Of 1 46 a Trophic Cascade and the Potential

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A Trophic Cascade and the Potential Consequences of Trophic Downgrading:

The Cougar-Elk-Aspen System

A Thesis

Presented to

The Faculty of the Environmental Studies Program

The Colorado College

In Partial Fulfillment of the requirements for the degree

Bachelor of Science

By:

Bryson Sawyer Camp

May/2019

______

Miroslav Kummel

Associate Professor of Environmental Science

______

Brian Linkhart

Professor of Organismal Biology and Ecology 2 of 46

Table of Contents

• Page 3: Abstract

• Page 4: Introduction/Literature Review

• Page 15: Methods

• Page 23: Results

• Page 31: Discussion

• Page 41: Conclusions

• Page 43: Works Cited 3 of 46

Abstract A trophic cascade can be defined as a specific food web or trophic structure where a predator preys on a herbivorous consumer which forages on a local vegetative resource; therefore, in this type of trophic structure top-down processes allow carnivorous apex predators to have indirect effects on local vegetative resources through their effects on the density or behavior/traits of the herbivores (M. Kummel, personal communication, April 8, 2019 and Ford et. al. 2015). In the case of predation on herbivorous consumers, both density and trait mediation can indirectly effect the density and growth pattern of vegetation that correlate directly to the alteration of prey populations via density and trait mediation (Ford et. al. 2015). Cougars have been identified as one of the seven apex predators that have been specifically associated with trophic cascades based on other empirical studies (Ripple et. al. 2014). Trophic downgrading follows the same pattern as alterations to trophic cascade structures: Trophic downgrading can have numerous direct and indirect ramifications on the local ecology. Trophic downgrading has similar consequences and is defined as, “the consequences of removing large apex consumers from nature (Estes et. al. 2011, 301).” Due to the unique characteristics that define the 6th mass extinction, one species has been the cause of most of the extinctions and the period has been characterized by the extinction of various large bodied animals, addressing trophic downgrading has become a prominent issue in the management of a wide array of ecological contexts globally (Estes et. al. 2011). In addition, apex predators, like cougars, facilitate ecosystem services such as carbon storage to buffer climate change, biodiversity enhancement, the reestablishment of native plant diversity, riparian restoration, and even the regulation of diseases (Estes et. al. 2011 and Ripple et. al. 2014). Thorough analyses of cougar habitat selection are rare, and have yet to be conducted in relation to the movement of elk and the growth of aspen saplings in the Pikes Peak region of Colorado U.S.A. until now. Through this study, it was observed and statistically shown that the number of aspen saplings tends to increase in areas that correspond with preferential habitat usage of cougars; whereas, the number of aspen saplings decreases in areas that correspond with a high prominence of observed elk herbivory. Therefore, in the Cougar-Elk-Aspen system within the Pikes Peak region cougars, carnivorous apex predators, are having indirect effects on local plants through top-down processes: This is a trophic cascade scenario. 4 of 46

Introduction/Literature Review

Earth’s 6th Mass Extinction:

The ongoing process of what is considered to be Earth’s 6th mass extinction has been unique in two distinct ways: one species has been the cause of most of the extinctions, and the period has been characterized by the extinction of various large bodied animals (Estes et. al. 2011). Large bodied animals are particularly at risk due to their tendency to have a low reproductive rate and large home ranges due to low density populations these qualities minimize the chance for adapting to changing environmental conditions and to pass on favorable traits for the new conditions to their offspring; furthermore, since climatic conditions are generally warming species are adapting by becoming smaller because larger surface-to-volume ratios are generally favorable under warmer conditions, due to standard metabolic principles (Scheffers et. al. 2016).

To survive climate change, and avoid being affected by the 6th mass extinction or local extirpations species will have to adapt in at least one of three ways: adjust the range they use, alter themselves physiologically, or change how they operate in time which entails changing their phenology (Bellard et. al. 2012). Such adaptations are much more difficult when elongated life histories are taken into account: For this reason, smaller bodied species, those with shorter life histories, and/or those with a large capacity for phenotypic plasticity tend to be more able to adapt to changing environmental conditions which allows these species to pass on favorable traits for the new conditions to their offspring (Scheffers et. al. 2016).

Trophic Cascades and Trophic Downgrading: 5 of 46

Trophic cascades have numerous direct and indirect ramifications on the local ecology. Trophic cascades are a well known concept within ecology that have striking patterns across ecological contexts (Estes et. al 2011). A trophic cascade can be defined as a specific food web or trophic structure where a predator preys on a herbivorous consumer which forages on a local vegetative resource; therefore, in this type of trophic structure top-down processes allow carnivorous apex predators to have indirect effects on local vegetative resources through their effects on the density or behavior/traits of the herbivores (M. Kummel, personal communication, April 8, 2019 and Ford et. al. 2015).

It is also well known that the consequences of altering trophic cascade structures are far- reaching, often leading to regime shifts and alternative states of ecosystems, and the strength of these impacts will likely differ among species and ecosystems (Estes et. al

2011). Trophic downgrading has similar consequences and is defined as, “the consequences of removing large apex consumers from nature (Estes et. al. 2011, 301).”

Trophic downgrading follows the same pattern as alterations to trophic cascade structures: Trophic downgrading can have numerous direct and indirect ramifications on the local ecology. For this reason, along with the impending prominence of trophic downgrading ecological triggering events, due to the 6th mass extinction, Estes et. al

2011 encouraged a shift in the ecological paradigm to focus more management efforts and resources on maintaining the integrity of top-down trophic interactions, on top of maintaining the status quo of bottom-up oriented management. Although, as a relatively new focus within ecology, there is numerous gaps in our scientific understanding of the top-down control aspects of trophic interactions since the ensuing consequences are unique to their ecological context. The time for action, research and conservation to limit 6 of 46 local extirpations and entire extinctions for some species is limited due to rapid and radical ecological changes associated with climate change and human development.

The Role of Apex Predators:

Notably, large bodied animals include numerous apex predators (Estes et. al.

2011). Due to the unique characteristics that define the 6th mass extinction, addressing trophic downgrading has become a prominent issue in the management of a wide array of ecological contexts globally. Thus, the production of novel and more effective management solutions to address the upcoming and unidentified consequences of trophic downgrading will be reliant on our ability to continually extract ecologically contextualized knowledge of specific events, encroachments, or local extirpations that cause trophic downgrading, alterations to trophic cascade structures, and/or ecological collapse.

In an effort to elucidate ecological events that trigger alterations to trophic cascade structures and trophic downgrading, such as extinctions and local extirpations, ecologists must continue to study the intricacies of food webs, with a specific focus on the behaviors and ecological impacts of apex predators and large bodied animals. This must be done extensively in a variety of ecological contexts globally in order to understand the potential consequences of impending alterations to trophic cascades structures and trophic downgrading. In the case of specifically attempting to elucidate trophic downgrading ecological triggering events, wide ranging apex predators may be ideal to focus on for uniformity. Hopefully, such scientific endeavors will elucidate 7 of 46 potential management strategies to protect apex predators and large bodied animals in general, within unique ecological contexts around the world.

Historically, ecological studies have tended to lack focus on apex predators and large bodied animals alike due to the strong focus on bottom-up processes, since bottom- up processes has been viewed as fundamental to the function of ecosystems (Estes et. al.

2011). However, apex predators, are now commonly considered to be keystone species within their ecosystems who uphold overlooked roles in regulating natural occurrences of disease, fire, carbon sequestration, invasive species along with biogeochemical exchanges amongst Earth’s soil, water, and air (Estes et. al. 2011). Consequently, trophic downgrading has been associated with biodiversity loss (Estes et. al. 2011). Thus, the new found importance of apex predators and the rise of extinctions and local extirpations due to the ongoing 6th mass extinction is encouraging a shift in ecological and conservation management paradigms from a focal point on bottom-up processes towards necessitating an understanding of top-down trophic processes, in addition to, not in place of, bottom-up processes, through a plethora of on the ground ecologically contextualized pursuits of knowledge and pertinent information. For the sake of managing ecosystems in an attempt to prevent ecosystem collapses throughout the globe when possible, this is a necessary shift.

Density Mediation vs. Trait Mediation:

Apex predators can alter prey populations through both density mediation and trait mediation. Density mediation entails thinning the population of prey through direct predation; whereas, trait mediation is a little more complex (Ford et. al. 2015). Trait 8 of 46 mediation can lead to both behavioral changes in prey as well as physical trait alterations in the future offspring of populations that are preyed upon (Ford et. al. 2015). In the case of predation on herbivorous consumers, both density and trait mediation can indirectly effect the density and growth pattern of vegetation that correlate directly to the alteration of prey populations via density and trait mediation (Ford et. al. 2015). These two forms of mediation through predation will be explained through two thoroughly investigated ecological systems which entail both trophic cascades and trophic downgrading.

One astute example where the absence of an apex predator, i.e. trophic downgrading, limited the impacts of density mediation and trait mediation within a trophic cascade structure was examined by Painter et. al. 2018: The Wolf-Elk-Aspen system within and surrounding Yellowstone National Park. Quaking aspen (Populus tremuloides) are one of the few deciduous tree species in the Rocky Mountains, which entails Yellowstone National Park; therefore, this tree adds to the habitat diversity in the region (Painter et. al. 2018). Rocky Mountain elk (Cervus canadiensis) forage on young aspen; thus, an inflated presence of elk can lead to decreased recruitment of aspen saplings and the eventual loss of aspen stands in the affected area if the issue goes unchecked, either naturally by predation on elk or the meticulous management of the issue at hand (Painter et. al. 2018). During the late 1800’s and early 1900’s, aspen stands spanned the valleys of northern Yellowstone; however, when gray wolves (Canis lupus) and cougars (Puma concolor) were extirpated locally in the 1920’s, foraging by elk became very intensive and aspen stands in the elk winter range of northern Yellowstone began to fail to recruit new aspen trees. This process slowly reversed, beginning in the late 1990’s, after the cougars return along with the reintroduction of gray wolves to 9 of 46

Yellowstone (Beschta et. al. 2018 and Painter et. al. 2018). This trophic cascade system revolves around the “predator guild” in the Yellowstone area that includes gray wolves, cougars, grizzly bears (Ursus arctus), and black bears (Ursus americanus) (Beschta et. al.

2018, Beschta et. al. 2018, and Painter et. al. 2018). When gray wolf and cougar populations returned to Yellowstone the “predator guild” was complete once again.

Therefore, the presence of various apex predators effects both prey density and behavior, through density and trait mediation, which indirectly upholds the integrity of local aspen stands (Painter et. al. 2018).

Another astute example where the absence of an apex predator, i.e. trophic downgrading, limited the impacts of density mediation and trait mediation within a trophic cascade structure was examined by Berger et. al. 2001 when they detailed the consequences of trophic downgrading after the local extirpation of two species of apex predators, grizzly bears and gray wolves in the Yellowstone area. Leaving just two sparse predators in the area, black bears and cougars, whose predation efforts on moose were not enough to limit the growing moose populations due to the fortitude of these massive herbivorous ungulates (Berger et. al. 2001). Now that predation was no longer the major limiting factor of moose populations, the new limiting factor was posed by the abundance of food resources (Berger et. al. 2001). The loss of these apex predators allowed the rapid growth of moose populations; however, this was not the the only consequence. Soon after, the imposing presence of numerous herbivorous ungulates essentially decimated local willows, cotton-woods, and aspen via excessive herbivory causing a fundamental alteration to the local vegetative structure and the habitat structure itself (Berger et. al.

2001). Ultimately, resulting in a less migratory stopovers from multiple species of avian 10 of 46

Neotropical migrants even forcing the local extirpation of Gray Catbirds (Dumetella carolinensis) and MacGillivray’s Warblers (Oporonis tolmiei) (Berger et. al. 2001).

Cougars:

Cougars (Puma concolor) are apex predators with a notoriously broad distribution. In the Americas, the distribution ranges from the Yukon Providence, Canada all the way down to southern Chile (Gau et al. 2001). With such a wide range, human development is inevitably encroaching on vulnerable cougar territories throughout the

Americas, which could be especially detrimental since cougar behavior and territorial distributions are dictated by intraspecies and interspecies social dynamics (Elbroch et al.

2016). Within British Columbia specifically and beyond cougar predation tends to focus on mule deer (Odocoileus hemionus) and whitetail deer (Odocoileus virginianus), and their habitat selection tends to rely on the spatial distribution of their prey (Gau et al.

2001). Elk are also a well known food source for cougars (Anderson et al. 2003). Male cougars commonly select elk whereas females commonly select mule deer (Anderson et al. 2003). When a cougar kills an elk it tends to spend 6.0 nights within 200 meters of the location of the carcass to feast on the prey; whereas, when a deer is killed cougars tend to spend 3.4 nights within 200 meters of the location of the carcass (Anderson et al. 2003).

Cougars are able to rely on the consistent predation of ungulates for the majority of their diet, local extirpations of cougars could potentially lead to excessive ungulate populations. Factors influencing cougar habitat selections have been elucidated by other studies. As I previously mentioned their habitat selection tends to rely on the spatial 11 of 46 distribution of their prey: Prey selection and the quality of habitat can vary for individual cougars based on health, age, and social status of the individual cougar (Elbroch et al.

2017). Additionally, abiotic variables factor into habitat selection as well. Annual temperature range, minimum temperature of coldest month, distance to permanent wetlands, distance to seasonal wetlands, and annual precipitation all play a decisive role in defining ideal habitats in the eyes of these apex predators (Cuyckens et al. 2015). For cougars, the proximity to permanent wetlands was found to be the most important abiotic variable that factors into habitat selection (Cuyckens et al. 2015). Thorough analyses of cougar habitat selection are rare, and have yet to be conducted in relation to the movement of elk and the growth of aspen saplings in the Pikes Peak region of Colorado

U.S.A. until now. Therefore, ecologists have not been able to thoroughly depict and pinpoint the potential qualitative consequences of a local extirpation of cougars in the

Pikes Peak region, through quantitative means.

The Current Study:

This is a particularly interesting region to look into since cougars in the front range have been urged westward due to human development, whereas urban deer have been a reported issue in Colorado Springs since the 1980’s, this likely became an issue due to the plethora of food along with a lack of predation and hunting within the city

(Conover et al. 1995). Furthermore, in Colorado cougars are not alone, in regards to being predators of ungulates; however, Rocky Mountain National Park has a relatively low density of black bears, and grizzly bears are very rare in the Rocky Mountain region, which are both likely true of Colorado in general as well (Baldwin et al. 2009, Primm et 12 of 46 al. 1996). Therefore, local extirpations of cougars in this area could potentially have similar affects to the defaunation that occurred in both the Wolf-Elk-Aspen and Wolf-

Bear-Moose systems around Yellowstone national park.

Cougars naturally play a key role in managing ungulate populations including both deer and elk, which leads to benefits for local ecosystems along with improving ecosystem services while improving socioeconomic circumstances that benefit humans in various ways: financially, medically, and recreationally. Excessive populations of ungulates are associated with a variety of negative consequences, both ecologically and socioeconomically, due to excessive herbivory and increased ungulate-vehicle collisions

(Van Horn et. al. 2012, Gilbert et al. 2016).

In an attempt to better understand the behaviors, movements, and habitat usage of cougars I delved into differentiating the effects of what I presumed to be potential predicting factors of cougar habitat usage. The preliminary questions of interest in this observational study are focused on elucidating if there are natural or human constructed features that dictate the preferential usage of habitat by cougars.

Habitat usage by cougars:

• Do cougars tend to prefer to climb aspen trees within pure aspen tree stands or mixed

tree stands?

• Do cougars tend to prefer to climb aspen trees closer or relatively farther from human

constructed features?

• Does the proximity to the stream within the area of interest dictate or effect the cougars

tendency to climb certain aspen trees? 13 of 46

In regards to these questions, I have multiple hypotheses.

• I hypothesize that cougars will equally climb aspen trees within pure aspen tree stands

and mixed tree stands.

• I hypothesize that cougars will equally climb aspen trees close and relatively far from

human constructed features, since the distance is likely negligible in comparison to the

typical extent of range and movement of cougars.

• I hypothesize that cougars will tend to climb a higher proportion of aspen trees within a

closer proximity to the stream, since the cougars are likely well aware that their prey

needs water to survive just like themselves.

To go a step further, the next round of inquires and data collection attempt to discern if there is a significant relationship between how cougars choose to utilize their habitat and the prominence of elk herbivory, both of which may in turn effect the recruitment rate of aspen saplings in the immediate area.

Elk foraging patterns:

• Do elk tend to prefer to forage on aspen trees within pure aspen tree stands or mixed

tree stands?

• Do elk tend to prefer to forage on aspen trees closer or relatively farther from human

constructed features?

• Do elk tend to prefer to forage on aspen trees in areas where cougars are less often

hidden in the trees?

In regards to these questions, I have multiple hypotheses. 14 of 46

• I hypothesize that elk will equally forage aspen trees within pure aspen tree stands and

mixed tree stands.

• I hypothesize that elk will equally forage aspen trees close and relatively far from

human constructed features, since the distance is likely negligible in comparison to the

typical extent of range and movement of elk.

• I hypothesize that elk will tend to more thoroughly forage aspen trees where cougars do

not tend to choose to climb trees in an attempt to avoid the risk of falling victim to

predation.

Tropic Cascade Potential in the Cougar-Elk-Aspen System:

• Is there a significant relationship between the areas of preferential habitat usage of

cougars and/or the prominence of observed elk herbivory that in turn effect the number

of aspen saplings in the immediate area?

• In regards to this inquiry, I expect to observe a generally higher number of aspen

saplings in areas that correspond with preferential habitat usage of cougars and a lower

number of aspen saplings in areas that correspond with a high prominence of observed

elk herbivory.

In an attempt to answer my inquires and test these hypotheses I embarked on an observational study to document the movements of cougars in relation to elk, and its effects or lack there of on the recruitment rate of aspen saplings in the immediate area, within the confines of the Catamount Center research area. 15 of 46

Methods

The Study Area:

The setting for this observational study was The Catamount Center, a research area just southwest of Woodland Park, Colorado, U.S.A. This is a unique area with a minimal presence of human built structures. Human constructed buildings within the research area include two residential buildings, a yurt, a picnic area, a sauna, a dining hall, bathrooms, and a classroom/all-purpose building for small events (The Catamount

Center). The human built structures that do exist also includes a hiking path, that is a decommissioned dirt road without any further vehicular access, which extends through the research area to paths within The Catamount Ranch Open Space and Resource

Protection Area (M. Kummel, personal communication, April 8, 2019). The trees stands in this area tend to be of various combinations of Engelmann Spruce, Douglas Fir

(Pseudotsuga menziesii), Limber Pines (Pinus flexilis) and Quaking Aspen trees; whereas, ground cover tends to largely be composed of common juniper (Juniperus communis) and bearberry (Arctostaphylos uva-ursi) (Marchand et. al. 2003). The elevation of this area is around 2,900 meters and located at 33˚55”18.48 N,

105˚06”12.77’ W. This area entails a broad valley with one slope significantly more steep than the opposite side. The steep side tree stand is almost entirely composed of mixed conifer and aspen stands where the trees are particularly dense; whereas, the opposite less steep side of the valley is composed of both mixed conifer and aspen tree stands, which are less dense than similar tree stands on the opposite slope, along with substantial areas of pure if not almost pure aspen tree stands that tend to be the least dense of the tree stands observed within the area of interest. There is a perennial stream at the of the 16 of 46 bottom of valley and two lakes near the area of interest. One lake is slightly to the northeast of the area of interest; while, the other is a little fartherm to the southwest of the area of interest.

The research area has had various uses over the past 150 years. During the late

19th century this area was a old cattle ranch that featured mixed conifer and aspen stands

("History"). In 1894, a fire ran rampant in this area and burned up the majority of the trees in this area (M. Kummel, personal communication, April 8, 2019). In the first half of the 20th century the YMCA bought the ranch to create a camp, which was decommissioned in the early 1990’s (M. Kummel, personal communication, April 8,

2019). Most recently in 1997, the land was bought by the both teller county and the

Catamount Center founders, Julie Francis and Howard Drossman, in order to designate this space for a natural research facility ("History").

Habitat usage by cougars:

Here, I conducted preliminary GPS mapping of trace markings left by cougars which were denoted by identifiable claw mark scars that extend up aspen trees. I strategically and mindfully walked in a lawnmower-like pattern across the valley within the area of interest to examine every tree present while identifying and classifying all cougar trace markings that I came across. I denoted both the age classification and abundance of trace markings on each marked aspen tree with strategically named GPS points. After, collecting the preliminary spatial data points associated with the clear presence and usage by a cougar I defined multiple categorical classifications of the land based on the relative presence of cougars (High or low), the tree stand type in relation to 17 of 46 aspens (Pure aspen or mixed aspen and conifer), and the relative distance from buildings constructed by humans (near or far). In order to distinguish these categorical classifications within the area of interest I made a GIS layer to go over top of a Google

Earth Pro satellite photograph of the study area, which contained my preliminary data that corresponds to the GPS locations of trace markings of cougars denoted by identifiable claw mark scars that extend up aspen trees. Then I distinguished high and low cougar plots based on the presence and clustering of cougar trace markings that were visually evident on the ARCGIS map that I created. Distinguishing areas based on the high and low presence of cougars was a distinctly visual process: This process entailed looking at the area of interest on ARCGIS for the distribution and density of cougar trace markings then constructing pertinent ARCGIS polygons associated with the high and low presence of cougar trace markings. I then turned off the ARCGIS polygons pertinent to the high and low presence of cougars in order to create unbiased ARCGIS polygons that related to the tree stand type in relation to aspens (Pure aspen or mixed aspen and conifer), and the relative distance from buildings constructed by humans (near or far).

The tree stand type in relation to Aspens was determined visually by utilizing the Google

Earth Pro satellite photograph of the research area taken on 10/22/2011, since this was the most recent satellite photograph that was accessible and easy to distinguish pure aspen and mixed aspen/conifer stands from one another. With this satellite image, I was able to identify areas based on the visible tree stand composition from a bird’s eye view: I denoted tree stands with over 85% visible aspen canopy cover to be “pure” aspen stands and anything with less than that proportion of aspen coverage to be mixed aspen and conifer stands. Furthermore, I was able to distinguish the relative distance from buildings 18 of 46 constructed by humans via this satellite photograph; however, due the extent of cougar movements and territory this distance was likely to be negligible. Therefore, the line between near and far from buildings constructed by humans was arguably arbitrary and merely cut the area of interest almost in half at an angle determined visually based on the location of the human-constructed buildings associated with the Catamount Center.

When I finished categorizing the entirety of the area of interest in relation to each of these three categorical variables, individually, I then turned on all of the ARCGIS polygons that I had just created and made them all hallow in order to create finalized

ARCGIS layers that pertain to all of these categorical variables at once. This process culminated in the entire area of interest being distinctly categorized and defined based on three categorical variables: the relative presence of cougars (High or low), the tree stand type in relation to aspens (Pure aspen or mixed aspen and conifer), and the relative distance from buildings constructed by humans (near or far). Therefore, I was left with 8 unique distinctions within the area of interest: high cougar presence aspen tree stand farther from human influence, high cougar presence mixed tree stand farther from human influence, high cougar presence aspen tree stand closer to human influence, high cougar presence mixed tree stand closer to human influence, low cougar presence aspen tree stand farther from human influence, low cougar presence mixed tree stand farther from human influence, low cougar presence aspen tree stand closer to human influence, and low cougar presence mixed tree stand closer to human influence. After defining and constructing these 8 distinct ARCGIS layers that correspond to each unique three part distinction, I was able to definitively test my inquiries via statistical analyses on these

ARCGIS layers. 19 of 46

Elk foraging patterns:

After identifying distinctions within the area of interest I was able to proceed with my next round of data collection by identifying 5 randomized plots within each distinction: high cougar presence aspen tree stand farther from human influence, high cougar presence mixed tree stand farther from human influence, high cougar presence aspen tree stand closer to human influence, high cougar presence mixed tree stand closer to human influence, low cougar presence aspen tree stand farther from human influence, low cougar presence mixed tree stand farther from human influence, low cougar presence aspen tree stand closer to human influence, and low cougar presence mixed tree stand closer to human influence. I used a random point generator in ARCGIS to define randomized plots within each distinct area and then go to the study area with a sufficient

GPS unit in order to locate the corresponding area to the randomized plot of land. Prior to this process I distinguished areas that entirely lacked trees, to avoid having randomized test plots in these areas, since I would not actually be able to identify trace markings on aspen trees in those areas considering there were no aspen trees, or trees at all for that matter.

The purpose of defining and utilizing randomized plots in this portion of data collection was to address inquiries related to elk foraging patterns while definitively identifying their preferential habitat usage, with the integrity of randomization, and comparing that to the preferential habitat usage of cougars in this ecological context:

• Do elk tend to prefer to forage on aspen trees within pure aspen tree stands or mixed

tree stands? 20 of 46

• Do elk tend to prefer to forage on aspen trees closer or relatively farther from human

constructed features?

• Do elk tend to prefer to forage on aspen trees in areas where cougars are less often

hidden in the trees?

Within each of these randomized plots, I was able to identify elk foraging marks on aspen trees as well cougar claw marks due to the visible scaring on aspen trees in 10-by-10 meter plots. At each corresponding area to the randomly generated points, I measured out a 10-by-10 meter plot and approached every aspen tree within these distinct randomized plots in order to identify the trace markings of both elk and cougars. Data on elk trace markings were taken by placing the top of a meter stick at about 2 meters high on each aspen tree and denoting, yes or no, to the presence of elk herbivory every 10 centimeters,

I repeated this process four times per aspen tree at equal distances from each other going around the circumference of the tree; whereas, the presence of cougar trace markings was simply denoted once per aspen tree and taken as a count per randomized plot. I only had two and a half weeks to collect this data, but I was able to attain and analyze data for 5 randomized plots within each of the 8 distinctions that I created for a total of 40 randomized plots.

Addressing arising inquiries on habitat usage by cougars:

After creating ACRGIS maps that cataloged my data, I started to notice visually apparent clustering of cougar trace markings around both the stream and the decommissioned dirt road, which is now a hiking path. This visualized story map of the data elucidated new questions in regards to habitat usage by cougars: 21 of 46

• Does the proximity to the stream within the area of interest dictate or effect the cougars

tendency to climb certain aspen trees?

• Does the proximity to the hiking path within the area of interest dictate or effect the

cougars tendency to climb certain aspen trees?

In order to address these arising inquiries I created an alternative version of my original map that utilized the same satellite image from Google Earth Pro along with my preliminary data, to identify if there was a significant overrepresentation of cougar trace markings within various buffer distances from both the stream and the hiking path located within the area of interest, in comparison to the entire area of interest, which I later analyzed through numerous chi-squared tests. The trajectory of the path and stream were distinguished visually by utilizing this satellite image, which corresponded with my prior experience within the area of interest. Notably, this process likely entailed being up to 5 meter off of the actually trajectory of both the stream and path, which could effect the results; however, during this process I strategically removed the visibility of the cougar GPS points to avoid introducing bias as I was tracing the stream, which was made evident by this satellite image.

Once all the data was collected and entered into ARCGIS, I spatially joined my preliminary data points with each of the 8 unique distinctions that I created. I also spatially joined my preliminary data points with each of the 4 buffers of different distances around both the stream and the path that I created: 25m, 20m, 15m, and 10m.

Notably, I avoided going as low as a five meter buffer since the process of delineating the stream and path likely entailed being up to five meters off of the actually trajectory of both. To run the chi-squared tests I adjusted the area of the entire area of interest by 22 of 46 excluding the areas that entirely lacked trees, since I would not actually be able to identify trace markings on aspen trees in those areas considering there were no aspen trees, or trees at all for that matter. I then took count of cougar trace marking occurrences within each distinction and in each buffer zone in order to run chi-squared analyses focus on determining if any of the areas were over represented by the number of cougar trace markings compared to what would be expected if the cougars were randomly distributed amongst the area of interest based on the proportional area of the entire area of interest.

Tropic cascade potential in the Cougar-Elk-Aspen System:

Once the preliminary chi-squared tests were conducted, I delved into the statistical analysis of my second round of data collection by constructing an excel sheet with pertinent variables necessary to run a 2-by-2-by-2 Anova test. This excel sheet entailed 3 discrete variables Cougar presence (high or low), Stand type (aspen or mixed), and Distance from human structures (near or far), 2 independent variables (average presence of elk herbivory and the number of aspen saplings present), along with 2 fixed covariate variables (average aspen circumference and the number of cougar trace markings present) all of these variables were assessed and denoted for each of the 40 unique randomized test plots. All of this data had normal distributions except for the number of aspen saplings present and the number of cougar trace markings present: For these data sets I conducted a logarithmic transformation to normalize the data, which was necessary to run the 2-by-2-by-2 Anova test. I then ran 2-by-2-by-2 Anova tests and

Pearson correlation two-tailed tests to identify statistically significant correlations within 23 of 46 this ecological context, which were computed using SPSS and the aforementioned variables.

Results

Habitat usage by cougars:

Within each unique distinction and in each buffer zone I strategically ran chi- squared analyses in order to differentiate and identify statistical patterns that pertain to inquires on habitat usage by cougars:

• Do cougars tend to prefer to climb aspen trees within pure aspen tree stands or mixed

tree stands?

• Do cougars tend to prefer to climb aspen trees closer or relatively farther from human

constructed features?

• Does the proximity to the stream within the area of interest dictate or effect the cougars

tendency to climb certain aspen trees?

• Does the proximity to the hiking path within the area of interest dictate or effect the

cougars tendency to climb certain aspen trees?

The chi-squared analyses in relation to these inquires statistically identified any of the areas that were over or under represented in the number of cougar trace markings present compared to what would be expected if the cougars were randomly distributed amongst the area of interest based on the proportional area of the entire area of interest. With one chi-squared analysis I was attempting to see if either areas denoted as tree stands with over 85% visible aspen canopy cover to be “pure” aspen stands or the alternative mixed aspen and conifer stands were over represented by the number of cougar trace markings 24 of 46 compared to what would be expected if the cougars were randomly distributed amongst the area of interest based on the proportional area of the entire area of interest. This test resulted in a chi-squared statistic equal to 10.157 with 1 degree of freedom. The results of this chi-squared test correspond with a two-tail p-value less than 0.0014. Thus, the results of this test confirmed that the mixed aspen and conifer stands were significantly over represented by the number of cougar trace markings compared to what would be expected if the cougars were randomly distributed amongst the entire area of interest and the “pure” aspen stands were significantly under represented.

With another chi-squared analysis I attempted to see if either areas relatively far from human constructed buildings or relatively closer were over represented by the number of cougar trace markings compared to what would be expected if the cougars were randomly distributed amongst the area of interest based on the proportional area of the entire area of interest. This test resulted in a chi-squared statistic equal to 0.0 with a corresponding p-value less than 0.0005 and 1 degree of freedom. Thus, the results of this test confirmed that neither areas relatively far from human constructed buildings or relatively closer were significantly over represented by the number of cougar trace markings compared to what would be expected if the cougars were randomly distributed, in direct comparison to one another: In fact in this case, for both areas relatively far from human constructed buildings and relatively closer the observed amount of cougar trace markings was exactly equivalent to the expected number if the cougars were randomly distributed amongst these relative distances based on their proportional area in comparison to the entire area of interest. Therefore, this spatial disparity between human constructed buildings and cougar habitat usage was insignificant to the preferences of the 25 of 46 cougars. We could have experienced these results for at least a couple different reasons:

Either, cougars are unfazed by the presence of human structures paired with minimal human activity, or in comparison to the extent of cougar movements and territory this distance was merely a negligible difference.

With a series of four chi-squared analyses I attempted to show whether or not areas of various proximities to the stream within the area of interest were over represented by the number of cougar trace markings compared to what would be expected if the cougars were randomly distributed amongst the area of interest based on the proportional area of the entire area of interest. The largest and first stream buffer that I created entailed the 25m of land on either side of the stream: The first chi-squared test in this series resulted in a chi-squared statistic equal to 64.711 with 1 degree of freedom.

The results of this chi-squared test correspond with a two-tail p-value less than 0.0001.

The second stream buffer that I created entailed the 20m of land on either side of the stream: The second chi-squared test in this series resulted in a chi-squared statistic equal to 49.076 with 1 degree of freedom. The results of this chi-squared test correspond with a two-tail p-value less than 0.0001. The third stream buffer that I created entailed the 15m of land on either side of the stream: The third chi-squared test in this series resulted in a chi-squared statistic equal to 40.010 with 1 degrees of freedom. The results of this chi- squared test correspond with a two-tail p-value less than 0.0001. The fourth stream buffer that I created entailed the 10m of land on either side of the stream: The fourth chi-squared test in this series resulted in a chi-squared statistic equal to 43.952 with 1 degree of freedom. The results of this chi-squared test correspond with a two-tail p-value less than

0.0001. Thus, the results of these tests confirmed that every proximity to the stream 26 of 46 tested was significantly over represented by the number of cougar trace markings compared to what would be expected if the cougars were randomly distributed amongst the area of interest and the rest of the area of interest was significantly underrepresented; however, the chi-squared statistic decreased as the buffer zone decreased in proximity to the stream outside of the fourth and closest proximity. These results could potentially indicate that the cougars use a band of land of a certain width around the stream: The width of the band may correspond to the buffer with the highest chi-square statistic.

However, as you make the buffer narrower than the band, cougar-marked trees start appearing outside of the buffer decreasing the chi-square statistic.

With another series of four chi-squared analyses I attempted to show whether or not areas of various proximities to the hiking path within the area of interest were over represented by the number of cougar trace markings compared to what would be expected if the cougars were randomly distributed amongst the area of interest based on the proportional area of the entire area of interest. The largest and first path buffer that I created entailed the 25m of land on either side of the stream: The first chi-squared test in this series resulted in a chi-squared statistic equal to 26.928 with 1 degree of freedom.

The results of this chi-squared test correspond with a two-tail p-value less than 0.0001.

The second path buffer that I created entailed the 20m of land on either side of the stream: The second chi-squared test in this series resulted in a chi-squared statistic equal to 16.202 with 1 degree of freedom. The results of this chi-squared test correspond with a two-tail p-value less than 0.0001. The third path buffer that I created entailed the 15m of land on either side of the stream: The third chi-squared test in this series resulted in a chi- squared statistic equal to 10.178 with 1 degree of freedom. The results of this chi-squared 27 of 46 test correspond with a two-tail p-value less than 0.0014. The fourth path buffer that I created entailed the 10m of land on either side of the stream: The fourth chi-squared test in this series resulted in a chi-squared statistic equal to 9.810 with 1 degree of freedom.

The results of this chi-squared test correspond with a two-tail p-value less than 0.0017.

Thus, the results of these tests confirmed that every proximity to the path tested was significantly over represented by the number of cougar trace markings compared to what would be expected if the cougars were randomly distributed amongst the area of interest and the rest of the area of interest was significantly underrepresented; however, the chi- squared statistic decreased as the buffer zone decreased in proximity to the path. These results could potentially indicate that the cougars use a band of land of a certain width around the hiking path: The width of the band may correspond to the buffer with the highest chi-square statistic. However, as you make the buffer narrower than the band, cougar-marked trees start appearing outside of the buffer decreasing the chi-square statistic.

With Pearson correlation statistics two-tailed test, I was able to confirm that cougars tend to prefer to climb aspen trees as the circumference of the aspen tree increases: This Pearson correlation indicated that for the addition of every single cougar trace mark present within a plot the average circumference of the aspen trees within that plot increased by 0.692 meters, which corresponded with a p-value less than 0.0005.

Elk foraging patterns:

I ran 2-by-2-by-2 Anova test with the dependent variable being average elk herbivory observed in order to understand the potential effects of three discrete fixed 28 of 46 variables: high cougar presence, mixed tree stand, and being relatively far from human constructed features. This anova test resulted in an F of 7.641 and 7 degrees of freedom with a corresponding p-value less than 0.0005 for the entire corrected model. There was a statistically significant main effect of cougar activity density, F of 51.672 and 1 degrees of freedom with a corresponding p-value less than 0.0005, signifying that elk foraged less on aspen that were located in areas of high cougar activity. There was a statistically significant main effect of Stand type, F of 21.758 and 1 degree of freedom with a corresponding p-value of 0.001, signifying that elk foraged less on aspen that were located in areas within mixed aspen and conifer stands. Finally, there was a statistically significant interactive effect between the presence of a mixed tree stand and relative proximity to the human constructed features present at the research facility: F of 8.165 and 1 degree of freedom with a corresponding p-value of 0.034. This means that when elk forage in close proximity to human structures they avoid foraging in mixed conifer stands avidly; whereas, far away from people there is not as much of an avoidance of foraging in mixed conifer stands, except for when cougar signs are present. Therefore these elk seem to be more cautious when foraging in the presence of human structures and activity; whereas, further away from human structures and human activity their decisions to forage a more heavily dictated by the presence of cougars.

With Pearson correlation two-tailed tests I also was able to confirm that elk tend to prefer to forage more on trees as the circumference of aspen trees decrease: This

Pearson correlation indicated that for the addition of every 10% increase in average elk herbivory trace markings present within a plot the average circumference of the aspen trees within that plot decreased by 0.370 meters, which corresponded with a p-value of 29 of 46

0.019. I also was able to confirm in alternative statistical fashion that elk tend to prefer to forage in the more open aspen tree stands rather than mixed aspen and coniferous stands:

This Pearson correlation indicated that within a mixed aspen and coniferous stand the average elk herbivory trace markings within that plot decreased by 3.91%, which corresponded with a p-value of 0.013. I also was able to confirm in alternative statistical fashion that elk tend to prefer to forage in areas with lower amount of cougar trace markings observed in the immediate area: This Pearson correlation indicated that for the addition of every single cougar trace mark present within a plot the average elk herbivory trace markings within that plot decreased by 6.56%, which corresponded with a p-value less than 0.0005.

Tropic Cascade Potential in the Cougar-Elk-Aspen System:

Through running the 2-by-2-by-2 Anova test with the dependent variable being average elk herbivory, it was clear that elk tend to prefer to forage in aspen stands rather than mixed conifer stands, which merely intuitively seems to be the case due to an increased visibility in the more open aspen stands in contrast to the more convoluted visibility experienced when looking into the canopy of mixed conifer stands. This test alone did not attest to a significant relationship between the areas of preferential habitat usage of cougars and/or the prominence of observed elk herbivory that in turn effect the number of aspen saplings present in the immediate area. So, I ran 2-by-2-by-2 Anova test with the dependent variable being the number of aspen saplings present, adjusted via a logarithmic transformation to attain normality for the anova test, in order to understand the potential effects of three discrete fixed variables: high cougar presence, mixed tree 30 of 46 stand, and being relatively far from human constructed features. This anova test resulted in statistically insignificant results, which was a surprise. So in an attempt to delve deeper into this perplexing situation I ran Pearson correlation two-tailed tests to see if the logarithmic transformation on the number of aspen saplings present was affecting the significance of the results which originally denied the presence of a strong correlation between these natural occurrences, statistically speaking.

The subsequent tests entailed multiple Pearson correlation two-tailed tests to confirm the significant impacts within this trophic cascade system, along with the potential impacts if trophic downgrading were to occur in this ecological context, in an alternative statistical fashion. I was able to confirm in alternative statistical fashion that where elk tend to prefer to forage, less aspen saplings were found to be present: This

Pearson correlation indicated that for the addition of every 10% increase in average elk herbivory trace markings present within a plot the number of aspen tree saplings within that plot decreased by 0.542, which corresponded with a p-value less than 0.0005. I also was able to confirm in alternative statistical fashion that where cougars tend to be more prevalent more aspen saplings were found to be present: This Pearson correlation indicated that for the addition of every single cougar trace mark present within a plot the number of aspen tree saplings within that plot increased by 0.395, which corresponded with a p-value of 0.012. However, I was able to confirm this same correlation was not found to be significant between the logarithmically transformed cougar count data and the logarithmically transformed sapling count data: This Pearson correlation indicated an insignificant correlation between the logarithmically transformed cougar count data and the logarithmically transformed sapling count data with a corresponding p-value of 0.066. 31 of 46

Therefore, these logarithmic transformations were confounding the results of the anova test, but the correlations were able to be confirmed in an alternative fashion.

Discussion

The aforementioned results are not only statistically significant, but ecologically significant as well. Here, I will go more in depth on the ecological significance of my observational study.

Habitat usage by cougars:

• Cougars tend to prefer to climb aspen trees within mixed tree stands.

• Cougars tend to prefer to climb aspen trees relatively close and relatively farther from

human constructed features at the same rate.

• Cougars tend to climb a higher proportion of aspen trees within a closer proximity to

the stream, which indicates that cougars are likely well aware that their prey needs

water to survive just like themselves.

• Cougars tend to climb a higher proportion of aspen trees within a closer proximity to

the hiking path.

• Cougars tend to prefer to climb aspen trees more as the circumference of the aspen

trees increase.

Elk foraging patterns:

• Elk tend to prefer to forage on aspen trees within pure aspen tree stands. 32 of 46

• Elk equally tend to forage aspen trees close and relatively far from human constructed

features, since the distance is likely negligible in comparison to the typical extent of

range and movement of elk.

• Elk tend to prefer to forage on aspen trees more as the circumference of the aspen trees

decrease.

• Elk tend to more thoroughly forage aspen trees where cougars do not tend to choose to

climb trees, which is likely an attempt to avoid the risk of falling victim to predation.

As shown by decreased average elk herbivory in both mixed conifer and aspen stands

along with in high cougar count plots. The tendency of elk to prefer to forage on aspen

trees more as the circumference of the aspen trees decrease is also indicative of elk

attempting to avoid contact with cougars.

Tropic Cascade Potential in the Cougar-Elk-Aspen System:

• It was observed and statistically shown that the number of aspen saplings tends to

increase in areas that correspond with preferential habitat usage of cougars; whereas,

the number of aspen saplings decreases in areas that correspond with a high

prominence of observed elk herbivory.

Broader Context:

In order to understand the broader context of this study we must revisit the foundation, trophic cascades: A trophic cascade can be defined as a specific food web or trophic structure where a predator preys on a herbivorous consumer which forages on a local vegetative resource through their effects on the density or behavior/traits of the 33 of 46 herbivores; therefore, in this type of trophic structure top-down processes allow carnivorous apex predators to have indirect effects on local vegetative resources (M.

Kummel, personal communication, April 8, 2019, Ford et. al. 2015). This is not the first study that has attempted to understand the cascading effects of cougar predation on ungulate foraging and the local recruitment of new trees. In fact, Ripple et. al. 2014 highlighted the threats to the conservation status and ecological roles of this planet’s thirty-one largest mammalian carnivores: During this process, cougars were identified as one of the seven apex predators that have been specifically associated with trophic cascades based on other empirical studies (Ripple et. al. 2014). In addition, apex predators, like cougars, facilitate ecosystem services such as carbon storage to buffer climate change, biodiversity enhancement, the reestablishment of native plant diversity, riparian restoration, and even the regulation of diseases (Ripple et. al. 2014). Throughout the Rocky Mountain region, specifically and beyond, the presence of apex predators like cougars, minimizes stream bank erosion by indirectly facilitating the growth of woody plants, through predation on herbivores, allowing for enhanced water quality and natural

flood control through restored beaver populations that can persist due to the presence of woody vegetation (Ripple et. al. 2014).

Cougars have been linked to trophic cascades by multiple ecological studies:

Ripple et. al. 2014, Ripple et. al. 2006, Estes et. al. 2011, Beschta et. al. 2018, Beschta et. al. 2018, and Wallach et. al. 2015. Notably, this is not an exhaustive list of all the ecological studies that have linked cougars to trophic cascades. Due to their expansive range cougars have been associated with trophic cascades involving a variety of herbivorous ungulates: elk, mule deer, white-tailed deer, boar (Sus scrofa), wild horses 34 of 46

(Equus ferus), and wild donkeys (Equus africanus) (Wallach et. al. 2015). Irruptions of these ungulates and the ensuing over-grazing can cause ecological issues including loss of biodiversity and desertification, amongst other issues (Wallach et. al. 2015). At various times, throughout their careers ecologists Beschta and Ripple have delved into the trophic cascade system revolving around cougars, elk, and riparian trees. Most recently the duo delved into the “predator guild” in the Yellowstone area that included gray wolves, cougars, grizzly bears, and black bears (Beschta et. al. 2018 and Beschta et. al. 2018). When gray wolves and cougars were extirpated locally in the 1920’s, foraging by elk became very intensive and aspen stands in elk winter range of northern

Yellowstone began to fail to recruit new aspen trees: The local extirpation of gray wolves and cougars ended the fearsome reign of the “predator guild,” directly allowing elk populations to become excessive while indirectly facilitating the decimation of aspen stands spanned across the valleys of northern Yellowstone during the early 1900s and well before (Beschta et. al. 2018 and Painter et. al. 2018). In the same area, Beschta and

Ripple also identified similar effects of excessive ungulate herbivory on Geyer willow

(Salix Geyeriana) (Beschta et. al. 2018) Excessive elk herbivory, up until the 1990’s when the “predator guild” was once again complete with the reintroduction of gray wolves, continually kept Geyer willows short (Beschta et. al. 2018). Concurrently that excessive elk herbivory resulted in the local streams widening and drastically reduced the frequency of inset floodplains. However, Beschta and Ripple returned in 2017, and found that the Geyer willow canopy cover over the same streams had increased 43% and 93%, respectively (Beschta et. al. 2018). Observations taken by Beschta et. al. 2018 including well vegetated stream banks, and the recent development of frequent inset floodplains 35 of 46 point towards the recovery of these riparian ecosystems. The findings in regards to the influence of having apex predators present on the geomorphology of riparian ecosystems in Beschta et. al. 2018 echoed the findings in Ripple et. al. 2006.

Back then, Ripple and Beschta delved into the trophic cascade system involving cougars, elk, and cottonwood trees near and within Zion National Park: Here, these ecologists did a comparative observational study between areas known to commonly have cougars present versus, the area adjacent of Zion National Park to the west, versus the areas with a rare cougar presence within Zion National Park, due to potential “human shielding” (Ripple et. al. 2006 and Beschta et. al. 2018). In this case scenario, Ripple and

Beschta thoroughly highlighted the stark contrast between the biodiversity levels within the two land distinctions of their observational study: Within the rare cougar areas hydrophytic plants, wildflowers, amphibians, lizards, and butterflies all experienced a significant loss of biodiversity as determined by the present abundance of species within each land distinctions (Ripple et. al. 2006)

My observations and statistical analyses concur with the ecological studies that have linked cougars to trophic cascades; since I observed and statistically showed that the number of aspen saplings tends to increase in areas that correspond with preferential habitat usage of cougars; whereas, the number of aspen saplings decreases in areas that correspond with a high prominence of observed elk herbivory. Therefore, in the Cougar-

Elk-Aspen system within the Pikes Peak region cougars, carnivorous apex predators, are having indirect effects on local plants through top-down processes: This is a trophic cascade scenario. If cougars were to be locally extirpated from the Pikes Peak region, 36 of 46 altering this trophic cascade structure through trophic downgrading in this case would likely lead to an excessive presence of herbivorous ungulates, including elk and mule deer, along with excessive amounts of herbivory on riparian trees, specifically aspen. It is unlikely that the consequences of trophic downgrading within this trophic cascade system would halt there. Based on similar case studies and known ecosystem services provided by cougars, in the Rocky Mountain region, it would not be surprising if local willows and cotton-woods were decimated, along with the aspen, causing a fundamental alteration to the local riparian vegetation structure and the habitat structure within the riparian system itself; furthermore, such changes to the local riparian system could cause local beaver populations to struggle, or even result in less stopovers from migratory birds (Ripple et. al. 2006, Ripple et. al. 2014, Berger et. al. 2001, and Beschta et. al. 2018). The indirect effects of excessive ungulate herbivory due trophic downgrading caused by the absence of an apex predator, like cougars, are numerous, not easily foreseen and could potentially cause local ecological collapse.

The direct effects of excessive ungulate foraging can be just as troublesome to the ecology of riparian systems along with the viability of local aquatic habitats. Van Horn et. al. 2012 specifically delved into the interconnectedness of riparian characteristics with ungulate foraging. In their study, Van Horn et. al. 2012 delved into the effects of ungulate foraging on geomorphology and nutrient cycling in a riparian ecological context. Their efforts revealed that without natural management, the presence of an apex predator, or meticulous conservation management, via measures like ungulate exclosures or controlled hunting, uncontrolled populations of herbivorous ungulates can also influence various abiotic elements including, but not limited to, surface soil composition 37 of 46 and the geomorphology of the stream ecology: These abiotic consequences pertain to aquatic habitats as well (Beschta et. al. 2018, Ripple et. al. 2006, and Van Horn et. al.

2012).

Over an extended period of time, even as little as two years, uncontrolled populations of herbivorous ungulates can fundamentally alter the geomorphology of the stream ecosystem: The presence of these large bodied ungulates inadvertently increases the width, decreases depth, and increasing the width:depth ratio of local streams (Beschta et. al. 2018, Ripple et. al. 2006, and Van Horn et. al. 2012). Subsequently, leading to a decreased availability of fish and aquatic invertebrate habitat (Beschta et. al. 2018, Ripple et. al. 2006, and Van Horn et. al. 2012). Concurrently, Van Horn et. al. 2012 denoted that the presence of large populations of herbivorous ungulates results in significant deposits of nitrogen and carbon into the surface soil chemistry, due to deposits of fecal matter.

These well known issues with excessive populations of large herbivorous ungulates have often been addressed by environmental managers by imposing herbivore exclosures.

Moreover, the results in Van Horn et. al. 2012 suggested potential ecological benefits if herbivore merely persist for a 5 year duration, to maintain nutrient levels; however, this ideal management duration may vary based on the ecological context and the local severity of both trampling, deposits of fecal matter, and herbivory imposed by ungulates on riparian ecosystems (Van Horn et. al. 2012).

Natural and consistent predation by cougars, wolves, and bears have been known to minimize and naturally manage the negative consequences associated with excessive populations of large herbivorous ungulates. With contextual knowledge on the tangible consequences of trophic downgrading, conservation managers will be able to more 38 of 46 effectively portray the importance of managing populations of both large bodied predators and prey alike: At the same time these results allow managers to be meticulous when attempting to spread out the benefits of management strategies without causing any collateral damage to the local ecological integrity.

When cougars are present and consuming ungulates and other herbivores they naturally minimize the negative consequences associated with excessive populations of large herbivorous ungulates; concurrently, cougars inadvertently become secondary seed dispersers, based on their dietary preferences, even though these felids have a strictly carnivorous diet (Sarasola et al. 2015). Cougars are particularly effective seed dispersers due to the extent of their range and movement, Sarasola et al. 2015 stated that cougars could on average spread 5,000 seeds per kilometer squared annually! The recolonization of cougars has also been associated with the socioeconomic benefit of reduced ungulate- car collisions due to a limited amount of ungulates via predation (Gilbert et al. 2016).

Based on the documented savings of $1.1 million in collision costs annually in South

Dakota and similar case scenarios, Gilbert et al. 2016 predicted the following benefits to society if humans were to choose to pursue recolonization efforts of cougars on the east cost:

Our coupled deer population models and socioeconomic valuations revealed that

cougars could reduce deer densities and DVCs by 22% in the Eastern United

States, preventing 21,400 human injuries, 155 fatalities, and $2.13 billion in

avoided costs within 30 years of establishment. (Gilbert et al. 2016, 431)

Notably, the benefits associated recolonization efforts with are not merely financial savings human lives would be saved as well. This study also implicitly indicates that 39 of 46 there would be financial and human consequences associated with allowing cougars to struggle, dwindle, or even become extirpated anywhere locally. In addition, the presence of cougars tends to minimize the damage imposed on agriculture and forestry from ungulate herbivory along with limiting disease transmission via ungulates (Gilbert et al.

2016). Without an apex predator around to limit herbivory via predation on ungulates over an extended period of time, even as little as two years, can fundamentally alter the geomorphology of the stream ecosystem by inadvertently increasing the width, decreasing depth, and increasing the width:depth ratio of the local stream; subsequently, leading to a decreased availability of fish and aquatic invertebrate habitat, which corresponds with negative impacts on recreational fishing (Van Horn et. al. 2012).

Despite these benefits to society, cougars fall under the influence of social taboos associated with apex predator conservation: Conservation efforts geared towards apex predator tend to be associated with negative connotations for humans, since apex predators are commonly associated with fear a and potential risk to humans, livestock and the livelihood of ranchers (Estes et. al. 2011). However, counterintuitively, cougars, like other large carnivores, provide crucial ecosystem and economic services to ranchers and pastoralists by limiting the density of wild large bodied herbivores, or competing grazers, which may enable pastoral activities to be more sustainable (Ripple et. al. 2014) In addition, guard animals can be particularly effective at minimizing or eliminating any threat that cougars have on livestock (Andelt et. al. 2004). Guard animals can also reduce labor necessitated to confine sheep and goats at night, facilitate more efficient use of pastures for grazing, reduce reliance on other predator control techniques, and allow for a greater peace of mind. Within this area, along with many other areas, cougars will have to 40 of 46 adapt in order to persist, amidst continuing human development and changing environmental conditions (Andelt et. al. 2004 and Bellard et. al. 2012). If these animals are unable to adapt quickly enough to their ever-changing ecological conditions, cougars and/or any population of pumas could potentially experience a genetic bottleneck effect and decline due to external threats imposed by humanity. The biggest threat to the safety of cougars and humans, in relation to cougars, revolve around human encroachment and the ever-changing social dynamics of interspecies and intraspecies interactions due to the restriction of habitats and the decline in habitat connectivity, with a better understanding of these processes we can minimize direct conflicts between humans and cougars while maintaining the ecological and socioeconomic benefits of sustaining and facilitating the livelihood of an apex predator in this region.

Events that trigger trophic down grading via trophic cascades are various, and can have numerous direct and indirect ramifications on the local ecology: The, geologically, recent rise in the rate of extinctions will only make the pressure of trophic downgrading more prominent in the field of ecology and conservation management, since apex predators and large animal species in general have been the hardest hit by rapid extinction and local extirpation events. The production of novel and more effective management solutions to address the upcoming consequences of trophic downgrading will be reliant on our ability to continually extract ecologically contextualized knowledge of specific events. Even in well studied case scenarios, we have still not found the perfect management parameters. Therefore, further investigation into the complex interactions between food web disruptions and both, biotic and abiotic ecological elements is necessary. To go a step further ecological researchers and conservation managers alike 41 of 46 must learn to recognize the impending signs of events that trigger trophic downgrading along with meticulously attempting to foster healthy apex predator populations.

Conclusion

As ecologists and environmental managers, we should adhere to the message of

Estes et. al. 2011 by embracing the ecological paradigm shift towards a more well rounded image of ecological processes which includes extensive efforts to understand the influence of top-down ecological processes, without neglecting the importance and influence of bottom-up ecological processes. All the while, Ecologists and environmental managers alike should avoid presuming aspiring to maintain ideal niches and ecological states; rather, we should focus on understanding the flow of ecological niches and alternative ecological states, through various on the ground ecological studies aimed on elucidating specific vulnerabilities in various communities, species, and populations.

In the process of expanding knowledge across all ecological contexts: Ecologists and conservation managers alike must not over extrapolate by assuming uniformity across ecological contexts. On the ground ecological data collection across ecological contexts will be key to understanding and managing the rising issues associated with trophic downgrading. Where and when funding is applicable and present these on the ground efforts to take data should include long-term intergenerational studies on apex predators and other organisms, within the same ecological context, that are effected by the presence or lack there of an apex predator.

There are unquestionably, socio-ecological ramifications associated with the success and aims of conservation management practices. Ecosystems are only stable in 42 of 46 the sense that they are dynamic. Therefore, management goals should not be geared towards strictly adhering to one stable state. Preservation of that stable state should not be our priority, instead we should instead focus on minimizing ways that humans affect the stable state of ecosystems by delving into the current condition and life history of keystone species. Alternative stable states naturally arise in ecosystems when perturbations occur. Notably, there are winners and losers in terms of species and individuals; however, we must maintain close attention to known keystone species and study ecosystem collapses, trophic downgrading, and trophic cascades in oder to designate new keystone species. Without significant knowledge about keystone species, we cannot prevent ecological collapses: we can merely sit idly by while ecological collapses continue to occur. When denoted keystone species must be documented and studied in various ecological contexts globally. 43 of 46

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