Background: We wanted to scout an island. To do that we thought about using the Conjure Animals spell to summon a bird that could speak, and using Tongues to communicate with the bird after it had returned from scouting. The only bird with a language we could find was the Giant Eagle.
My question is: since Conjure Animals doesn't actually conjure the beast, but a fey, do the fey creatures also inherit the beast's language?
I know this question (Communicating with Conjured Creatures)
asks about communicating with beasts already, but I couldn't find an answer to whether, if a beast does know a language, the summoned fey also inherits this language.
Best Answer
The Conjure Animals spell says:
The fey spirit(s) summoned is a beast and it has all the statistics that the beast has as they appear in the monster manual. Note that most beasts don't actually have a language.
The Giant Eagle, though, is special. Its stat block does list a language that it knows and therefore can speak; the Giant Eagle language.
The Tongues spell says:
Since the Giant Eagle has a listed language that it can speak, casting Tongues on it will grant you the ability to communicate with it as you wish.
Normally, casting Tongues on a Conjure[d] Animal would allow the animal to understand you but not allow you to understand it because most beasts are unable to speak.
According to page 9 of the monster manual: