Editor's note: This updates with NPS's preferred alternative to bring 20-30 wolves into Isle Royale National Park.
National Park Service officials, in a move likely to spur debate over how wilderness is managed, are proposing to bring 20-30 wolves into Isle Royale National Park in Michigan to offset a dwindling presence of wolves and at the same time counter a burgeoning moose population that biologists fear could overwhelm the island park's ecosystem.
In a draft Environmental Impact Statement released Friday morning, the Park Service outlines four options for dealing with Isle Royale's plummeting wolf population, which is thought to be down to no more than two animals. The moose population, meanwhile, is thought to number around 1,300. Their preferred alternative is to bring 20-30 wolves into the park during a three-year period to greatly diversify the gene pool of the predators.
"This is about more than wolves,” park Superintendent Phyllis Green said in a prepared statement. “It’s about the entire park ecosystem and where it is heading in the future with changing conditions. This is a complex issue to address. We have sought input from subject matter experts to evaluate the situation, and we would like to hear from the public on the current draft plan."
Chronic inbreeding appears to have impacted the health of the wolf population. There was hope that "ice bridges" that formed between the Lake Superior island and the Canadian mainland during the winter of 2013-14 would enable wolves to arrive from Canada with new genes. But no new wolves reached the island, while one female left and was killed by a gunshot wound in February 2014 near Grand Portage National Monument in Minnesota.
Isle Royale wolves have been in decline for more than a decade. In recent years, park managers have discussed island and wolf management with wildlife managers and geneticists from across the United States and Canada, and have received input during public meetings and from Native American tribes of the area. Those discussions have examined the question of whether wolves should be physically transported to Isle Royale, in large part due to concerns that a loss of the predators would lead to a boom in the moose population that likely would over-browse island vegetation.
Last winter, just two wolves were spotted in the national park. A survey is scheduled for later this winter to confirm the presence of wolves there.
Although wolves have not always been part of the Isle Royale ecosystem, they have been present for more than 65 years, and have played a key role in the ecosystem, affecting the moose population and other species during that time. The average wolf population on the island over the past 65 years has been about 22, but there have been as many as 50 wolves documented on the island and as few as two. Over the past five years, the population has declined steeply, which has given rise to the need to determine whether the NPS should bring additional wolves to the island. There were three wolves documented on the island in 2015 and only two wolves were confirmed in 2016. At this time, natural recovery of the population is unlikely.
The four alternatives contained in the draft EIS are:
- Alternative A would continue existing management practices and assume no new management actions would be implemented beyond those available at the outset of the wolf planning process. Wolves may arrive or depart independently via an ice bridge.
- Under Alternative B, between 20 and 30 wolves with a wide genetic diversity would be introduced to the island. The social makeup of introduced wolves could include packs, established pairs with pups, or unrelated individuals. Wolves may be supplemented as needed up to the third year after initial introduction. After the third year, should an unforeseen event occur that impacts the wolf population, such as a mass die-off or introduction of disease, and the goals of the alternative are not being met due to this event, wolves may be supplemented for an additional two years.
- Alternative C would involve the initial introduction of a smaller number of wolves than Alternative B. The social makeup of introduced wolves could include an established pair with pups, or a pack, as well as unrelated individuals. The NPS would bring wolves to the island as often as needed in order to maintain a population of wolves on the island for at least the next 20 years.
- Under Alternative D, the NPS would not take immediate action and would continue current management, allowing natural processes to continue. This alternative is meant to continue the study of island ecosystem changes without an apex predator and only take action should the weight of evidence suggest an apex predator is necessary for the ecosystem to function. Resource indicators, such as population size and growth rate of moose, would be used to determine if and when wolf introduction actions should be taken. If the weight of evidence indicates wolf introduction actions should be taken, the NPS would follow procedures outlined within Alternative C.
The document calls for a 90-day public comment period running into mid-March.