As Isle Royale wolves slide toward extinction, a call for ‘genetic rescue’

Isle Royale’s wolves appear to be at the brink of extinction, and over the next few months the National Park Service will decide whether to intervene and save them or leave their fate to nature.

Intensive study since 1958 has established that the island’s population of wolves rises and falls in a see-saw relationship with the moose herd they prey upon, averaging about two dozen. But isolation and inbreeding have introduced vulnerabilities, and canine parvovirus — from pets brought to the island in violation of park rules — has taken a toll in two waves, one from the 1980s into the 1990s, another since 2007.

The trend for the last six years has been steadily downward, and this year’s late-winter survey found just eight wolves. Four of them were female, which could work in favor of recovery, but all are middle-aged, which works against it.

Now the wolves’ plummeting numbers have virtually stopped moose predation, and the park service plans to decide by this fall whether to:

  • Let the wolves disappear (and possibly return on their own), or
  • Let them disappear and then deliberately reintroduce a new population, or
  • Attempt “genetic rescue” by adding a small number of new wolves to the remnant population.

The latter is the preferred option, at least for now, of John Vucetich at Michigan Technological University. He leads the 55-year-old Isle Royale Wolf-Moose Study, said to be the world’s longest examination of predator/prey relationships in a single ecosystem.

Last week Vucetich laid out the case for intervention in a New York Times op-ed, and on Monday we discussed his views in more depth.


Wolves are essential predators on Isle Royale, culling the moose herds and keeping them healthy. More in article linked above

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