In 2005, high-speed video of singing males captured by the biologist Kimberly Bostwick in the Ecuadorean forest revealed that the male’s wing feathers oscillate over the bird’s back. In subsequent research, Dr. Bostwick and colleagues demonstrated that the birds’ songs involve more than just unusual feathers and movements. The surface of their ulnas also features a shelf with huge bumps for the attachments of ligaments that hold the vibrating wing feathers. PhotoMore surprising, their wing bones are solid, while every other species of flying bird has hollow ulnas. Developmentally, avian wing bones take shape early in the life of an embryo, before sexual differentiation has begun.

Source: New York Times May 05, 2017 19:34 UTC