Wolves Airlifted To US Island For Reboot Of World’s Longest-Running Predator-Prey Experiment


One of Isle Royale's two new gray wolf residents cautiously exits her crate, strategically located by NHS staff outside the territory of the island's last remaining native wolves. (C) NPS

At some point during the turn of the 20th century, moose and gray wolves wandered across the frozen surface of the Minnesota side of Lake Superior and settled onto Isle Royale, a forested, picturesque, and human-free Island. From these pioneering individuals, distinct populations of each species were founded – one predator and one prey.   

This neatly contained ecosystem soon drew the curiosity of biologists, and a research project observing the moose-wolf dynamic was initiated in 1958. It has been running ever since, making it the longest ongoing study of its kind, according to Science


Yet in the past couple of years, there has not been much lupine activity to document. Due to health issues caused by inbreeding, the number of wolves has been steadily declining for some time. Now, only two elderly wolves remain on Isle Royale, whereas the moose population has rocketed out of control.

To fix this imbalance, the National Park Service (NPS) is planning to airlift six wild-caught gray wolves from the US mainland onto the island. Royale Isle park superintendent Phyllis Green announced the details in a press conference on September 21, stating that the transfer is expected to be complete by the end of October.

Just six days later, the NPS reported that they had successfully relocated the first two wolves onto the island – a 5-year-old male and 4-year-old female were captured from separate packs in the Grand Portage Reservation in northeastern Minnesota, the region the first Isle Royale canines are believed to have migrated from. 

Project staff load a crated wolf into a seaplane for a flight to the island. USFWS/Courtney Celley

Although the newcomers were released into areas away from the two resident wolves’ territory, there will likely be some conflict as they learn to co-exist. Yet the park scientists won’t need to intervene.


“We intend to let [the wolves] work it out,” Green said.

Over the next three years, Green and her colleagues will transfer more wolves, in several waves, until a total population of 20 to 30 individuals has been achieved. This number, chosen after two years of careful research by the NPS and several partner organizations, should be enough to establish healthy breeding and reestablish moose predation. To ensure high genetic diversity, some of the transplants will be selected from packs in Michigan.

One possible wrinkle to the project is that none of these new island wolves will know how to hunt moose. Some wolves from the two source areas may have never even seen a moose, according to longtime Isle Royale wolf-moose study researcher Rolf Peterson.

 “However, wolves are wonderful observational learners, and hunger is a strong motivation to test any potential prey,” Peterson told Science.


The NPS plans to remain involved in the predator-prey project for least the next 20 years.

Both wolves received medical examinations an NPS wildlife veterinarian before they were transported, and found to be in good condition. Each wolf weighs approximately 75 pounds and has a thick coat of light tan, gray, and white fur with black markings, which is typical of gray wolves in the region. The wolves were vaccinated and fitted with GPS collars, as seen above.USFWS/Courtney Celley


  • tag
  • conservation,

  • threatened,

  • biology,

  • gray wolf,

  • moose,

  • ecology