Geese with fleas?

[Astrx]

How can you tell if a geese has fleas? My geese keep biting their feathers with their beaks and kinda do a annoyed sound like if it’s bothering them.Do they have fleas or is it normal for them to do that? After biting their feathers they do fall asleep every time so do they just do that before resting

 

[sourland]

They are likely just preening themselves.