"I found this pair of molted, central tail (deck) feathers from a Turquoise-browed Motmot the other day while hiking along a stream bed on base. What a find! The male motmot performs a pendulum-like display, swinging the racket-shaped tail feathers from side to side, and calling a low, resonant 'woop-woop-woop' in perfect time to the swings. In spanish, the bird is known as 'pajaro reloj' which literally means 'clock bird' because of this display. "
They are unusual not just in shape or color but because the bird helps create the structure, stripping the barbs off the middle part of the feather to create the "racquets" at the end.
More on the motmot can be found here (HT John at Prairie Ice.