I saw it myself, otherwise would not belive it - Yellow Finches are plucking the pettals off. Ever heard of this?
Certified GKH Gardening Expert
Yes birds use all sorts of plant materials for nest making. They also are attracted to the scent and sweetness of certain flowers for food. Like deer and rabbits, birds will eat different things if food or water is scarce. Maybe distract them from the gerberas by hanging feeders, providing bird baths and leaving a little plant debris around. This article may also help