Can you activate a mana ability in response to another mana ability?

Mana abilities are a special category of abilities that resolve immediately without using the stack (CR 605.3b). Because they never go on the stack, no player receives priority while a mana ability is resolving, which means there is no opportunity to activate another ability in response in the traditional sense.

You can activate a mana ability at almost any time you have priority, including just before or just after another mana ability resolves — but not during its resolution, and not as a response to it being placed on the stack, because there is no such placement (CR 605.3a).

This is different from most activated and triggered abilities, which do go on the stack and allow responses. Mana abilities are exempt from this rule specifically so mana can be generated quickly and predictably when paying costs (CR 605.3b).

Example: Your opponent taps a Forest for green mana. You cannot activate your own Birds of Paradise in response, because that tap ability never hit the stack — it already resolved the moment it was activated. You could, however, activate Birds of Paradise on your own turn whenever you have priority.

The practical takeaway: treat mana abilities as instantaneous events. Plan your mana generation before passing priority, knowing you cannot interject between an opponent's mana ability activation and its resolution.