Learn Russian: Зимами волки охотятся в лесу.

Зимами is the instrumental plural of зима. Using the bare instrumental plural of a season emphasizes a repeated, habitual action across multiple time periods, meaning "during winters" or "winter after winter." While зимой (instrumental singular) can also describe a general winter habit, зимами explicitly stresses the recurring nature of the wolves' behavior over many years.

Why is the prepositional case form в лесу instead of в лесе?

The noun лес belongs to a small group of short masculine nouns that take a special locative ending -у (which is always stressed) in the prepositional case when indicating a physical location with в or на. Therefore, "in the forest" is always в лесу.

The verb охотятся has the reflexive ending -ся. Is that required for the verb "to hunt"?

Yes, the Russian verb for "to hunt" is охотиться. It is a permanently reflexive verb, meaning it always takes the -ся or -сь suffix in its conjugations, even though the action of hunting is directed outward at prey rather than back at the subject.

How does putting зимами at the very beginning of the sentence affect the tone?