Three Wolves on Isle Royale
by Cat Urbigkit, Pinedale Online!
April 18, 2015
Researchers have been able to locate only three wolves on Isle Royale, the remote Minnesota island 15 miles from Lake Superior's northwest shoreline. The Isle Royale wolf-moose research project is the world's longest continuous study of predator-prey, now in its 57th year.
Moose arrived on Isle Royale in the early 1900s and without the presence of a major predator, the population increased quickly. For the next 50 years, the moose population was limited only by starvation and the population underwent significant fluctuations, but in the late 1940s, wolves crossed an ice bridge from Ontario onto the island. Wolves are the only predator of moose on the island, and moose serve as the main prey source for the wolf population.
Scientists began studying the moose-wolf relationship on Isle Royale in 1958, and the research continues. Researchers John Vucetich and Rolf O. Peterson recently released their annual research report, entitled "Ecological Studies of Wolves on Isle Royale 2014-2015."
The Isle Royale wolf population dropped from nine animals in 2014 to only three wolves in January 2015, with one of the three animals appearing unhealthy and apparently on the verge of death.
While the wolf population experienced decline in the last year, the moose population increased 19 percent. The report notes that if the current growth rate continues, the moose population will double in size in the next three years. While the two researchers have advocated that federal officials augment the wolf population (which has suffered from the effects of inbreeding, including resulting spinal deformities), the report states "There is now a very good chance that it is too late to conduct genetic rescue."
An ice bridge to the mainland formed for a few days in 2014, allowing wolf movement to and from the island. Two mainland wolves briefly visited the island during that time, but there is no evidence the visiting wolves made contact with the island's resident wolves.
The main researchers involved in the Isle Royale wolf-moose project have long advocated that federal officials augment the island's ailing wolf population. But other wolf scientists have countered that the population should not be manipulated by humans, that there is a value in continuing to document what happens next, even if that is the extinction of the island's wolf population.
Perhaps a new group of wolves will cross an ice bridge and take up residence, preying on the abundant moose. Or perhaps the wolf population will disappear, and the moose population will continue to increase until it suffers a severe decline due to starvation, as has happened in the past. Only time will tell.
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