Excerpt from the book Animals Evolution Avoided. This book describes 40 animals that ought to exist but don’t, because I made them up.
The Trois Rivieres Goose is of tremendous scientific interest. Experts have shown that the calls of this bird have a distinctive tone or accent, separating them from all other geese in Canada.
There are three living genera of true geese: Anser – grey geese, including the greylag Goose; Chen – white geese; and Branta – black geese, such as the Canada Goose. Along with the Cape Barren goose, and the prehistoric New Zealand goose, the Trois Rivieres goose may form a subfamily of their own.
Although Trois Rivieres geese look similar to other geese found in eastern Canada, if a Trois Rivieres lands in a flock of Canada geese it can’t make itself understood as its pitch is slightly higher.
The voice box sits on top of the windpipe and contains the vocal chords, which open during breathing and close when the goose wants to honk. When the goose produces the airstream that will become the honk, the airstream passes between the vocal cords, which then vibrate between 100 and 1000 times per second, depending on the pitch of the honk. By themselves, the vocal cords produce a noise that sounds like simple buzzing.
A resonator is required to create a meaningful honk and the structure above the vocal cords, including the throat, nose, and mouth, are part of the resonator system in geese as well as in humans. The buzzing sound created by the vocal cord vibration is changed by the shape of the resonator tract to produce the unique goose sound. What this means is that over the centuries the throat, nose, and mouth structure of the Trois Rivieres goose has changed compared to the same resonator structure in other Canadian geese.