Reading Barry Lopez’s book “Of Wolves and Men”:
[…] disadvantage. The important thing to bear in mind is that generally wolves do not overrun the prey population and kill it out, although they have been known to do so, just as they have, extraordinary as it seems, practiced a kind of fallow-field farming by not killing deer in certain parts of their territories for four or five years, letting the prey population recover there.
I think he got his fiction mixed up with reality, wolves don’t live very long; this would be half of their lifespan.
They could very well be leaving an area alone because there’s less of their favorite prey there. How would you determine their motivation?