The presence of gray wolves at Isle Royale National Park could come to an end soon, with a recent census finding only three remain.
The Pioneer Press reports that inbreeding and illness has led to a "sharp drop-off" in wolf numbers, which stood at 24 in 2009 but has continued to fall since.
The island in Lake Superior and its population of wolves and moose have been subject to a scientific study for more than 50 years, the newspaper notes.
According to the Detroit News, the moose population has now risen to 1,250 because the number of wolves who prey on them has fallen so drastically.
The newspaper adds that the leaders of the study, Rolf Peterson and John Vucetich, from Michigan Technological University, have been calling on park officials to bring more wolves to the island to "replenish the gene" pool.
But even then there is a chance the wolves won't survive or proliferate, with the Star Tribune noting that the three remaining wolves consist of two adults and a 9-month old pup.
The two adults are believed to be a breeding pair, so they are unlikely to mate with another wolf, and though they could have more pups together, Peterson told the newspaper they are reaching the end of their reproductive lives.
"You don't have the sense there is much time left." he said, adding that the other option would be moving an entirely new wolf pack over to the 45-mile long island.
Figures from the Isle Royale Wolf and Moose Project show that wolf numbers peaked at around 50 in 1980. Moose numbers reached around 2,400 in 1990s, which led to mass starvation due to a harsh winter in 1996.