Timeline of Events

A brief history of the wolves on Isle Royale National Park

Early 1900’s

Moose Arrive on Isle Royale

Moose venture to Isle Royale (presumably by swimming to the island from mainland Minnesota or Canada), marking the start of their future over-abundance on the island.


Isle Royale National Park

On April 3, 1940, Isle Royale was established as a national park, consisting of 893 square miles of protected land. Due to its remoteness (only accessible by plane or ferry), the park is one of the least visited yet most revisited parks in the country.


Wolves arrive on Isle Royale

In the winter of 1948, wolves cross from mainland Canada to Isle Royale on an ice bridge. These are the first known wolves to inhabit the island.


Start of Predator-Prey Study

This marks the start of the longest continuous study of any predator-prey system in the world. The research project aims to help us better understand the ecology of predation between wolves and moose on the island.


Isle Royale Wilderness Area

Isle Royale is given a Wilderness designation by the The Wilderness Act of 1964, giving the island additional protections from development.


Wolf Numbers Peak

Wolf numbers reach 50 animals, their highest recorded count on the island.


Wolf Numbers Plummet

Wolf numbers fall to just 14 after humans inadvertently introduce a dog disease (canine parvovirus) that proves deadly for wolves living on the island.


Moose Numbers Peak

With low predation due to the drop in wolf population, moose numbers skyrocket and reach an all time high of 2,400 animals.


Moose Numbers Plummet

Due to harsh winter conditions, lack of food (caused by overpopulation), and moose ticks, the population drops to 500.


Wolf Comes to Isle Royale

During the winter of 1997, a male wolf crossed from mainland Canada to Isle Royale via an ice bridge. The immigrating wolf bred with wolves living on the island, revitalizing the packs’ genetic diversity.


Only two wolves remain

Due to climate change, inbreding, and other factors, only two wolves remain on the island, incapable of producing viable offspring. Without human intervention, these will likely be last wolves on the island.


NPS Takes Action

In the summer of 2018, the National Park Service announces their plan to reintroduce 20-30 wolves onto Isle Royale.


First Two Wolves Released

On September 26th, 2018, two gray wolves (4-year old female and 5-year old male) were released on the island, relocated from Minnesota’s Grand Portage Indian Reservation. The wolves were vaccinated and fitted with GPS collars.


Two More Wolves Released

On October 2nd and 4th of 2018, two female wolves are released on Isle Royale, bringing the total to four wolves.


Wolf Leaves Isle Royale

On January 31, 2019, GPS collar information shows that one of the recently relocated female wolves left the island for mainland Canada on an ice bridge.


Wolf Relocation Continues

The reintroduction of wolves continue onto Isle Royale by the National Park Serve and partners from Minnesota, Michigan, and Ontario. One wolf was discovered to have died on the island and another died in transit to the island after being captured. In total, 19 wolves were brought to Isle Royale National Park.


Two wolves die

With GPS collar data and necropsy reports, it is determined that two wolves were mortally wounded in territory disputes on the island. Fifteen wolves are estimated to be on Isle Royale.


Wolf Pups Born

At least two wolf pups are born on Island Royale from wolves brought to the island as part of the reintroduction. These pups mark a key element of the National Park Service wolf introduction program’s success.