The Importance of Conserving the Wolves of Isle Royale National Park

Transcription

1 The Importance of Conserving the Wolves of Isle Royale National Park June 28, 2013 John A. Vucetich, School of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI USA, Rolf O. Peterson, School of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI USA, Michael P. Nelson, Department of Forest Ecosystems and Society, Oregon State University, Corvallis, OR USA, DRAFT DO NOT DISTRIBUTE We are grateful to Daniel Botkin, Rich Fredrickson, Phil Hedrick, Mike Phillips, and Lucas Westcott for dialogue that inspired the development of various elements of this document. The views expressed here do not necessarily represent their views or the views of our employers. We express special thanks The George Wright Forum for allowing us to reprint excerpts of papers that had originally been published there ( Suggestion citation: Vucetich, JA., R. O. Peterson, M. P. Nelson The importance of conserving the wolves of Isle Royale National Park. Michigan Technological University., 50 pages. 1

2 ANNOTATED CONTENTS Preface Executive Summary The history of wolves and moose on Isle Royale As long as there are moose, there should be wolves.. 14 The analysis presented here considers some of key environmental values, such as ecosystem health and wilderness character, that would be affected by deciding how to treat the wolves of Isle Royale. That analysis indicates that wolves should be present on Isle Royale so long as moose inhabit the island and so long as ecosystem health is a priority for the National Park Service. As such, not intervening, even in the event of extinction, would be antithetical to the NPS mission. 3. Conservation is preferable to restoration The analysis presented here explains why preserving predation through genetic rescue is preferable to attempting to restore predation, if the population should go extinct. The precautionary principle plays an important role in arriving at this conclusion. 4. Climate Change and moose The analysis presented here addresses the concern that detrimental effects of climate change on moose provides reason for allowing wolves to go extinct. The analysis indicates how that concern is misplaced. 5. Isle Royale s dynamic fauna The analysis presented here addresses the concern that wolves should be allowed to go extinct because humans may have played a role in wolves and moose colonizing Isle Royale or because extinction on a small island is a natural process that should be allowed. The analysis indicates how these concerns are misplaced. 6. Pandora s box? The analysis presented here addresses the concern that conserving Isle Royale wolves would represent a radical departure from NPS s strong, effective and time- tested tradition of giving deference to non- intervention as a method for fultilling its mission to preserve ecosystem health. There is also concern that conserving Isle Royale wolves would open Pandora s Box, justifying a myriad of misguided attempts to resist the inevitable affects of human- caused global change. The analysis indicates how these concerns are misplaced. Literature Cited...39 Appendices

3 PREFACE In 2012, the director of the National Park Service commissioned a report, Revisiting Leopold: Resource Stewardship in the National Parks. That report presents a management philosophy that confronts the unprecedented level of human- caused global changes changes such as climate destabilization, widespread carnivore extinctions, spread of exotic species and novel diseases, altered biogeochemical cycles, and rampant habitat destruction. While the analysis of policy is routinely the purview of government employees or their representatives, one conclusion of that report is that: the public must be made aware of the challenges facing the National Park System and urged and empowered to take action to preserve and protect these resources as part of their enduring responsibility as citizens. The analysis presented in this document is our accepting of that call to responsibility. The analysis is also constructed with special reference to the mission of the National Park Service, which is to preserve unimpaired the natural and cultural resources and values of the national park system for the enjoyment, education, and inspiration of this and future generations. We hope this document is found to be constructive and useful. 3

4 EXECUTIVE SUMMARY Isle Royale National Park is a remote wilderness island in Lake Superior where wolves and moose have been entangled in a dynamic interconnectedness and dramatic expression of life and death since wolves Tirst arrived there in the late 1940s by crossing an ice bridge from Canada. But the wolf population is small and decades of inbreeding have taken their toll. Human- introduced disease is also likely to have exacerbated the wolves situation. Ice bridges that once would have allowed mainland wolves to infuse the wolf population with new genes form far less frequently because of climate warming. Now Isle Royale wolves face considerable risk of extinction and humans have likely contributed signiticantly to this impairment. The impaired condition of Isle Royale wolves provides occasion to evaluate what kind of management response is appropriate given the wolf population s condition. There seem to be three options: (i) conserve Isle Royale wolves with an action known as genetic rescue by bringing some wolves to the island to mitigate inbreeding; (ii) restore predation by reintroducing wolves to Isle Royale, if and when they go extinct; or (iii) do not intervene, even if wolves go extinct. The mission of our National Park Service is to preserve outstanding examples of ecosystem integrity for the education and enjoyment of this and future generations. In this regard, Isle Royale is an exceedingly rare and outstanding kind of ecosystem on the planet because humans hunt neither its wolves nor moose, nor log its forests. Isle Royale is critically unique because each year many thousands of citizens experience and learn of that beauty. Isle Royale wolves are also the subject of the longest continuous study of any predator- prey system in the world. That research is some of the best- known research in the NPS system. This is germane because the NPS also has a mandate to 4 facilitate the development of scientitic knowledge about the natural world. Non- intervention is an inappropriate option because the presence of wolf predation is a critical component of health for ecosystems inhabited by ungulates. In general, top predators are important because exhaustive scientitic evidence has demonstrated their pervasive intluences on ecosystems intluences that are not substituted for by hunting or culling large ungulates. Nevertheless, humans have driven to extinction a staggering number of predator populations from many different kinds of ecosystems across the planet. The harm in that loss is well retlected by the conservation philosophy of Aldo Leopold, aspects of which are aptly captured by his oft- repeated aphorisms, To keep every cog and wheel is the Tirst precaution of intelligent tinkering and A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise. For all of these reasons, there should be wolves on Isle Royale as long as there are moose. Moreover, the precautionary principle indicates that conserving Isle Royale wolves through genetic rescue is considerably more appropriate than attempting restoration should they go extinct. One problem with attempting restoration is that it will almost certainly be associated with a signiticant discontinuity in predation processes. Even a brief discontinuity in predation would likely result in long- lasting detrimental impacts of the ecological integrity of Isle Royale s forests. For these reasons, genetic rescue seems the most appropriate response. Genetic rescue is the easiest, quickest, and most reliable means of preserving the ecosystem integrity of Isle Royale. In general, if a natural process is valued, it seems straightforward to conserve it, rather than let it be lost with the expectation that it can later be restored.

5 Some has said that the detrimental affects of climate change on the Isle Royale moose population is a reason not to conserve predation on Isle Royale. While moose are certainly affected by climate, existing evidence does not support the claim that climate change has impaired Isle Royale moose. It would be boldly unwise, with far reaching implications, to suggest that a top predator should not be conserved because climate change might threaten the viability of their prey at some indetinite time in the future. Some have suggested that Isle Royale s wolves should be allowed to go extinct because humans may have played a role in wolves and moose colonizing Isle Royale. One reason for this concern being misplaced is that the evidence for those claims about colonization is wildly speculative, at best. Others have suggested that Isle Royale s wolves should be allowed to go extinct because extinction is a natural process, especially on small, remote islands. Preserving (or restoring) wolf predation would interfere with that natural process. This perspective is misplace insomuch as evidence suggests humans played an important role in the impairment and potential extinction of Isle Royale wolves. Nevertheless, suppose that Isle Royale would, in some sense, be more natural if wolves were allowed to go extinct. Honoring extinction as a natural process might be appropriate if we lived in a world where intact ecosystems, complete with top predators, were common. We do not live in such a world. We live in a world that has summarily dishonored top- predators and their contributions to ecosystem health. Top predators have been impaired or driven to extinction across most of the planet s land- and sea- scapes. We have given more than enough honor to anthropogenic losses like those occurring with Isle Royale wolves. Because of the what we have done to the world, Isle Royale has become a globally unique ecosystem for simultaneously being inhabited by a top predator; for being intact in the sense that humans hunt neither wolves nor moose, nor log its forests; and for being accessible for citizens to witness. Honoring predation overrides the interest to honor extinction. Some are concerned that conserving Isle Royale wolves would open a Pandora s Box, justifying a myriad of misguided attempts to resist the inevitable affects of human- caused global change. A related concern is that conserving Isle Royale wolves would represent a radical departure from the NPS s strong, effective and time- tested tradition of giving deference to non- intervention as a method for fultilling its mission to preserve ecosystem health. In the past, the most reliable means of preserving the integrity of ecosystems required refraining from intervening with ecosystems, or at most intervening only to mitigate what humans had altered. Today, we live in a world where every portion of the earth has been altered by one or several human intluences climate change, exotic species, introduced diseases, widespread loss of predators, and so on. From today forward, there will be increasing instances where the preservation of an ecosystem s integrity will require human assistance. Wisdom will always be required for knowing when to assist. Intervening in such cases is not contrary to the mission of the National Park Service, it is essential for fultilling it. The wolf population of Isle Royale seems to be one of these cases. 5

6 1. THE HISTORY OF WOLVES AND MOOSE ON ISLE ROYALE 1 Isle Royale National Park is located in the northwest portion of Lake Superior, approximately 24 km from the Canadian mainland. Moose arrived on Isle Royale, apparently for the Tirst time, early in the 20 th century (Clark 1995). Moose most likely swam to Isle Royale (Mech 1966). However, some staff members of Isle Royale National Park (IRNP) and long- time residents of Isle Royale believe moose were brought to Isle Royale by humans (see also Scarpino 2011). There is no direct evidence to indicate how moose arrived. Moose lived on Isle Royale for about Tive decades in the absence of wolves. Without predation, moose increased to a very high level, perhaps 3,000 or more (>6 moose/km 2 ) by the late 1920s (Murie 1934). During this population increase, moose browsing dramatically impacted Isle Royale s forest vegetation (Murie 1934). The moose population crashed in 1934 due to an acute lack of food, increased again, and then died back once more in the 1940s (Krefting 1974). Signs of overbrowsing were still apparent in the early 1960s (Mech 1996). 6 Figure 1. The loca0on of Isle Royale Na0onal Park in Lake Superior, North America. Isle Royale moose were seen as overabundant during the 1920s and 1940s, and that concern was a primary wildlife management issue for the National Park Service in the late 1940s (Allen 1979). The impact of moose browsing during the Tirst half of the 20 th century was dramatic enough to motivate Adolph Murie (1934) to urge that moose be culled or removed, or that large carnivores be introduced. A second important argument for introducing wolves to Isle Royale was to provide the only sanctuary from human exploitation for wolves in the central part of North America (unpublished correspondence, Michigan Technological University archives). Aldo Leopold and Sigurd Olson also supported introducing wolves to Isle Royale in the 1940s (unpublished correspondence, University of Wisconsin archives). Durward Allen (US Fish and Wildlife Service) and Victor Calahane (National Park Service) discussed how wolves might be introduced (Allen 1979). These leaders were not only advocating on behalf of Isle Royale s wilderness character, they were also among the intellectual forefathers of our modern concept of wilderness, including the Wilderness Act of Lee Smits, a Detroit newspaper editor, strongly advocated wolf reintroduction and led a private effort (in collaboration with the NPS) that in 1952 resulted in the release of four captive- raised wolves to Isle Royale. These plans were carried out even though it was known that wolves had already colonized Isle Royale on their own, most likely by crossing an ice bridge sometime between 1948 and 1950 (unpublished correspondence, Michigan Technological University 1 This section is adapted from Vucetich et al. (2012) Managing wolves on Isle Royale, icons of wilderness culture in a changing world. George Wright Forum 29:

7 archives). Two of the four wolves that had been introduced by humans were killed or removed after they became a public nuisance and the other disappeared (Mech 1966), and detinitive evidence for the fate of the other two wolves does not exist 2. Ultimately, wild wolves Tlourished 2, and controversy over moose overabundance on Isle Royale largely ceased when wolves colonized the island (Peterson 1995). Since their establishment on Isle Royale, wolves have been the primary source of moose mortality, and moose have comprised more than 90% of wolves diet. In 1958 researchers began studying the population dynamics of wolves and moose on Isle Royale. Between 1958 and 1980 wolf predation had a substantial impact on moose abundance and rates of browsing (McLaren and Peterson 1994; Wilmers et al. 2006). Then in the early 1980s the wolf population crashed, declining 80%. The cause of the crash was almost certainly the combined intluence of food limitation and a disease that had been introduced by humans, canine parvovirus (CPV, Peterson et al. 1998; Fig. 2). 3,4 By the mid- 1980s the increased to approximately 5 moose/km 2, a remarkably (perhaps unprecedented) high density for a naturally regulated moose population (Karns 1998). With this high density the impact of moose on the forest also rose to levels never previously measured (McLaren and Peterson 1994). Although the presence of CPV was not detected after 1990 (Peterson et al. 1998), the disease fundamentally altered wolf population dynamics for the next several decades (Wilmers et al. 2006). SpeciTically, the period after the wolf crash was characterized by: (i) fewer wolves per moose than the two decades prior to the human- introduced disease (Fig. 3), and (ii) climatic variation replacing wolves as the dominant intluence on moose dynamics (Wilmers et al. 2006). Moreover, wolf abundance was tied tightly to the abundance of old moose 5 prior to 1980; but after 1980 wolf abundance became unrelated to abundance of old moose (Fig. 3, Vucetich and wolf population seemed to begin making a quick recovery, but then declined again and remained in the low teens for the better part of a decade. With wolf predation dramatically reduced, moose abundance Figure 2. Wolf and moose fluctua0ons, Isle Royale Na0onal Park, Red arrows point to wolf declines associated with the presence of canine parvovirus, a disease that humans brought to Isle Royale. See text for details. 2 See section 5 of this document for details. 3 After CPV was suspected to be the cause of the crash, NPS staff decided not to vaccinate Isle Royale wolves because doing so would have made it impossible to know if the disease was still present (antibody levels would be similar in response to disease exposure or vaccination.) The decision was based on the value of scientific knowledge, not the wilderness value of non-intervention (reference). 4 For additional details about canine parvovirus, see the appendix. 5 Old moose (>9 years of age) are an important source of food for the Isle Royale wolf population. 7

8 Peterson 2004). One plausible mechanism for these long- lasting effects is the general tendency for some ecosystems to remain altered for long periods following a major perturbation (Wu and Loucks 1995; Beisner et al. 2003). Another plausible mechanism is that the population bottleneck caused by the disease led to elevated levels of inbreeding, which reduced the wolf population s ability to control the moose population (Räikkönen et al. 2009). One long- lasting effect of the disease- induced wolf reduction during the 1980s was a Tivefold increase in moose abundance that ended when the population crashed in 1996 (Fig. 2). Approximately two thousand moose (~75% of the population) starved to death in a four- month period. The dramatic rise of moose abundance that coincided with the arrival of CPV and the subsequent collapse of the moose population in 1996, led to an altered age structure in the moose population that lasted for another 15 years (until about 2010). The altered age structure began with the substantial decline in birth rates of moose for several years following the crash. Those years of low birth rate led to a shortage of old moose by Because wolves cannot easily kill middle- aged moose, a shortage of old moose is associated with a shortage of food for wolves (Vucetich and Peterson 2004). The salient point is that the recent decline in wolf abundance is associated with a chain of events that coincide with the introduction of CPV by humans in the early 1980s. In addition to an altered age structure, total moose abundance declined by more than 50% between 2001 and 2011 (from ~1100 to ~500). These are the lowest estimates of moose abundance ever documented on Isle Royale, and they may play a role in the elevated extinction risk now facing wolves. The moose decline was likely caused by a set of three interrelated factors: wolf predation, a series of warm summers, and winter ticks (Dermacentor albipictus). In 2007, CPV was again detected in the wolf population, along with adenovirus, Anaplasma phagocytophilum, and West Nile 6. Human introduction is the most likely source of CPV and is at least plausibly, if not likely, the source of adenovirus and A. phagocytophilum. Although these diseases are not expected to impact the population dynamics of wolves, they Figure 3. Prior to 1980, when humans had introduced canine- parvovirus, wolf abundance was well correlated to the abundance of old moose (dashed line), which are a main source of food for Isle Royale wolves. During the next two decades that rela0onship dissolved (solid line). Inbreeding depression, exacerbated by human- introduced disease, is a plausible explana0on for the change (Wilmers et al. 2006). 6 More specifically, of six wolves tested in 2007, two had antibodies for CPV. In 2009, five wolves were tested for disease. One had antibodies for adenovirus and two had antibodies for CPV. In 2012, two wolves were tested. One had antibodies for A. phagocytophilum. Failing to detect antibodies for CPV in 2012 in two wolves may be not strong evidence that the disease is absent, given its presence in 2007 and Canine anaplasmosis is caused by one of two gram-negative, obligate, intracellular bacterial agents, A. phagocytophilum or A. platys. Infection with A. phagocytophilum, the species more commonly associated with anaplasmosis, causes lameness and is often confused with Lyme disease. Anaplasmosis is likely spread by ticks. A review of available evidence would likely show that reports of humans bringing ticks from the mainland to Isle Royale has been on the increase in recent years. The adenovirus test is for type II (respiratory infection) antibodies, though there is some cross reactivity with type I (infectious hepatitis). 8

9 could be detrimental to an isolated population with limited exposure or an inbred population. What is known is that the wolf population began declining when those diseases were detected. In particular, the population declined by 70%, from 30 to 8 wolves, between 2006 and Moreover, three of the island s XX wolves died when they fell into a mineshaft in 200X. The mineshaft is an artifact of human activities from the 19th century. It is, at the very least, plausible that human- introduced disease has played an important role in this most recent decline of wolves. Genetic deterioration The Isle Royale wolf population was founded in the late 1940s about 15 wolf generations ago. Analysis of mitochondrial DNA and the Y chromosome suggests that the population was originally founded by only one female and two males (Adams et al. 2011). The mean census size of the population has been ~24 wolves. In most years, the population includes 3 pairs of reproducing wolves. The effective population size of a population (Ne) quantities the rate of inbreeding for that population. The Ne for Isle Royale wolves is extremely low, i.e., ~3.8 (Peterson et al. 1998). The estimated inbreeding coefticient has been as high as ~0.80 (Fig. 4). Maintaining inbreeding coefticients below approximately 0.2 is generally considered a safe conservation standard (Frankham et al. 2007; Allendorf and Luikart 2003). The Isle Royale wolf population is, without doubt, highly inbred. Moreover, the incidence of congenital deformities in the vertebral column of Isle Royale wolf population has been high and on the rise (Fig. 5; Raikkonen et al. 2009). Congenital malformations that have been found include e.g. severe cervical anomalies, extra vertebrae and lumbosacral malformations (Raikkonen et al. 2009). A normal specimen has not been collected since A particular kind of deformity (lumbosacral transitional vertebrae, LSTV) that is Figure 4. The inbreeding coefficient for Isle Royale wolves, (Adams et al. 2011). The drama0c drop in the level of inbreeding that began in the late 1990s was the result of an immigrant wolf that arrived to Isle Royale by crossing an ice bridge. Figure 5. The incidence of malforma0ons in Isle Royale wolves ( ) has been increasing over 0me (p=0.02). Each symbol represents the year of birth for a different Isle Royale wolves, with (1) and without (0) vertebral malforma0ons. The red curve is a logis0c regression curve and represents the increasing probability of having a malforma0on over 0me (Raikkonen et al. 2009). Since 2005, the vertebral remains of more than XX addi0onal wolves have been inves0gated. Each of those individuals exhibit vertebral malforma0on. 9

10 common among Isle Royale wolves (Figs. 6 and 7) has also been studied in other wolf populations. It tends to be rare among wolves in outbred wolf populations, more common among inbred wolf populations, and quite common among Isle Royale wolves (Raikkonen et al. 2009, 2013). The effect of these malformities on Titness is unknown. However, the kinds of vertebral malformations common among Isle Royale wolves are likely detrimental (Morgan et al., 1993; Morgan, 1999; Steffen et al., 2004; Flückiger et al., 2006). For example, domestic dogs (Canis lupus familiaris) with lumbosacral transitional vertebrae tend to suffer from cauda equina syndrome, CES (Morgan et al., 1993). CES entails injury to the cauda equina, the most caudal region of the spinal cord and associated nerve roots (Berzon and Dueland, 1979). The consequences of CES, which are independent of its etiology (Morgan et al., 2000), are variable and include paresis or paralysis; deticits in placing reactions when walking; deticits in voluntary movement of the tail; loss of muscle tone causing weakness of the hind limbs and Tlaccidity of the tail, low back pain and incontinence (Morgan et al., 1993, 2000). Because of the clinical problems and genetic background associated with LSTV in purebred dogs, affected individuals are not recommended for breeding (Morgan et al., 1993; Wigger et al., 2009; Ondreka et al., 2013). Several Isle Royale individuals exhibited a sacral process with strong illial attachment on one side and a process of lumbar nature on the other side. This condition weakens the sacroiliac joint, may accelerate degeneration of the disc and result in disc protrusions (Morgan et al., 2000). Such disc degeneration with dorsal protrusion is also a common cause of CES. Dogs exhibiting disc protrusion also tend to suffer low back pain and lameness (Steffen et al., 2004). Asymmetrical sacroiliac attachment can also be associated with pelvic obliquity that can result in gait irregularities (Larsen, 1977) and detrimental development of the hip joints (Morgan et al., 2000). Some have expressed doubt about the relationship between LSTV and inbreeding, citing an unpublished analysis suggesting that LSTV is common in an outbred population of wolves in Wisconsin (S. Ware, pers. comm.). Though we have been told of this analysis, it has not been, to our knowledge, prepared as a formal analysis for review by scholars with relevant expertise. An important concern is that the frequency of LSTV in Figure 6. The red line highlights a gross malforma0on (lumbosacral transi0onal vertebrae) in the posterior edge of the sacrum of an Isle Royale wolf. This and other vertebral malforma0ons observed in Isle Royale wolves are thought to be caused by inbreeding. Figure 7. A par0cular kind of malformity (lumbosacral transi0onal vertebrae), is drama0cally more common among Isle Royale wolves than wolves in outbred popula0ons (Raikkonen et al. 2009). 10

11 a population depends on the standards used to determine whether any particular specimen should be classitied as exhibiting LSTV (Lappalainen et al 2012, Ondreka et al. 2013). Even if the high incidence of malformities in Isle Royale wolves were discounted, the tendency for those malformities to have increased over time is clearly suggestive of inbreeding depression (Fig. 7). Most importantly, if those malformations were overlooked entirely, the evidence that Isle Royale wolves have been exhibiting high rates of inbreeding and inbreeding depression is overwhelming (Figs. 4 and 8). In 1997 a male wolf (M93) immigrated from Ontario to Isle Royale by walking across an ice bridge. The inbreeding coefticient plummeted in the years immediately following his arrival, but then began to rise quickly again (Fig. 4). Within 2.5 generations of his arrival, he was related to every individual in the population and his ancestry Figure 8. The drama0c rise in ancestry of the immigrant wolf is defini0ve evidence for how severely impaired Isle Royale wolves had become due to inbreeding (Adams et al. 2011). The rise in ancestry quan0fies the extent to which the immigrant s lineage outcompeted the na0ve Isle Royale lineage. The rela0ve performance of the two lineages is a direct measure of the two lineage s rela0ve fitness. constituted 56 per cent of the population (Fig. 8). The superior performance of M93 and his lineage, compared to the performance of native Isle Royale wolves is unequivocal evidence that these wolves have been suffering signiticant, if not severe, inbreeding depression (Hedrick et al. 2011). L. David Mech, an intluential wolf biologist from the U.S. Geological Service, has been outspoken about his ardent belief that Isle Royale wolves are not suffering in any signiticant way from inbreeding (Mech and Cronin 2009, Mech 2013). His belief and the premises upon which they are based are well known to be at odds with leaders in the scientitic study of conservation genetics (P. Hedrick, pers. comm.). The disparity between his beliefs and the community of conservation geneticists is relevant because L. D. Mech s misunderstanding of conservation genetics lies at the root of his vocal belief that the NPS should refrain from implementing genetic rescue with the Isle Royale population. L. D. Mech s misunderstandings are not moot. For example, he was one of four presenters at a public forum held on the topic of whether or how to conserve Isle Royale wolves 7. While this issue depends critically on a proper understanding of conservation genetics, none of the presenters had expertise in that Tield. Phil Hedrick, a world authority in the Tield of wolf genetics, had agreed to participate in that forum, but was not invited. That forum included a survey of observers from the general public, who had witnessed the forum. Presumably that survey will be an important element of the NPS s decision- making process. Because L.D. Mech is an intluential voice, one should expect that his misunderstanding of the relevant science has affected the outcome of that survey. Finally, the immigrant wolf, M93, arrived to Isle Royale immediately after the moose population had crashed (Fig. 9). That decline was due, in large part, to a severe winter and was unrelated to wolf predation. That reduced availability of prey represented a challenging 7 The forum was held in June 2013 in Minneapolis, Minnesota and had been organized by the National Parks Conservation Association. 11

12 Figure 9. The gene0c rescue event that occurred with the arrival of immigrant M93 began in 1997, and that period is highlighted in gray. Panel (a) shows how that rescue took place immediately following the crash of the moose popula0on. Panel (b) shows how the moose- to- wolf ra0o, an important predictor of food availability for Isle Royale wolves (Vuce0ch et al. 2002), also crashed just as the rescue took place. environment in which Isle Royale wolves had to persist. Their persistence through that period was almost certainly aided by the genetic rescue that occurred with M93 crossed an ice bridge in 1997 (Adams et al. 2011). Reproductive failure There is no evidence that Isle Royale wolves reproduced in 2012 (Vucetich and Peterson 2012, 2013). As of July 1st, 2013, no reproduction had been detected for the year L. D. Mech has raised the concern that reproductive failure is common in wolf populations and observing reproductive failure on Isle Royale is not evidence that Isle Royale wolves Figure 10. The incidence of ice bridges to Isle Royale ( ) has been decreasing over 0me (p<0.01). Each symbol represents a different year with (1) and without (0) ice bridges. The red curve is a logis0c regression curve and represents the decreasing probability of ice bridges. During the mid 20th century, ice bridges occurred more frequently than 8 out of every 10 years. By 2013, they occur less frequently than once every 15 years. face critical risk of extinction due to inbreeding depression. Two observations indicate how this concern is misplaced. First, if evidence about reproduction were overlooked entirely, there is overwhelming evidence that Isle Royale wolves suffer signiticant, if not severe, inbreeding depression and face considerable risk of extinction. Second, reproductive failure is absolutely and unequivocally uncommon on Isle Royale. Reproduction has been monitored every year for the past 42 years. In that time, 2012 is the Tirst year with no evidence that wolves had reproduced. The Tirst observation clearly makes the second observation relevant and noteworthy. The importance of ice bridges Wolves colonized Isle Royale, on their own, sometime between 1948 and Genetic analyses also indicate that a lone male wolf immigrated to Isle Royale and mated with Isle 12

13 Royale wolves on one to three occasions between 1950 and 1997 (Adams et al. 2011). Moreover, an entire pack of wolves came to Isle Royale in After being attacked by resident, Isle Royale wolves the pack returned to the mainland 8. Each of these events occurred when wolves crossed an ice bridge connecting Isle Royale to the mainland. Anthropogenic climate warming has greatly reduced the frequency and duration of stable ice bridges (Fig. 10). During the 1960s stable bridges formed in most years and lasted for several weeks to well over a month. Now ice bridges are rare. Lake Superior is expected to be ice free by 2040 (Austin and Colman 2007). The frequency at which wolves seem to have used ice bridges in the past and the dramatic reduction in frequency of ice bridges suggests that humans have been and continue to impair the likelihood that wolves would mitigate rates of inbreeding by immigrating to Isle Royale. The loss of ice bridges also mean that wolves are very unlikely to re- colonize Isle Royale, should the population go extinct. Conclusion Isle Royale wolves face considerable risk of extinction. They are severely inbred (Fig. 4). They suffer from signiticant, if not severe, inbreeding depression (Figs. 6-9). For the past two years (2012 and 2013), predation rates were the lowest that have ever been observed. During that same period of time, the moose population has increased by ~70%. As such, the intluence of predation has been essentially nil. It is at least plausible, and may be likely, that diseases brought by humans (Fig. 2) have exacerbated rates of inbreeding, the impact of inbreeding depression, and the risk of extinction that wolves currently face. It is at least plausible, and may be likely, that anthropogenic climate change has been and continues to impair the likelihood that wolves would mitigate rates of inbreeding by immigrating to Isle Royale and would make their re- colonize Isle Royale a very unlikely event (Fig. 10). 8 Except one black wolf remained. It continued to live on Isle Royale for another five year. But it never reproduced. 13

14 2. AS LONG AS THERE ARE MOOSE, THERE SHOULD BE WOLVES 9 We structure this analysis by identifying and describing some key values that would be affected by any decision about how to manage Isle Royale wolves. Afterward describing these values, we evaluate whether they are best honored by preserving predation processes on Isle Royale or by not intervening. The value of non- intervention. A central management principle of wilderness policy is the principle of non- intervention, which is sometimes casually characterized as: not intervening, so that nature can take its course. As a central principle of wilderness, non- intervention is not valuable for its own sake; instead it is thought to be valuable as a means toward two critical ends. First, it can prompt an attitude of humility that mitigates pathological obsessions to control nature (Meffe and Holling 1996; Landres 2010). Second, using language of the U.S. Wilderness Act 1964, non- intervention can help maintain natural conditions and the primeval character of landscapes that have not already been intluenced by human activities 10. According to well- established wilderness policy, non- intervention is not, in general, a preferred management option when nature s course has been altered by humans. In such cases, intervention is commonly adopted in an effort to mitigate human intluence (Dawson and Hendee 2008; Cole and Yung 2010). During the past three decades the wolf population has been affected by disease and moose population decline, which was intluenced by predation, ticks, and climate warming. Humans had a nontrivial hand in all of these intluences. If wolves were to go extinct, it would be plausible to conclude that humans had exacerbated the extinction risk of wolves during the past three decades and that humans have signiticantly reduced the chances of natural recolonization. Given that intervening to mitigate human intluences is a wilderness value, intervention in the Isle Royale case would enhance and honor wilderness values of Isle Royale. One might object and suggest, hypothetically, that Isle Royale wolves would go extinct due to inbreeding and chance demographic events (e.g., skewed sex ratio) that are likely to occur naturally and inevitably on a small island. However, a fundamental principle of extinction is that it is not in general the result of a single cause. Extinction is almost always the result of an interrelated web of both proximate and ultimate causes. Even if inbreeding or natural random chance occurrences were part of the extinction process, the salient conclusion remains: Human actions importantly increased extinction risk and decreased the chance of re- colonization. The value of wilderness character. Preserving the wilderness character of a landscape is another fundamental value of wilderness management, particularly for Isle Royale National Park (U.S. NPS 1999). Wilderness character arises from the properties of a landscape that evoke a feeling or emotion that the landscape is wild and primeval. Wilderness character is also a special kind of sense of place, which is formed when the natural history, culture, and geography of a place commingle in our minds and form the stories lyrical stories and scientitic stories that detine a place. Sense of place and wilderness character are 9 This section is adapted from Vucetich et al. (2012) Managing wolves on Isle Royale, icons of wilderness culture in a changing world. George Wright Forum 29: The US Wilderness Act of 1964 says: An area of wilderness is further defined to mean an area of undeveloped Federal land retaining its primeval character and influence which is protected and managed so as to preserve its natural conditions. 14

15 critical because they provide the points of connection between a place and a person s knowledge, emotions, and values. Wolves are a critical component of Isle Royale s wilderness character not merely the presence of wolves, but the interactions among wolves, moose, and the forest, all in the absence of any hunting or logging by humans. This condition is, on our planet today, rare, special, and critical for evoking a feeling that Isle Royale s landscape is wild and primeval 11. Wolves and their connections provide the most important and widely appreciated narratives that create a wilderness sense of place for this island. This importance is retlected in NPS policy, interpretive activities, and widespread interest among park visitors, scientists, and supporters of wild places (see Appendix 2 for details). For Isle Royale, wolves are the icons of wilderness culture. Therefore, allowing wolves to remain extinct on Isle Royale would signiticantly wound Isle Royale s wilderness character and important points of connection between people and Isle Royale. It may seem odd that non- intervention would contlict with the preservation of a land s wilderness character. However, this ironic juxtaposition is not odd, so much as it is the result of a tragedy: humans have reduced the planet s unexploited landscapes to small remnants in remote places. The value of ecosystem health. In the United States, the preservation of ecosystem health is also broadly appreciated as a central value of wilderness (Nelson 2009a, 2009b). Ecosystem health has been detined, roughly, as the structure, function, composition, and resilience of an ecosystem that was native prior to the modern era (Rapport et al. 2002). Ecosystem health is a coherent blend of normative and objective concepts (Nelson 2009a). That is, society, led by the voices of conservation leaders, has indicated that structure, function, composition, and resilience are the ecosystem properties that have moral value; and, science is able to objectively measure and evaluate these properties. The meaning of ecosystem health is both Tlexible enough to be applied to any particular place or time and concrete enough to make it a useful platform for management. A great deal of conservation science aftirms that ungulate overabundance is a widespread and severe threat to ecosystem health, and that top predators, like wolves, are vital components of ecosystem health for limiting ungulate abundance (Miller et al. 2001; Beschta and Ripple 2009; Estes et al. 2011). North American national parks, in particular, have been challenged by this fact (e.g., Rocky Mountain, Great Smoky Mountains, and Yellowstone national parks). In Canada s Gros Morne National Park the loss of wolves resulted in moose overabundance that degraded 44% of that park s forests (Woodley 2010). The health of island ecosystems seems particularly vulnerable to ungulate overabundance in the absence of predators, for example at Anticosti Island, Quebec (Potvin et al. 2003) and North Manitou Island of Sleeping Bear Dunes National Lakeshore (Case and McCullough 1987). In several parks where wolves have (or had) been excluded, hunting or culling of ungulates has been, with great controversy, considered or mandated (e.g., Rocky Mountain and Yellowstone national parks). Unless possibly very high rates of moose harvest were mandated, 12 allowing wolves to be 11 This value is related to another traditional value of wilderness, i.e., wilderness as a sanctuary for nature (see Leopold 1949, Sanders 2008). Wolves on Isle Royale have been and continue to be the only wolves in North America who can live their lives without the risk of being legally hunted or poached. That Isle Royale might be a sanctuary for wolves had also been a motivation for those who had originally considered reintroducing wolves to Isle Royale in 1940s and 1950s (unpublished correspondence, Michigan Technological University archives). 12 Although non-extraction is an important principle of wilderness, hunting (and fishing) is permitted in many federally designated wilderness areas. While it may seem far-fetched to be concerned that the loss of wolves would lead to hunting Isle Royale moose, that prospect has been considered in cases where the absence of top predators led to ungulate overabundance in a national park (e.g., Theodore Roosevelt National Park, Rocky Mountain National Park). 15

16 lost from Isle Royale would signiticantly diminish its ecosystem health. A detractor of this perspective might suggest that using ecosystem health in this way to justify wolf reintroduction disguises a romantic and outdated desire to preserve vignettes of primitive America, and that wolves were a critical part of IRNP s ecosystem health from ca until the time of their extinction, but not afterward. Certainly, top carnivores were an important aspect of historic conditions. This does not mean, however, that maintaining and restoring top carnivores to places where large herbivores live represents maintaining vignettes of primitive America. Instead, top predators are a basic principle of ecosystem health (Estes et al. 2011). A detractor might also object by Tirst citing NPS management policies (2006) which mandates maintain[ing] all the components and processes of naturally evolving park ecosystems, including the natural abundance, diversity, and genetic and ecological integrity of the plant and animal species native to those ecosystems [and recognize] natural change as an integral part of the functioning of natural systems [italics added]. With this policy in mind, a detractor might assert that the detining characteristic of Isle Royale s ecosystem health is its small, isolated nature, where colonization by wolves and moose are rare accidents and extinction is a natural process. Isle Royale is a dynamic place, and wolves and moose have been a part of Isle Royale s history for only a short time. For these reasons, the argument would go, losing wolves from Isle Royale leaves the place no less healthy than it had been before their arrival. The weakness of this argument may be Tirst recognized by noting that wolf ungulate vegetation interactions used to be a dominant set of ecological relationships throughout much of North America. By the 21 st century, however, humans have restricted such relationships, operating in the absence of human exploitation, to very rare and small remnants. The detractor s perspective pits the value of one natural process (extinction on small islands) against another (predation) (Peterson and Krumenaker 1989; Peterson 1995). The detractor s position overlooks the process of wolf predation, which is essential to the health of Isle Royale s ecosystem. The weakness of the detractor s position arises from the concept of natural being fraught with debilitating dilemmas that have remained intractable despite being considered for more than two millennia (Desjardins 2000; Cole and Yung 2010). The concept of natural is increasingly difticult to make sense of because of human impact on the planet. Because of these problems with the concept of natural, Parks Canada recently replaced naturalness with ecological integrity 13 as a general management objective for their natural areas (Woodley et al. 2010). A specitic example of this attitude is likewise retlected in the general management plan for IRNP (1999), which indicates that preserving and protecting the park s wilderness character, natural resources and ecological processes is one of the park s purposes and that preserve ecological integrity of Isle Royale is one of the park s priorities (NPS 1999). Again it seems ironic to pit the value of non- intervention and natural processes (like extinction on small islands) against the value of ecosystem health. However, the tragedy is having reduced the planet s unexploited areas to small remnants, resulting in the need to actively maintain ecosystem health in these tiny remnants. This concern is aptly captured by: What escapes the eye... is a much more insidious kind of extinction: the extinction of ecological interactions (Janzen 1974). The value of science. The primary scientitic mission of the Isle Royale wolf moose project is to document and understand predation and herbivory two of the most important ecological relationships on the planet. Isle Royale s biogeography is critically unique for this mission. 13 Ecosystem integrity and ecosystem health are essentially synonymous. 16

17 The island s isolation means that Tluctuations of wolves and moose are caused almost entirely by births and deaths, not immigration and emigration. Isle Royale is also the only location on the planet where wolves and moose interact in the absence of other important predators and prey, such as coyotes, deer, and bears. Studying simplitied food webs is critical to ecologists understanding of nature. Perhaps most importantly, the wolves, moose, and vegetation on Isle Royale are not hunted or logged. This circumstance is very rare on the planet today. Wilderness areas are uniquely valuable to science as places for establishing baselines of ecosystem health that can be applied in areas far beyond wilderness. These baselines cannot be established overnight, as they require long- term research. Long- term research is not only rare, it is valuable for its distinctive ability to help us better understand how ecosystems are affected by unexpected events, rare events, and multicausal relationships (Turner et al. 2003). The Isle Royale wolf moose project is the longest study of any predator prey system in the world. The project has made valuable scholarly contributions on a wide range of topics, including population biology of wolves (e.g., Vucetich and Peterson 2004), effect of wolf predation on moose (e.g., McLaren and Peterson 1994, Vucetich et al. 2011), effect of climate and disease on population dynamics (e.g., Post et al. 1999, Wilmers et al. 2006), the nature of extinction risk (e.g., Vucetich et al. 1997, 2009), the effect of genetic rescue on population dynamics (e.g., Adams et al. 2011), the nature of inbreeding depression (e.g., Räikkönen et al. 2009), connections between individual life history and population dynamics (Peterson et al. 1984), social behavior of wolves (Vucetich et al. 2004), the effect of the U.S. clean air and water legislation on mercury pollution (Vucetich et al. 2009), the role of predation in nutrient cycling (Bump et al. 2009), the ecology of arthritis in moose (Peterson et al. 2011), the relationship between ecological science and environmental ethics (Nelson et al. 2010; Vucetich et al. 2010), and the relationship between ecological science and sociology (Gore et al. 2011). Papers from the wolf moose project have been cited more than 1,200 times during the past 10 years. The scientitic value of the wolf- moose project was recently aftirmed by an independent panel of scientists commissioned by the National Park Service who reviewed the state of science in Isle Royale National Park (Schlesinger et al. 2009). 14 Allowing wolves to be excluded from Isle Royale would cause the end of wolf- moose research and its extensive outreach program. SuperTicially, one might think the loss of wolves would simply cause the wolf moose project to become a moose vegetation study. While studies focusing on three trophic levels are rare, studies focusing on ungulate herbivory in the absence of top predators are extremely common. Moreover, the approach and methods used to conduct state- of- the- art herbivory research are very different from the methods appropriate for studying interactions across three trophic levels. As such, the Isle Royale wolf moose project is in no position to effectively compete for funding from the US National Science Foundation, the loss of which would be the death of the project. In 2009 and 2010, the wolf moose project proposed research to NPS that would expand the moose- vegetation component of the research. NPS chose to not fund that research. There is little reason to think that the longest study of any predator prey 14 The number two Priority Recommendation of this panel was Maintain financial support for and expansion of ongoing studies of moose wolf dynamics at Isle Royale. 17

18 system in the world would survive the loss of wolves from Isle Royale. Should science ever, in principle, trump wilderness values in a wilderness area? Well- established wilderness policy clearly indicates the answer to this question is, yes. 15 The question at stake here is: Should one of the longest and most prominent research projects to ever take place in a federally designated wilderness be sacriticed for the far- from- solid claim that doing so might aftirm the value of non- intervention? The value of education. Wilderness policy also recognizes the vital role that education about wilderness character, resources, and ethics play in maintaining values that promote healthy relationships with nature ( in NPS 2006). The educational mission of the Isle Royale wolf moose project is to use scientitic discoveries about the wolves and moose of Isle Royale as a basis for generat[ing] a sense of wonder toward nature in as many people as possible, a sense of wonder that would inspire a caring relationship with nature (Vucetich 2010). The mission is not only true to the project s science, but it is informed by inclusion of an environmental philosopher (MPN) as part of the wolf- moose project. To this end, associates of the wolf moose project disseminate knowledge to the general public through a vigorous outreach program that includes books, DVDs, annual reports, a website, pieces of art, museum exhibit displays, and public presentations delivered to thousands annually by the project principal investigators and other associates, and opportunities for members of the general public to volunteer for the research project (see Appendix 3 for details). The extent of outreach associated with the wolf moose project and sophistication of its purpose is rare among research projects of any kind. Wilderness policy also recognizes that recreation is an important value that is sometimes associated with compromising the wilderness value of non- intervention ( in NPS 2006). Hiking trails, boat docks, and sleeping shelters (and the machinery and infrastructure necessary to maintain them) are examples of such concessions. The wolf moose project also represents an important form of recreation. For many people, participating in the wolf moose project s outreach activities represent a particularly deep kind of recreation, an opportunity to re- evaluate and subsequently re- create their relationship with nature. Synthesis. Should the wolves of Isle Royale go extinct, human response involves Tive principal values: non- intervention, wilderness character, ecosystem health, science, and education. Failing to reintroduce wolves would: dismiss the value of science and education by resulting in the end of a long- term research project that is globally signiticant, unique, and irreplaceable. more likely denigrate the value of non- intervention because this value is contingent on humans not having impaired the wolf population s viability or the chances for subsequent recolonization; human activities have impaired these processes. diminish the island s wilderness character and ecosystem health; For these reasons, failing to reintroduce wolves would degrade the wilderness value of Isle Royale, 15 Scientific activities are to be encouraged in wilderness. Even those scientific activities (including inventory, monitoring, and research) that involve a potential impact to wilderness resources or values (including access, ground disturbance, use of equipment, and animal welfare) should be allowed when the benefits of what can be learned outweigh the impacts on wilderness resources or values. ( of U.S. NPS 2006). Additionally, Isle Royale s General Management Plan (1999) states that two of the park s five purposes are not only to preserve and protect the park s natural resources and ecological processes but also to provide opportunities for scientific study of ecosystem components and processes. 18

19 and wolf reintroduction is an appropriate way to honor that value. Lingering concerns about the inappropriateness of intervening in a wilderness are further mollitied by the evolution of our understanding of wilderness. That is, ecosystem health may well be superseding non- intervention as the central value of wilderness (Cole and Yung 2010). These perspectives are complemented by sociological research indicating that an overwhelming majority of Michigan residents do not believe that allowing nature to take its course is an adequate reason to allow the extinction of Isle Royale wolves and support the belief that Isle Royale wolves should be maintained should they begin to disappear from the park. 16 Would reintroducing Isle Royale wolves because of their contributions to ecosystem health in boreal forests open a kind of Pandora s box requiring one to consider introducing black bears which also prey upon moose in many boreal forest ecosystems, and consider reintroducing lynx and caribou to IRNP for their contributions to ecosystem health? Perhaps. There would be nothing wrong with conducting an analysis like t h a t p r e s e n t e d h e r e t o c o n s i d e r t h e appropriateness of introducing or reintroducing these species to Isle Royale. The development of such arguments is beyond the scope of this essay, except to mention a few considerations. First, the ecology of black bear predation on moose differs substantially from the ecology of wolf predation. If wolf predation is essential for ecosystem health where moose live, then bear predation is unlikely a substitute for wolf predation. Consequently, if a robust argument could be developed for black bear introduction 17, it is difticult to imagine how that would end up being an argument against wolf reintroduction. Similarly, if a robust argument could be developed for establishing a lynx population, such an argument is unlikely to be an argument against wolf reintroduction. Caribou persistence on Isle Royale is unlikely in the presence of wolves (Cochrane 1996). As such, an argument for caribou reintroduction may well be an argument against wolf reintroduction. If so, one would have to assess whether the value of caribou on Isle Royale would outweigh the value of wolves. Both species probably have similar value in terms of wilderness character. However, the scientitic and educational value of caribou on Isle Royale is likely less than the scientitic value of wolves on Isle Royale (because the wolves have been studied for over half a century). Introducing caribou, rather than wolves, would add a second large ungulate to an ecosystem lacking a top predator. While these considerations do not represent a complete argument, they do suggest, at least prima facia, that a complete argument would support wolf reintroduction. General lessons. Our ideas about what wilderness is, and why wilderness is valuable, change over time. During the Tirst half of the 20 th century, wilderness philosophy focused on woodcraft, a principle of self- sufticient living in the wilderness characterized by experiences like utilizing trees for temporary structures and Tires. By the mid- 20 th century wilderness leaders grew to realize that the growing number of people wishing to have this kind of wilderness experience in a diminishing number of wilderness areas would result in a devastating loss of wilderness. From this concern grew a new philosophy of wilderness, a philosophy associated with the principles of leave- no- trace, and along with it the principle of non- intervention (Turner 2002). By the early 21 st century, wilderness areas had been reduced even further and human impacts on those areas had become pervasive. 16 Specifically, 62% of surveyed residents strongly or moderately disagreed with the statement we should let nature take its course even if wolves start to disappear from Isle Royale National Park, and 73% of respondents strongly or moderately agreed with the statement wolf numbers should be maintained in Isle Royale National Park if they start to disappear from the park (Kellert 1990, pages 57 and 61). 17 Other considerations, beyond the scope of this essay, suggest it is doubtful that a robust argument could be developed. 19

20 Anthropogenic climate change and exotic species have altered the course of nature in nearly every protected area. Consequently, the principle of managing for naturalness is becoming less coherent, and the value of non- intervention as a means of preserving naturalness is becoming less useful. The transition from naturalness to ecosystem health as a basis for understanding the value of wilderness was retlected in the life- long development of Leopold s thought on wilderness (Nelson 2009b). This transition was fully articulated by wilderness scholars from the 1980s to 2000s (Callicott and Nelson 1998; Nelson and Callicott 2008). By 2010, these ideas were being appreciated by land management agencies including the U. S. National Park Service (Cole and Yung 2010, Harmon 2010, Parsons 2011). The emerging challenge is to better understand the meaning of ecosystem health in a world that appears committed to anthropogenic climate change, species invasions and extinction, and increasing resource extraction (Vucetich and Nelson, in press). 20