Migrate, Mutate, or Die: The effects of the lake trout introduction in Yellowstone Lake on populations outside the aquatic A Meta-Analytic Study

By Sarah Z. Gandhi-Besbes University of Colorado at Boulder

A thesis submitted to the University of Colorado at Boulder in partial fulfilment of the requirements to receive Honours designation in Environmental Studies May 2016

Thesis Advisors:

Alexander Cruz, Ecology and Evolutionary Biology, Committee Chair Dale Miller, Environmental Studies Andrew Martin, Ecology and Evolutionary Biology

© 2016 by Sarah Z. Gandhi-Besbes All rights reserved

i Abstract Yellowstone National Park is a relatively pristine ecosystem preserved through time. The Yellowstone cutthroat trout Oncorhynchus clarkii bouvieri population, inhabiting shallower waters in Yellowstone Lake and spawning in its tributaries, has been declining primarily due to the introduction of a predatory fish. The lake trout Salvelinus namaycush, which rapidly grow to large sizes, feed on the Yellowstone cutthroat trout, breed and spawn in Yellowstone Lake, and dwell in deeper waters out of predatory reach.

The Yellowstone cutthroat trout is relied upon both directly and indirectly by more than

40 species within Yellowstone National Park. The grizzly bear Ursus arctos horribilis, bald eagle Haliaeetus leucocephalus, and osprey Pandion halaetus all feed directly on the spawning fish. This study looks at how the declining Yellowstone cutthroat trout populations affect these predatory populations, and what their populations may look like should current trends continue into the year 2030. Conducting a meta-analysis and collecting primary data allowed for statistical projections predicting and comparing estimated future populations. The ecological change in Yellowstone Lake provides insight into how the concerns of one ecosystem affects multiple.

ii Preface Understanding the cascading effects through different ecosystems can help researchers solve problems of environmental degradation before they become permanent.

The decline in the Yellowstone cutthroat trout provides insight into the enormity of management practice needed to remove the lake trout, and the encompassing, lasting effects of a single ecological problem. By realizing the scope of a problem early on, organizing efficient management practices allows for potentially quicker remedial implementation. Keeping Yellowstone National Park unspoiled is essential for future scientific study, and preservation of a naturally beautiful landscape.

I would like to thank Dale Miller, Alexander Cruz, and Andy Martin for their encouragement, advice, critiques, and help. I would also like to thank Christina Chase for assisting me with the statistical projections. Finally, I would like to thank Dick Crysdale for introducing me to the depth of this on-going problem.

iii Table of Contents Abstract ...... ii Preface ...... iii List of Figures ...... v Introduction ...... 1 Background and Review of Literature ...... 3 Fish Dispersal ...... 4 Conservation Strategies ...... 6 Organisms Discussed ...... 8 Grizzly Bears ...... 8 Bald Eagles...... 11 Osprey ...... 12 Methods ...... 15 Data Results and Analysis ...... 16 Discussion ...... 20 Conclusion ...... 23 Recommendations for Further Research ...... 24 Relevant Figures ...... 26 Additional Figures ...... 43 Bibliography ...... 47

iv List of Figures Figure 1: Yellowstone cutthroat trout monitoring sites (Koel et. al. 2005) ...... 26 Figure 2: past and current range of the Yellowstone cutthroat trout (Kaeding 2001) ...... 27 Figure 3: bald eagle nesting sites in the Greater Yellowstone Ecosystem (Swenson et. al. 1986) ...... 27 Figure 4: comparison percent frequency of bald eagle diets in three areas within the Grand Teton-Yellowstone National Parks complex (Alt 1980) ...... 28 Figure 5: approximate osprey dive sites and occupied area on Yellowstone Lake (Swenson 1978) ...... 28 Figure 6: comparison of osprey diets of those nesting within Grand Teton National Park with those nesting on Yellowstone Lake and Hebgen Lake (Alt 1980) ...... 29 Figure 7: Yellowstone cutthroat trout counted on Clear Creek, a tributary of Yellowstone Lake historically used for spawning and location of the first monitoring station 1954- 2007 ...... 29 Figure 8: mean Yellowstone cutthroat trout counted per survet at varying Yellowstone Lake tributaries 1989-2011: 8 North Shore and 4 West Thumb spawning streams tributaries to Yellowstone Lake (Cain 2012) ...... 30 Figure 9: number of lake trout gillnetted on Yellowstone Lake 1994-2014, and their average weight in kilograms 2011-2014 ...... 30 Figure 10: number of Yellowstone cutthroat trout counted on Yellowstone Lake 2004-2014 ...... 31 Figure 11: average angler success rates measuring the number of Yellowstone cutthroat trout caught per hour on Yellowstone Lake 1994-2014 ...... 31 Figure 12: total number of active osprey nests counted in Yellowstone National Park, and counted on Yellowstone Lake and its tributaries 1917-2014 ...... 32 Figure 13: number of osprey fledglings born in Yellowstone National Park 1987-2014...... 32 Figure 14: number of bald eagle breeding pairs in Yellowstone National Park, and on Yellowstone Lake and its tributaries 1925-2014 ...... 33 Figure 15: number of bald eagle fledglings born in Yellowstone National Park, and on Yellowstone Lake and its tributaries 1973-2014 ...... 33 Figure 16: mean amount of grizzly bear activity observed at varying Yellowstone Lake tributaries 1989-2011: 8 North Shore and 4 West Thumb spawning stream tributaries to Yellowstone Lake (Cain 2012) ...... 34 Figure 17: approximate grizzly bear population trends in Yellowstone National Park compared to grizzly bear population trends in the Greater Yellowstone Area 1994- 2014 ...... 34 Figure 18: average cone produced per tree per transect with line of best fit. Cone production averages fewer than 20 per tree, an insufficient amount for grizzly bear consumption 1980-2014...... 35 Figure 19: estimated elk population found in the Greater Yellowstone Ecosystem 1994-2015 ...... 35 Figure 20: population of grey wolves in the Greater Yellowstone Ecosystem, and number of grizzly bears sighted in the greater Yellowstone Ecosystem ...... 36 Figure 21: population of grey wolves in Yellowstone National Park, and number of grizzly bears captured in Yellowstone National Park 1990-2014 ...... 36 Figure 22: current trends and estimated mean number of Yellowstone cutthroat trout counted per survey at varying Yellowstone Lake tributaries 1989-2030: 8 North Shore and 4 West Thumb spawning stream tributaries to Yellowstone Lake (Cain 2012) ...... 37

v Figure 23: current and estimated number of Yellowstone cutthroat trout counted on Yellowstone Lake 2004-2030 ...... 37 Figure 24: current and estimated number of lake trout gillnetted on Yellowstone Lake 1994- 2030 ...... 38 Figure 25: current and estimated total numbers of active osprey nests counted in Yellowstone National Park 1987-2030 ...... 38 Figure 26: current and estimated number of osprey fledglings born in Yellowstone National Park 1987-2030 ...... 39 Figure 27: current and estimated number of bald eagle breeding pairs in Yellowstone National Park, and on Yellowstone Lake and its tributaries 1980-2030 ...... 39 Figure 28: current and estimated number of bald eagle fledglings born in Yellowstone National Park, and on Yellowstone Lake and its tributaries 1987-2030 ...... 40 Figure 29: current and estimated mean amount of grizzly bear activity observed at varying Yellowstone Lake tributaries 1989-2030: 8 North Shore and 4 West Thumb spawning stream tributaries to Yellowstone Lake (Cain 2012) ...... 40 Figure 30: current and estimated approximate grizzly bear population trends in Yellowstone National Park compared to grizzly bear population trends in the Greater Yellowstone Area 1994-2030 ...... 41 Figure 31: current and estimated average cone production produced per whitebark pine tree per transect in Yellowstone National Park 1980-2030 ...... 41 Figure 32: current and estimated population of grey wolves in teh Greater Yellowstone Ecosystem, and number of grizzly bears sighted in the greater Yellowstone Ecosystem 1994-2030...... 42 Figure 33: current and estimated elk population found in the Greater Yellowstone Ecosystem 1994-2030 ...... 42 Figure 34: Yellowstone cutthroat trout survey areas, spawning streams and tributaries (Cain 2015) ...... 43 Figure 35: spring ungulate carcass survey transects (Cain 2012) ...... 43 Figure 36: breeding bird survey routs (Mammoth, North Entrance, Yellowstone) in Yellowstone National Park 1982-present (Baril and Smith 2009) ...... 44 Figure 37: Yellowstone cutthroat trout catch per unit effort (CPUE); average number of Yellowstone cutthroat trout caught per net showing YCT abundance in Yellowstone Lake from 1987-2009 (Koel et. al. 2005) ...... 44 Figure 38: the relationship between both osprey breeding pairs and productivity, and YCT CPUE 1987-2009; bald eagle breeding pairs and productivity, and YCT CPUE 1987- 2009 at Yellowstone Lake (Baril et. al. 2013) ...... 45 Figure 39: norther range elk calves killed by predator per year in Yellowstone National Park 2003-2005 (Barber-Meyer et. al. 2008) ...... 45 Figure 40: comparison of percent of elk calves killed by bears and wolves in the Greater Yellowstone Ecosystem 2003-2006 (Barber-Meyer et. al. 2008) ...... 46

vi Introduction National parks are the mascot of American environmentalism, and Yellowstone is the beginning of this era. Established by Theodore Roosevelt in 1872, Yellowstone is the first national park in world history, the birthplace of the National Park Service, and the federally institutional icon of the American spirit (Wilson 2013). The idea behind these national parks is based upon “civic egalitarianism;” establishment is by the people, and availability is for the people (Wilson 2004). What makes Yellowstone genuinely unique is its untamed and untouched naturalness; it has remained uncultivated land since the end of the 19th century. Yellowstone National Park is a social and scientific haven, allowing people the opportunity to observe and study biological processes in a landscape almost undisturbed through time, and compare the impact of human activity to most other

“wilderness” areas. Preserving this land in its integrity will allow others to enjoy it for years to come; however, human intervention is inevitable, whether intentional or not.

This study examines the subspecies Yellowstone cutthroat trout as a keystone species by analyzing their effect on the surrounding ecosystems of Yellowstone Lake in

Yellowstone National Park using the literary research, looking at the effects on bald eagle, osprey, and grizzly bear populations. I choose these animals specifically because they are not aquatic, yet cutthroat trout play a vital role in their dietary choices; I can therefore further understand the natural capacity of the cutthroat trout in an ecosystem.

Yellowstone cutthroat trout population declination is also affected by many other human- induced changes, such as land alteration and hybridization with other introduced trout; however, in order to better understand the greater effects a non-native species can have, I focus this thesis on lake trout as an invasive species (United States n.d.). At Yellowstone

1 Lake, however, the Yellowstone cutthroat trout is genetically pure (United States n.d.).

This paper will examine the effects of the decline in cutthroat trout due to the introduction of lake trout Salvelinus namaycush on organisms surrounding Yellowstone

Lake’s perimeter. For example, the change in grizzly bear diet to obtain the necessary nutrients provided by the cutthroat may affect the grey wolves, who rely primarily on ungulates for nourishment (Maughan 2013; “Potential Interactions Between Bears and

Wolves, 2015). It is possible that the results found here will continue to be applicable in further instances of invasive aquatic species in mountain lakes. Studying the broader characteristics shared by these lakes may allow researchers to improve their concepts of the effects of invasive species. Results from my research will hopefully provide the scientific, political, and social communities knowledge on the importance of preserving not only the cutthroat, but also other keystone species and ecosystems, and preventing further anthropogenic introductions.

2 Background and Review of Literature The Yellowstone cutthroat trout populations have been declining over the course of three decades, due to an anthropogenically-introduced invasive predatory species

(Crysdale 2009). This is not the first human-initiated problem to affect the cutthroat in

Yellowstone, another being whirling disease in fish (N.O.R.O.C.K. 2013). Whirling disease Myxobolus cerebralis, an exotic parasite, was first detected in Yellowstone Lake cutthroat trout in 1998, coinciding with a period of drought (Koel et. al. 2015). After monitoring and research done between 1999-2005, Pelican Creek has the most severe case, with spawning populations up to 30,000 now essentially eliminated. Yellowstone

River downstream from the lake was also affected (Koel et. al. 2015). Studies done in

2012 have determined that Pelican Creek is still at high risk for whirling disease, while

Yellowstone River upstream is at lower risk, and only 10% of the cutthroat trout in

Yellowstone Lake were infected. The results demonstrate that whirling disease is not spreading throughout the spawning tributaries to Yellowstone Lake, and the incidence of infection in juveniles and adults remains low (Koel et. al. 2015). National Park Service policies provide intensive habitat protection from pollution and harmful land-use practices; however, the fish are still subject to non-native fish introductions, spawn- taking operations, and commercial and sports fishing (Gresswell 2011).

How far do the affects travel in Yellowstone ecosystems? The introduction of lake trout to Yellowstone Lake has seen adverse effects not only within the lake itself, but also amongst the avian communities and terrestrial ecosystems around the park (Syslo 2015).

Over 42 avian and terrestrial organisms rely on the cutthroat at some point in the food web as a source of fuel (Crysdale 2013). Multiple studies have already been presented on

3 the decline in aquatic ecosystem health, not only with fish and microbials - including aquatic mammals such as river otters - but also in the reliance of avian species on cutthroat trout as part of their diet. These studies have included the effects on grizzly bears, and what they are turning to as an alternative source of energy (Gunther 1995;

United States 2015a).

Fish Dispersal Part of the Salmonidae family, Yellowstone cutthroat trout are a freshwater fish subspecies to Oncorhynchus clarkii, historically found in the Yellowstone River drainage in Wyoming, and the Snake River drainage in Wyoming, Idaho, Utah, and Nevada

(Varley et. al. 1988). Presently, however, the range of Yellowstone cutthroat tout remains within the boundaries of Yellowstone National Park (Figure 1) (Gresswell et. al. 1994).

Yellowstone Lake and the Yellowstone River hold the largest population of inland cutthroat trout globally (Flemming n.d.). Studies done in 1959 then again in 1984 have documented a continued decrease in Yellowstone cutthroat trout populations (Hadley

1984; Hanzel 1959). Over half of the existing cutthroat trout habitat includes other introduced salmonids, such as rainbow trout Oncorhynchus mykiss and brook trout

Salvelinus fontinalis (Varley et. al. 1988). Hybridization with rainbow trout in most, but not all, Yellowstone River tributaries is a significant cause of the decline in genetic purity of the Yellowstone cutthroat (Allendorf et. al. 1988). Apart from the cutthroat trout, the only other native fish to Yellowstone Lake is the longnose dace Rhinichthys cataractae.

Besides the lake trout, other introduced and invasive species found in the lake are redside shiners Richardsonius balteatus, longnose suckers Catostomus catostomus, and lake chub

Couesius plumbeus (Haroldson 2005). Rainbow trout provide the greatest threat to

Yellowstone cutthroat trout genetic purity; lake chub and other introduced species are not

4 common in Yellowstone Lake (Varley et. al. 1995).

Spawning Yellowstone cutthroat trout are found in West Thumb, West Shore, and

Lake Area streams shortly after the breakup of ice; spawning activity on East Shore streams comes 3-4 weeks later, usually near the end of June. Spawning duration is typically longest on West and East Shore streams (Haroldson et. al. 2013). The trout weighing between 1 to 1.5 pounds when spawning are the easiest prey for both mammals and birds, because of the narrow and shallow streams that they inhabit during this time

(Robbins et. al. 2006).

Yellowstone cutthroat can tolerate a wide range of temperatures, although typically residing in colder waters. Yellowstone cutthroat trout found beneath one metre of ice (0-4°C) were actively feeding (Gresswell 1995). Migrations begin in March when temperatures are near 5°C. The optimum temperature, as Robert Gresswell suggests, is between 4.5 and 15.5°C, although summer maxima is typically between 5 and 8°C

(Gresswell 1995). Juvenile Yellowstone cutthroat trout in Yellowstone Lake, typically pelagic, feed on zooplankton Daphnia shoedleri and Diaptomus Shoshone; mature trout, typically in the littoral zone, feed on zooplankton, crustaceans Gammarus lacustris and

Hyalella azteca, and aquatic insects (Gresswell 1995). The fish prefer insects, but are known to also eat smaller fish, fish eggs, and small frogs (Flemming n.d.).

Because lake trout are large predatory bottom dwellers, lake trout as an alternative dietary source is impossible for all species (Varley, et. al. 1995). The lake trout live deeper in the water, and quickly grow to large sizes; they are unsuitable as an alternative prey option irrelevant of their abundance. The size and mass is too great for the raptors to carry, and the amount of mercury from living deep in the sulphuric water is unappetizing

5 (Ruzycki et. al. 2003). None of the other fish species available in Yellowstone Lake are as widely distributed or abundant as the cutthroat trout. They are also relatively small, at less than 11 cm, making them incompatible as prey for most species (Swenson et. al.

1978; Varley et. al. 1998).

Conservation Strategies “The Greater Yellowstone public lands represent a test case — or paradigm — for redefining mankind's role in wildland areas of ecological importance” (Keiter and Boyce,

1991). The human experience, and therefore perception, is extremely finite and centres on personal experiences; ecological processes span over an unlimited period of time.

Constraining adaptation beyond perception limits acceptance and solution implementation, but Leopold et al. 1963 constructed new management goals for national parks preservation to maintain as much ecological purity as possible, calling not only for policy implementation, but habitat manipulation when appropriate. His goal was to maintain ecological purity so that the area remains as it was during colonial times.

Objective improvements in management decisions are more efficiently found through scientific debate and research, and in 1998, the National Parks Omnibus Management Act began requiring National Parks Service agencies to use science as a basis for management decisions (Keiter and Boyce, 1991; Oliff et al., 2013). Today, National Park

Services work with state fish and game management (and others) in conducting necessary research to provide adequate management strategies (Leopold et al., 1963). The document calls for maintenance of ecological integrity, use of practical economic methods, and implementation of inclusive programs and recognizing the relationship between culture and nature.

As the breadth of the lake trout dispersal increases, outside employment and

6 program implementation is becoming necessary. The implementation of a Native Fish

Conservation Plan/Environmental Assessment in 2011 increases the lake trout suppression efforts with newly contracted crews primarily using gillnets, amongst other techniques (Koel et al. 2011). Live entrapment was also used in areas where both lake trout and Yellowstone cutthroat trout were found; this type of capture allowed for live entrapment of larger lake trout. The nets were lifted every three days, when the cutthroat trout would be sorted from the lake trout and released back into the lake unharmed (Koel et. al. 2011). The live trap nets allows for specific removal of female lake trout from the population, hindering species reproductive ability. Three types of netting strategies have been used to study and remove lake trout from Yellowstone Lake: control netting, spawner netting, and distribution netting. The net mesh sizes and location placing can also be altered to target certain age classes and populations of fish (Koel et. al. 2011).

Leopold also introduces the idea of a biotic pyramid, which he uses as an indicator of ecosystem health. The flow of energy, and cooperation and competition of the different parts of the ecosystem showcase how well it is functioning. The Endangered

Species Act bases their ecosystem protection goals on his “land ethic” by measuring ecosystem health based on keystone species, indicator species, and apex predators. They classify the organisms into endangered or threatened. An endangered species is described as any species that is in danger of extinction throughout significant part of its range; a threatened species is one that is likely to become an endangered species within the foreseeable future. Although many have petitioned, and their current range is smaller than the historical range, the U.S. Fish and Wildlife Service have deduced that the

Yellowstone cutthroat trout is not applicable as a threatened or endangered species

7 (Figure 2) (Kaeding 2001). However, with so many organisms within the Yellowstone ecosystem depending both directly and indirectly on the Yellowstone cutthroat trout, it can be considered a keystone species.

Organisms Discussed Forty-two species of birds and mammals are either partially or totally dependent on Yellowstone cutthroat trout during breeding season, including grizzly bears, and raptors such as bald eagles and osprey (Varley et. al. 1995). The loss in cutthroat trout could significantly alter the important trophic links between avian, terrestrial, and aquatic ecosystems, ultimately diminishing Yellowstone Lake’s regional ecological integrity.

Migratory patterns are based on food and resource availability. White et. al. 2013 have noted that ungulates have begun moving to lower elevations and outside Yellowstone

National Park during the winter as local populations have increased and resources are becoming competitive. The dispersal range of wolves and grizzlies have therefore expanded as well. Contrarily, bald eagles have relied on dispersal within the park for mating and nesting success (White et. al. 2013). Here I discuss the relationship between these organisms, their respective ecosystem, and the Yellowstone cutthroat trout.

Grizzly Bears The Yellowstone grizzly bear is currently on the threatened and endangered species list; however, the Yellowstone Ecosystem Subcommittee, the Interagency Grizzly

Bear Committee, and Interagency Grizzly Bear Study Team recommended in 2013 that the grizzly bears be removed from the list (United States 2016). Compared to other North

American landscapes frequented by grizzly bear populations, the Greater Yellowstone

Ecosystem has a smaller abundance of nutritious plant matter, including berry bushes, resulting in few high-quality alternatives to animal prey (Knight et. al. 1995). When

8 available in sufficient quantities (22 cones per tree minimum), whitebark pine provides a suitable vegetarian option (Knight et. al. 1995). Yellowstone cutthroat trout spawning migrations and seasonal elk migrations overlap in space and time, providing the grizzlies with an adequate solution to high-value nutritional foods (Middleton 2013). The cutthroat trout and ungulates provide the greatest caloric value, at 6.1 kcal.g and 6.8 kcal/g respectively (Gunther et al. 2014). Of these options, ungulates have the most distributional overlap with the Yellowstone grizzly range (Gunther et. al. 2014). The decline in cutthroat spawning in the spring leaves a lack a fatty protein source; they are now turning to ungulate calves for the same nutrients (Maughan 2013). Lake trout are large predatory bottom dwellers in an acidic volcanic lake, whereas cutthroats are pelagic. Because of the extremely high and toxic levels of mercury they absorb being closer to the bottom of the lake, as well as spawning in the lake rather than in its tributaries, lake trout as an alternative dietary source is impossible for all species (Varley, et. al. 1995).

Yellowstone cutthroat trout migrating upstream within the Yellowstone Lake tributaries have served as a significant source of energy for bears in the lake area (Koel et. al. 2005). Cutthroat trout were included in grizzly bear scat up until the year 2000, when feeding site studies indicated the lack of grizzly bear visits after that year (Fortin et al. 2013). If a food source of higher energy content is available within their home range, the grizzly bear will be more likely drawn to that over berries or other forbs and grasses

(Gunther et al. 2014). Elk are found to have the most distributional overlap with grizzly bear residence, and the bears have compensated for lack of cutthroat by preying more heavily on elk calves during what would be cutthroat spawning season (Fortin et al.

9 2013). Grizzly bear diet is flexible: between Plantae, Fungi, Animalia, Protista, and human food; but the most efficient diet in terms of calories expended and received, would be one centered on Animalia (Gunther et al. 2014). In Yellowstone National Park, the change in springtime grizzly bear diet from cutthroat to ungulate in order to obtain the necessary nutrients provided by the cutthroat affect the grey wolves, who rely primarily on ungulates for nourishment (Maughan 2013; United States 2015b).

The Greater Yellowstone Ecosystem is where grizzly bears consume a substantial amount of ungulate meat in comparison to other areas in North America (Gunther et al.

2004). In areas where grizzly bears and wolves coexist, interspecific killings- where both species compete for the same resource- occasionally occurred (Servheen and Knight

1993). Prior to wolf reintroduction, bears would scavenge winterkilled ungulates and bison in the summer, preying on weaker elk and bison in the late summer and fall

(Gunther 2004). It is estimated that more than 90% of prey killed by wolves in

Yellowstone National Park is elk and the restoration of wolves has turned bears from hunters to wolf-kill scavengers, where the bears will visit the kill site and take control of the carcass (Smith et al. 2003). Today, where both wolf and bear exist, calve survival is reduced linearly; should wolves move towards hunting more bison, elk populations will undoubtedly fluctuate differently (Smith et al. 2003). The productive northern range of

Yellowstone national park harbours and nourishes most of the native ungulate species of

Yellowstone: elk, bison, mule deer, white tailed deer, moos, pronghorn antelope, and bighorn sheep, and some native carnivorous species: grey wolf, coyote, grizzly and black bear, and cougar; the high levels of plant biomass could potentially sustain a high population of elk and other ungulates even in the face of predators (Smith et al. 2003).

10 Other ungulates living alongside northern Yellowstone elk on their winter range include:

700–1,000 bison Bison bison, 2,000–2,500 mule deer Odocoileus hemionus, 175–250 bighorn sheep Ovis canadensis, 200–250 pronghorn Antilocapra americana, 200 moose

Alces alces, 100 mountain goats Oreamnos americanus, and 25 white-tailed deer.

Coexistant predators include: black bears, 70–92 grizzly bears, 20 cougars, 225 coyotes, and 50–100 wolves (Barber-Meyer et. al. 2008)

Because cougars and coyotes often prey on larger elk and do not compete directly with wolves or grizzlies, they are not included in this study (Barber-Meyer 2008).

Around the same time as the reintroduction of wolves into the Greater Yellowstone

Ecosystem, the predatory lake trout was found in Yellowstone Lake (Gresswell and

Tronstad 2013). Each ecosystem has reacted differently to their respective alteration; the terrestrial continues to grow and evolve, but the aquatic cutthroat trout is on the brink of collapse, evolving into a novel system for the lake (Gresswell and Tronstad 2013).

Bald Eagles

Before European occupation in North America, bald eagles are believed to have nested in the entire continental US, with exceptions being Rhode Island, West Virginia, and Vermont (Northern States Bald Eagle Recovery Plan 1983; Mattsson 1988). Bald eagles in Yellowstone National Park breed on the high-altitude, rolling plateaus, at 2100-

2400 m (Figure 3). Vegetation in this area consists mainly of lodgepole pine Pinus contorta, Engelmann spruce Picea engelmanni, and subalpine fir Abies lasiocarpa. Over the past 200+ years, populations have declined due to habitat loss, shooting, trapping, and poisoning of DDT throughout the 50s and 60s.Their population had grown steadily after becoming part of the endangered species list in 1967, and has been fairly stable since;

11 they were officially delisted as an endangered species in 2007 (Swenson et. al. 1986; NPS and Peaco n.d.). Size and mass increase with latitude, with migration and breeding timing playing a small role in changes (Mattsson 1988).

The bald eagle diet consists primarily of Yellowstone cutthroat trout during breeding season, which overlaps with the trout’s spawning season, peaking during the months of May and June (Swenson et. al. 1986). Swenson et al. discovered in 1986 that the peak consumption period of Yellowstone cutthroat trout by bald eagles is during the breeding season, which is April through August; the fish accounts for approximately 23% of the bald eagle diet around Yellowstone Lake, Yellowstone River, and other tributaries

(Figure 4). Although not preferred, as fish become less available they resort to small birds and mammals such as the American coot Fulica americana and muskrat Ondatra zibethicus (Swenson et. al. 1986; Swenson et. al. 1978; Ball et. al. 1961).

Yellowstone hosts both resident, non-migratory bald eagles, as well as regional and statewide migrants (Swenson et. al. 1986). Migration patterns depend on age, location of breeding site, climate at breeding site, and year-round food availability; during the August-January migratory months, these raptors typically follow the salmon runs. Immature birds move itinerantly, thought so because they are not attached to a nesting site. Adult birds migrate as needed when food becomes unavailable; this is important to note because of the declining cutthroat trout populations. What will their future migratory and residency patterns look like?

Osprey Annual studies of osprey in Yellowstone National Park did not occur until 1987 with the Yellowstone National Park bird program monitoring system. Many osprey nest on and around Yellowstone Lake, nearby their dive and foraging sites of deeper water

12 (Figure 5). Nesting density strongly depends on food supply, even with a lack of nest sites or heavy anthropogenic activities (Vana-Miller 1987). 93-99% of fish taken by osprey at Yellowstone Lake and Yellowstone River are cutthroat trout, comprising that percentage of their total diet (Figure 6) (Swenson 1978). The average estimated size of the fish preyed upon by osprey is about 28 cm at both Yellowstone Lake and the

Yellowstone River, with 83% being immature fish that are found near the surface of deeper water, and mature fish mainly found in shallow water.

Springs migrations back to breeding areas are usually March-May. Breeding dates for osprey populations are determined by latitude, reflecting temperature, day length, and availability of prey (Poole et. al. 2002). Important features of the nesting site include: proximity to water and thus prey, openness to allow for easy access to the nest, safety from ground predators, and a stable and wide base. Although the birds can habituate to human activity, successful reproductive rates are influenced by human presence along the shoreline and on the lake, notably due to boating and fishing near nests (Poole 2002;

Swenson 1979). Anthropogenic disturbance during the summer months can disrupt the osprey incubation period, as the adult birds become startled and the egg-warming is interrupted, leading to low egg hatchability; however, osprey developing their nests in areas prone to human appearances are likely to be more tolerant of later human activities

(hiking, fishing, etc) (Swenson 1979). Reduction in young is often due to low food availability and/or distance from nest to foraging areas (Vana-Miller 1987).

Osprey do not compete directly with other piscovorian animals because they primarily prey on smaller cutthroat trout. Grizzly bears primarily feed on mature fish from spawning runs in stream tributaries (Swenson 1978). Osprey foraging success

13 measures the relative ease of capture; it is less influenced by prey availability and weather conditions than time required per fish caught (Swenson 1979). For Osprey, benthic-feeding fish are the most easily captured, and piscivorous are the most difficult

(Swenson 1979). Benthic-feeding fish are more vulnerable possibly due to the behavioural adaptations for procuring food from the aquatic floor rendering them unable to perceive an attack from above (Swenson 1979). Though not preferred and seldom hunted, non-fish prey in and around Yellowstone National Park include birds, snakes, voles, squirrels, and muskrats Ondatra zibethica, usually caused by early arrival to breeding grounds when the lakes are still frozen over (Poole et. al. 2002).

14 Methods In order to study the effects of the cutthroat trout on grizzly bear, osprey, and bald eagle populations, and that of their respective prey, a literature review and literary analysis is necessary. The review allows for a meta-analysis of data regarding population, dispersal, and dietary choices. This meta-analysis will be a statistical combination of findings from other, independent studies. Selection criteria include scholarly articles, peer-review sources, and government documents for reports, including three decades of data, from the 1990s until 2014. Using search engines geared towards these types of sources - such as JSTOR, Google Scholar, and the National Parks Service – facilitates access to results. Assessing the methodological quality is done by: noticing the publishing companies, duration of study, previous knowledge of the researchers, and scientific methods used for each study. The population analysis will conclude with a statistical projection predicting future populations by using the data already reviewed and collected. Because the data collected will originate from different studies using varied collection techniques, a random-effect model, where the studies used are related but not identical, is appropriate. As the studies will not be functionally equivalent, the effect size will vary and the result will be a generalized range of populations over time.

15 Data Results and Analysis Yellowstone cutthroat trout are not seen spawning at their historical tributaries

(Figure 7 and Figure 8); however, they are still being observed in Yellowstone Lake.

As the lake trout suppression programs have continued and gillnetting has increased, as well as the development of other methods, the amount of lake trout netted has increased

(Figure 9), allowing the population of Yellowstone cutthroat trout to begin a substantial recovery in Yellowstone Lake (Figure 10 and Figure 11).

The number of osprey in Yellowstone National Park are declining, especially those on Yellowstone Lake and its tributaries (Figure 12). The number of these piscavorian fledglings observed in Yellowstone National Park is possibly increasing again after a sharp drop in numbers in 2000 (Figure 13). Bald eagle populations have been relatively stable, with a spike in 2002 due to territorial shifts, and a drop in 2006 due to extreme weather patterns of wind, precipitation, and a difficult winter (Figure 14 and Figure 15)

(McEneaney 2003; McEneaney 2007).

Grizzly activity has become less frequent at Yellowstone Lake tributaries, where they catch the spawning Yellowstone cutthroat trout (Figure 16). Their populations are on the decline in Yellowstone National Park; however, their numbers are increasing in the

Greater Yellowstone Ecosystem (Figure 17). With an average of fewer than 22 cones per whitebark pine tree (Figure 18), the assumption is that the bears are migrating looking for alternative food sources.

The elk population on the Greater Yellowstone Ecosystem has steadily declined over the years (Figure 19), which could be due to the introduced wolves or the migrating bears, both of which populations have been rising in the Greater Yellowstone Ecosystem

16 (Figure 20) and generally declining in Yellowstone National Park (Figure 21).

Based on current trends derived from the literary sources, calculating a statistical projection allows for insight into future trends and estimation on the long-term effects using the statistical program STATA. Trends were estimated until the year 2030 in order to maintain relevancy and accuracy.

The mean Yellowstone cutthroat trout found per survey at Yellowstone Lake tributaries produced an r-squared value of 0.6006, and a quadratic equation of y=

0.1397798x2-562.0055x+564913.8. Its graph shows that should current trends persist, the populations will begin increasing and thus returning to their historical spawning tributaries (Figure 22). The number of Yellowstone cutthroat trout found on Yellowstone

Lake produced an r-squared value of 0.8162, and a quadratic equation of y= 1.398396x2-

5602.354+5611150. The graph shows that the populations found on the lake will begin rising and increasing substantially (Figure 23). The number of lake trout gillnetted in

Yellowstone Lake produced an r-squared value of 0.9131 and a cubic equation of y=

0.7050163x3-2117.139x2+2830000000. The resulting graph shows that the number of lake trout found in Yellowstone Lake will continue to increase rapidly (Figure 24).

The number of active osprey nests found in Yellowstone National Park produced an r-squared value of 0.7265 and the quadratic equation y= -.1872658 x2+747.0203x-

744904.1. The number of osprey fledglings born in Yellowstone National Park produced an r-squared value of 0.4916 and the quadratic equation y= .0386533x2-

156.9484x+159332.4. The population of breeding pairs in Yellowstone National Park will continue to decline and the birds may not continue migrations to the park come 2030

(Figure 25). The number of fledglings born inside the park will decrease; however, the

17 number of fledglings estimated to be born is not considered statistically significant

(<60%) (Figure 26). The population of osprey found in Yellowstone National Park, and thus a majority on Yellowstone Lake and tributaries, is statistically significant.

The number of bald eagle breeding pairs on Yellowstone Lake and Tributaries produced an r-squared value of 0.5783 and the quadratic equation y= -

.0198258x2+79.34754x-79379.36 (Figure 27). The number of bald eagle breeding pairs in Yellowstone National Park produced an r-squared value of 0.3813 and the quadratic equation y= -.0330234x2+132.2593x-132400.5 (Figure 27). The number of bald eagle fledglings found on Yellowstone Lake and tributaries produced an r-squared value of

0.4925 and the quadratic equation y= -.0388234x2+154.9002x-154499.2 (Figure 28). The number of bald eagle fledglings found in Yellowstone National Park produced an r- squared value of 0.2038 and the quadratic equation y= -.0279567x2+112.0847x-112325.9

(Figure 28). The resulting graphs show that the populations both on Yellowstone Lake and tributaries, as well as elsewhere in the park, will decline and eventually disappear from the park altogether by the year 2030. Because the r-squared value is low (<60%) with each of these population counts, the resulting analysis is not considered statistically significant and the populations too varied to properly predict.

The mean amount of grizzly bear activity per survey on Yellowstone Lake and tributaries produced an r-squares value of 0.6721 and the linear equation y = -

.0251877x+50.6481. The resulting graph shows that, based on current trends, these bears may not return to Yellowstone Lake tributaries to catch the spawning Yellowstone cutthroat trout (Figure 29). The number of grizzly bears monitored in the Greater

Yellowstone Ecosystem produced an r-squared value of 0.6872 and the quadratic

18 equation y= -.037386x2+151.5494x-153478.7. The population is estimated to steadily increase. The number of grizzly bears captured in Yellowstone National Park produced an r-squared value of 0.4250 and a quadratic equation of y=0.0588071x2+236.0676-

236890.9; however, the data is not statistically significant because it’s r-squared value is too low (<60%) (Figure 30).

The mean number of whitebark pine cones found per tree per transect produced an r-squared value of 0.0170 and the quadratic equation y= .0140943x2-

56.20136x+56039.74 (Figure 31). Because the r-squared value is too low, the results are not considered statistically significant.

The wolf population of the Greater Yellowstone Ecosystem produced an r- squared value of 0.9833 and the quadratic equation y= -1.561126x2+6290.557x-6336435.

The wolf population is estimated to have already reached its peak, and will slowly decrease over time (Figure 32). The number of Northern Range elk counted in the

Greater Yellowstone Ecosystem produced an r-squared value of 0.9530 and the quadratic equation y= 27.66737x2-111615.3x+113000000. This population is estimated to dramatically increase over time, and eventually reach a plateau (Figure 33).

19 Discussion This study aims to provide an insight into potential future trends; it does not accurately predict what the exact population will be by the year 2030 for any organism.

The r-squared value dictates how far from the mean the point on the graph is.

Although current trends show that little to no Yellowstone cutthroat trout are visiting their historical spawning streams, a basic statistical analysis shows that this will change should numbers continue to follow the trend they are set at. This is assumed without consideration to climate change or human influence. The number of lake trout found in

Yellowstone Lake and tributaries is estimated to increase, which is a conclusion rejecting the null hypothesis that the suppression programs will eliminate the invasive species.

Extensive monitoring of the lake trout populations in needed, as well as continuance of the suppression efforts already put into place. The results indicate that the invasive species may not be permanently eliminated and will require observation for many years.

The number of osprey breeding pairs is estimated to decline, and by 2030 cease altogether, according to this model. Because Osprey live within the shoreline of a given water body with adequate food supply, and the Yellowstone cutthroat trout make up almost their entire diet while at Yellowstone National Park, the fluctuations in the raptor populations can be attributed to the cutthroat trout decline, and recent recovery trend. If the Yellowstone cutthroat trout do not make a full recovery, it is possible that the osprey migratory patterns could be altered from historical routes as they search for nesting ground closer to other stocked lakes and rivers. Determining what other areas these birds will migrate to during breeding season is important in determining what effects they will have on the local ecosystem, as well as what will happen to prey populations on

20 Yellowstone Lake and tributaries shorelines.

Bald eagle trend are seen declining using this statistical analysis; however, the results are not statistically significant. The Yellowstone cutthroat trout make up little of the bald eagle diet, therefore the bald eagles could be scavenging other organisms, such as small mammals, at other areas of the park or ecosystems. How this change in trophic cascade hierarchy will affect the park’s ecosystem, and whether it will eventually change the eagle migratory patterns or park population remains to be seen. Monitoring bald eagle populations and territorial shifts are required to understand the expanse of their ecological effects. For example, bald eagles are currently reported taking over osprey nests, which tend to be within the shoreline of a given water body. Bald eagle and osprey breeding pairs are not significantly correlated with temperature, therefore that was not taken into account in study (Baril et. al. 2013).

A lack in whitebark pine limits the vegetarian options available for grizzly bears in

Yellowstone National Park and the Greater Yellowstone Ecosystem. The results for this projection are not statistically significant, therefore monitoring the amount of cones per tree is necessary to determine what food options are available to the grizzly bears in this ecosystem. Because the density of the remaining trout cannot be exploited by the grizzly bears, they are unlikely to continue visiting streams used by the Yellowstone cutthroat trout (Teisburg 2014). However, the results show an increase of grizzly bears monitored in the Greater Yellowstone Area; it can be inferred that they will continue to search for alternative foods within this range, which is shared with elk herds hunted by wolf packs.

The wolf population is estimated to decline, but the elk population is going to increase drastically. This can potentially force the grizzly bears to migrate towards the increasing

21 herd sizes.

A lack in both vegetarian and Anamalia choices often result in the bears visiting lower elevations, which include areas of high human activity. This leads to a greater need for management actions resulting in capture and transport of bears; human-caused bear mortalities also increase during years of little cone production and increased visitation to sites at lower elevation (Knight 1998). A scat analysis was not included as it does not accurately reflect the proportions of indigested items; different food items are digested at different rates and to different degrees (Knight et. al. 1996). Understanding food habits means visiting and analyzing feed activities where bears are located visually and by radio-telemetry.

This study does not refer to the Yellowstone fire of 1988, nor the fire on Frank Island on Yellowstone Lake in 2003. It does not take include pesticide use of 1955-63, or human disturbances within the park and on the lake. It also does not look at vegetation health in terms of the raptor feasibility in creating new nesting territory or the mountain pine beetle outbreak affecting the whitebark pine. It also does not discuss the 1990-2000 drought affecting spawning stream flow rates and Yellowstone cutthroat trout reproductive abilities. Elk calf survival, nesting success rates, and cubs of the year are not included; measuring successful offspring and reproductive rates influences population trajectories and is necessary to understand before initiating predator management actions

(Barber-Meyer et. al. 2008). There was no direct collaboration with a park biologist, which will be necessary should this study be further pursued. The ability to use more data points for the calculations will provide better accuracy in the results.

22 Conclusion Yellowstone National Park provides a pristine ecosystem to study the effects of an interruption in historical ecological habits. The results found in this study are but a small part to a larger, on-going investigation on the effects of the decline in the Yellowstone cutthroat trout, and the invasion of the lake trout. As apex raptors, monitoring of bald eagle and osprey populations are needed to determine the cascading effects on their prey populations. Shifts in bear foraging behaviour—an indirect consequence of the lake trout invasion—are capable of changing the population dynamics of migratory elk, thus having cascading ecological effects and human interactions. Protection of a species inside of the park is insufficient for long-term biodiversity preservation; promotion of management responsibilities linking ecological findings with social and economic concerns, as well as understanding human-wildlife interactions will raise awareness to the issue of ecological decline (Wilson 2013). Conservation requires the demonstration of negative impacts before significant destruction of native communities is done, as well as enactment of control measures while the introduced population is still manageable, in order to hinder their establishment (Ruzycki 2004). Although the Yellowstone cutthroat trout, bald eagles, and osprey populations are not currently threatened or endangered, action taken now is more likely to prevent major ecological deterioration later. Keystone and apex populations are increasing in the Greater Yellowstone Ecosystem, and maintaining an accessible amount of food sources will prevent ecological collapse.

23 Recommendations for Further Research In order to maintain healthy population levels, extensive monitoring is needed for all populations involved. Increasing gilletting and live entrapment efforts in order to suppress an increase in the lake trout invasion in Yellowstone Lake, as well as prevent any kind of migration towards the surrounding tributaries, will decrease population levels as well as provide the opportunity for Yellowstone cutthroat trout revival. Monitoring the movements of the grizzly bears around Yellowstone National Park and the Greater

Yellowstone Ecosystem, while at the same time tracking both elk herd and grey wolf pack movements and populations, can provide scientist and analysts with insight into what the future of the park will look like in terms of large-scale interactions. Continual monitoring of raptor migratory patterns and possible movements to other lakes or river bodies for the same piscovorian caloric intake will help determine the outlook of prey for both the birds and other organisms in the ecosystem. Furthermore, tracking supplementary or replacement prey populations can determine ecological cascading shifts.

Further investigations are necessary to broaden the results found in this study.

Identifying large-scale habitat factors that influence the Yellowstone cutthroat trout distribution, dispersal, and recolonization – such as land-use activities, climate change, and human water activities – will help determine what other factors play a role in the population decline. Studying what can be done about the lake trout directly may provide solutions to manage their reproduction, such as extracting and genetically modifying as many male and females so that they are unable to reproduce. This is already seen when the lake trout hybridize with the brook trout, producing infertile offspring. Continual

24 study of the effects of climate change and potential drought is also necessary when designing management strategies.

25 Relevant Figures

Figure 1: Yellowstone cutthroat trout monitoring sites (Koel et. al. 2005)

26

Figure 2: past and current range of the Yellowstone cutthroat trout (Kaeding 2001)

Figure 3: bald eagle nesting sites in the Greater Yellowstone Ecosystem (Swenson et. al. 1986)

27

Figure 4: comparison percent frequency of bald eagle diets in three areas within the Grand Teton- Yellowstone National Parks complex (Alt 1980)

Figure 5: approximate osprey dive sites and occupied area on Yellowstone Lake (Swenson 1978)

28

Figure 6: comparison of osprey diets of those nesting within Grand Teton National Park with those nesting on Yellowstone Lake and Hebgen Lake (Alt 1980)

Yellowstone Cutthroat Trout Spawning at Clear Creek 80000 70000 60000 50000 40000 30000 20000 10000

0 Number Number of Observed YCT

Year

Figure 7: Yellowstone cutthroat trout counted on Clear Creek, a tributary of Yellowstone Lake historically used for spawning and location of the first monitoring station 1954-2007

29 Mean Yellowstone Cutthroat Trout Per Survey At Yellowstone Lake Tributaries 100

80

60

40

Fish/Survey 20

0

2010 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2011 Year

Figure 8: mean Yellowstone cutthroat trout counted per survey at varying Yellowstone Lake tributaries 1989-2011: 8 North Shore and 4 West Thumb spawning streams tributaries to Yellowstone Lake (Cain 2012)

Lake Trout Trends 350000 300000 250000 200000 150000 Lake trout caught and 100000 removed 50000 Lake trout weight 0 (KG)

Year

Figure 9: number of lake trout gillnetted on Yellowstone Lake 1994-2014, and their average weight in kilograms 2011-2014

30 Number of Cutthroat Trout Counted On Yellowstone Lake 200

150

100 # # CTT

50

0 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Year

Figure 10: number of Yellowstone cutthroat trout counted on Yellowstone Lake 2004-2014

Yellowstone Lake Angler Success Rate 2.5

2

1.5

1

YCT Caught/hour 0.5

0 1994 1998 2004 2012 2014 Year

Figure 11: average angler success rates measuring the number of Yellowstone cutthroat trout caught per hour on Yellowstone Lake 1994-2014

31 Osprey Observed in Yellowstone National Park

120 Active nests 100 YNP 80 60 40 Active nests on 20 Yellowstone 0 Lake and

Number Number of Osprey Pairs tributaries

1976 1917 1973 1987 1990 1993 1996 1999 2002 2005 2008 2011 2014 Year

Figure 12: total number of active osprey nests counted in Yellowstone National Park, and counted on Yellowstone Lake and its tributaries 1917-2014

Osprey Fledglings Observed in YNP 120

100

80

60

40

20 Number Number of Fledglings 0

Year

Figure 13: number of osprey fledglings born in Yellowstone National Park 1987-2014

32 Bald Eagles Observed in Yellowstone National Park 60 50 Breeding pairs YNP 40 30 Breeding pairs on 20 Yellowstone Lake and 10 tributaries

Number Number of Eagles Bald 0 Total population on Yellowstone Lake and

tributaries

1925 1963 1967 1971 1975 1979 1987 1991 1995 1999 2003 2007 2011 Year

Figure 14: number of bald eagle breeding pairs in Yellowstone National Park, and on Yellowstone Lake and its tributaries 1925-2014

Bald Eagle Fledglings Observed In YNP 30

25

20

15 YNP 10 Yellowstone Lake and

5 tributaries Number Number of Fledglings

0

1973 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012 Year

Figure 15: number of bald eagle fledglings born in Yellowstone National Park, and on Yellowstone Lake and its tributaries 1973-2014

33 Mean Grizzly Bear Activity Per Survey At Yellowstone Lake Tributaries 0.7 0.6 0.5 0.4 0.3 0.2 Activity/Survey 0.1

0

1992 2004 1989 1990 1991 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2005 2006 2007 2008 2009 2010 2011 Year

Figure 16: mean amount of grizzly bear activity observed at varying Yellowstone Lake tributaries 1989- 2011: 8 North Shore and 4 West Thumb spawning stream tributaries to Yellowstone Lake (Cain 2012)

Grizzly Bear Dispersal Trends 120

100

80

60 Grizzlies captured YNP 40 Bears Monitored GYE Number Number of Bears 20

0

2000 2008 1994 1996 1998 2002 2004 2006 2010 2012 2014 Year

Figure 17: approximate grizzly bear population trends in Yellowstone National Park compared to grizzly bear population trends in the Greater Yellowstone Area 1994-2014

34

Whitebark Pine Cone Count 60

50

40

30 Count 20

10

0

Year

Figure 18: average cone produced per tree per transect with line of best fit. Cone production averages fewer than 20 per tree, an insufficient amount for grizzly bear consumption 1980-2014

Elk Population in the Greater Yellowstone Ecosystem 20000

15000

10000

Population 5000

0

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 Year

Figure 19: estimated elk population found in the Greater Yellowstone Ecosystem 1994-2015

35 Grey Wolves Population In The Greater Yellostone Ecosystem 600 500 400 300

200 Grey Wolf Population

Number Number Counted 100

0

1994 2001 1995 1996 1997 1998 1999 2000 2002 2003 2004 2005 2006 2007 Year

Figure 20: population of grey wolves in the Greater Yellowstone Ecosystem

Grey Wolves Observed in Yellowstone National Park 200

150

100

Population 50 Wolf Population

0

1992 1990 1994 1997 1999 2001 2003 2005 2007 2009 2011 2013 Year

Figure 21: population of grey wolves in Yellowstone National Park 1994-2014

36 Mean Yellowstone Cutthroat Trout Per Survey At Yellowstone Lake Tributaries 100

80

60

40 Estimated Projection

YCT Counted 20 Current Trend

0

2016 1989 1992 1995 1998 2001 2004 2007 2010 2013 2019 2022 2025 2028 Year

Figure 22: current trends and estimated mean number of Yellowstone cutthroat trout counted per survey at varying Yellowstone Lake tributaries 1989-2030: 8 North Shore and 4 West Thumb spawning stream tributaries to Yellowstone Lake (Cain 2012)

Number Of Yellowstone Cutthroat Trout Counted On Yellowstone Lake 1200 1000 800 600

400 Estimated Projection YCT Counted 200 Current Trend

0

2026 2004 2006 2008 2010 2012 2014 2016 2018 2020 2022 2024 2028 2030 Year

Figure 23: current and estimated number of Yellowstone cutthroat trout counted on Yellowstone Lake 2004-2030

37 Number Of Lake Trout Gillnetted On Yellowstone Lake 3500000 3000000 2500000 2000000 1500000 Estimated Projection 1000000 Current Trend 500000

Number Number Lake Of Trout 0

2000 2003 2006 2009 2012 2015 2018 2021 2024 2027 2030 Year

Figure 24: current and estimated number of lake trout gillnetted on Yellowstone Lake 1994-2030

Number Of Osprey Breeding Pairs In Yellowstone National Park 120 100 80 60 40 Estimated Projection 20 Current Trend

0

Number Number Breeding Of Pairs

2015 1987 1991 1995 1999 2003 2007 2011 2019 2023 2027 Year

Figure 25: current and estimated total numbers of active osprey nests counted in Yellowstone National Park 1987-2030

38 Number Of Osprey Fledglings Born In Yellowstone National Park 120 100 80 60 40 Estimated Projection 20 Current Trend

Number Number FledglingsOf 0

2015 1987 1991 1995 1999 2003 2007 2011 2019 2023 2027 Year

Figure 26: current and estimated number of osprey fledglings born in Yellowstone National Park 1987- 2030

Bald Eagle Breeding Pairs In Yellowstone National Park Estimated Projection 40 For Breeding Pairs In 35 YNP 30 Estimated Projection 25 For Breeding Pairs On 20 Yellowstone Lake And 15 Tributaries Current Trend Of 10 Breeding Pairs In YNP 5 0 Current Trend Of

Number Number Breeding Of Pairs Breeding Pairs On

1984 1988 1992 1996 2000 2004 2008 2012 2016 2020 2024 2028 1980 Yellowstone Lake And Year Tributaries

Figure 27: current and estimated number of bald eagle breeding pairs in Yellowstone National Park, and on Yellowstone Lake and its tributaries 1980-2030

39 Bald Eagle Fledglings Born In Yellowstone

National Park Estimated Projection 30 For Fledglings Born In YNP 25 Estimated Projection 20 For Fledglings Born 15 On Yellowstone Lake And Tributaries 10 Current Trend Of 5 Fledglings Born In YNP Number Number FledglingsOf 0 Current Trend Of

Fledglings Born On

2008 1990 1993 1996 1999 2002 2005 2011 2014 2017 2020 2023 2026 2029 1987 Yellowstone Lake And Year Tributaries

Figure 28: current and estimated number of bald eagle fledglings born in Yellowstone National Park, and on Yellowstone Lake and its tributaries 1987-2030

Mean Number Of Grizzly Bears Counted Per Survey At Yellowstone Lake Tributaries 0.7 0.6 0.5 0.4 0.3 Estimated Projection 0.2 Current Trend 0.1

Grizzly Bears Counted 0

1989 1992 1995 1998 2001 2004 2007 2010 2013 2016 2019 2022 2025 2028 Year

Figure 29: current and estimated mean amount of grizzly bear activity observed at varying Yellowstone Lake tributaries 1989-2030: 8 North Shore and 4 West Thumb spawning stream tributaries to Yellowstone Lake (Cain 2012)

40 Number of Grizzly Bears Monitored In The Greater Yellowstone Ecosystem 120 Estimated Projection of Grizzlies Monitored 100 in GYE 80 Current Trend of 60 Grizzlies Monitored in GYE 40 Estimated Projection 20 of Grizzlies Captured in YNP 0 Grizzly Bears Monitored Current Trend of

Grizzlies Captured in

2000 1997 2003 2006 2009 2012 2015 2018 2021 2024 2027 2030 1994 YNP Year

Figure 30: current and estimated approximate grizzly bear population trends in Yellowstone National Park compared to grizzly bear population trends in the Greater Yellowstone Area 1994-2030

Mean Whitebark Pine Cones Counted Per Tree Per Transect In Yellowstone National Park 60 50 40 30 20 Estimated Projection

Cones Cones Counted 10 Current Trend

0

1984 1980 1988 1992 1996 2000 2004 2008 2012 2016 2020 2024 2028 Year

Figure 31: current and estimated average cone production produced per whitebark pine tree per transect in Yellowstone National Park 1980-2030

41 Estimated Population Trends In The Greater Yellowstone Ecosystem For Grey Wolves 600 500 400 300 Wolf Population 200 Estimated Projection 100 Wolf Population

0 Current Trend

Number Number Organism Of

1994 1997 2000 2003 2006 2009 2012 2015 2018 2021 2024 Year

Figure 32: current and estimated population of grey wolves in the Greater Yellowstone Ecosystem 1994- 2030

Number Of Elk Counted On The Northern Range Of Yellowstone National Park 500000

400000

300000

200000 Estimated Projection Elk CountedElk 100000 Current Trend

0

1994 1997 2000 2003 2006 2009 2012 2015 2018 2021 2024 2027 2030 Year

Figure 33: current and estimated elk population found in the Greater Yellowstone Ecosystem 1994-2030

42 Additional Figures

Figure 34: Yellowstone cutthroat trout survey areas, spawning streams and tributaries (Cain 2015)

Figure 35: spring ungulate carcass survey transects (Cain 2012)

43

Figure 36: breeding bird survey routs (Mammoth, North Entrance, Yellowstone) in Yellowstone National Park 1982-present (Baril and Smith 2009)

Figure 37: Yellowstone cutthroat trout catch per unit effort (CPUE); average number of Yellowstone cutthroat trout caught per net showing YCT abundance in Yellowstone Lake from 1987-2009 (Koel et. al. 2005)

44

Figure 38: the relationship between both osprey breeding pairs and productivity, and YCT CPUE 1987- 2009; bald eagle breeding pairs and productivity, and YCT CPUE 1987-2009 at Yellowstone Lake (Baril et. al. 2013)

Figure 39: norther range elk calves killed by predator per year in Yellowstone National Park 2003-2005 (Barber-Meyer et. al. 2008)

45

Figure 40: comparison of percent of elk calves killed by bears and wolves in the Greater Yellowstone Ecosystem 2003-2006 (Barber-Meyer et. al. 2008)

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