jupitersterrain four

and then I came across this : 



Machaeropterus deliciosus, shows them producing sustained harmonics derived from vibrating secondary wing feathers. This mechanism is the avian equivalent of arthroped stridulation

Adult male Red-billed Streamertail hummingbirds (Trochilus polytmus) have long tail streamers, but these do not produce their distinctive whirring flight sound. Evidence points to the wings instead - the whirring is synchronised with the wingbeats and video footage shows primary feather eight (P8) bending with each downstroke, creating a gap that produces the fluttering sound



1.58am, 2.12.12.