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.