yes 0.2 70.4 2.2 0 0 27.4 HC1 2860.7 108.6 29.9 -0.2 475072.7 504835 5028760 Yes 0.4 24.2 63.2 0 1.8 10.8 HC10 1745.3 50.4 29.2 0.3 1190.3 495296 5044315 No 0.2 22.4 8.8 6.8 0 62.0 HC11 1788.2 253.8 34.1 -0.2 16071.4 496446 5043695 No 0.2 62.0 31.2 0.4 0 6.4 HC12 1740.5 245.5 28.0 -0.2 2678.2 495355 5044368 No 0.2 59.6 20.6 0 5.8 14.0 HC13 1773.7 112.4 25.3 -0.2 2603.9 495240 5044275 Yes 0.2 31.76 16.92 5.8 3.4 42.12 HC14 1843.2 1.1 37.8 0.6 1860.3 497846 5043183 No 0.2 9.6 7.8 8.6 8.2 65.8 HC2 2765.6 307.4 25.8 0.3 2774509.4 506105 5028718 Yes 0.3 0.6 7.6 2.8 52.2 36.8 HC3 2182.0 286.4 11.9 0.1 10436.9 502893 5031418 Yes 0.4 11.4 15.8 5.0 7.4 60.4 HC4 2187.1 298.6 28.0 0.2 17890.9 502879 5031422 Yes 0.3 7.4 10.2 0 15.4 67.0 HC5 2175.4 221.9 24.3 -0.3 8195.6 505143 5035137 Yes 0.2 19.24 23.04 0.2 3 54.52 HC6 2134.7 245.6 15.3 -0.1 6259.3 505441 5034465 Yes 0.2 2.0 0.6 0.6 52.8 44.0 HC7 2177.2 63.8 28.7 0.2 11922.3 504969 503446 Yes 0.3 58.6 12.6 4.8 0 24.0 HC8 1745.6 204.1 37.7 -0.6 8852.9 495286 5044444 No 0.3 7 1.6 2.8 0 88.6 HC9 1845.7 204.4 45.2 -0.6 4836.6 497862 5043251 No 0.1 36.4 32.6 7.6 0 23.4 PC1 2789.8 161.4 26.9 0.4 158309.8 486655 5012306 Yes 0.1 26.6 25.0 9.6 30.8 8.0 PC10 1850.9 69.6 33.0 0.2 5379.6 485799 5017469 No 0.4 31.8 22.8 1.2 8.8 35.4 PC11 1865.8 262.4 35.0 -0.1 7770.4 485895 5017554 No 0.3 47.4 44.6 2.6 0 5.4 PC2 1949.5 209.4 40.6 -0.6 14944.5 486471 5016906 No 0.2 32.0 52.0 0 0 16.0 PC3 1898.2 252.1 35.4 -0.2 6276.4 486013 5017191 Yes 0.3 30.56 20.92 8.16 13.8 26.6 PC4 2129.0 206.2 35.2 -0.5 17261.2 487621 5016770 Yes 0.2 9.12 19.48 1.68 25.9 43.8 PC5 1983.1 184.6 33.0 -0.5 22416.6 487019 5016964 No 0.2 21.2 18.2 0 1.8 58.8 PC6 1935.0 44.6 32.8 0.4 24658.3 486049 5016977 No 0.2 13.4 0 0 21.8 64.8 PC7 1925.1 31.9 26.6 0.4 7397.7 486352 5016778 No 0.3 6.8 4.2 0 22.8 66.2 PC8 1889.8 212.7 31.5 -0.4 4184.3 486035 5017135 No 0.7 8.0 0 0 0 92.0 PC9 1883.1 47.4 33.4 0.4 7173.0 485881 5017220 No 0.3 11.28 4.8 0.56 9.28 74.08 Note. BB = Beehive Basin, HC = Hyalite Canyon, PC = Portal Creek. TFA = Talus Field Area, MBS = Mean boulder size, SLP = Slope, SLI = Solar Insolation Index, ASP = Aspect, ELV = Elevation, AVGG = Average percentage of graminoid coverage, AVGF = Average percentage of forb coverage, AVGC = Average percentage of cushion plant coverage, AVGW = Average percentage of woody plant coverage, and AVGB = Average percentage of bare ground coverage. (N=28). 58

APPENDIX D

ABIOTIC SITE CHARACTERISTICS & PIKA OCCUPANCY BOX AND WHISKER PLOTS

F(2, 22)=2.8018, p=.08242 F(2, 22)=.07301, p=.92981 F(2, 22)=.30568, p=.73970 Vertical bars denote 0.95 confidence intervals Vertical bars denote 0.95 confidence intervals Vertical bars denote 0.95 confidence intervals 50 450 0.6 Site Beehive Basin 400 0.4 45 Site Hyalite Canyon 350 0.2 Site Portal Creek 0.0 40 300 250 -0.2 35 200 -0.4 150 -0.6 30

MeanSlope MeanAspect 100 -0.8

MeanSolarInsolation 25 50 -1.0 Site Beehive Basin Site Beehive Basin 0 -1.2 Site Hyalite Canyon 20 Site Hyalite Canyon -50 Site Portal Creek -1.4 Site Portal Creek

15 -100 -1.6 no yes no yes no yes Occupied Occupied Occupied F(2, 22)=1.7560, p=.19610 F(2, 22)=2.9216, p=.07495 F(2, 22)=.36280, p=.69981 Vertical bars denote 0.95 confidence intervals Vertical bars denote 0.95 confidence intervals Vertical bars denote 0.95 confidence intervals 3800 11 1.5E6 3600 10 Site Beehive Basin 3400 Site Hyalite Canyon 1E6 9 Site Portal Creek 3200 8 3000 7 5E5 2800 6 2600 5 0 2400 Area MeanElev 2200 4 Boulders.per.M -5E5 2000 3 1800 2 Site Beehive Basin 1600 1 -1E6 Site Beehive Basin Site Hyalite Canyon Site Hyalite Canyon 1400 0 Site Portal Creek Site Portal Creek 1200 -1 -1.5E6 no yes no yes no yes Occupied Occupied Occupied F(2, 22)=.08799, p=.91609 Vertical bars denote 0.95 confidence intervals 1.4 Site Beehive Basin 1.2 Site Hyalite Canyon 1.0 Site Portal Creek 0.8 0.6 0.4 0.2 0.0

NearestNeighbor -0.2 -0.4 -0.6 -0.8 no yes Occupied Note. Abiotic habitat characteristics versus occupancy within each of the three drainages in the study area. 60

APPENDIX E

TABLE 6: MEAN ELEVATION AND PIKA EQUIVALENT ELEVATION

Table 6 Mean Elevation and Pika Equivalent Elevation Mean Elevation Pika Equivalent Site ID Occupied Latitude (deg) Longitude (deg) (m) Elevation (m) BB1 No 45.3 111.40 2901.0 2288.0 BB2 Yes 45.3 111.40 2948.4 2288.0 BB3 Yes 45.3 111.40 2581.2 2288.0 HC1 Yes 45.4 110.94 2860.7 2320.8 HC2 Yes 45.4 111.40 2765.6 2276.6 HC3 Yes 45.4 111.40 2182.0 2276.6 HC4 Yes 45.4 111.40 2187.1 2271.0 HC5 Yes 45.5 110.93 2175.4 2271.0 HC6 Yes 45.5 110.93 2134.7 2276.6 HC7 Yes 45.5 110.94 2177.2 2282.3 HC8 No 45.5 110.93 1745.6 2282.3 HC9 No 45.5 111.03 1845.7 2282.3 HC10 No 45.5 111.40 1745.3 2317.0 HC11 No 45.5 111.40 1788.2 2317.5 HC12 No 45.6 111.40 1740.5 2315.0 HC13 Yes 45.6 111.40 1773.7 2315.5 HC14 No 45.5 111.40 1843.2 2307.4 PC1 Yes 37.7 95.45 2789.8 2738.2 PC2 No 45.3 111.18 1949.5 2305.9 PC3 Yes 45.3 111.17 1898.2 2305.4 PC4 Yes 45.3 111.17 2129.0 2306.4 PC5 No 45.3 111.17 1983.1 2307.0 PC6 No 45.3 111.17 1935.0 2307.0 PC7 No 45.3 111.18 1925.1 2307.0 PC8 No 45.3 111.18 1889.8 2307.0 PC9 No 45.3 111.17 1883.1 2306.3 PC10 No 45.3 111.18 1850.9 2306.3 PC11 No 45.3 111.18 1865.8 2306.4 Note. BB = Beehive Basin, HC = Hyalite Canyon, PC = Portal Creek. Pika Equivalent elevation is determined by Hafner’s (1993) equation: E(m)= 14087 – 56.6 (°N) – 82.9 (°W). This equation suggests that appropriate habitat 800 m below this lower limit would be extremely rare. All sites are within the expected range. 62

APPENDIX F

AVERAGE PERCENTAGE OF VEGETATION CATEGORY & PIKA OCCUPANCY BOX

AND WHISKER PLOTS

F(1, 26)=.00397, p=.95022 F(1, 26)=.01571, p=.90122 Vertical bars denote 0.95 confidence intervals Vertical bars denote 0.95 confidence intervals 40 30 28 35 26 24 30 22 20 25 18 16

AVG.Forbes AVG.Graminoid 20 14 12 15 10 8 10 6 no yes no yes Occupied Occupied

F(1, 26)=3.5234, p=.07177 Current effect: F(1, 26)=.17468, p=.67942 Vertical bars denote 0.95 confidence intervals Vertical bars denote 0.95 confidence intervals 30 9 8 25 7

20 6 5 15 4 3 10

AVG.Cushion 2

AVG.Woody.Plant 5 1 0 0 -1 -5 -2 no yes no yes Occupied Occupied Note. Average percentage coverage of four vegetation categories versus occupancy – only woody plants are significant (p=0.07).