If my opponent is trying to play Stalking Wolf and sacrifice a bird token, could I reveal Evelynn at another battlefield in response to the sac trigger and move the bird?

No, you cannot move your opponent's Bird token using Evelynn, Entrancing in this situation.

Reasoning

1. Stalking Wolf Cost: Playing Stalking Wolf is a game action that requires announcing the card, choosing a location, and paying the mandatory additional cost of killing a Bird, Cat, Dog, or Poro you control.
2. Timing of Costs: Costs are paid as an integral part of the process of playing a card. When your opponent initiates the play of Stalking Wolf, they immediately pay the cost by killing their Bird token.
3. No Window for Reaction: Because killing the Bird token is a cost paid to initiate the play of the card, it does not use the chain. There is no window to react to the sacrifice because it is a cost, not a triggered ability.
4. Targeting: Evelynn, Entrancing specifies that you may move an enemy unit.

Sequence

1. Opponent initiates the play of Stalking Wolf.
2. Opponent pays the mandatory additional cost by killing their Bird token.
3. Because this cost is paid immediately upon initiation, the Bird is destroyed before you have any opportunity to play a reaction to move it.

Note: I could not fully verify this ruling against the retrieved rules.