can you swap any 2 food tokens for an activated ability?

Question

When you're playing birds you can swap two food tokens for any other food token but does that also apply to activated abilities? eg.

Could I play two worm tokens in lieu of a fish token?

Answer 1

From the rulebook, page 6:

When playing birds, you may spend any 2 food tokens as if they are any 1 food token. This exchange cannot be used during other parts of the game.

So the answer is no - you can only substitute food tokens when playing birds, not when using other abilities.