Study: With few wolves, Isle Royale moose population growing out of control; restored predator-prey balance needed

Isle Royale National Park in remote Michigan. (National Park Service)

A decision to potentially boost a dying wolf population at Isle Royale National Park – also meant to help manage a growing moose population – won’t come until at least fall.

Could that already be too late?

With just two older inbred wolves making up the population at the park, the moose population has reportedly ballooned at the remote Michigan park – to the point of already being out of control, according to scientists.

Researchers from Michigan Technological University released a report on a study Tuesday, April 18, showing the need for a restored predator-prey balance. According to one of the scientists, the moose are ravaging the park’s balsam fir trees. Although the trees are prominent at Isle Royale, moose have already started thinning out the forest, converting some areas to grassy plains, according to an Associated Press report.

So with fewer balsam firs and a growing moose population, scientists are concerned that the moose might starve and die off without a population of predators like the wolves to keep their numbers in check. Wolf numbers also slipped on the island in the 1990s and, as a result, moose numbers vaulted to nearly 2,500. But about two-thirds of that population died of starvation during the bitter winter of 1996, according to reports.

It’s believed that the first wolves arrived at Isle Royale in the late 1940s, having traversed the frozen lake surface 15 miles or more from nearby Minnesota or the Canadian province of Ontario. Up until recent years, they numbered somewhere around 20. But according to the National Park Service, the population at the park has declined steeply over the last five years, to the point where only two inbred wolves remain, and natural recovery of the population is unlikely.

In December, the NPS said four alternatives were being considered, including relocating as many as 30 gray wolves to the park that’s situated on the Lake Superior island chain. At that time, it was said that the park’s moose population exceeded 1,200. In Tuesday’s report, the scientists estimated moose numbers at 1,600, saying that could double over the next three to four years unless more wolves arrive soon, according to The AP report.

A public comment period ended in March. Although there has been talk that a decision could come by fall, back in January, Park Superintendent Phyllis Green told Michigan Outdoor News she expected a final decision by the end of 2017.

Besides a plan to relocate as many as 30 wolves to the park, another alternative – the preferred alternative, according to the NPS study – would be an immediate but limited introduction of six to 15 wolves over three years. The two other alternatives would involve taking no immediate action, with allowance for future action, and taking no action at all.

According to The AP report, in another sign of the wolves’ decline at Isle Royale, the island’s population of another prey species — beaver — has reached about 300, the highest total on record.

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