Notice the steady state (roughly) up to 1965, the increase in moose from 1965-1975, and the subsequent increase in wolves (and decrease in moose) from 1970-1980.

Also notice the reestablishment, just in the last year of this graph, of numbers close to those in the 1960's.   In the early 1980's the wolves decreased as a result of a viral epidemic brought to the island on the shoes of human hikers.   Soon afterward, the moose population soared.   By the late 1990's, the moose were running out of food, and the weakened moose became easier prey for wolves.   The wolf packs began to produce lots of puppies!