How does the trachea of a trumpeter swan affect its call?

The trumpeter swan possesses a highly elaborate trachea that significantly influences its vocalizations. Unlike the straight tracheae found in many other ducks and geese, the trumpeter swan's trachea enters the sternum, where it flexes twice into horizontal and vertical bony pockets before emerging to coil around and back into the lungs.1

This complex anatomical structure functions similarly to an orchestral wind instrument, allowing the bird to produce its characteristic far-carrying, low-pitched call. By extending the length of the airway through these internal loops, the swan is able to generate the resonant, trumpet-like sound for which it is named.21