From the Timberjay in northern St. Louis County, Minnesota:
VOYAGEURS NATIONAL PARK— Recently published research here suggests that beavers may make up a significantly larger percentage of the diet of gray wolves than has previously been documented, at least in regions with high beaver populations.
The study, by biologists Tom Gable and Steve Windells, tracked for several months the kills of a single radio-collared wolf from the Ash River pack, whose territory straddles the southern boundary of the park just south of Lake Kabetogama. Their research concludes that the wolf pack, comprised of four adult wolves, likely removed between 80-88 beavers from their territory between pond ice-out in April to late November, when ice cover returned. If so, that represented roughly 40 percent of the beaver population, a rate of mortality that is well above previous known levels, and would likely reduce the beaver population without in-migration from surrounding areas.