...
Hi, Altan,
Since "
quiver" has been used right above as a noun, I might go with
flutter:
(of a bird or other winged creature) fly unsteadily or hover by flapping the wings quickly and lightly.
Move with a light irregular or trembling motion.
παίζω: [...] ΙΙΙ.2.β. ταλαντεύομαι: Παίζει η βελόνα του μετρητή. Παίζουν οι τιμές στην αγορά.
However, "hesitates" seems to me a very good choice since "its wings beat" follows right after that —as "
wavers" would, too, conveying the image of the bird hovering while slightly moving its wings (σαλεύει as you correctly put it).