Overview:

Isle Royale is an island in Lake Superior that is designated as a Wilderness Area and managed by the National Park Service. In the 20th century, wolves and moose migrated to the island and their dynamic spurred one of the longest predator-prey studies in history. Now, the wolf population has dropped to 2 and the Park Service is planning a major intervention that will install an entirely new, synthetic population of wolves on the island. This plan is the result of myopic research perspective and disregard for eco-evolutionary dynamics. It is bad policy and even worse science. Here’s why:

Background:

Isle Royal is a smallish-island (just over 200 square miles) that sits about 8 miles from the north shore of Lake Superior. (Although it is small, it is large enough to host its own internal lake with an island, making it, as upper-midwesterners are fond of point out, the largest island on the largest lake on the largest island on the largest lake in the world.) The Isle and its many tiny satellite islands became a National Park in 1940 and were designated as a federal Wilderness Area in 1976.

Because the island is small and a long swim from the mainland, large fauna populations have been inconsistent denizens, historically. Moose first arrived on the island in the early 1900s. Wolves followed the moose in the 1940s, adding two major trophic levels to the island ecosystem. The complex predator-prey interactions became one of the classic test cases of ecological theory (see Peterson et al. 1984; McLaren & Peterson 1994).

Over the decades, the wolf and moose populations have demonstrated a standard predator-prey oscillation, with the wolves generally bouncing around about 20 individuals, but reaching a population maximum of 50 individuals in the 1980.

However, Isle Royale is a small place. Small islands are more susceptible to tipping points on the roller-coaster of demographic stochasticity. It’s kind of like drunkenly walking along the centerline of a bridge versus drunkenly walking a tightrope. If you stumble off course too far on the bridge, you have the latitude to recover and get back on course. Too big a waiver on a tightrope and you’re done for. The small size and isolation of Isle Royale makes it a tight rope for large predators. Like all oscillatory ecological patterns, what goes up eventually comes down, and in the last decade or so, the wolf population has declined in a mirror-like inversion of the population boom in the 1980s. As of this year, there are only two wolves left. As per the dynamics of island-biogeography, the natural course looks like the rein of the wolf will eclipse on the island, probably followed by a boom and eventually extirpation of moose, and the island will continue along as it did for the many decades prior to the most recent immigration events. That is, until the next colonists arrive, as has happened multiple times in the past. Coyotes immigrated and blinked out in 50 years in the early to mid-1900s. At times, lynx and caribou both made the pilgrimage to the island and subsequently slipped off the tightrope.

The issue:

Now, the National Park Service has released an Environmental Impact Statement (EIS) for a plan to install a new populations of wolves on the island (available here). If you are unfamiliar with the NEPA process, here’s how it works: When a land management agency like the National Park Service wants to embark on a project that might run counter to its mandate and/or result in large impacts, they are required to vet all potential options, usually as an EIS, and ask for the public’s comments on the plan. After the revision process, they make a final decision to enact one of those potential options, the “preferred alternative.”

Since 99% of  Isle Royale Park is a designated Wilderness, “where the earth and its community of life are untrammeled by man” and “generally appears to have been affected primarily by the forces of nature, with the imprint of man’s work substantially unnoticeable” (Wilderness Act, 1964), shipping in a boatload of wolves to manipulate the ecosystem required an EIS.

As a scientist and especially as an ecologist, I tend to view Wilderness Areas as our most critical ‘controls’ or ‘baselines’ for science to contrast other areas where human impact alters systems. Though every system is touched by human impact to some extent, there is huge value in preserving the least impacted places in an unmanipulated state. As an analogy, a blemished diamond might be worth a little less than a perfect diamond, but that doesn’t reduce it to equal value with a lump of coal.

But, not all scientists think that way.

To introduce or not to introduce:

The push to introduce wolves to Isle Royale has been championed primarily by two researchers at Michigan Tech, John Vucetich and Rolf Peterson, whose careers are rooted in the Isle’s wolf-moose study.

I first heard about this proposal when Vucetich gave a presentation at the Sigurd Olsen Environmental Institute. At the time, it wasn’t the science that bothered me about the presentation–it was the patent misrepresentation and obvious straw-man Vucetich employed to characterize the intention of the Wilderness Act. Since then, these researchers have made major pushes in film (and this one) and popular press to portray wolves as an ever-present and integral part of the Isle Royale ecosystem, and pit the “health” of the ecosystem against what they believe is an outdated philosophy of conservation.

Essentially, their argument is that since climate change impacts the whole globe, no wilderness is really free of human manipulation, so we should be free to further manipulate it to our own design. They explicitly argue for “new visions for the meaning of wilderness,” with their preferred vision being “a place where concern for ecosystem health is paramount, even if human action is required to maintain it” (from here).

Intentionally or not, their use of relativistic “ecosystem health” rhetoric and attempts to stretch the ‘wilderness myth’ concept into their own application has thoroughly muddied the debate.

And it’s resulted in a lot of public confusion on the topic. For instance, here’s one comment I pulled from the public response in the EIS:

I have visited Isle Royale twice and it remains one of my favorite places in the world. The wolves and the moose have become a part of the island and that is a good thing. Wolves and moose aren’t faring well on the mainland due to politics ignorance and climate change. Isle Royale remains a unique microcosm where we can still observe and study this ancient predator-prey relationship. In a world where species are becoming extinct on a daily basis, this rare relationship has endured and that should be given a lot of weight when making the decision of what to do about the wolf-moose problem on Isle Royale. Please use common sense and act sooner rather than when it is too late.

First off, it’s not an ancient relationship (it’s only been going on for 60 years on the island), and it’s not a rare relationship (wolves eat moose all over the continent all the time). What makes it “rare” is the fact that it happens without human intervention (at least until NPS takes control of the population) on an isolated island with researchers tracking every move.

This person’s comment shows that opinions on the wolf issue are completely colored by human perception: i.e. anything that happened before your lifetime is “ancient,” anything that looks the way it is when you first saw it is “natural,” if you’ve only heard about something in one place, it must be “rare,” etc. The most pernicious perception is that the only species that are worth concerning ourselves with are the big ones with faces that you can relate to (after all, amphibian populations fluctuate on and off in ponds all over the upper midwest following the exact biogeographic pattern as the wolves of Isle Royle, but I’ve yet to see an outrage).

Even the main proponents of wolf introduction, Vucetich et al. and the National Parks Conservation Association invoke the myth that a “sustainable” wolf population is critical to the island’s “health.” Considering that wolves only appeared on the island within a human lifetime and probably blinked on and off the island historically, wolves are only an ephemeral component of this dynamic ecosystem. They never have been “sustainable,” and if ecosystem “health” hinges on the presence of wolves, the island has always been naturally unhealthy.

The rhetoric of “healthy” ecosystems is useless in science, because its meaning is entirely relative. Rolf Peterson, the researcher who initiated the moose-wolf study in the 70s, states that, “There’s a mythical belief that Isle Royale has been working well because we kept our hands off it; my opinion is, it worked well because there were wolves there” (from here). You can only consider a wolf-inhabited Isle Royale as “healthy” if you define a “healthy” ecosystem as one that looks the same way it did when you started your research plan. The real myth is conflating wolf presence with Isle Royale’s natural state, and in this case, it seems a personal mythology crafted to shore the legacy of Peterson’s research project.

The Park’s plan:

The preferred action of NPS is to install 20-30 wolves on the island over the next 3 years, and if those don’t take, to continue introducing for 2 more years.

Originally, the proponents of airdropping new wolves onto the Isle proposed it as genetic “rescue.” But with only two post-breeding age, inbred stock left, there is little chance that new wolves will breed with the two relics. Thus, in reality, this is not a genetic rescue project, it is a genetic replacement project.

So, where do the replacement wolves come from? The EIS suggests that wolves should be sourced from the mainland near the Park, but that many different populations around Lake Superior should be mixed on the island. They also suggest sourcing wolves with experience hunting moose (which are rare in mid-western populations).

Will a new population fair better? The reason wolves lost the plot in the first place was due to the ubiquitous force of natural selection. When faced with strong selection pressure, organisms are faced with three choices: move (not possible on an island), adapt, or disappear. The current wolves were not able to adapt to the ecological scenario they found on the island, so they are disappearing. The NPS knows that new wolves will be even more likely to succumb to selection pressure because they will not be locally adapted. This is why they are planning recurring introductions for a total of up to 5 years. The new population, with lots of diverse genetic material to work with, might be more prone to local adaptation, or it might be more prone to crash because the animals are too locally adapted to their naive system to cope in the new setting.

It might be tempting to think that evolution won’t be a factor considering the short tenure of wolves on the island, but wolf generation times are under 5 years (Mech et al. 2016) which means that they’ve had about 20 generations on the island. We know from the deluge of rapid evolution studies in the past few years that 20 generations is well within the timespan for marked evolution. Similarly, one can expect that moose have been evolving in that time too (Hoy et al. 2018), as have the plants that are browsed by moose, and the small mammals, and the microorganisms that exists in concert… In other words, the entire trophic system has been subject to dynamic eco-evolutionary change that has refined its assemblage and genetic composition. Replacing local wolves with wolves from elsewhere will short-circuit that dynamic process and set a new eco-evolutionary trajectory. Any study that occurs post-introduction will be studying a different eco-evolutionary system, altogether.

Proponents have made the case that occasional genetic influx from the mainland population (when a wolf might cross the ice to the island in cold winters) is part of the natural dynamic, but that climate change has disrupted this process. Leaving aside the fact that much of Isle Royales history was wolf-less long before climate change, reintroducing wolves does not simulate this natural process. In natural migration events, wolves are not randomly selected from a larger pool. The process of migration is a selective sieve that winnows out some potential migrants and selects for others. By high-grading the genetic stock from the mainland based on their own criteria, the Park Service will not be replicating nature, they will be conducting a large-scale, manipulative selection experiment.

The value of non-intervention:

As I mentioned, one of the most critical values of Wildernesses are their role as baselines. This is a point  repeatedly highlighted in the “Strategic Plan for Scientific Research in Isle Royal National Park” (Schlesinger et al. 2009).  The Plan lists as “Unique Attributes of Isle Royale National Park” that it is “An Isolated Location for Baseline Studies”, and “an Ideal Place to Study Fundamental Ecological Concepts” like island-biogeography and predator-prey dynamics.

Isle Royale attracts biogeographers, whose focus is the distribution of life forms as determined by the balance of regional dispersal and local extinction processes (MacArthur and Wilson 1967). Determination of the relative importance of both dispersal and extinction is of central interest to ecologists wishing to explain variability in the species diversity of a given environment and the potential changes brought about by environmental change. As the Strategic Plan states, “the pristine nature of Isle Royale offers an opportunity to examine the potential influence of regime shifts due to natural causes or indirect anthropogenic causes such as climate change.” If we choose a policy of artificially imposing stasis on a naturally dynamic ecosystem we lose that value almost entirely.

On the other hand, if we practice humility and allow natural systems to be dynamic, we can ask a list of interesting questions: What happens if we remove those top trophic levels of moose and wolf? How will that impact the nutrient cycle? How will it impact community dynamics? In what ways will the change in selection pressures drive evolution? Will the eco-evo dynamic play out in predicatable ways based on theory and inference from other archipelagos? What will the post-wolf community composition look like and will it be the same as the pre-wolf community? Etc. etc…

There are endless scientific questions that a wolf-less IR can answer. On the other hand, a replacement wolf population cannot even answer the original question that it is intended to address because such a manipulation cannot be considered a continuation of that community; at best, we can only consider this a manipulative experiment at the price of sacrificing an entire natural ecosystem and ruining an exemplary opportunity to study eco-evo dynamics.

 

---

References:

Hoy, S.R., Peterson, R.O., and Vuctich, J.A. 2018. Climate warming is associated with smaller body size and shorter lifespans in moose near their southern range limit. Global Change Biology. DOI: 10.1111/gcb.14015