Similar trends have been noted in neighboring Minnesota, and in the Upper Peninsula of Michigan. No resident wolves were known to exist in the UP until 1990. By 1998, around 120 wolves were present. The rebound in wolves witnessed during the decade of the 1990 s in the three upper Great Lakes states can be traced back in part to stringent adherence to federal and state endangered species protection and population management programs. The real recovery work was actually performed by the wolves.
Wolves are prolific .
Each breeding pair mates annually, and a litter of 5-6 pups is born each spring. Wolves are also inherently social beings , living in families called packs. Sexual maturity is delayed until the second year, affording one-year olds the opportunity to acquire an extra amount of learning under the tutelage of parents before they strike out on their own. Thus survivorship of offspring is enhanced. This means on average, two individuals from each litter of six, or an average of two wolves per pack each year become young adults.