Moved cell phone away from computer and seems to have solved the problem.
What you are probably seeing is when the young ones all look like females and when they are going to be fed you could say they get "excited" and shake and quiver.
The quiver holds arrows. Quiver also means "to shake or tremble."
Shake Tremble Jittery
to quiver or shake a lot and to vibrate
Shake Tremble Jittery
to quiver or shake a lot and to vibrate
Another word for vibrate or shake is tremble or quiver.
quiver
quiver either means... a quiver of arrows. wich is the plural noun of the word arrow. or if somebody quivers it is a verb and it is when they shake. usually because the person is cold or scared.
Vibrate, shudder, tremor, jitters.
Your muscles quiver (shake) when they are cold. Shaking increases their temperature.
A bevering is an instance of trembling or shaking.