Bird Song
How do birds sing and make calls? In mammals, sounds are produced by vocal folds, but birds don’t have these. The vocal organ of birds is the syrinx. It is a double instrument located deep in a bird's chest at the point where the trachea divides into two bronchi. A human creates sound using only 2% of the air exhaled through the larynx, but a songbird uses almost all the air passing through its syrinx, even though the syrinx may be no larger than a raindrop. Sound is produced by vibrations of some or all of the membrana tympaniformis (the walls of the syrinx) and the pessulus, caused by air flowing through the syrinx. This sets up a self-oscillating system that modulates the airflow creating the sound. In passerines, a part of the syrinx rests in each bronchus and each of these halves is capable of making sound. Muscles on the left and right branch modulate vibrations independently so that some songbirds can produce more than one sound at a time. This allows a bird to sing two different notes at the same time, or even sing a duet with itself. In crows, mynas and parrots, the syrinx allows mimicry of human sounds. The location of the syrinx and the muscles that control it varies between different bird groups. For example, the syrinx may be restricted to the bronchi, such as in some non-passerines (owls, cuckoos and nightjars). In other species known as tracheophonae (ovenbirds, woodcreepers, antbirds, and gnatbirds), the syrinx may be restricted to the trachea. Yet other species of bird, such as vultures, have no syrinx and communicate by throaty hisses. And, the world’s loudest bird song? That honour, once thought to be with the Screaming Piha, belongs to the White Bellbird of the Guianas. The males blast a song, which sounds like a melodic air horn, in the face of a nearby female. Although the male usually sings at around 116 decibels (dB), when one is wooing a female, they can get as loud as 125 dB. The White Bellbird may get its extreme volume in part from its large beak that flares out like a trumpet. As the sound gets louder, its duration gets shorter, possibly because of limitations in the ability of the birds' respiratory systems to control airflow and generate sound. https://www.sbs.com.au/news/this-is-the-loudest-bird-ever-recorded
0 Comments
Leave a Reply. |
Archives
February 2021
Categories |