Nineteen wolves to Isle Royale: how the relocation unfolded, 2018 to 2020

Between fall 2018 and fall 2019, nineteen gray wolves were captured around the Great Lakes and released on Isle Royale, to help restore predator-prey relationships on the island. The National Park Service (NPS) page tells it from the wolves' side: a sudden capture, an inspection, a ride, then a cage door opening onto an unfamiliar wilderness.

NPS / Jim Peaco.

The timeline

Wolves came to Isle Royale National Park from the Great Lakes region. NPS.

How the wolves were moved

The wolves were chosen for genetic diversity, and veterinarians inspected every one after capture. In Minnesota and Michigan, foothold traps baited with nuisance beaver and vehicle-killed white-tailed deer carcasses caught them; in Ontario, net guns fired from helicopters did. Healthy wolves got a GPS collar, ear tags and a passive integrated transponder (PIT) before travelling to the park by boat or plane.

Minnesota: September 24 to October 5, 2018

The first four wolves were captured in northeastern Minnesota at the Grand Portage Indian Reservation. Female 002F died soon after capture from an adverse reaction to the anesthetic. NPS says the death saddened staff and partners, that relocation can be unpredictable even with thorough planning, and that it is committed to protecting the lives of all wolves involved. One male (008M) and three females (001F, 003F, 004F) were relocated.

Four wolves from Minnesota were the first group relocated. NPS / Jacob Frank.

Ontario: February and March 2019

Three wolves came from Jostle Lake, within traditional lands of the Michipicoten First Nation, in the Lake Superior Highlands Conservation Reserve, which the Ontario Ministry of Natural Resources and Forestry manages. Eight came from Michipicoten Island, about 9.9 miles from mainland Ontario in northeastern Lake Superior, most of it a provincial park. From 2015 to 2018 the island's wolf numbers rose while their prey, caribou and beaver, fell, so far that scientists feared the caribou would be wiped out locally. Fifteen caribou were moved to predator-free islands, and wolves were moved to Isle Royale.

One wolf goes home

In winter 2019 a recently relocated wolf left. Researchers flying over the island noticed a collar signal coming from north of the shore, out toward open Lake Superior. Mark Romanski, the park's Division Chief for Natural Resources and project lead, then got the collar's GPS coordinates and confirmed that the wolf had reached the mainland. The map shows wolf 003F's movements from January 26 to February 2, 2019: the female crossed an ice bridge formed by the recent polar vortex on January 31, heading toward the area near Grand Portage where she was first captured.

Locations of wolf 003F, January 26 to February 2, 2019. NPS.

Research: predation, packs and aggression

From May to October 2019, after most wolves had arrived, NPS and collaborators studied predation, pack formation and territorial aggression. In summer they looked at GPS clusters, places where a collared wolf stayed at least four hours, using site evidence and prey remains to tell predation from scavenging or resting. They found 56 carcasses. Moose were found at 24 sites judged probable predation, mostly calves; 26 other sites had non-moose prey, including beaver, snowshoe hare, red fox kits, birds and muskrat.

Eight wolves died between fall 2018 and fall 2020. Four were killed by other wolves, which is common as wolves defend territory and set up social hierarchy. The causes of two deaths are unknown, one died of pneumonia, and one of cellulitis and suspected septicemia.

Michigan: September 4 to 14, 2019

Wolves were captured in the western Upper Peninsula of Michigan, in Baraga, Gogebic, Houghton and Ontonagon counties. Two males (017M, 019M) and two females (018F, 020F) were relocated. NPS veterinarians inspected them before release.

Wolves were inspected by NPS veterinarians before being released. NPS.

Pups

Tracking the population and its reproduction shows whether the introduction works in the long run and what wolves do to the island's ecosystem. Researchers use DNA from scats, GPS collar data, remote cameras, acoustic recorders and aerial observations by Michigan Technological University researchers.

In 2019, GPS data suggested wolf 014F denned and set up several rendezvous sites, and on September 29 a remote camera caught two apparent pups, judged pups from their behavior and size. If scat analysis shows they are related to 014F, then 014F would have bred on Michipicoten Island before being moved. No evidence supports any other 2019 reproduction. For 2020, GPS data suggested denning by wolf 001F in early April, when her collar failed to send a signal, a sign it was underground or under thick vegetation; wolves 012M and 015F may also have denned, but collar failures left it unconfirmed.

Remote camera images from late September 2019 show two pups likely born to wolf 014F in spring 2019. NPS.

Next, NPS and its partners will keep monitoring the population and plan more relocations.

Sources

• National Park Service, Isle Royale National Park, "Isle Royale Wolf Relocation" (https://www.nps.gov/articles/000/isle-royale-wolf-relocation.htm); rewritten in hubnx's own words.