Whistling Ways
There are several animals that vocalise using whistles.
Caterpillar Caterwaul
The walnut sphinx is a nocturnal moth that lives in North America.
It lays its eggs on walnut plants, hence the name. When the caterpillars hatch, they have to avoid becoming a tasty meal for birds. They have developed a special adaptation to scare predators away. The caterpillar compresses its body and squeezes air out of holes in its sides (called spiracles). The sound produced as a result of this, is a shrill whistle that startles the bird into leaving the caterpillar alone.
Pigsqueak
Guinea pigs, which are neither pigs nor from Guinea, use whistling to communicate a whole range of messages. They are a species of small South American rodents that are popular as pets. Their squeaky whistles tell their mother where they are if they become separated from her.
Pet guinea pigs literally whistle up a storm if they sense that they are going to be fed or hear the sounds of food being prepared! They also whistle if they want to be held by the owner and when they meet other guinea pigs.
Songs that Mice Sing
It has long been known to science that male mice use ultrasonic whistles to woo females and to warn rivals off their territory. An ultrasonic sound is one that is above the range of human hearing. However, scientists did not know how the mice produced these sounds.
Recent research has shown that the mice make these sounds not through the vocal cords but through the windpipe! They bounce a small jet of air off the inner wall of the larynx.
A video that was recorded at a very high speed showed that the vocal folds did not vibrate at all when the mice were whistling. The sound resembles the whine of a supersonic jet engine.