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As Isle Royale prepares to add wolves, a look at just how that might be done

Back in the 1940s, when biologists including the great Aldo Leopold were discussing a plan to import wolves to Isle Royale to control the moose population and preserve the forest, some enterprising folks quietly delivered a few from the Detroit Zoo. And then some wolves came across the ice on their own.

How differently things work now.

The news in the National Park Service’s announcement on Friday about the future of this embattled top predator is the long-awaited and scarcely surprising proposal to bring fresh wolves from the mainland — and to do it as quickly as possible, probably by the fall of 2018.

But the most interesting material, at least to me, is the document’s discussion of various strategic decisions made en route to this tentative plan.

Nothing about this reintroduction — or translocation, in the NPS terminology — is so simple as rounding up some wolves and dropping them off at the Windigo dock to eat moose and make pups as they please.

What follows are a few key questions about the translocation and how the park service has proposed to answer them. Subject, of course, to change in the process of public comment and revision that will take place over the next year or so.

These answers were informed by an expert panel consisting of Rolf Peterson and John Vucetich of Michigan Tech University and the long-running study of the wolf/moose balance on Isle Royale, along with seven others:

Brent Patterson, a Trent University research scientist who works with the Ontario Ministry of Natural Resources; Daniel Pletscher, professor emeritus in forestry and conservation at the University of Montana; Thomas Rooney, a biology professor at Wright State University; Tim Van Deelen, an professor of wildlife ecology professor at the University of Wisconsin;  Robert Wayne, a professor of ecology and evolutionary biology at the University of California – Los Angeles; and Adrian Wydeven, who runs the Timber Wolf Alliance in the Sigurd Olson Environmental Institute at Northland College; and Matthew Gompper, a professor in the University of Missouri’s School of Natural Resources, who coordinated the panel’s work.

Where should the wolves come from?

Ideally, from areas near the park: northern Minnesota, Michigan, Wisconsin and north-central Ontario. Growing up in areas that contributed wild wolves to the park after 1948 increases the chances that a wolf will be genetically adapted in ways that enhance survival and reproduction chances; also, that it will have experience preying on moose (as well as beaver, another Isle Royale species that may get out of hand without wolves to keep it in check).

Just as the geographic isolation of the island’s wolves has produced a deepening “inbreeding depression,” with a variety of physical defects traced to the shrinking gene pool, bringing in wolves from far away raises the risk of “outbreeding depression,” which can compromise the fitness and survival of pups whose parents are too genetically different.

The experts also generally cautioned against selecting wolves that were raised or have been held in captivity, because populating a national park with wolves that have lost some instinctive aversion to humans is probably not the best idea.

(This will disappoint Maureen Hackett of Howling For Wolves, who sent out a press release over the weekend urging that “wherever possible, wolves living in captivity that can survive in the wild should be chosen.”)

However, the NPS says it would not necessarily reject the offer of an individual wolf that had been trapped to stop it from preying on livestock.

How many wolves, and how quickly?

NPS prefers an option that calls for bringing 20 to 30 wolves to the island within a three-year period, with the details arranged to maximize likely breeding success. Another option, to start with a smaller number of wolves initially (say, six) and augment it (by, say, another 15) over a 20-year period as indicated by various monitoring metrics, was considered but judged inferior.

The experts agreed that the average long-term ratio of wolf to moose numbers supports a target population of at least 30 wolves in as many as six packs (with three packs the most common number during the wolf/moose study over the past 60 years).

And they agreed it was possible to start smaller and build up the population over a longer time frame, but saw no clear advantage in that phased approach, which would also probably cost considerably more. (The planning documents are silent on the subject of cost estimates.)

However, nothing guarantees permanent success, in the views of some experts. Given the size of the park, one expert said, “I do not believe that any mix of wolf genetics introduced will result in long-term viability without human intervention” unless more wolves arrive via ice bridges, whose recent decline in frequency may be a major driver of the current collapse.

Another agreed, but pointed out that the NPS’ planning is only for a 20-year time frame, and viability for two decades is a feasible goal.

There was wide disagreement about what metrics should drive decisions to add more wolves as time went on; the NPS proposes to fit at least some and possibly all of the new wolves with radio collars to allow tracking of their whereabouts, and the Peterson/Vucetich genetic analysis (mostly through fecal samples) would continue.

How to capture them, and when?

In compliance with state and federal requirements, wolves selected for introduction would be captured using available tools ranging from helicopter net-gunning, modified padded foot-traps, darting from a helicopter or modified snares with appropriate stops. Human and wolf interactions would be minimized…. The capture and release periods to bring wolves to Isle Royale would occur primarily between late fall and late winter.

It was the expert discussion on this point that focused for me just how tricky this project could be, and how some serious difficulties in the lives of immigrant wolves just can’t be managed.

During open water season (May-October) moose calves and beaver are available and the likelihood of leaving the island is reduced by the lack of an ice bridge. During the late summer and early fall wolves are using rendezvous sites, which might improve trapping success, and if trapping involves foot-hold traps, there is decreased chance of freezing digits or of hypothermia.

However, the cons for a late summer/early fall focus include greater opportunity for capturing non-target individuals (both wolf pups and domestic hunting dogs), and an increase in nomadic activity in late fall.

A winter focus would increase the chances of capturing packs, as pups are travelling with packs and pack are more cohesive and wolves tend to be in good condition. However, a winter release date would leave less time for pair-bonding and increase the potential for attempted escape. Winter release on IRNP would also be logistically problematic.

*  *  *

For discussion of other questions considered by NPS — “Soft release” or hard? Provide dead moose to the new arrivals or not? Try to eliminate any currently surviving wolves before adding new ones, or let them be? — you can find the full analysis here.

Comments (7)

  1. Submitted by joe smith on 12/21/2016 - 10:14 am.

    I remember when the “experts” said the introduction

    of wolves to Isle Royale the last time would solve the moose problem. The old timers (not experts ) said if wolf wanted to live on the island they would walk out on the ice and do it. The wolf use the ice to leave Isle Royale not to inhabit the island…. More wasteful spending coming up and another time when common sense of the locals will trump some biologist with a 5 year study grant from the Federal Govt on wolf behavior…. History does repeat itself…

  2. Submitted by E.August Allen on 12/21/2016 - 12:28 pm.

    Bottom line: 20 to 30 wolves lives will be transformed permanently. They will be trapped, snared; darted or netted via helicopter. Many wolves will be injured, some will be gravely injured, some will live, some will die, most will be torn forever from family members. Certainly, all will be traumatized.

    And what of the primary food source. The moose population was near 2,400 individuals in 1996, but plummeted in just one year to 500 animals due to an outbreak of moose ticks and a severe winter. When moose became increasingly rare in 2006, capturing food became increasingly difficult for the wolves…“One wolf pack failed after another [starved], with the population reduced by half. ” The 1,250 or so moose presently on Isle Royale, feeling the effects of #climatechange, can easily be devoured by a couple of dozen wolves and “wink out” leaving the wolves without a key and primary food source.

    Given the population size and relative isolation of the Island from the mainland, it is simply inevitable that there will be a loss (rapid loss) of genetic diversity. And yes, history will repeat itself, again, with the wolves paying the ultimate price.

    The moose population can easily be controlled with PZP.

  3. Submitted by Nancy Gibson on 12/21/2016 - 12:57 pm.

    Isle Royale wolves

    A good in-depth story on the challenges of re-introduction of wolves. The wolves did succeed on their own natural introduction to Isle Royale 60 years ago, but the overwhelming problems associated with climate change was not anticipated nor was the death of three healthy wolves when they encountered a copper mine shaft left open by misguided humans.
    There are many lessons to learn by the successful introduction of wolves both in packs and individuals in Yellowstone National Park and Idaho. That includes the increase in tourism in and around the Park that clearly demonstrates people are willing to support these efforts.

    • Submitted by E.August Allen on 12/21/2016 - 01:28 pm.

      The survival of an isolated population of wolves.

      The loss of wolves (due to unnatural circumstances) would not have changed the end result, it would only delay (perhaps) the inevitable.

      The wolves populated Isle Royale around 1949, and were believed to have been basically isolated ever since, comprised typically of just a couple dozen wolves. Small, isolated populations of wildlife never fare well and always exhibit high rates of inbreeding. The deleterious effects of inbreeding begin to become evident at a COI (coefficient of inbreeding) of about 5%. At a COI of 10%, there is significant loss of vitality in the offspring as well as an increase in the expression of deleterious recessive mutations. The combined effects of these make 10% the threshold of the extinction vortex – the level of inbreeding at which smaller litters, higher mortality, and expression of genetic defects have a negative effect on the size of the population, and as the population gets smaller the rate of inbreeding goes up, resulting in a negative feedback loop that eventually drives a population to extinction.
      Fragmentation of natural habitats is associated with population declines of many species. The resulting small and isolated populations are threatened by extinction for several reasons. Such populations are more vulnerable to demographic and environmental stochasticity. They also face several genetic threats. First, due to restricted mating opportunities, inbreeding becomes more likely. Second, if populations remain small and isolated for many generations, they lose genetic variation necessary to respond to environmental challenges (random fixation or loss of alleles through genetic drift). Third, unfavourable mutations are
      expected to accumulate because selection operates less efficiently in small populations. Of these processes, inbreeding poses a more immediate threat, whereas genetic drift and mutation accumulation affect the population in the long term. Environmental, demographic and genetic factors can interact and reinforce each other in a downward spiral, an extinction vortex.

      “For many decades, the wolves of Isle Royale had been taken as an example of a very small, isolated and highly inbred population which showed no signs of inbreeding depression, the negative impact of inbreeding. But we had it wrong, very wrong. In fact, the population dynamics of Isle Royale wolves have been affected by genetic processes in ways that have been as important as they are subtle.

      In 2009, with the help of Jannike Räikkönen, an expert in Canid anatomy from the Swedish National Museum, we systematically inspected the skeletal remains from 50, or so, Isle Royale wolves that had been collected over the past five decades. A surprising number of these wolves suffered from several different kinds of congenital malformity in the spine… A particular kind of deformity, known as a lumbosacral transitional vertebrae (LSTV), is particularly well studied in dogs and wolves. Among healthy, outbred populations LSTV occurs in one out of a 100 wolves. On Isle Royale, a third of the wolves suffered from this malformity.

      Not only did Isle Royale wolves exhibit LSTV at a high rate, but the rate of malformities had once been relatively low and increased over the decades…”. -John A. Vucetich

  4. Submitted by E.August Allen on 12/21/2016 - 01:48 pm.

    Isle Royale National Park or Laboratory

    So, should wolves be reintroduced to Isle Royale?
    I say absolutely not.
    No mention in this discussion is the welfare of the wolves captured for augmentation, forced to live in an isolated situation with family left behind. Wolves for re-introduction on Isle Royale would have to be sourced from multiple populations to give an initial genetic diversity. More wolves would possibly have to be added later to maintain this genetic diversity and prevent inbreeding.
    Then, there is the physical collection of wolves which would pose difficulties and is likely to result in some deaths.
    During the collection of animals for the Yellowstone re-introduction programme at least 10 wolves died early in the process through trapping and snaring and at least one died during incapacitation from the helicopter.

    Bottom line: 20 to 30 wolves lives will be transformed permanently. They will be trapped, snared; darted or netted via helicopter. Many wolves will be injured, some will be gravely injured, some will live, some will die, most will be torn forever from family members. Certainly, all will be traumatized. And they will be dependent on another isolated species as a primary food source, which is suffering the effects of climate change.

  5. Submitted by Ray J Wallin on 12/21/2016 - 07:13 pm.

    Chaos theory vs laminar flow, DNR style…

    Humans meddling in nature to make it more natural.

  6. Submitted by Tom Anderson on 12/21/2016 - 09:32 pm.

    Anyone think to ask David Mech?

    Or is an expert right next to the area too obvious?

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