The importance of talking can be seen throughout Hurston's Their Eyes Were Watching God. The best example can be seen in a comparison of the three men in Janie's life. Her first husband, Logan, does not have much to say to Janie. He silently treats her like a rather fragile princess for awhile; later he begins to disrespect her and basically orders her to do manual labor. Janie leaves, at least in part, because Logan is such a poor communicator. Conversely, Janie leaves with Jody (Joe) Starks because he is a smooth talker. He "sweet-talks" her into running away with him. Soon, though, Joe does not stop talking. He talks for Janie, treating her as a second-class citizen; and he continually boasts about his own worth, which eventually alienates him from his wife. Finally, Tea Cake finds Janie and speaks words of love which are like balm to Janie's wounded soul. After they leave together, Tea Cake is able to talk his way out of several questionable incidents, mollifying Janie with words.
Each of these men keeps or loses Janie based, at least in part, on how he speaks to her.
Excellent observation. Is that the only significance of the buzzards - that they speak like humans and refer to the mule as a "man?"